Eighth Grazing Lands Forum

An Explosion in Slow Motion: Noxious Weeds and Invasive Alien Plants on Grazing Lands

Washington, DC
December 2, 1993



What is the Grazing Lands Forum?
National Organizations


Executive Summary

Harmful Non-Indigenous Species in the United States

How do weeds affect us All?
What is a Weed?
Weeds Impacts; So What's the Big Deal?
Cropland and forage production impacts
Soil stability and water quality impacts
Wildlife forage and habitat impacts
Species diversity and impact on native plant habitat
Open space and wilderness area impacts
Plant succession dynamics impacts
Human health hazard impacts
Economic impacts
Summary and Recommendations

How do Weeds Spread?
How Do Weeds Get Established?
How Weeds Spread Once Established
Model of Weed Spread

Biological Pollution: A Historic Perspective of Nonindigenous Invasive Plants of Grazing Lands in the United States
The World Movement of Weeds: An Explosion in Slow Motion
Introduced Pasture and Range Weeds: A Sampler
Cheatgrass and Knapweeds Invade the Intermountain West
European Invaders at Home onthe Great Plains
Introduced Weeds of Eastern Pastures
Avenues of Entry for Alien Weeds: Regulatory Exclusion by USDA-APHIS

Federal Noxious Weed Legislation and National Strategy
Questions and Answers

Luncheon Address: Agricultural Chemicals, Weed Control, and National Legislation

Clean Water Act

Safe Drinking Water Act

FIFRA Reauthorization

Endangered Species Act & Associatted Regulations Impact on Pesticide Use

Working Tools: The Science and Technology of Weed Management
What's So Noxious About These Weeds?
Noxious Weed Management--An Integrated Approach
Long Term control of Noxious Weeds
Questions and Answers

An overview of the Western Weed Coordinating Committee

Weeds and Natural Areas Management
The Nature Conservancy's Mission
Overview of threats to Natural Areas and Biodiversity Posed by Weeds
Assessment of Weed Problems on Nature Conservancy Preserves
Specific Examples of Weed Problems on Nature Conservancy Preserves
Difficult and Unusual Challenges Posed by Weeds in Natural Areas
Prevention of New Problems
The Purple Loosestrife Biocontrol Program
Aspects to Consider in a Biocontrol Program

Range War on Weeds
The Irvine Flats Weed Project
Problems, Challenges, and Hindsight

Weed Control Programs in Wyoming
Weed Control Methods
Lessons Learned
Barriers to More Effective Management of Noxious Weeds
Questions and Answers
Concluding Comments

The Grasslands and Rangelands Coalition: Partners In Research and Education that Benefits Society

1993 GLF Officers

GLF VII Planning Committee

GLFV III Report writers

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The Grazing Lands Forum (GLF) is a coalition of twenty-nine organizations, Federal agencies, professional societies, and individuals that seeks to promote cooperation to improve stewardship on America's public and private grazing lands and associated water resources. Grazing lands include range, pasture, and forest lands grazed by livestock and wildlife. GLF seeks to improve cooperation by increasing knowledge, understanding, and awareness. The Forum process is the most important of GLF's activities.

The Forum process promotes an ongoing exchange of information and viewpoints about selected grazing issues. Each year the process culminates in a conference designed to foster open discussion among representatives of GLF's diverse membership. The results of these discussions are presented in in-depth reports.

The first Forum discussed water quality and grazing lands management. Multiple use values and management of grazing lands was the focus of the second Forum. The third Forum concentrated on grazing lands and the Conservation Reserve Program. Strategic planning for grazing land issues was reviewed at the fourth Forum. The fifth Forum focused on research and education needs for grazing lands. Environmental impacts on grazing lands from chemical use and pesticides and mining reclamation were the topics discussed at the sixth Forum. The seventh Forum discussed public policy for private grazing lands. This report summarizes discussion about noxious weeds and invasive alien plants on grazing lands.


  • American Forage & Grassland Council
  • American Society of Agronomy
  • American Society of Animal Science
  • Colorado State University
  • Crop Science Society of America
  • Environmental Protection Agency
  • Nat'l Assoc. of Conservation Districts
  • National Park Service
  • Society for Range Management
  • Soil and Water Conservation Society
  • Soil Science Society of America
  • USDA/Agricultural Research Service
  • USDA/Cooperative State Research Service
  • USDA/Economic Research Service
  • USDA/Extension Service
  • USDA/Forest Service
  • USDA/Soil Conservation Service
  • USDOI/Bureau of Indian Affairs
  • USDOI/Bureau of Land Management
  • Weed Science Society of America
  • Winrock International

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    An Explosion in Slow Motion: Noxious Weeds and Invasive Plants on Grazing Lands

    Welcome and Introduction to GLF Robert Lucey, GLF President, Cornell University

    Overview: Motivation and Science Janette Kaiser, Forest Service, USDA (moderator)

  • How Do Weeds Affect Us All? George Beck, Intermountain Weed Advisory Council (INWAC) and Western Weed Science Society, Colorado State University.
  • How Weeds Spread? John Randall, University of California-Davis and The Nature Conservancy

    Overview: Status and Policy Faith Campbell, Natural Resources Defense Council (moderator)

  • Biological Pollution: An Historical Perspective Randy Westbrooks, APHIS, USDA, North Carolina
  • Legislation and National Strategy Howard Singletary, North Carolina Department of Agriculture

    Luncheon--Agricultural Chemicals, Weed Control, and National Legislation Ralph Heimlich, GLF First Vice President, Economic Research Service, USDA (introduction)

  • Ray McAllister, National Agricultural Chemicals Association

    Working Tools:

    The Science and Technology of Weed Management Ken Krupa, Economic Research Service, USDA (moderator)

  • Scott Glenn, Professor of Weed Science, University of Maryland

    Panel Discussion--Working arrangements, approaches, and institutions that have achieved success in addressing and controlling noxious weed and invasive plant infestations on grazing lands through integrated approaches. Greg Hendricks, GLF Second Vice President, Soil Conservation Service, USDA (moderator)

  • Tim Butler, Oregon Department of Agriculture and Western Weed Coordinating Council
  • John Randall, The Nature Conservancy
  • Richard Malecki, U.S. National Biological Survey, Cornell University
  • Charles Jarecki, retired rancher, Montana
  • George Hittle, Wyoming Department of Agriculture and INWAC
  • Wrap Up Deen Boe, GLF Past President, Forest Service, USDA


    The Grasslands and Rangelands Coalition: Partners in Research and Education that Benefits Society David B. Hannaway, Oregon State University

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    An Explosion in Slow Motion: Noxious Weeds and Invasive Plants on Grazing Lands

    Concerns about the effects of invasive alien plants and noxious weeds are intensifying across a wide variety of interests. This is evident in the heightened level of state and federal agency action, legislative activity, and public pressure for more research and resources to effectively deal with the problem. Unmanaged weed populations are increasingly threatening the integrity of grazing lands, reducing land values, crowding out native plant habitat, changing wilderness areas, and reducing crop and forage production. Weeds know no ownership boundaries. To most effectively deal with the issue requires improving common understanding and a high degree of coordination and cooperation across land ownerships. GLF's program was designed to motivate interest in this problem and explore technical and institutional, and organizational solutions.

    How Do Weeds Affect Us All?--Dr. George Beck set the stage for the day, painting a broad picture in terms of the breadth and depth of this issue. Dr. Beck helped all participants become aware of the relevance weeds have in our everyday lives and the common ground we share regarding this issue. Participants gained an understanding of the threat weeds pose to the health and sustainability of both cropland and native ecosystems, including:

    How Weeds Spread--Dr. John Randall set the stage by describing the ecology and dynamics of plant communities; how communities are influenced by physical settings, climate and disturbance, including human uses. This presentation provided background for understanding unwanted plant introduction, invasion, and spread. Dr. Randall discussed differences in modes of infestation between disturbed and undisturbed ecosystems.

    Biological Pollution:

    An Historical Perspective--Dr. Randy Westbrooks gave the audience an understanding of the history of weed infestations in the U.S., conveying an historic perspective and the urgency of this "explosion in slow motion". Using a unique timeline perspective, Dr. Westbrooks helped participants become aware of pathways of introduction that have been used by various species. Participants gained an understanding of the consequences and opportunities regarding weed management.

    Legislation and National Strategy--Dr. Howard Singletary described existing Federal statutes, with emphasis on the Federal Noxious Weed Act [7 U.S.C. sections 2801-2813], the 1990 Food, Agriculture, Conservation, and Trade Act [FACTA; 7 U.S.C. section 2814(e)(7)], and Executive Order 11987. He described weaknesses in present programs, both in the statutes themselves, their execution, and funding. Problems encountered in applying the Federal Noxious Weed Act were discussed, including:

    The impact of current funding constraints and variations from year to year in implementing both the Federal Noxious Weed Act and the 1990 FACTA were explored, including lack of funding for research for adequate control methods. Dr. Singletary went on to describe bills to amend the Federal Noxious Weed Act, their status in Congress, and the Administration's position. This presentation provided information to participants regarding key decision-makers in Congress and the Administration, organizations that are actively working on the issue, and other paths to press for improvements.

    Luncheon Address:

    Agricultural Chemicals, Weed Control, and National Legislation--Dr. Ray McAllister shared his personal and professional perspectives on controlling noxious weeds, emphasizing the need for an integrated approach that uses all potential control methods within the context of a comprehensive regional program cutting across all private and governmental landownerships. Dr. McAllister went on to outline upcoming legislation that could affect the ability to use weed control chemicals on grazing lands, including reauthorization of the Clean Water and Safe Drinking Water Acts, the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and the Endangered Species Act.

    Working Tools:

    The Science and Technology of Weed Management-- Dr. Scott Glenn cataloged the types of tools available for weed management, including human hand weeding, animal grazing, mechanical methods, herbicides, natural biological control agents, and competitive plants. The pros and cons of each method, including costs, effectiveness, and environmental externalities, were discussed. The concepts of combining tools via integrated pest management (IPM) was thoroughly explored. Dr. Glenn briefly speculated on possible weed management tools of the near-term future, including plant sterility agents, species- specific pesticides, genetic alteration, and introduction of superior forage-producing strains of grazing plants. Developing information/infrastructure management tools, such as government interagency computer linkages and new check-point monitoring and detection devices at border and public land entrances to deter the introduction and spread of weeds, was raised. The types of academic research, funding levels, and possible sources of funding needed to implement a regional or national weed strategy were also addressed.

    Panel Discussion--A panel of five presenters from diverse regional and professional backgrounds offered their perspectives on working arrangements, approaches, and institutions that have achieved success in addressing and controlling noxious weed and invasive plant infestations on grazing lands through integrated approaches. The panel was comprised of Dr. Tim Butler, Dr. John Randall, Dr. Richard Malecki, Mr. Charles Jarecki, and Dr. George Hittle, moderated by Greg Hendricks. The speakers explained what motivated their organizations to address this issue, and described the organization's membership and operating procedures, including ties with other organizations and State and Federal agencies. Methods for noxious plant management used by the organization were outlined. Lessons learned from both successes achieved and failures of efforts attempted were drawn and barriers to effective action that need to be addressed were identified.

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    U.S. Congress, Office of Technology Assessment

    Phyllis N. Windle, Project Director for the U.S. Congress, Office of Technology Assessment study provided copies of a report brief and report summary of their new report, released in September, 1993. The OTA report documents 4,500 non-indigenous species (NIS) of foreign origin that have established free-living populations in the United States. At least 15 percent of the species identified trigger severe harm, and just 79 caused documented losses of $97 billion in control costs and losses of marketable goods.

    The OTA report stresses that prevention is the best strategy, but recognizes that "zero entry" is an unrealistic goal. Integrated control programs that use available chemical pesticides, biologically based measures, and genetic engineering remain a necessary part of NIS management.

    OTA criticizes Federal NIS policy as a "largely uncoordinated patchwork of laws, regulations, policies and programs," noting that at least 20 agencies are involved. Federal laws leave obvious and subtle gaps, which most States do not fill. OTA's report discusses needs for a more stringent national policy, better management of NIS fish, wildlife, and diseases, growing problems with NIS weeds, damage to natural areas, education, emergency action, funding, and gaps in legislation and regulation. Options for Congressional action are raised and their pros and cons discussed.

    Copies of the 391 page full report can be ordered from:

    Superintendent of Documents
    U.S. Government Printing Office
    S/N 052-003-01347-9
    P.O. Box 371954
    Pittsburgh, PA 15250-7954


    Publications Office of Technology Assessment
    U.S. Congress
    Washington, DC 20510-8025

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    K. George Beck
    Associate Professor of Weed Science
    Colorado State University
    Ft. Collins, Colorado

    What is a Weed?

    Many definitions of weeds have been created and historically, all definitions are centered around human activities. For example, the Weed Science Society of America defines a weed as 'a plant out of place'; Emerson in 1978, thought a weed was 'a plant whose virtues have yet to be discovered'; and Torrell defined a weed as 'a plant that interferes with the management objectives of a given area of land at a given point in time'. Anthropomorphic definitions of weeds are not inherently bad as humans evolved on earth and we use our natural resources and weeds are plants that inhibit our efficient use of natural resources. However, there are physiological and biological characteristics of the group of plants that we call weeds and careful examination of these factors will help one to better understand why weeds are problematic.

    Grime (1979) indicated that two basic external factors limit the amount of plant material found in any given environment; i.e., stress and disturbance. Stress includes environmental phenomena that reduce production such as limiting light intensity, water availability, nutrients, or optimal temperatures for growth. Disturbance is the partial to total disruption of plant biomass typically caused by fire, flooding, mowing, tillage, grazing, etc. If one considers the four extremes of stress and disturbance (e.g. high and low stress v. high and low disturbance) four outcomes for plant production ensue. Plant death occurs under high stress and high disturbance; the development of a population of stress tolerators occurs under high stress and low disturbance; a population of ruderal plants establishes under low stress and high disturbance; and competitor species dominate under low stress and low disturbance. Thus, in an environment limited by abiotic (physical factors such as climate, fire, flooding, etc.) and biotic (insect predators, plant pathogens, plant competition, etc.) factors, three evolutionary strategies for plants occur. Stress tolerators are those plants that reduce allocations to vegetative growth and reproduction to ensure a population of relatively mature individuals in a limiting environment; competitors maximize resource capture in productive but relatively undisturbed environments; and ruderals are plants with short life cycles and high seed output that are found in highly disturbed environments and occupy the early stages of secondary succession. Few plants fall into these extreme categories and most are combinations of the three evolutionary strategies. Many herbaceous annual, biennial, and perennial weeds can be characterized as competitive ruderals. These plants occupy sites where dominance by true competitors does not occur because of disturbance; occasional disturbance is expected but frequent or severe disturbance would favor ruderal plants.

    Environments favoring competitive ruderals would include meadows, seasonal grasslands, rangeland subject to seasonal disturbance (e.g. grazing), floodplains, eroded areas, lake and ditch margins, and arable lands. Thus, most weedy species occupy land in early to intermediate stages of secondary succession.

    Weed Impacts; So What's the Big Deal?

    Noxious weeds are typically plants of foreign origin and thus, did not evolve in North America. When these plants were inadvertently or otherwise imported into the United States, biotic factors, such as insect predators and plant pathogens, that evolved with the weed at its points of origin were not imported. Thus, in their 'new home', alien plant populations are regulated only by abiotic factors and this is not enough to keep their populations from increasing exponentially. For example, leafy spurge (Euphorbia esula) was introduced into the Red River Valley of North Dakota and Minnesota in the 1880's and this plant infests over 1 million acres in North Dakota alone today (Lacey et al., 1985). Spotted knapweed (Centaurea maculosa) was introduced into Gallatin County, Montana in the 1920's; by 1984 it had spread to all 56 Montana counties occupying over 2 million acres and today, over 4.7 million Montana acres are infested with this weed (Lacey et al., 1986). Yellow Starthistle (Centaurea solstitialis) was introduced into California in 1869 near Oakland; by 1965 over 1.9 million acres were infested with yellow starthistle and by 1985, infestations increased to 7.9 million acres (Thomsen et al., 1989). Purple loosestrife (Lythrum salicaria) infestations were studied from 1965 through 1978 at the Montezuma National Wildlife refuge in New York and biomass yield of purple loosestrife increased over this time from 0 percent of that harvested in 1965 to 90 percent in 1978 (Thompson et al., 1987). A recent study in Colorado assessing the encroachment of Dalmatian toadflax (Linaria genistifolia spp. dalmatica) on rangeland showed over 4 years that this weed increased 322 percent in cover, 1250 percent in shoot density per acre, while crested wheatgrass cover decreased 172 percent (K.G. Beck unpublished data, Colorado State University, Ft. Collins).

    We have significant alien plant infestations occupying rangeland and other natural resource areas in the United States and Canada today. Spotted knapweed occupies over 7.2 million acres in nine states and 2 Canadian provinces (Lacey, 1989). Diffuse knapweed (Centaurea diffusa) occupies over 3.2 million acres in 10 states and 2 Canadian provinces (Lacey, 1989). Russian knapweed (Acroptilon repens) occupies over 1.4 million acres in 9 states and 2 Canadian provinces (Lacey, 1989). Yellow starthistle occupies over 9.4 million acres in 10 states and 2 Canadian provinces (Lacey, 1989; Maddox and Mayfield, 1985). Leafy spurge infested over 2.5 million acres in 30 states in 479 U.S. counties as of 1979 (Lacey et al., 1985). Downy brome or cheatgrass (Bromus tectorum) infests over 101 million western U.S. acres and is listed as the dominant plant in the Intermountain West (Mack, 1981). A recent article in the Atlantic (Devine, 1993) laments the displacement of native bunchgrasses from downy brome encroachment in the west.

    Cropland and forage production impacts:

    In 1984, the average annual yield loss in 64 U.S. and 36 Canadian crops caused by weeds was $7.4 billion and $909 million, respectively (WSSA, 1984). Leafy spurge reduces the cattle carrying capacity of rangeland in North Dakota and Montana by 75 (Thompson et al., 1990) and 63 percent (Bucher, 1984), respectively. Forage losses in Montana from spotted knapweed infestations were valued at $4.5 million in 1984 and if spotted knapweed continues to spread in Montana at its current rate, at least 33 million acres will be infested by 2009 causing $155 million in annual forage losses (Bucher, 1984).

    Soil stability and water quality impacts:

    Soil and water losses have occurred and continue to occur on millions of acres where grass communities have been replaced by tap-rooted plants. Lacey et al (1989) measured surface water runoff and sediment yield (soil erosion) during a 30 minute simulated rainfall event on spotted knapweed dominated rangeland compared to native bunchgrass dominated sites. They found surface water runoff and soil erosion were 56 and 192 percent higher, respectively, on spotted knapweed dominated sites. This indicates that the presence of spotted knapweed on Montana rangeland is detrimental to soil and water resources. Soil on spotted knapweed dominated sites is eroded to a much higher degree compared to bunchgrass communities and water infiltration into the soil profile is less. This could and most likely has contributed to the displacement of native grasses because soil-water relationships have been altered due to the presence of spotted knapweed. This equates to greater sedimentation of streams, rivers, and lakes and will negatively impact fisheries.

    Wildlife forage and habitat impacts:

    The influence of noxious weeds on wildlife is not well understood or documented, but a few facts exist and the impact appears mostly to be detrimental. In western Montana, elk (Cervus canadensis) use of rangeland was estimated by counting pellet groups and there were 1575 pellet groups per acre in bunchgrass sites compared to 35 pellet groups per acre in spotted knapweed dominated sites (Hakim, 1975). Several studies indicated that spotted knapweed was not found in elk diets (Kufield, 1973;Lovaas, 1958;Mackie, 1970;Morris and Schwartz, 1957;Stevens, 1966). However, a recent study by the University of Montana indicates that elk grazed spotted knapweed in early winter, but in late winter, their diets were primarily grasses (Bedunah and Carpenter, 1990). Little to no spotted knapweed was found in their diets during February, March, or April even though the study area was dominated by spotted knapweed. Elk and deer eat spotted knapweed seedheads in winter and rosettes leaves in spring in the Bitteroot Valley of Montana; however, they may do so because of availability and not because of preference. In another study, spotted knapweed was common on mule deer (Odocoileus hemionus) range in Montana although the plant was not detected in their diets (Guenther, 1989). A game damage survey to alfalfa was conducted in 1986 in northeastern Wyoming, an area badly infested with leafy spurge; feces were examined histologically to determine which plant species were being consumed and they found no leafy spurge in deer diets. In North America, purple loosestrife encroaches upon and displaces desirable food plants and waterfowl nesting sites (Thompson, 1987). Cattails (Typha latifolia) were displaced by purple loosestrife competition, exacerbated by the selection pressure placed on cattails by muskrat feeding; and when these sites are dominated by purple loosestrife, muskrats move out. Purple loosestrife infestations make waterfowl broods more susceptible to predation because of the increased cover provided by tall purple loosestrife and the lack of a direct route from water to nesting sites. Certain waterfowl species, e.g. canvasback (Aythya valisineria) and black tern (Chlidonia niger) prefer to nest on relatively open sites such as abandoned muskrat nests built from cattails. With purple loosestrife encroachment and displacement of cattails and other riparian plants that provide these sites, suitable nesting sites are decreased.

    Noxious weeds are not entirely harmful to wildlife. A Montana Outdoors article indicates that weeds provide cover, habitat diversity, and a source of feed for many game and non-game birds (Wiegand, 1977). It is worth noting however, that the tendency of noxious weeds to form monocultures would decrease habitat biodiversity once this occurred. In British Columbia, knapweed rosettes were found to be important components in the diets of deer and elk in early spring (Miller, 1990). A recent study in Colorado and Wyoming indicates that three times as many small mammals frequented Russian knapweed infested rangeland compared to adjacent non-infested sites (R. Olson, University of Wyoming, personal communication). Adaptation occurs as evidenced by one small mammal, a harvester mouse, using the Russian knapweed infested sites and this mammal may serve to spread the weed as they cache seeds.

    Species diversity and impact on native plant habitat:

    Many noxious weeds dominate plant communities and tend to form monocultures and this obviously negatively impacts native biological diversity in the United States. Downy brome communities in the Intermountain West are poor in species composition compared to steady state (climax) sagebrush/bluebunch wheatgrass (Artemisia tridentata/Agropyron spicatum) communities (Rickard and Cline, 1980). Displacement of native plants by spotted knapweed was assessed in Glacier National Park in Montana from 1984 through 1987 (Tyser and Key, 1988). These sites were originally classified as Idaho fescue (Festuca idahoensis) and rough fescue (Festuca scrabella) dominated plant communities. Spotted knapweed impacts to native plant communities were assessed on perimeter, fringe, and core weed infestations. These researchers found the species richness gradient to be inversely proportional to spotted knapweed stem density; i.e., the more spotted knapweed stems per unit area, the fewer number of plant species present. Species richness declined as one moved along the transects from the perimeter to the core infestations (species richness ranked perimeter>fringe>core). Spotted knapweed stem density was the only variable associated with the species richness effect. These researchers further classified plants in the fringe infestations as common, uncommon, or rare. Of the 38 species evaluated in 1984, 31 were reclassified at the same frequency in 1987. However, seven of the original species were reclassified into lower frequency categories in 1987 (Galium boreale, Hieracium umbellatum, Potentilla arguta, Potentilla gracilis, Silene parryi, Stipa occidentalis, and Tragopogon dubuis - note the last species was an uncommon, weedy, alien). Six species were classified as common in 1984 and five of these remained in this category in 1987. Of the 21 uncommon species in 1984, only 16 remained as such in 1987 with six being reclassified as rare in 1987. Additionally, five rare and two uncommon species found in 1984 were not present in 1987 (Agropyron spciatum, rare; Castilleja cusickii, rare; Collomia linearis, rare; Heuchera cylindrica, rare; Lithospermum ruderale, rare; Stipa occidentialis, uncommon; and Tragopogon dubius, uncommon and alien). Additionally, native plants are being displaced in Utah by dyer's woad (Isatis tinctoria) (West and Farah, 1989) and in California by yellow starthistle (Maddox and Mayfield, 1985).

    The impact of noxious, alien weeds on rangelands and other natural resource areas are not well understood nor documented. The weed science community has spent a lot of time learning how to control weeds v. understanding their biology, ecology, and impacts. This trend is changing and with increased opportunities for grant supported research in these areas, a greater understanding will occur. Nonetheless, aggressive, alien plants will continue to displace native plants in their habitats primarily due to a lack of biotic pressure placed on alien plant populations (no biological control - in the absence of other control measures). This is further exacerbated by the rapid rate of spread by alien weedy species and the difficulty associated with effectively managing all infestations in any given year because infestations are very large and scattered across landscapes.

    Open space and wilderness area impacts:

    Open spaces are prime areas for alien plant invasion. Open spaces associated with cities and counties typically are former grazingland or abandoned farmland. Thus, open spaces have been disturbed to one degree or another and subject to secondary succession - weed invasion. Open space infestations serve as sources for new infestations on adjacent land and land farther away. For example, open spaces along Colorado's Front Range communities are dominated by alien plants. Boulder City and County Open Space ground is infested with diffuse knapweed, spotted knapweed, Russian knapweed, Canada thistle, field bindweed (Convolvulus arvensis), Dalmatian toadflax, downy brome, and musk thistle; Cherry Creek State Park in the greater Denver Metropolitan area is badly infested with diffuse knapweed, leafy spurge, musk thistle, Canada thistle, and field bindweed and these infestations are spreading along Cherry Creek into the South Platte River which flows into Nebraska; Fort Collins open space areas are infested with leafy spurge, Canada thistle, musk thistle, diffuse knapweed, field bindweed, downy brome, puncturevine (Tribulus terrestris), and these plants are particularly troublesome along the Poudre River corridor which flows into the South Platte, thus, these infestations are spreading into Weld, Morgan, Logan, and Sedgwick Counties in Colorado and into Nebraska.

    Backpackers and horsepackers inadvertently spread alien plants into wilderness areas. Seeds on clothing, packs, animals, or in contaminated hay brought into wilderness, or excreted in feces by domestic animals, are sources for new infestations. For example, the Rawah Wilderness in Colorado is infested with musk thistle and it is spreading rapidly because of the plant's biology and lack of weed management input. Canada thistle infestations in Rocky Mountain National Park have been the object of interest for the past 3 years. Infestations started along horse and foot trails and have spread from there into native plant communities (T. Mclendon, Colorado State University, personal communication). Dry, upslope conditions, thick canopies from woody species, and well-established grass meadows (especially wet meadows) inhibited Canada thistle invasions. Canada thistle populations appear to thin with time and become part of the plant community in many instances, in the absence of further disturbance. However, even minor disturbance from elk grazing promoted Canada thistle invasion and establishment into grasslands.

    Plant succession dynamics impacts:

    Weeds (alien or native) would be classified under 'natural systems' as pioneers, invaders, or increasers. Disturbance creates an opportunity for secondary succession to occur and weeds will occupy the site initially. Depending upon the degree of disturbance, annual weeds will occupy the site first and be replaced with time by herbaceous perennial weeds. In abandoned farmland, the systematic replacement of early and intermediate plant seral stages occurs over time until a steady state community develops - not necessarily identical to the pristine community before farming was practiced; this is termed old field succession. The time associated with these changes varies with climate, soil nutrient status, weed species present, availability of native plant propagules and species composition thereof.

    The impact of noxious weeds on plant succession dynamics of grazinglands is not well understood. Patches of noxious weeds, such as leafy spurge or Russian knapweed, survive for extended periods. For example, a Russian knapweed stand in Saskatchewan has survived over 75 years (Watson, 1980). Presumably because these plants are competitive ruderals, they should be replaced over time by those plants that occupy later stages of succession. However, the time frame is unknown and apparently may be long relative to a human perspective. Alien plant persistence is further exacerbated by the lack of biotic pressure on these plant communities in North America. Furthermore, if alien plant species eventually yield to later successional species (presumably desirable native species), the time that they occupy an area may render that area less useful to useless for productive purposes (e.g., interfere with any agricultural operation, forestry, wildlife foraging, or recreational use).

    Human health hazard impacts:

    Virtually any pollen producing plant has the potential of affecting hay fever sufferers. In Colorado for example, ragweed (Ambrosia spp.) - native plants - cause significant problems for those with respiratory allergies. However, kochia (Kochia scoparia) and Russian thistle (Salsola iberica and S. collina) cause equivalent problems for those with hay fever. Latex in leafy spurge can cause irritation to broken skin, eyes, or simply may cause a dermal rash. Several volunteers in Boulder County, Colorado that hand-pulled diffuse and spotted knapweeds contracted a dermal rash from these weeds. This is another area where weed impacts are not well understood or documented.

    Economic impacts:

    The common denominator for human endeavors is our means of barter - i.e., money. Economic impacts caused by alien weeds on grazinglands has not been thoroughly documented but some information is available. Scotch thistle (Onopordum acanthium) infestations in northern California cause annual losses to ranchers equating to $60.50/acre on wet meadows, $39.50/A on wheatgrass stands, and $20.16/A on cheatgrass rangelands (Hooper et al., 1970).

    The most thorough study on weed impacts on grazinglands was conducted by the Agricultural Economists at North Dakota State University. They determined the direct impacts caused by leafy spurge on North Dakota grazinglands and wildlands then used an input-output model to determine secondary effects (Leistritz et al., 1993). Direct annual losses from leafy spurge included $8.7 million in reduced personal incomes for North Dakota cattle producers and an additional $14.4 million reduction in rancher spending (i.e. lost cash outlays) due to reduced livestock production. In 1990, leafy spurge infestations reduced cattle carrying capacity by approximately 580,000 animal unit months (AUMs) or enough to support 63,100 cows for 7.5 months. Total annual direct grazingland losses were valued at $23.1 million. Indirect grazingland losses caused by leafy spurge infestations totalled $53.2 million and these losses were incurred by businesses outside of livestock production but caused by reduced income and expenditures from the cattle industry. Annual direct losses due to leafy spurge on North Dakota wildland totalled $2.9 million because of reduced wildlife associated recreation. An additional $0.7 million direct wildland loss was estimated in reduced soil and water conservation caused by leafy spurge infestations. Indirect annual losses to North Dakota wildland from leafy spurge were caused by reduced expenditures within their economy from direct losses and totalled $7.4 million. Therefore, total direct and indirect annual losses to North Dakota grazingland and wildland caused by leafy spurge were valued at $87.3 million! The majority of indirect losses in grazingland and wildland was in the household sector and totalled $28.7 million annually and equated to approximately $26.00/A infested with leafy spurge. Additionally, current infestations cause a reduction in over 1,000 jobs per year in North Dakota.

    Summary and Recommendations

    The negative impacts caused by noxious weeds are very real and clear where recognized. Unknown impacts exist and must be determined so we can better decide where to focus our attention. Grazingland, wildland, farmland, native habitat, open spaces, and urban landscapes all are negatively impacted by the presence of alien plant species. The domino effect from the economic impacts caused by the presence of alien plant species indicates that our daily lives indeed are negatively impacted by this 'mundane' group of plants.

    We can choose to act and invoke integrated weed management strategies to reduce infestations and their impacts. Or, we can choose not to act and allow alien plants to continue to displace desirable plants thus, destroying the native biological diversity of our country and the value of our grazinglands and wildlands and further negatively impact our nation's economy. It seems very unnecessary and illogical for this latter scenario to occur!


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    John Randall
    The Nature Conservancy
    Galt, California
    Section of Plant Biology
    University of California, Davis

    Roughly 5 million acres of lands that BLM manages were infested with weeds in 1985. In 1991, some 16-20 million acres were infested, a lot more in just six years. Part of that increase may be better awareness of weeds, but clearly, there has been a tremendous increase in infestation. This is a graph of the increase in the acreage covered by yellow starthistle in the period from 1958 to 1985, some of the same information presented by Dr. Beck. We go from roughly 1 million acres in the state of California to 8 million acres in the span of not quite 20 years with just one species, an incredible increase in a short time period. Clearly, we are facing worthy adversaries. How do they spread so quickly? Why are we so powerless, or seemingly powerless, to defend against their rapid spread?

    What I want to do in this paper is give a brief explanation of how some of these species got to be where they are today. As Dr. Beck mentioned, most of the plants that we call weeds are not native to North America. A few species are native to a part of North America, and are not considered weeds where they originated, but have been introduced to another part of the continent where they do behave as weeds. I'll talk about how these plants got where they are in the first place, and then move on to discuss how they spread after they have been introduced and established a toehold.

    With a lot of these species, what we get is not simply a plant that takes its place in the system, but one that dominates the plant community. My perspective is different than that of other presenters because many of the examples I use are from preserves, national parks, and other natural areas where I work. However, the same types of problems affect rangelands and other agricultural lands. We have a great deal in common. In central California, and in much of the country, we have ecosystems that are now so altered because of the weeds that we don't really know what they might have been like before European settlement. For example, in one of the few Southern California grasslands where there is substantial cover of the native bunch grasses, we don't have a good idea of what the community was like only 140 years ago. In ecological time, that is not very long ago, yet we're not even sure what the dominant species was then, because the non-native species have come in and so thoroughly taken over. We don't have a good idea of what the various components of the natural system were and how they related to one another. That's how complete the changes have been in this system and the same is true for other portions of the country.

    How Do Weeds Get Established?

    I use the modern example of the airplane as a mechanism for introduction of alien species because these new plant species are still being brought in all the time, on purpose and unintentionally. But let's move back and talk about how plants that we consider weeds have gotten here in the past. From the time of Columbus' discovery of the Americas, there has been a tremendous increase in non-native species on the two continents. California's flora is now 17.5 percent non-native. New York State's flora is 35 percent non-native. Hawaii's flora is 47 percent non-native, almost half of the plants that grow there, without any help from people (that is, they seed and reproduce on their own) are non-native plants. It's clear that there has been a tremendous transfer of plants from one place to another. How did it start? How does it continue?

    The unintentional introductions were many and varied. We used to use solid ballast in our ships, usually consisting of soil placed in the hold when ships that had transported bulk commodities abroad returned to the Americas empty or only partly laden. This ballast was dumped at the landing site and often contained seeds of non-native plant species. This probably didn't happen at just one time, or just one place. San Francisco, New Orleans, Boston, ports up and down the coasts on both sides of the continent received introductions of plants in this way. Today, we don't use solid ballast as much, we use liquid ballast (water). That's probably how we got the zebra mussel and other non-native aquatic organisms.

    There were also tremendous numbers of introductions in agricultural commodities themselves. We imported a lot of seed and root stock from other parts of the world. Many times, in the soil, or in the hay, or in the seed itself, there were contaminants. We imported many animals. In the coats of the animals or inside the animal waste, there were seeds of non-native plants. They may have been shoveled off in the manure and thus provided a nurturing growing medium for species on arrival in a new continent. Hundreds of species got here in these unintentional ways.

    There were a lot of intentional introductions as well. As Dr. Beck indicated, many species were introduced for ornamental purposes. Many species that we consider weeds, some of the knapweeds for example, are attractive, at least singly. Spotted knapweed is a beautiful plant, with a beautiful purple flower. Purple loosestrife is quite lovely. It's planted in planters around American University here in Washington, DC, and until very recently, it was in the planters in front of the U.S. Fish and Wildlife Service building. It's a pretty plant and is going to be distributed. It was brought to the United States, on several occaisions, as an ornamental plant.

    Other species were brought here for medicinal use. Foxglove was introduced, at least in parts of the country, as a medicinal plant. There are a lot of different uses for different plants. Johnsongrass was brought in as a forage plant, but later became problematic. It escaped it's master. Many of these species followed the same path. We brought them here for one purpose or another, and then they reproduced themselves. They did what was natural for them and they had few or no biotic restraints. The climate was appropriate, and they took off.

    Most of the plants that we have as weeds were introduced repeatedly, often via several different pathways. They weren't generally introduced just to one spot, from there to spread to other locations. Seed stocks were brought into port cities and distributed, and then a subsequent introduction at a number of places.

    Leafy spurge, which is a tremendous problem in the Northern Plains, was introduced in 1827 in Massachusetts, and it's still there. I saw lots of it in northeastern Massachusetts this spring. It was probably introduced again some time in the late 1800's, to the upper Midwest (Minnesota and the Dakotas) when people were settling from Germany and further east in Europe and in Russia. It was probably also introduced along with another species called Euphorbia waldensenia. Apparently, what we have as a troublesome species in the United States is, in fact, a hybrid of those two species. The two species didn't hybridize in Europe, but they did here and now we have a plant that is slightly different from either of its forebears and is an extremely worthy adversary. So we have all sorts of new situations here on this continent.

    Some of the plants that have been transfered from other parts of the continent are plants like Spartina alterniflora, the marsh cordgrass that grows so nicely in Eastern and Gulf coast saltmarshes. It was introduced to West coast estuaries, probably as packing material around oysters that were seeded there, and now it's a tremendous problem in certain estuaries, such as Willapa Bay, Washington. Another species, black locust Robinia pseudoacacia, has been distributed as an ornamental. Thus, the same pathways of introduction that were used between other continents and the Americas have been used, to a lesser degree, to spread plants from one part of North America to another.

    In Oregon and Washington, a species called Hemizonia pungens, or spikeweed, is now listed as a county noxious weed in several counties along the Columbia River. It is a native plant where I work in California, but was carried by human action over several mountain ranges to northern Oregon, probably in grain or other agricultural commodities. It's insect enemies probably do not follow it and it is doing very well; too well for agricultural interests and too well for The Nature Conservancy. It's pushing out some of the native plants we're concerned about in at least one preserve in this area.

    How Weeds Spread Once Established

    This is mostly common sense. Plants are introduced all around the country because we travel so much and are so mobile. I was reading an historical analysis of human civilization. The author, William McNeill's idea was that you could evaluate the advancement of civilization by the advancement of the technology for travel. It's quite clear that in the last millenium, we've increased our ability to travel greatly. About 500 years ago, we gained the ability to cross the Atlantic reliably. Once trans-Atlantic travel became commonplace, many species were introduced to this continent by ship. Now we travel all over the world and ship commodities by plane and train.

    Transport is extremely rapid, even plants that have short-lived seeds can be carried thousands of miles and be dropped off on purpose or accidently with plenty of time to germinate and become established. Once a plant like purple loosestrife is in the country, it sells very well as an ornamental. It won't be kept secret. In fact, many nurseries will want to sell the plant across the country. Most of the plants that we're talking about don't need much help to spread. Most weeds, are quite well adapted to spread on their own. Think of dandelions with their thistledown seeds. They diffuse out, at least on smaller scales, quite well.

    I did my dissertation work in Yosemite Valley on bull thistle (Cirsium vulgase). One of the studies I conducted involved simply following newly released seed. It was a lot of fun, but we looked pretty loony out there following seeds around. What we would do is wait for a seed to leave the seed head, and just track it down. Most dropped within 2 meters of the plant. But, over 5 percent of them went beyond my 50 meter tape, and a lot of them went completely out of sight. The thistles in Yosemite produced hundreds of thousands of seeds all together and five percent of hundreds of thousands of seeds is still a lot of seeds. When there is a burn in Yosemite National Park, usually bull thistle pops up. It can be miles from the nearest known plant, but apparently the seed has gotten there. The seeds don't usually last that long in the soil, so it's likely that those which germinate arrived just last year.

    Many of the plants that we're talking about spread very well in the same types of ways. Some are spread by wind, others are spread by animals. On the preserve where I work, we have wild edible figs. They produce fruits which birds like to eat. The birds then excrete the seeds, and a new fig tree grows up in another part of the preserve. So, we're dealing with plants that are well able to spread to new areas. And, as Dr. Beck pointed out, many of these plant species are adapted for disturbed areas: areas where the soil has been turned over or where the vegetative cover has been broken in some way. Some can move into areas with extremely small disturbances (a molehill, anthill, or even a deer trail), but others can move into areas where there is no apparent disturbance.

    I want to turn to the patterns of spread. An example from one of TNC's preserves is fairly typical of the type of patterns seen when weeds spread. The Pine Butte preserve in Montana covers about 18,000 acres. Leafy spurge infests roughly 1,000 acres here. The larger areas of the infestation, what we call the core areas, are probably the areas where spurge was first established on the preserve. The plant is known to have moved into the county in the 1930's, but it is still spreading quite rapidly on the preserve. We also see several smaller, outlying infestations. These have been called "nascent focii" or "outliers"; you can think of them as spot fires, like in a forest fire. These small infestations expand once established, and then coalesce to form bigger and bigger areas, which in turn throw off new outliers, repeating the process. When you get this pattern of spread, the overall front of spread is extremely rapid, at least in terms of ecological time. What we see here is a preserve that now has 1,000 acres infested and which probably had less than 400 acres infested just 10 years ago.

    On a map of the Western United States, maps of the Bromus tectorum infestation at different times since 1889 have the same pattern of core areas and outliers, but on a much larger scale. At first, it infested a small area, but by the 1930's, much of the intermountain West was infested.

    Model of Weed Spread

    The last thing I wanted to discuss is a model of infestation. These models, developed by Rob Hengueld, depict t how diffusion of this kind may work. One way to depict spread is to draw a series of cells packed together and to assume that, from an initial establishment site in one cell, spread can occur to adjacent cells only. That's the simplest form of diffusion model. Another model using the same set of cells but allowing not only spread to adjacent areas, but also longer distance spread from one cell to another not immediately adjacent to it and with further diffusion from there. In this second scenario, a cluster of cell may fill after just 3 steps, while it would require 5 step to fill with simple diffusion alone (the first model). This second type of hierarchical diffusion results in much quicker spread and the infestation of much larger area than simple diffusion would. What we are seeing on the land with most of the weeds that we deal with, is more often the hierarchical model, due to their natural abilities and to our transport of plants from one place to another.

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    Randy G. Westbrooks
    Station Leader
    Whiteville Noxious Weed Station
    Whiteville, North Carolina


    In the past, a great deal of concern has been voiced about nonindigenous invasive plants of agricultural lands (Rodgers, 1974; Westbrooks, 1981, 1991). This is because agriculture is a business based on profits, and such species cause major losses in farm profits. However, in recent years, this concern has been expanded to include invasive plants in natural areas (Harty, 1986, Mooney and Drake, 1986), which I call botanical invaders. A term that aptly describes both agricultural weeds and botanical invaders is biological pollution. Essentially, biological pollutants are nonindigenous invasive organisms that threaten the biodiversity of natural ecosystems or the production capacity of agricultural lands (McKnight, 1993; Westbrooks, 1991, 1992). This article will explore the issue of introduced plants that threaten grazing lands in the United States.

    The World Movement of Weeds: An Explosion in Slow Motion

    Since the breakup of the super continent Pangaea about 180 million years ago, there has been little chance for intermixing of taxa between the world's continents. Thus, without opportunities for genetic exchange, new species evolved on each continent, in response to local environmental pressures. Consequently, we now find quite distinct groups of plants and animals in six biogeographical realms that correspond closely to the continents (Elton, 1958; Walter, 1985).

    As a hunter-gatherer, early man probably had no more effect on the distribution of plants and animals than any of the fur-bearing animals. However, with the development of agriculture, man began to move plants around both intentionally and by accident. Opportunities for movement were further enhanced with the advent of oceanic travel by sailing ships. Today, man has created artificial bridges of international commerce between distant lands that are allowing the movement of plants and animals on an unprecedented scale. This is a major ecological event, a silent explosion in slow motion, with no historical counterpart.

    The main problem with introduced species is that they usually come without co-evolved predators and parasites which keep them under control (Elton, 1958). Without this pressure, introduced species often outcompete or even displace native species. In agricultural settings, they complicate pest management practices and reduce crop production. Two classic examples of this were the introduction of the rabbit (Oryctolagus cuniculus) and the common prickly pear cactus (Opuntia stricta (Haw.) Haw.) into Australia by European colonists. Both were well meaning introductions that turned out to be disastrous for the Australian countryside.

    Based on an extensive review of the problem, The U.S. Office of Technology Assessment concluded that the total number of harmful nonindigenous introduced species and their cumulative impacts are creating a growing economic and environmental burden for the country. According to the report, documented losses of $97 billion were caused by 79 nonindigenous invasive species in the United States between 1909-1991 (OTA, 1993). Clearly, nonindigenous invasive plants are a real cause for concern.

    Introduced Pasture and Range Weeds: A Sampler

    Since the onset of European colonization, over 4,500 introduced species have established free living populations in the United States. In some cases, introduced plants are beneficial, such as soybeans (Glycine max (L.) Merr.), and wheat (Triticum spp.). However, approximately 625 introduced species (15 percent of the total) cause severe harm (OTA, 1993). Introduced weeds of grazing lands are a good case in point. Over the past 150 years, the displacement of native plants by introduced weeds has reduced the biodiversity and production capability of grazing lands in the United States. A few of the more dramatic examples are included here for illustration.

    Cheatgrass and Knapweeds Invade the Intermountain West:

    Prior to the mid-1800s, the grasslands of the Intermountain West (The region between the Rocky Mountains and the Cascade/Sierra Nevada Ranges) were dominated by perennial bunchgrasses such as bluebunch wheatgrass (Agropyron spicatum (Pursh) Scribner and Smith), Idaho fescue (Festuca idahoensis Elmer) and a number of broadleaf forbs. Due to the arid climate in the region, these plants evolved to germinate and grow in the spring and early summer when soil moisture from winter snowfall is plentiful. They survive hot summers in a state of dormancy and as seeds. In between the plants, lichens and other cryptogams provided a thick ground cover that retarded evaporation of moisture from the soil (Mack, 1981).

    When cattle were introduced onto the Intermountain rangelands in the 1850s, they overgrazed and trampled the bunchgrasses, and broke up the cryptogam layer. This disturbance increased evaporation of soil moisture and significantly reduced the bunchgrass populations which had evolved in the absence of large hooved ungulates (Mack 1981). Subsequently, this disturbance made the rangeland very susceptible to invasion by alien plant species that grow in the fall and winter. Homesteading and cultivation of winter wheat beginning with the railroad boom of the 1880s, disturbed the land even further, and accelerated the introduction and establishment of alien invasive plants. One of the first alien weeds that began the replace the steppe vegetation of the Intermountain West was downy brome (Mack, 1984).

    Downy brome (Bromus tectorum L.) is an annual or winter annual grass from the Mediterranean region that was introduced to the United States in packing materials and as a contaminant of crop seeds (Mack, 1984; Whitson et al., 1991). It occurs throughout the United States along roadsides, in waste areas, overgrazed pastures, and rangelands, and in cultivated crops. Downy brome was first collected in the Intermountain West around 1890. However, by the 1930s, county agents were referring to "cheatgrass lands", often whole counties, in which the alien had become the dominant grass (Mack, 1984). Downy brome is now estimated to infest over 41 million hectares in the western states (Mack, 1981).

    Diffuse knapweed (Centaurea diffusa Lam.), Russian knapweed (Acroptilon repens (L.) DC), and yellow starthistle (Centaurea solstitialis L.), are weeds of western grazing lands that were introduced into the United States from Eurasia over the last 100 years as contaminants of crop seeds. Diffuse knapweed infests roadsides, waste areas and dry rangelands. It is a highly competitive plant that crowds out many desirable forage species. It is now estimated to infest over 1.3 million ha in 9 states and 2 Canadian provinces (Lacey and Olson, 1991; Whitson et al, 1991). Russian knapweed forms colonies in cultivated fields, orchards, pastures, and roadsides (Whitson et al., 1991). Originally, it became established in wet alkaline spots of drylands, of the Intermountain West and on the Great Plains. It is a new problem on winter wheatlands of the Palouse Prairie (Richard Old, Washington State Univ., pers. comm., Nov. 1993). It now infests over 568,000 ha in nine states and 2 Canadian provinces (Lacey and Olson, 1991). Yellow starthistle is a very invasive plant with spiny flower heads. It now grows on millions of acres of rangeland as well as roadsides and waste areas. It is now estimated to infest over 3.8 million ha in 10 states and 2 Canadian provinces (Lacey and Olson 1991). Chewing disease (loss of jaw muscle control) caused by chemical constituents in the plant, results when horses are forced to eat it. Continued feeding can result in death by thirst and/or starvation.

    European Invaders at Home on the Great Plains:

    Unlike the steppe vegetation of the Intermountain West that grows in the spring and early summer, the grasslands of the Great Plains were originally dominated by summer growing sod-forming grasses with underground rhizomes. Some of these taxa included big bluestem (Andropogon gerardii Vitman var. gerardii), grama grass (Bouteloua spp.), wheatgrass (Agropyron spp.), and buffalo grass (Buchloe spp.). As sod-formers, they were pre-adapted to grazing and trampling by hooved ungulates such as bison (Bison bison) and pronghorn antelope (Antilocapra americana). However, with the onset of European colonization in the 1800s, the Great Plains was invaded by perennial dicots such as leafy spurge and Canada thistle. A few examples of weeds that have become major problems on the Great Plains over the past 100 years include:

    Spotted Knapweed (Centaurea maculosa Lam.) is a biennial or short-lived perennial herb with a stout taproot, up to 1 m tall. It was introduced into the Midwest from Eurasia as a contaminant of alfalfa and clover. It is now ranked as the number one weed problem on rangelands in western Montana (Whitson et al., 1991). As weeds go, spotted knapweed is very aggressive, and can infest large areas quickly. In addition, it provides very little forage for big game or livestock. It now occurs about 3 million ha in nine states and two Canadian provinces (Lacey and Olson, 1991).

    Leafy Spurge (Euphorbia esula L.) is a perennial herb, up to 1 m tall that was introduced into the United States in the 1820s as a contaminant of crop seeds. It now occurs on the Great Plains, on mesic pastures of the intermountain West, and in coastal areas west of the Cascade Mountains. It now infests over 729,000 ha in Montana and North Dakota alone (Lacey and Olson, 1991). It causes severe irritation of the mouth and digestive tract in cattle which may result in death. Direct livestock production losses along with indirect economic effects to leafy spurge was about $110 million in 1990 (Bangsund and Leistritz, 1991). The extensive root system which provides large nutrient reserves make it very difficult to control (Whitson et al., 1991).

    Musk Thistle (Carduus nutans L.) is a biennial or winter annual herb, which grows up to 3 m tall. It was introduced from southern Europe and western Asia in the early 1900s and is now widespread throughout the U.S. and Canada. It invades pastures, range and forest lands, roadsides, waste areas, ditch banks, stream banks and grain fields. It can also be a serious problem in alfalfa and grass hay fields (Dewey, 1991). It occurs on the Great Plains and also in mesic pastures of the Intermountain West (Whitson et al., 1991). It has been reported in 42 states and is considered a noxious weed in at least 16 states (Dewey, 1991).

    Canada thistle (Cirsium arvense (L.) Scop.) is a colony forming perennial herb with deep and extensive horizontal roots, that grows up to 2 m tall. It is native to southeastern Eurasia, and was introduced into Canada as a contaminant of crop seeds in the late 18th century. Unlike other thistles, female and male flowers are produced on separate plants. Thus, a colony of male plants can maintain itself by asexual reproduction. Breaking up the roots by plowing only serves to increase the number of plants (Whitson et al., 1991). It occurs throughout most of the United States north of the 35th latitude. However, it has been declared a noxious weed in at least 33 states (Dewey, 1991).

    Introduced Weeds of Eastern Pastures:

    Grazing lands in much of the eastern United States were originally converted from deciduous and evergreen forests that stretched from Maine to Illinois and southward. As disturbed sites, such pastures are quite susceptible to invasion by alien taxa. However, modern agronomic practices permit the growth of introduced grass as a crop and allow it to outcompete many would be weeds. Two introduced pasture grasses that have been used successfully in the eastern United States include bahiagrass (Paspalum notatum Fluegge), and tall fescue (Festuca arundinacea Schreb.). A few examples of introduced plants that have become serious problems in improved pastures of the Eastern United States include:

    Multiflora rose (Rosa multiflora Thunb.) is a thorny perennial shrub that is native to Japan, Korea, and eastern China. It was first introduced into the United States in the early 1800s for breeding roses, root stock, and as a garden plant. In the 1930s and 40s, it was promoted by the USDA, Soil Conservation Service for use as an erosion control, a wildlife food, and as a living fence. Over the years, millions of plants were given to farmers and conservation groups throughout the country (Amrine and Stasny, 1993). As a consequence, it now occurs throughout the United States to some degree (Anonymous, 1970). In West Virginia, over 14 million seedlings were planted from the 1940s to the 1960s (Dugan 1960). The weedy characteristics of the plant were first noted in the 1940s and 1950s. It is now a serious weed of marginal land such as hilly pastures, roadsides, fence rows, and right-of-ways. Multiflora rose is another example of a well intended introduction that has gone awry.

    Bull thistle (Cirsium vulgare (Savi) Ten.) is a bushy, biennial plant, with spine-tipped leaves and a taproot, that grows up to 1 m tall. It is native to Europe and now occurs throughout the 48 lower states. It is listed as a noxious weed in IA, MN, PA, and WA. It occurs in meadows, pastures and along roadsides (Dewey, 1991).

    Serrated Tussock. One Federal Noxious Weed that is of deep concern to American weed scientists is serrated tussock (Nassella trichotoma (Nees) Hack.), a tussock forming grass weed from South America. Currently, serrated tussock is rated as the #1 noxious weed in New South Wales, Australia, where it occurs on over 400,000 ha of pastures and causes over $11 million in losses per year to wool production (Westbrooks, 1991). Serrated tussock was introduced into the United States in 1988 as a contaminant of nine shipments of tall fescue seeds from Argentina through the ports of Jacksonville, Houston, and Portland. After documenting the contaminants, Plant Protection and Quarantine (PPQ) released the shipments to the importers due to a clause in Section 12 of the Federal Noxious Weed Act that prohibits regulation of seed shipments under the Act. By the time the law was re-examined and a stop sale order issued by PPQ in early 1989, over 25,000 kg of the contaminated seeds had been sold in 49 counties in North Carolina, South Carolina, Kentucky, Illinois, and Missouri. Surveys are being conducted in affected states to detect incipient infestations (Westbrooks and Cross, 1993).

    Tropical Soda Apple. The newest threat to America's grazing lands is tropical soda apple (Solanum viarum Dunal), a newly introduced nightshade from Brazil with stout rootstocks and sharp prickles on the leaves and stems. This species was first observed in Glades County, Florida, in 1987 (Mullahey et al., 1993). It is now estimated to occur on at least 150,000 ha (370,000 acres) of improved pastures and 12,000 ha (30,000 acres) of pinelands in 26 counties of the state. Total losses due to the plant are estimated to already be over $28 million per year (J. Mullahey, Univ. Fl., pers. comm., Oct. 1993). Currently, the USDA Agricultural Research Service is conducting a study to determine the potential ecological range of the Plant in the United States. This study will reveal which areas of the U.S. are most vulnerable to invasion by the plant. It will also help determine the need for regulating the movement of livestock (which eat the fruits), hay, and sod from infested pastures and rangelands to prevent the movement of the plant to other states.

    Avenues of Entry for Alien Weeds: Regulatory Exclusion by USDA-APHIS

    While weed seeds may hitch hike on almost any commodity, means of conveyance, or in soil, most weed seeds are found associated with commodities that grow in their same environment. Potential vectors of pasture and rangeland weeds include crop and grass seeds, spices, miscellaneous dried plants, medicinal herbs, research specimens, raw animal hair (wool, etc.), raw animals hides, straw handicrafts, and used bagging.

    In the past, one major pathway of introduction for foreign weeds was dry ship ballast in the form of rocks and soil. Today, modern ships use water as ballast and have effectively closed this avenue of entry for weeds. On the other hand, water ballast provides a pathway for movement of nuisance aquatic species into the United States. The dreaded zebra (Dreissena polymorpha Pallas) is the most recent example of this type introduction.

    High risk vectors, including the commodities listed above, baggage, and other personal effects are inspected at ports of entry by PPQ Officers to ensure they are not infested with regulated weeds. Items found to be contaminated are either cleaned, fumigated, or rejected entry into the United States to eliminate potential risk. Soil contaminated equipment and vehicles are generally washed to eliminate the risk of introducing regulated weeds.


    Nonindigenous invasive plants are biological pollutants that threaten the biodiversity of natural areas and crop production of agricultural lands. Alien invasive weeds including downy brome, European knapweeds, and thistles, have transformed the prairies and grasslands of the Great Plains and the Intermountain West. In the eastern United States, other aliens pose a serious threat to improved pastures. In particular, tropical soda apple, a prickly new nightshade from Brazil presents an imminent threat to Florida and perhaps other states as well.

    Once native plants are replaced by primary invaders, these invaders are typically only replaced by other invaders that are even more undesirable. In the Intermountain West, downy brome has opened the rangelands for invasion by secondary invaders such as the European knapweeds and thistles. Considering the problems that now being seen with the dozen or so European knapweeds already in the United States, the prospects for dealing with the remaining 1,400 European species are frightening. The most effective answer is to keep them out (prevention (keep high risk foreign commodities from becoming contaminated), preclearance (inspection at ports of export), and exclusion (inspection at ports of import)); to detect incipient infestations (that breech our exclusion system); and to eradicate incipient infestations before they become established and spread.

    The long term effects of continued homogenizing of the world's flora and fauna are unknown. However, the short term effects of alien weeds on natural and agricultural ecosystems are obvious. Unlike chemicals that start to degrade as soon as they are applied, biological pollutants have the potential to reproduce and to spread. This problem is further exacerbated by the fact that incipient infestations usually go unnoticed by the average person and often represent no more than a curiosity or "new record" to most plant scientists. For these reasons, it appears that the world movement of invasive plants and animals that become biological pollutants is one of the most underestimated threats to the sustainability of agriculture and natural ecosystems.

    On a geological scale, we are recreating a global Pangaea, where invasive species will come to occupy their maximum potential ecological range. In the process, many highly desirable and functional species are likely to be displaced or eliminated all together. If left unchecked, the effects of the world movement of harmful nonindigenous species are certain to be far reaching. Therefore, the main objective of plant regulatory agencies must be to protect our natural and agricultural ecosystems from invasion by nonindigenous invasive species. This can only be done by closer scrutiny of plants and animals that are moved around the world. The lessons of the past serve to remind us of the urgent situation at hand.


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    Howard M. Singletary, Jr.
    Director, Division of Plant Industry


    Gene B. Cross
    Weed Specialist, Division of Plant Industry
    North Carolina Department of Agriculture
    Raleigh, North Carolina

    Concerns over the introduction of alien, invasive species have escalated over the past several years and are rapidly approaching the crisis level. Exotic species dissect our national interests creating problems in agriculture, industry, natural areas and can impact human health. According to the recently released Office of Technology (OTA) Report on Harmful Non-Indigenous Species in the United States, at least 4,500 species of foreign origin have established independent populations in the United States. An estimate of documented losses from 79 exotic plant and animal species from 1906 to 1991 is placed at $97 billion. The stage is set then for an increase in the number and secondary spread of introduced exotic species whether by natural means or by human activity. One of the goals of regulatory agencies is to provide the fundamental mechanisms to detect, delimit, and control or eradicate these species before they are able to fully establish themselves and cause additional problems.

    I would like to focus our discussion today of invasive exotics specifically to weeds and the potential impacts on pasture and rangeland areas. The OTA report estimates that the total direct costs of non-indigenous weeds in the United States range from $3.6 billion to $5.4 billion each year. These figures exclude the environmental, human health, regulatory, and other indirect costs of using herbicides or other means of management on exotic weed species which may exceed $1 billion yearly. Weeds, for purposes of our discussion, can be simply defined as plants growing where they are not desired. Weeds compete with our desirable crop plants for water, light, nutrients, and ultimately reduce yields. Their presence interferes with the cultivation and harvest of crops in agricultural areas. Navigational problems occur when aquatic weeds are allowed to spread into our lakes, streams, ponds, and other waterways. Introduced into a new and suitable environmental area, non-indigenous weed species are often able to grow unabated due to the lack of natural enemies. As referenced earlier, many of the documented weed pests in agricultural settings today are of foreign origin. According to the OTA report, over 2,000 plants have origins outside of the United States. Policies, then, relating to the importation of potentially damaging exotics must serve as the first line of defense in preventing future problems. To prevent the entry of harmful exotics, it has been suggested that introduced species must be examined for their ability to invade waterways, croplands, pastures, rangelands and forests. Methods of dissemination and longevity of seeds or other reproductive structures must also be reviewed. Finally, other undesirable characteristics associated with the genus or family to which the species belongs must be reviewed during the screening process.

    To date, approaches addressing non-indigenous weed species in the United States have been splintered. Federal initiatives in many cases are flawed. State weed laws, while effective in preventing the intrastate movement of weeds, lack full authority for preventing interstate movement. The following initiatives represent the current federal legislative approaches regarding alien plant introductions:

    Of the initiatives described, the Federal Noxious Weed Law should serve as the introductory step in preventing the entry and spread of exotic, invasive weed species into and within the United States. However, interpretations of the Act and a preconceived lack of authority have created significant difficulties with regulatory enforcement and action alternatives at both the state and federal levels. I would like to document problems with the Federal Noxious Weed Law and review with you proposed changes that would strengthen its enforcement. First, the definition of a noxious weed in the current Law is not adequate. The lack of a clear definition does not allow for a distinct manner in which noxious weeds are to be regulated under the Act. A proposal has been developed that would revise and expand the definition of noxious weeds to include plants such as wetland weed species and weedy pests of natural areas.

    In order to provide for sound field implementation of the Law, supporting biological information and documentation of weeds as potential plant pests must be generated. The current Federal Noxious Weed Law has provisions which would allow for the establishment of a technical committee to evaluate potential candidates for designation as noxious weeds. Unfortunately, the composition and structure of this committee was poorly arranged and the group has not met since 1978. This lack of specific direction has prevented the timely listing of weed species and the development of policies and procedures for full implementation of the Law. A proposed rewrite of the Act would establish a Noxious Weed Technical Advisory Group to evaluate candidate species, develop appropriate classification criteria for noxious weeds, and to make recommendations essential to implement the Act. Presently, there is no emergency action that will prohibit the introduction of nonindigenous weed species that are not already listed as Federal noxious weeds. As a part of the rewrite, a section is proposed, that if adopted, would grant emergency authority to the APHIS Administrator to prohibit the entry of foreign weeds which meet the definition of a federal noxious weed, but have not been formally added to the list. Presently, several federal noxious weeds are being offered for sale as ornamentals in the seed and nursery trade even though Section 4 of the Act stipulates that listed federal noxious weeds cannot be moved interstate without a permit.

    The interpretation up to this point within the Law has applied only to movement of species that are being moved from quarantine areas. Only one quarantine relating to the federally listed species, witchweed, has been invoked. This loose interpretation has allowed the interstate movement of all other federal noxious weeds to continue. Language has been drafted that will prohibit the intentional movement of all federal noxious weeds across state lines except under permit. Additionally, there is no classification system that would permit regulatory officials to prioritize actions taken against specific noxious weeds. A proposed amendment would outline a weed classification system that categorizes the status of federal noxious weeds. Finally, Section 12 of the Law contained a statement that the exempted the regulation of shipments of agricultural and vegetable seeds. The original intent was to avoid regulating seed shipments under two separate laws by also listing all federal noxious weeds under the Federal Seed Act. The listing under the Federal Seed Act was never accomplished. A proposed amendment would delete the statement exempting the regulation of shipments of agricultural and vegetable seeds in Section 12 of the Federal Noxious Weed Law.

    As presently written, the Federal Noxious Weed Law does not adequately provide the components necessary to effectively regulate the movement of nonindigenous weed species in the United States. Examples of its shortcomings are numerous. I would like to highlight several that will be of interest to you.

    Serrated Tussock (Nassella trichotoma), a federally listed noxious weed, was found as a contaminant in three shipments of tall fescue seeds imported from Argentina through the ports of Jacksonville, Florida and Houston, Texas. This weed is a clump-forming grass native to South America and has been designated as a Federal Noxious Weed. This weed is capable of reducing the productivity and carrying capacity of rangelands and pastures. In making recommendations on action alternatives, United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine (USDA,APHIS,PPQ) staff initially indicated that it had no authority to hold or require treatment of the contaminated shipments due to the provision in Section 12 of the Federal Noxious Weed Law that exempts shipments of seed regulated under the Federal Seed Act. The contaminated tall fescue seed were released for distribution; however, warning statements were issued to each state outlining the potential problems with the shipments. Approximately three months later, the USDA Office of General Counsel was requested by Senator McClure of Idaho to review the decision and determine if any actions were available to prevent the sale of the contaminated tall fescue. An interpretation was handed down by the Office of General Counsel indicating that Section 6 provisions of the Federal Noxious Weed Law took precedence over the provision cited in Section 12 of the Law which referred to the Federal Seed Act.

    The majority of the tall fescue seeds that had been distributed were recalled and destroyed. Unfortunately, contaminated seed were distributed in North Carolina, South Carolina, Kentucky, Illinois and Missouri in at least 50 counties. Educational efforts aimed at reminding the public about the potential devastation of this weed have been launched in most of the affected states. This example clearly illustrates the inconsistencies associated with current shipments of agricultural and vegetable seed.

    Another potential rangeland weed problem is Lightning weed (Drymaria arenarioides). Lightning weed is a short-lived perennial rangeland weed that is extremely toxic to cattle, sheep, and goats. It invades rangeland areas that may be stressed from drought or improper grazing and displaces much of the desirable vegetation. It is native to north-central Mexico and has been listed as a Federal Noxious Weed. Individual states such as Arizona have launched ongoing detection programs to survey for the presence of this toxic weed since infestations exist less than 80 miles south of Arizona's border and 1\4 mile south of New Mexico's border. Support through funding and development of regulatory policies from APHIS has been nonexistent. Proposed changes in the Federal Noxious Weed Law would enhance basic state activities by providing policy direction through staff or the advisory group.

    A final example illustrating potential problems with implementation of the Federal Noxious Weed Law would be the threat of Tropic Soda Apple (Solanum viarum). This is a broadleaf perennial weed reaching heights of up to 2 m. The stems, leaves, flower-stalks, and calyxes have yellowish prickles up to 12 mm long. It may be easily confused with a number of other plants in this genus. This weed can infest a rangeland area within one to two years and lower the number of animals which can be grazed because of it's unpalatability. Observed in Florida as early as 1987, it has been found as a common weed in pastures, ditch banks, citrus groves, sugar cane fields, and rangeland. Tropic Soda Apple infestations of pastures in south Florida have been estimated to be nearly 61,000 ha. Presently, it is not known to occur at any other location in the United States. Given its potential economic impact in agricultural fields, rangelands, and natural areas, this weed deserves listing on an emergency basis to prevent spread to additional areas. The emergency listing would provide needed time to devote to basic plant biology and range studies to examine its potential threat to other areas in the United States. The proposed rewrite of the Federal Noxious Weed Law would provide for emergency listing.

    The incorporation of these necessary changes within the Federal Noxious Weed Law originated several years ago within the Federal Noxious Weed Law Committee of the Weed Science Society of America (WSSA). These proposed amendments were carried by representatives of WSSA to Washington on their visit with members of Congress. The Intermountain Noxious Weed Advisory Council (INWAC) has also been a major player and both groups have worked cooperatively on a rewrite of the Federal Noxious Weed Law. INWAC is a grassroots action oriented organization that serves as a liaison between states, Congress, federal agencies, and trade organizations on issues regarding undesirable plants. The rewritten Federal Noxious Weed Law was circulated among members of several groups for comment and discussion including WSSA, INWAC, Nature Conservancy, Natural Resources Defense Council (NRDC), and National Coalition Against the Misuse of Pesticides (NCAMP). Representatives within state agencies throughout the country have also reviewed the rewrite.

    Presently, the rewritten version of the Federal Noxious Weed Law is waiting to be introduced into Congress. It is scheduled to be introduced by Senator Bryan Dorgan, North Dakota tentatively as part of updates to the 1990 Farm Bill. It will likely be introduced in the House of Representatives by Charlie Rose of North Carolina. The hope is with these additions and an adequate funding base, federal agencies will have the proper and necessary framework to prevent the entry and spread of non-indigenous weed species.


    Questions and Answers

    Q: Is there any time frame for introduction of legislation to amend the Federal Noxious Weed Act?

    A: George Hittle: We're just waiting for Senator Dorgan to identify an opportune moment to drop the bill in. We might wake up one morning to a call saying, hey, we introduced the bill today.

    A: Howard Singletary: What we're doing is sitting on the launching platform, we have the necessary contacts and linkages and the opportunity I outlined is the major opportunity that's being considered right now.

    Q: Could you comment on the changing role for Federal agencies?

    A: Howard Singletary: Let me see if I can do that in the context of what this Forum is about, rangelands. Let's talk about Midwest and West first, and then I'll move to the East Coast. I think the impetus for a lot of additional cooperation at the Federal and State level is the 1990 Farm Bill amendment that I mentioned that added Section 15 to the Federal Noxious Weed law. It provided the impetus for communication forums between Federal land managers and State agencies. There has been considerable progress made in that area. One of the principal deterrents at this point in time is a lack of funding. You've seen how some of these exotic rangeland invaders can spread, in terms of the number of acres. There is no one single strategy that will effectively deal with all these plants; it will take integrated approaches that are now being worked out. One of the things that we hope to see more fully utilized is the application of biological controls where they are feasible and where there are adequate natural enemies that can be used against some of these introduced species.

    Now, let's move east and let's talk about the evolution of Federal policy. I think there was a hearing held in Washington several years ago where the Administrator of APHIS was called forward to lay out the agency position as regards noxious weeds. Essentially Congress called the Administrator of APHIS on the carpet. That was the impetus for the agency to reexamine their approach and policy on noxious weeds. APHIS does have a rewritten policy that is presently in the Undersecretary's office under review. I think it will ultimately be released and I think it will be in concert with the approaches we have outlined in terms of where we need to go to deal with alien invaders and noxious weeds. That, plus the OTA study all coming together may be enough of a critical mass to move more appropriately in terms of the legislative authority as a first line of defense in preventing future introductions, to the extent that you can utilizing an approach like this. I hope it will also provide a better domestic program in terms of programs through out the country to deal with weeds.

    A: Randy Westbrooks: In reference to the OTA report, the best thing is that there was nothing new in it. It might be new to you, but to us in APHIS, we've known these things for a long time. It was nice to have someone else do an independent evaluation and say "Yes, these are the problems, this is what we need to be doing". It almost gives us a blueprint of activities that we can pursue. Faith worked with us on this policy project over the last several years and we're all really happy with how it turned out. After it gets approved, I think you will all be happy about it, too. We're just beginning a plan for actually implementing this policy. We really are addressing the concerns that were addressed in the OTA report.

    The two points I wanted to make, but ran out of time are these: There are about 12 or so European knapweeds in the U.S. that are infesting millions of acres and causing millions of dollars of damages. Remember this, however, there are 1,400 species left in Europe that have never come here. What's going to happen if 10 more or 20 more are allowed to be introduced? You folks are the ones concerned about grazing lands: What will they look like in 15 years if we don't do something now? APHIS can't take the blame for letting these knapweeds into the U.S. because we weren't around when they were first introduced. But now we have to really take a serious look at these things because there's a lot more to come in.

    The last comment is that about 5 years ago I did a study of Australian plants. I know of 100 poisonous rangeland plants in Australia that don't occur here. So, youv'e got 100 in Australia that are poisonous to cattle and 1,400 European knapweeds, so there's an awful lot out there that could cause us future problems.

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    Ray S. McAllister
    Director of Regulatory Affairs
    National Agricultural Chemicals Association
    Washington, DC

    The National Agricultural Chemicals Association is the trade group that represents the common interests of the manufacturers and formulators of crop protection chemicals in the United States. We are the folks whom, it seems, many in the media and public interest groups love to hate. My responsibilities in regulatory affairs keeps me in frequent contact with the Environmental Protection Agency, interpreting and implementing laws through regulation that Congress, in its finite wisdom, sees fit to inflict upon us.

    My professional training from the age of 16 on has been in Weed Science, so the theme of this year's Grazing Lands Forum is of particular interest to me. I have come face to face or should I say hand to spiny leaf with many of the noxious critters we have been discussing today. Given the long struggle to put in place and enforce an effective Federal Noxious Weed Act, weed scientists have often felt neglected and forgotten. It is a long-standing lament among weed scientists that Integrated Pest Management, a renewed battle cry in the Clinton Administration's pesticide reform proposals, means "give more money to your friendly entomologist."

    To set the stage for my perspectives on noxious weeds on grazing lands, I'd like to share with you a couple of anecdotes.

    In Cache Valley, Utah where I grew up, I remember numerous pastures within or near the city limits where forlorn four-legged creatures grazed among but ignored what appeared to be very lush forage. On my first real summer job as a teenager assisting in weed science research at Utah State University, I learned that the lush forage the horses wouldn't touch is a plant called goats rue, aptly named because not even goats will eat it. It is also known locally as professor weed, named for the hapless academic who decades ago introduced it from a foreign source. He thought it had potential as a forage crop, only to discover to his dismay that it is unpalatable and toxic to livestock, fairly vigorous though not an aggressive spreader, and a prolific seed producer. In recent years coordinated efforts to eradicate this weed have been quite successful.

    In 1989 I took my family to visit Yellowstone National Park on a vacation trip. One evening we stayed at Mammoth Hot Springs near the norther border of the park. The next morning as I wandered leisurely along the nearby trails I noticed an unfamiliar pretty yellow flowering plant, Although I grew up in the west and had taken botany and plant taxonomy courses and had wandered the hills to study plants, I didn't recognize it. It turned out to be quite common in that area of Yellowstone Park, growing along many of the road sides. A short while later I noticed a crew of workmen dressed in rather elaborate protective clothing, including what looked like yellow rubberized coveralls, gloves and hats, pulling up these same plants--not spraying or cutting or mowing them, just pulling them up with their gloved hands. I learned that the rather attractive target of their eradication efforts was Dalmatian toadflax, a pernicious weed creeping into the park from areas further north. The incongruous image has stuck in my mind of elaborate high tech preparations to combat a lowly but very successful enemy using primitive means, totally ignoring the enemy's ability to escape such tactics and outwit its attackers.

    These are just a few examples of weeds that can strike fear in the hearts of knowledgeable farmers and rancher who must use, manage, and depend on grazing lands for a livelihood. Other such weeds, ranging from the well-known to rather obscure, include leafy spurge, Russia knapweed, Astragalus, Texan blueweed, musk thistle, and whitetop. They are noxious, pernicious, aggressive invaders of grazing lands that injure and poison livestock, reduce productivity and land values, crowd out desirable forage species and endangered plants, and defy attempts to control them. Common among them are vigorously creeping perennials and allelopathic plants that produce there own natural herbicides to discourage competing plants.

    As a representative of the crop protection industry I wish I could say your weed worries are over, that we have a new batch of herbicides coming on the market that, used individually or in mixtures, will handle any combination of weed problems you will find in range or pasture. But that is not the case. First of all, our wits and ingenuity and good fortune in research do not yet match nature's diversity, complexity, and resourcefulness. Second, we as a society sometimes are our own worst enemy by importing new weedy plants from other areas, usually unknowingly, but sometimes knowingly though unwittingly. One wonders if it might sometimes be intentional. You will recall in the biblical parable the master's response to the servant's report of tares sown among the wheat: "An enemy hath done this."

    And third, in spite of the large land area represented by grazing lands in the United States, far more than any other single crop, forage weed control is by no means a major target of commercial research for new product development. The economics of grazing land management are such that expenses for weed control assume a relatively low priority. It seems ridiculous to consider the forage grown on hundreds of millions of acres as a "minor crop," but for purposes of pesticide product development, that is indeed the case.

    In the successful fight against noxious weeds, whether one species or many, there must be three facets:

    Regional planning and coordination--The serious noxious weed problems that afflict grazing lands are typically very widespread or threaten large areas. The plants are aggressive competitors, spreading vigorously by prolific seed production and efficient natural seed dispersal, and/or vigorous creeping roots or rhizomes. Localized efforts, no matter how successful the strategy, cannot expect to prevail if the species can simply move back in a year or two later. It must of necessity be a long-term coordinated plan, or success will spotty and ephemeral.

    Cooperative efforts of landowners and land-controlling state and federal government agencies--If any one landowner or land controlling state or federal agency refuses or neglects to perform his duty in a well planned regional strategy against a particularly aggressive weed, his land serves as a reservoir of seed and other propagules for the surrounding area, hampering and frustrating the efforts of others. Whether it is opposition to the use of herbicides, failure to budget the necessary resources, or other reasons, all can suffer because of the actions or inactions of one party.

    Integrated weed management - using all available tools, techniques, and strategies--Above all, proper management of desirable forage species is most important. Their competitiveness against weed species must be encouraged and enhanced by maintaining soil fertility levels and properly controlling grazing. Without such practices, any other strategies for directly attacking the weeds themselves can only have limited success, at best.

    In many, but unfortunately not all circumstances, herbicides make a significant, effective, and economical contribution to controlling serious rangeland weed problems. They must of course be used with due consideration for the risks involved of residues transmitted to feed and food, and potential harm to nontarget species. For the most part, fears of these problems are vastly overrated. The mere presence of insignificant quantities of a man-made compound in a natural area is not necessarily evidence ecological disaster or even any hazard at all. It may be a small and utterly meaningless price to pay for the tremendous benefit to mankind.

    It would be shortsighted to avoid effective chemical use for weed control in rangelands because of misguided concerns about pollution, when weeds themselves are a severe form of self-perpetuating biological pollution that does not degrade and disappear if you leave it alone.

    Development of resistance of weed populations to herbicides is a growing but not unmanageable problem. Herbicide resistance is not a permanent genetic change in a weed population. In absence of the selection pressure created by continued use of a particular herbicide active ingredient, those resistant plants are generally less fit ecologically than non-resistant plants, and will be crowded out due to competition. Rotation of effective herbicide tools is an important and viable IPM technique. This means we need more, not fewer, choices of herbicides for weed control.

    In a few situations we have been spectacularly successful in controlling rangeland weeds with classical biological control strategies--St Johnswort in the United States with a natural insect enemy and prickly pear cactus in Australia with plant disease are well known examples. However, the research process is long and expensive and even more dependent on good luck than is the search for a commercially successful new herbicide. Biological control for all its hype and promise, is still a distant dream for most weed problems. Research efforts in this area can and must continue, and the promise of biotechnology hints excitingly at possible commercially exploitable biological strategies. In the long run, the biological approach to weed control must prove itself in the marketplace, both in efficacy and economics. Over-reliance on the yet unfulfilled promise of biological control and so-called "biological" products from a public policy perspective, while the use of herbicides is curtailed on high moral grounds, will lead to bitter disappointment and potential disaster while we wait for the miracles to happen.

    I'd like to share with you some insights into the status of various laws and regulations that have an impact on grazing lands, some dealing with weed control and some which don't. I'm indebted to Dr. John Thorne of the NACA staff for sharing his thoughts on these topics with me.

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    (now being reauthorized & amended)

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    (to be reauthorized in 1994)

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    (now being reauthorized & significantly amended)

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    (mandatory regulations expected soon)

    One estimate places 90 percent of the identified endangered species in the Western U.S., with 75 percent of them being plants. A high proportion of those will occur on the grazing lands of concern to you folks. This has serious potential repercussions for controlling weeds with effective herbicide treatments on grazing lands. While herbicide use may even enhance the habitat for endangered plant species (more on this in a moment), the mechanics of the regulations can very easily impede or prohibit approval of herbicide use in areas where endangered may occur. One comes to the inescapable conclusion that any herbicide "may affect" an endangered plant species, just because it is a plant. We can't test the herbicide directly on that plant, simply because it is endangered, and the fact of herbicide selectivity make inferences from other species questionable or meaningless. Furthermore, EPA and FWS lack adequate mapping data for habitats of the various endangered plant species, are reluctant to disclose what data they do have for fear collectors will destroy the plants, and lack the resources the develop the data. These combined concerns have been reason enough to place the Endangered Species Protection Plan on hold in the Office of Pesticide Programs.

    Last August I attended a regional workshop at Utah State University that addressed the problems and challenges of implementing an endangered species protection plan for pesticide use. One of the most interesting recommendations to come out of the discussions at that workshop was that no restrictions should be placed on pesticide use if habitats or locations cannot be revealed because of concern that such action would further endanger the species. In other words, if the hazards to the endangered species of publicly revealing its location are greater than the hazards of pesticide use to that same species (which I suspect will occur in the vast majority of cases), no restrictions should be placed on pesticide use.

    One last anecdote reveals a potential folly in categorically avoiding the use of herbicides to solve weed problems of a magnitude analogous to those found on grazing lands, supposedly for reasons of ecological ethics. Rick Johnstone runs the rights-of-way vegetation management program for Delmarva Power Company here in the mid-Atlantic states. He has developed a very successful system of judicious herbicide use to maintain vegetation along power lines in various stages of ecological succession. Obviously, fully developed forests are not compatible with maintaining utility rights-of-way, but bare ground is not desirable either. Mechanical means of destroying unwanted vegetation over the large areas involved are highly disruptive of wildlife habitat and encourage devastating soil erosion problems. The use of herbicides solves these specific problems. It has also produced some unexpected but most welcome ecological benefits. A few endangered plants species have recently been discovered thriving along these rights of way which were thought to have long since disappeared from the area. The opening up of the forest canopy to maintain habitats of intermediate ecological succession has reduced plant competition so that these delicate species can return and survive. It would not be economically or physically feasible without herbicides.

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    Working Tools: The Science and Technology of Weed Management

    Scott Glenn
    Professor of Weed Science
    University of Maryland
    College Park, Maryland

    What's So Noxious About These Weeds?

    Noxious weeds infest millions of hectares for grazing land in North America. These weeds reduce the amount of available grazing land and reduce the palatability and quality of the forage available to grazing livestock. Thorny weeds, such as thistles, briars (Rubus species), multiflora rose (Rosa multiflora), spiny amaranth (Amaranthus spinosus), and horsenettle (Solanum carolinese) can form dense, unpalatable patches rendering large areas of fields useless for grazing. Most weeds have less nutritional value than the forage on grazing lands, but even if the weed is nutritious, toxic substances may be present. If consumed in large enough quantities, many weeds are poisonous, creating sickness and death. Fortunately, most animals avoid grazing near poisonous weeds unless forage is limited. Thus, the incidence of livestock poisoning from poisonous weeds is unusual, but light infestations of weeds can render large areas of fields unproductive for grazing.

    Leafy spurge (Euphoribia esula) infests over one million hectares of grazing land in the northern Great Plain states. Latex is present throughout the plant. This latex has been shown to contain a toxic substance that can result in sickness or death in livestock. Cattle avoid grazing fields that are only lightly infested with leafy spurge. The cattle carrying capacity is reduced to near zero, even in fields only lightly infested with leafy spurge.

    Noxious Weed Management--An Integrated Approach

    Five strategies should be considered in the management of noxious weeds on grazing lands. These strategies include:

    1. Prevention
    2. Cultural control
    3. Mechanical control
    4. Biological control
    5. Chemical control

    The most effective method of controlling noxious weeds is to employ several or all of these strategies for an integrated weed management approach.

    Prevention--Of great importance, but often ignored, preventing the introduction and spread of noxious weeds is a vital link to management. State laws can be used to prevent the introduction and spread of noxious weeds. To be effective, personnel must be in place to identify problems and enforce the laws. In Maryland, there are personnel located in each county with the responsibility of developing weed control programs for public land an with landowners whose land is infested with noxious weeds [thistles (Cirsium and Carduus species), johnsongrass (Sorghum halepense), and shattercane (Sorghum bicolor)]. Landowners who are not in compliance are subject to stiff penalties. The high profile of the Maryland Weed Control Program brings attention to the needs of weed management on grazing land. Enforcement of weed laws, however, is much more difficult in states with more agricultural land.

    Noxious weeds are often introduced to uninfested fields through uncontrolled weeds growing in neighboring fields and contaminated hay and straw. Laws designed to prevent seed production of noxious weeds and the sale of products containing noxious weed seeds can help reduce the further spread of these weeds. Extension programs that educate farmers about the biology and identification of weeds and the importance of timely control of these weeds can also play a vital role in preventing the spread of noxious weeds.

    Cultural Control--Dense, lush stands of forage are much less likely to be infested with weeds than thin stands of forage. Weeds usually first invade fields where the forage growth is poor and open space exists. Some weeds, such as Canada thistle (Cirsium arvense) and the knapweeds, grow poorly in shade. Good fertility and aggressive forage cultivars can limit the growth and spread of these weeds. Leaving farm implements and other equipment in the field for extended periods of time can weaken or destroy the forage growth beneath them. This practice should be avoided.

    Mechanical Control--Tillage of grazing land can disrupt and destroy the roots and rhizomes of many noxious weeds. However, tillage is not often an option in perennial forage stands. Timely mowing can be a most effective weed management tool. Mowing has little immediate impact on the root or rhizome of most perennial weeds, but mowing prior to seed set can prevent further spreading of the weed. Also, many weeds are less competitive and more palatable in a young, succulent stage of regrowth following mowing.

    Biological Control--Biological control of weeds is usually accomplished through the release of insects, application of plant pathogens, or the management of weed-consuming animals. Rhynocyllus conicus is a weevil that has been released to selectively manage musk thistle (Carduus nutans). The larvae of this weevil feeds on the seeds of the musk thistle, thus reducing the production of viable seeds. In Maryland, the Rhynocyllus conicus release program is now eighteen years old, and musk thistle populations have slowly declined.

    Application of plant pathogens that infect specific weeds has shown some promise for controlling weeds. Applications of Alternaria species in a modified water-in-oil invert emulsion has shown some promise for controlling leafy spurge. Star thistles (Centaurea species) and knapweeds (Centaurea species) have been found to be susceptible to a rust disease caused by Pucinia jacerae introduced from Europe. A number of other plant pathogens are also being evaluated for control of noxious weeds.

    Selective grazing of weeds by livestock can effectively control some weeds if the livestock have a preference for the weed. For livestock to be effective as biotic agents, the following conditions must exist:

    Sheep have been effectively used to control leafy spurge in the northern Great Plains. Sheep selectively graze young leafy spurge and continue to graze leafy spurge until it matures, thus limiting impact of this weed.

    Chemical Control--Herbicides are available for the control of many weeds that infest grazing land. Herbicides can also be used to control weeds in fence rows and rock outcrops. To control perennial weeds, systemic herbicides that translocate into roots and rhizomes should be used. In field crops, herbicides have become the preferred method of managing weeds. However, herbicide use on grazing lands is somewhat limited by the following factors:

    Herbicides, although sometimes very effective, usually need to be supplemented with other weed management strategies.

    Long-Term Control of Noxious Weeds

    The purpose of weed management is to obtain long-term control of noxious weeds. In general, long-term control of weeds that reach the status of "noxious weeds" cannot be obtained with any single weed management approach. The best strategy to control these weeds is to implement several or all of the weed management methods in an integrated approach. Still, the battle against noxious weeds usually requires a continuous effort to remove them from a field and prevent further infestations.

    The integrated weed management approach is not a new idea. Many states have very active integrated weed management research and extension programs. In many states, however, most of these programs focus on cropland, with very little emphasis on grazing lands. This is unfortunate since there are great opportunities to make significant strides towards managing noxious weeds in grazing land if proper funding is available for integrated weed management research and extension programs.

    Questions and Answers

    Q: Is CURTAIL sold in the East?

    A: Scott Glenn: No it is not. CURTAIL is a package mix of Stinger, Clopyralid and 2,4-D, that's correct. My understanding is that out in the West that is priced reasonably enough to be able to use in the grasslands. Here in the East, we've had good success with Clopyralid, but as I said, we can't spend $25-$30 per acre for one weed. A more reasonably priced product may work better. It's my understanding that they are not going to market CURTAIL out here.

    A: Unidentified: What the researchers originally thought was that the CURTAIL, because it is a mix, would work better on the Canada Thistle on grassland than Stinger. But what they found out is that Stinger works just as well on Canada Thistle in woody shrubs, whereas the CURTAIL works better on the knapweeds.

    A: Scott Glenn: That makes sense because, I think the CURTAIL rate is low on Clopyralid (?)

    Q: If you use HILITE? on Canadian Thistle, will it clean out everything else?

    A: Scott Glenn: Not always, but it is a broad spectrum herbicide. We've had good success with multiflora rose, and its very good on the briar species and spiny amaranth, as well. It has a pretty broad spectrum, but it does do well on a variety of weeds. It will also take clover out of the pasture, and leave you with the grass. Also, something that we have an education problem with our farmers using Sulfuron with fescue anyway, which is predominant grass here, is it reduces seed head production. I know it does on a number of other grasses in the Midwest, as well. This reduces total production, hay production on the first cutting or forage production. We're trying to convince the farmers that those seed heads aren't necessarily an advantage to them. Certainly the stock are eating more lignin and nondigestible materials when the livestock are eating those seed heads. But it's a hard sell. But, because of the weed laws, it's used quite a bit in Maryland and also in the surrounding states.

    Q: Biological control can only be targeted on one weed, right? That means it has to be species specific, and is therefore more acceptable for grazing land use.

    A: Scott Glenn: Absolutely. I agree with that almost 100 percent. I tried to make just that point. That's almost a definition of biological control: that it should have host specificity. That's only a pitfall if you're looking at it as a replacement for herbicides because it's not going to have the broad spectrum activity of a chemical. It has to be used along with other methods.

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    Tim Butler
    Western Weed Coordinating Committee,


    Oregon Department of Agriculture
    Salem, Oregon

    The Western Weed Coordinating Committee (WWCC) is a voluntary, informal organization designed to help coordinate weed management efforts of state and federal agencies. It exists to provide a forum for discussion and resolution of problems for agencies involved in weed management. The Committee and its members are dedicated to preventing the introduction and spread of noxious weeds and undesirable plants in the western United States. WWCC was formed in 1990 during the Noxious Range Weed Symposium, held in Logan, Utah. By strengthening coordination and cooperation between state and federal agencies the Committee aims to improve the effectiveness of noxious weed management throughout the west.

    Noxious weeds are invading vast acreages of lands in the west. Noxious weeds are invading rangelands, forests, and natural areas causing negative economic and environmental impacts on natural resources. It is for this reason that aggressive integrated weed control programs should be implemented and supported.

    One accomplishment of WWCC included the support and development of the Noxious Weed Management Short Course held annually in Bozeman, Montana. This course targets federal land managers and is sponsored by the Western Society of Weed Science and Montana Weed Control Association. WWCC members also work with the U.S. Department of Agriculture and U.S. Department of Interior to develop national policies for weed management on federal lands and in the development of Memoranda of Understanding between the states and federal agencies.

    An example of a successful cooperative program that exemplifies the mission of WWCC is the regional control of tansy ragwort in Oregon. In the mid-1970's and early 1980's livestock losses in Oregon due to tansy ragwort were an estimated $4 million annually. In 1975 the Oregon Legislature passed and funded a measure which established an integrated control program for tansy ragwort. The primary focus of the program was on biological control.

    The Oregon Department of Agriculture (ODA) organized an intensive regional effort to distribute three biological control agents throughout 16 tansy ragwort infested counties in western Oregon. These bioagents included the cinnabar moth, the ragwort flea beetle, and a seed head fly.

    In 1976 the Bureau of Land Management (BLM) and the U.S. Forest Service (USFS) signed agreements with ODA and provided funding and support for implementation of the tansy ragwort control program on their lands. Support of the BLM and USFS was an essential element in the ultimate success in controlling tansy ragwort below an economic level.

    An economic study completed in 1992 of the Oregon tansy ragwort program revealed a internal rate of return of greater than 80 percent on investments in control. Current annual benefits from the tansy control program were estimated at $5 million annually. Benefits and costs over the life of the program are shown in Figure 1.

    The mission of WWCC, the Noxious Weed Management Short Course, and the cooperative tansy ragwort control program can serve as models of how multiple agencies can implement effective noxious weed management efforts.

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    John M. Randall
    Exotic Species Program, The Nature Conservancy,
    Galt, California
    Section of Plant Biology,
    University of California, Davis


    Weed invasions pose severe threats to the preservation of many plant and animal species and communities. Among those of us in agencies and organizations that manage land, such as the National Park Service and The Nature Conservancy, awareness of weed invasions of natural habitats has greatly increased in the last decade or so. Interest in this subject among ecological researchers has also risen in recent years. In fact, there is good reason to believe that more and more people in the larger "environmental community" and among the public at large are now beginning to recognize the dangers posed by weeds.

    My aim in this presentation is to demonstrate that:

    1. Weed invasions threaten our ecosystems and the preservation of native plants and animals;
    2. We share many concerns about weeds with ranchers, farmers and foresters;
    3. Actions can be taken by land managers and policy-makers to reduce these threats.

    I will first outline the mission of The Nature Conservancy and present an overview of how weeds threaten the protection of natural areas and biodiversity. Next I will present results of a survey on weed problems on our preserves and then offer specific examples and indicate how we are dealing with them. I will finish by describing some of the more difficult and unusual challenges weed invasions present to natural area managers and advocating efforts to prevent introductions of new pests.

    The Nature Conservancy's Mission

    The mission of The Nature Conservancy is to preserve plants, animals and natural communities that represent the diversity of life on earth by protecting the lands and waters they need to survive. We manage over 1,300 preserves in the U.S. and Canada, the largest private system of nature sanctuaries in the world.

    We use domesticated grazing animals including cattle, bison and sheep on certain preserves where they can help us achieve our management goals by helping to maintain, enhance or restore natural communities. In a limited number of cases our primary motivation for using grazers was to reduce weed populations. In other cases our management goals have dictated the removal of domesticated grazers or reduction of their herd sizes.

    Overview of Threats to Natural Areas and Biodiversity Posed by Weeds

    Weed invasions may appear to be of minor importance at first glance, especially when compared to threats like air and water pollution or habitat destruction for urban development . However, the examples below will prove otherwise. And, unlike other threats, invasions by pest plants (and animals) continue to spread on their own once initiated; their effects are not limited to one site or even to one region.

    The pest species that cause the greatest damage are those that can dominate and change plant communities or alter ecosystem processes. Unfortunately, examples of this type abound. Cheat grass (Bromus tectorum) invaded millions of acres of rangeland in the Great Basin which in turn lead to an increase in frequency of fires from once every 60-110 years to once every 3-5 years. Native shrubs, which do not recover well from the more frequent fires, have been eliminated or reduced to minor components in many of these areas. Nitrogen-fixing plants such as firetree (Myrica faya) were introduced to areas where they sharply increased the rate of nitrogen accumulation in the soil. This drastically altered patterns of succession and allowed other weedy species with high nutrient requirements to invade.

    There are two characteristics common to most species considered weeds in natural areas:

    1. The great majority are not native to the areas they infest although they may be native to other parts of the continent. Such species may be referred to as non-native, non-indigenous, alien or exotic.
    2. The great majority of natural area weeds are also invasive. This means that they move into and can dominate or disrupt natural communities.

    Some natural area weeds have been declared noxious by the federal government, or by certain states or counties. In almost all cases they were designated noxious because they are detrimental to crop agriculture, ranching and/or forestry.

    Assessment of Weed Problems on Nature Conservancy Preserves

    I mailed weed questionnaires to all 122 Nature Conservancy stewards with land management responsibilities in April 1992. Ninety-three stewards (76 percent) from 46 states completed the questionnaires (there were no stewards in AK, AL, DE & MS at the time). Weed problems were reported from all 46 states, but stewards from California, Florida and Hawaii reported the greatest numbers of pests. Seventy-nine stewards ranked weed control relative to other problems they face in their conservation work. Ten (13 percent) listed it as their worst problem and another 47 (59 percent) ranked it among their top-10 concerns.

    A total of 197 non-native pest species were reported. The pests included ferns, gymnosperms and flowering plants ranging from annual, biennial and perennial herbs, floating, emergent and submersed aquatics, vines, shrubs, understory trees and canopy dominants. Five species were reported from 10 or more states: Alliaria petiolata [11]; Lonicera japonica [13], Lythrum salicaria [11]; Phragmites australis [10] and; Robinia pseudoacacia [10]. Tamarix spp. Centaurea spp., Ailanthus altissima, Cirsium arvense, Elaeagnus spp., Melilotus spp. and Sorghum halapense were among the other widely reported species.

    Stewards cited a variety of threats posed by weedy species including: altering water tables; altering fire regimes; suppressing native species recruitment and thereby affecting community structure; outcompeting native species (particularly rare species); altering or eliminating habitat for native animals; and providing food and cover for undesirable non-native animals. Tamarix spp. lowered water tables reducing or eliminating surface water habitats required by native plants and animals at several preserves in the southwest. Alliaria petiolata and Vinca major suppress recruitment of tree seedlings in forested areas they infest. If these pests are allowed to persist, the species composition and structure of the forest canopies will likely be altered. Lonicera japonica infestations threaten to smother and eliminate populations of rare native species at two sites in South Carolina. Phragmites australis and Lythrum salicaria are threats to waterfowl habitat in many northeastern and midwestern wetland preserves. Hawaiian stewards reported that feral pigs favor the fruits of Psidium guajava and P. cattleianum (guava and strawberry guava). The pigs in turn disperse the seeds of these plants and disturb the soil promoting their establishment and that of other weeds.

    Specific Examples of Weed Problems on Nature Conservancy Preserves

    Leafy spurge (Euphorbia esula) at Pine Butte Swamp Preserve, Montana.

    Yellow star thistle (Centaurea solstitialis), another range pest, also infests preserves in Idaho, Oregon and California.

    European beachgrass (Ammophila arenaria) at Lanphere-Christiansen Dunes in northern California.

    Fennel (Foeniculum vulgare) on Santa Cruz Island, California.

    Tamarisk (Tamarix spp.) on southwestern Preserves.

    Non-native shrubs in midwestern and northeastern preserves

    Vines in midwestern, northeastern and southeastern Preserves.

    Difficult and Unusual Challenges Posed by Weeds in Natural Areas

    When weeds are controlled or eliminated from a natural area do desirable species return? Does the original community rebound or are some species missing? Little work examining the species that return following control efforts has been conducted. In some cases where studies have been done it appears that original species composition will return.

    When weeds support native animal species should they be left in place? What supported these animals before the weeds invaded?

    Do some weeds benefit from associations with non-native animals which have also been introduced? The evidence is clear that some pest species in the Hawaiian Islands benefit from their interactions with feral pigs. Do other pests benefit because they are more likely to be pollinated by introduced honeybees than the native species they compete with?

    Some pest species are favored by natural disturbances as well as human caused disturbances - do they alter the course of succession? If so, can anything be done to insure native communities have a chance to recover?

    Prevention of New Problems

    Pest plants have not stopped arriving in North America and Hawaii. It appears that some relative new-comers will push out other weeds. In most cases, the aggressive new-comer is apparently even harder on native species and communities and more damaging to agricultural interests. One of the most important things we could do to help native communities and species would be to slow the establishment of new pests. Ways this might be accomplished include:

    The Purple Loosestrife Biocontrol Program

    Richard Malecki
    U.S. National Biological Survey
    Cornell University
    Ithaca, New York

    I'm a little bit of an outlier for this meeting. I'm not a weed scientist, I'm not an entomologist, and I'm not working with a plant that has direct application to grazing lands. But I have been working with a noxious weed and coordinating a program that does have some application to this group and the things we've been talking about today. Perhaps I can give a little different perspective on the subject. I'll give you an overview of the program that we have for purple loosestrife. Then I'll get into a few of the things that I've come to realize over the 5 or 6 years that I've been working with this topic; things that involve interagency agreements and subjects like that.

    Purple loosestrife is an extremely pretty plant. It's a Eurasian species that was brought over in the early- to mid-1800's. So it's been here for about 150 years. It likes wetland areas, moist habitats along stream channels, dug canals, and ditches. It's really taken off in the last 40 or 50 years. In the last 10 to 20 years, it's moved rapidly through the West along irrigation systems. It's pretty well distributed across the U.S., although it's somewhat restricted and found in larger concentrations in the temperate parts of the U.S. and southern Canada.

    Over the last 30 to 40 years, we've tried a lot of the conventional control techniques: hand pulling, cutting, flooding, herbicides, plant competition. In particular areas and certain locales, each of these has had some effect, but overall they have not been effective in controlling the spread and distribution of the plant or numbers of it within an area. That got us into biocontrol in the mid-1980's. It was the last choice in looking for a control that could provide some relief from this plant.

    Biocontrol is the use of natural enemies by man to reduce populations of a plant pest to an acceptable level. We are dealing with an exotic, a plant that is growing outside it's native range. It's a weed, a plant growing where it's not wanted. The main problem is that you see a lot of prolific growth when there are no natural enemies to control it: None of the pathogens, predators, or diseases that control it in it's native range.

    What we did was go to Europe and get involved with scientists there who could identify insects that were host specific to purple loosestrife. We brought these insects into the U.S. The first one is a snout beetle that lays it's egg in the stem or upper root of the plant. The larva develop and eat the root tissue. Purple loosestrife is a perennial plant with a massive root system. If you get enough larvae feeding on the root, they destroy the storage capacities of the plant.

    A few other species. We have two leaf eating beetles. The larva of these species basically skeletonize the leaf, removing all the green material. Two additional beetle species that we are looking at are flower feeding beetles that lay their eggs inside the ovary. The developing larvae eat out the ovary and destroy the seed-producing capabilities of the plant. So we have a multi-directed approach to putting stress on the plant from a variety of different aspects with regards to the use of insects. We have insect-rearing facilities established in 7 different states thoughout the U.S. We just started this last year, so we're just getting into this phase of our program. The idea is to have major release facilities thoughout the U.S. Our Canadian counterparts are developing a similar program. That's where we're at right now with the purple loosestrife program.

    Aspects to Consider in a Biocontrol Program

    There are a number of different things to consider if you're thinking about getting into a biological control program for noxious weeds. First, you have to select the target weed. You have to identify potential control agents, screen and propagate the control agents, and then get into a release program in the field. Most of this is under the control of USDA's Animal/Plant Health Inspection Service (APHIS) for weed control through insects.

    An advisory group for APHIS that's found throughout the country and is instrumental in the introduction of control agents for weeds is a group known as the TAG, Technical Advisory Group. There are 12-13 members representing a variety of agencies within the U.S. government (Agriculture, Interior, EPA, and Corps of Engineers had members on our TAG group) and the Weed Science Society. Their function is to review proposals for the selection of target weeds. They also recommend test plants for host specificity tests that are done on the insects that are proposed for introduction. And they review the adequacy of results showing the safety for release of organisms into the environment. There's quite a procedure and protocol involved in bringing insects into the U.S. and Canada to combat any particular target weed that is selected.

    In looking at the selection of the target weed, there are a number of components to this procedure. You have to elaborately detail the geographic distribution of the plant, the taxonomic status and related species of the plant, it's biology and growth characteristics, the nature and extent of damages caused by the plant, it's economic importance, and any beneficial effects that are found. These need to pertain not only to the U.S., but to adjoining countries that may be affected. You have to show the current status of research on the plant and lay out the justification and expected results of the control program. So, there's a lot of documentation that's needed. A lot of this can be done in the United States. We did this for purple loosestrife by putting out a pretty detailed publication documenting the case for biological control of purple loosestrife on North American wetlands.

    When it comes to identifying insects for control, though, you have to go to the native range of the target weed. You have a detailed list of criteria for selecting different insects that feed on the plant, developing host specificity criteria for the plant, screening, and a number of different issues. You really can't do it by yourself. I work for the National Biological Survey, formerly the Fish and Wildlife Service. When I got into this, I incorporated help from the Beneficial Insects Laboratory of the U.S. Department of Agriculture, and the International Institute of Biological Control field station out of Switzerland. We set up work with a student at a university in Kiel,Germany, and worked with the Beneficial Insects Quarantine Lab in Blacksburg, Virginia.

    Once you select your target weed and identify potential control agents. You begin an implementation period, which is basically where we are at now. This involves bringing insects into the country and releasing them. There's a lot of research that needs to go on regarding breeding of the insects, problems you may have with natural predators that may be here, whether you release one insect species or multiple numbers into each area, and whether the insects can establish in all the areas where the plant is found. There are number of components there. You also have a monitoring situation and an evaluation phase.

    With the loosestrife program, we developed a working group, which is an international scientific advisory staff. A lot of the people that started with the program and their respective organizations make up that group. We also have a number of individuals from universities across the country and from Ag Canada to help advise on how to best implement the program. We enlist the help of a lot of State and additional Federal agency personnel to help implement the program and to make them aware of what is going on. We have contact with natural resource and agricultural agencies in at least 35 states, regional offices of the Fish and Wildlife Service, BLM, BOR, BIA, National Park Service, USDA-Forest Service, Corps of Engineers, and Canada. All of these people are on a mailing list and we distribute a newsletter of research highlights and solicit funding from all these different agencies at one time or another to keep the program going. We also put on workshops to keep people informed and try to get them involved and up to date. A good overview of our program can be found in the November 1993 issue of BioScience.

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    Charles M. Jarecki
    Ranch Owner/Operator (retired)
    Polson, Montana

    The spread of noxious weeds throughout Montana's rangelands has reached an epidemic state. Every range manager in the state is confronted with the challenge of coping with the invasion of foreign plants.

    Although many of these invader plants have been in the area for several decades, it has only been in the past twenty years or so that there has been an explosive rate of spread. Native plants are being crowded out. In many areas, the diverse mix of native vegetation now is largely replaced by a monoculture of a particular weed species. Soil stability is threatened and surface runoff increases as fibrous-rooted grasses are replaced by taprooted herbaceous weeds. Quality of wildlife habitat declines as the plant species change, and ranchers must adapt their livestock operation to a much smaller forage base.

    Montana's 64 million acres of rangeland and grazable woodland now has an estimated infestation of 4.7 million acres of spotted knapweed (with the potential to infest one-third of the state), 550,000 acres of leafy spurge, 100,000 acres of dalmation toadflax, and lesser amounts of diffuse knapweed, Russian knapweed, white top, goat weed, and sulfur cinquefoil, which is probably the fastest spreading weed in the state. Several new noxious rangeland weeds (yellow star thistle, common crupina) are now invading Montana from surrounding states.

    The Irvine Flats Weed Project

    Twelve ranchers in an area known as Irvine Flats fifteen miles west of Polson in Lake County, Montana, were faced with the situation described above. I was one of the twelve ranchers. After several years of individual weed control efforts by some and none by others, we decided in 1986 to develop a coordinated program to control the range weeds. This paper describes our program, summarizes our accomplishments, and discusses the problems that we encountered. The things we learned on Irvine Flats should help other groups implement weed management programs.

    The seventy-square-mile project area is mostly native rangeland. The predominant grass species are bluebunch wheatgrass, rough fescue, Idaho fescue, and basin wildrye. The soils are generally fine-textured on the flatter valley bottom and silty on the surrounding hills. Elevations range from 2,800 feet to 5,000 feet. Average annual precipitations range from 13 to 16 inches, depending on location.

    Small infestations of various noxious weeds have grown on Irvine Flats for at least three decades. During recent years, however, the magnitude of the problem increased dramatically as the scattered weed patches aggressively spread to new sites. For several years some local ranchers had an on-going weed control program on their own land and lands they leased.

    The first steps were initiated in 1985 when five of the twelve ranchers entered into an agreement with the Lake County Weed Control Board to spray right-of-ways along 25 miles of roads on Irvine Flats. Normally this work would have been done by the County, but with 1,200 miles of roads in Lake County and only three spray trucks, Irvine Flats was often done last, or not at all. We believed we could do a better, more timely application at less cost. Besides, we already knew the location of all weed patches. Per agreement, the County supplied the chemical, and we did the application at our own expense. All adjoining property owners were notified of the pending spray progam. No objections were received.

    Our coordinated effort began in 1986. At the first organizational meeting of the twelve ranchers, we delineated property ownership on an area map. It was probably the first time that we knew the boundary, location, and size of our neighbors' land holdings. Transparent overlays were used to record the exact location and acreage of spotted knapweed, goat weed, leafy spurge, white top, sulfur cinquefoil, and other noxious weeds. Another overlay was used to delineate previous control efforts in the region. The objectives of our project were defined:

    The next task was to determine what the estimated annual cost would be for each rancher for a three-year control program and what each of us could budget for that purpose. There was some foot-dragging on the part of a few, and some were not in a financial position to fund their total needs. To solve this problem, the group decided to submit a grant request to the Montana Weed Trust Fund to cover the monetary shortfall.

    The Montana Weed Trust Fund is administered by the Montana Department of Agriculture. The monies are mainly derived from an annual $1.50 assessment on each licensed car and light truck in Montana. This raises approximately $2 million each year. By law, at least 25 percent of the funds must go to non-chemical weed control research. The balance is available on a competitive basis for project areas such as the Irvine Flats group. A Noxious Weed Advisory Council appointed by the Governor evaluates and ranks the proposals, and the Director of the Montana Department of Agriculture awards the grants. The Lake County Weed Board agreed to "sponsor" our group, thereby providing the mechanism needed to transfer funds from the State to the ranchers.


    During the three-year period (1987-89), we sprayed 15,031 acres of weeds in Irvine Flats at a total cost of $182,650. The Weed Trust Fund contributed 21 percent of the monies spent. Because there was still some control work to do, we prepared and submitted an application for an additional year of funding. Our Irvine Flats project was awarded $15,000, which we pooled with $31,680 of our own money.

    In the four years, 18,122 acres of weeds on Irvine Flats were sprayed at an average cost of $12.65 per acre. Most of the application was done aerially, using a locally-based helicopter. Neighbors cooperated together, serving as flagmen for the aircraft. Numerous flaggers, as little as one-quarter mile apart, resulted in accurate application with very few skips, even on rough terrain. Ground sprayers were used on small acreages and roadsides. Eleven of the ranchers had one or more ground sprayers. Several had trucks equipped with water tanks holding up to 1,000 gallons.

    Some additional accomplishments were:

    Problems, Challenges, and Hindsight

    Our program was affected by economic factors, public perceptions, government bureaucrats, personalities, and other problems. We purchased chemicals as a group, which resulted in considerable savings for the project. Our attempt to economize created an unusual problem. After the second year, the chairman of the Lake County Weed Board wanted us to purchase our chemicals from the Lake County Weed District. Because the County's prices were much higher than our wholesale price, the County could make a profit on the sales. However, in order to control the most weeds for the dollars available, we wanted chemicals at the lowest possible price. After we bought our chemicals elsewhere at a more favorable price, the chairman, in all his wisdom, terminated the Irvine Flats road spraying agreement between the Weed District and our group. He also suspended the office support sponsorship for grant preparation that had previously been available to us. After that, the right-of-ways along county roads in Irvine Flats never got properly sprayed. The action of the Weed Board chairman did illustrate that is is difficult for a group of ranchers to correspond, communicate, and develop grants without administrative support. Fortunately, the Lake County Soil Conservation District donated office support and sponsorship after the Weed Control Board declined further assistance.

    Our program was not as well perceived as it should have been by the general public. We were frequently asked, "Why do you only rely on herbicides? Why not cultural, grazing, and biological control?" First of all, pulling, mowing, and cultivating weeds is not feasible on rangeland. It is not being farmed for good reasons: steep terrain, rocky ground, and shallow, arid soils. Large acreages are often involved.

    Some ranchers in Montana and researchers have tried using various grazing methods to control weeds. Their only success has been to use sheep for leafy spurge control in small pastures. Animals have not controlled spurge on extensive rangelands, or controlled cinquefoil, knapweeds, or toadflax in any situation.

    Biological control is still not available. Although eleven insects either have been or are about ready to be released to control spotted and diffuse knapweed, to date knapweed densitites have not been reduced. Other weeds, such as sulfur cinquefoil, are not even being studied yet.

    The success of our project was also affected by personalities of individual ranchers. Because most of us are independent, it takes strong leadership to keep individuals focused on the objectives and working as a team. Several of the ranchers are now embroiled in an issue involving water rights, so they are not on speaking terms with each other.

    In hindsight, I believe that only a few of the twelve ranchers were the driving force that got this project started, but all of us contributed toward its success! We realized that if we didn't do something big and do it fast, our rangeland would soon become a wasteland of weeds. To put it bluntly, the range had a case of AIDS, and it was slowly dying. We were motivated.

    The monies from the Montana Weed Trust Fund served as a catalyst that allowed the coordinated effort to succeed. It brought the group together to work as a whole as well as getting some foot-draggers and low achievers to join in the effort. The improvements in range condition and productivity made believers out of those who first hung back. As in every group, there were personality problems and different short-term goals. But by keeping lines of communication open and using peer pressure, the project progressed to a successful conclusion.

    Finally, there were no Federal lands involved in the Irvine Flats weed project area. No time and energy were wasted dealing with bureaucratic red tape and foot dragging. The ranchers just got on with the job that needed to be done.

    Where does the Irvine Flats Weed Control project stand in 1993? Without communication, peer pressure, the incentive of the Trust Fund monies, and leadership, the group has become fragmented and ineffective. Individuals have retrogressed to individual weed control efforts. Some of the members have abandoned any real effort. Others are doing their best.

    Rangelands on Irvine Flats are probably in better condition than they have been in years. Much of the improved condition is the result of our cooperative weed project. However, constant vigilance on everyone's part is needed to preserve what we now have in range forage production and soil stability. Perhaps, when other issues become resolved, the cooperative spirit in the community will return to the benefit of everyone.

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    George F. Hittle
    Weed & Pest Coordinator
    Wyoming Department of Agriculture
    Cheyenne, Wyoming


    Before we motivated anyone, it was imperative that we have effective laws in place that involved numerous groups working together, including agriculture organizations, public interest groups, municipalities, and private, state and federal landowners. We have two laws that complement one another:

    1. Wyoming Weed and Pest Control Act, and
    2. Wyoming Weed and Pest Special Management Program.

    The amendment to the Federal Noxious Weed Act (P.L. 93-629); Section 15, The Management of Noxious Weeds on Federal Lands, was added in 1990. The two Wyoming laws pull numerous groups together - All private, state, and federal landowners and municipalities are included in a district. Section 15 unites federal agencies with state agencies, including political subdivisions through cooperative agreements and memorandums of understanding.

    You have to think positive and be willing to try new, innovative ideas. You need a state-wide coordinated system. You need qualified weed supervisors to provide the leadership that is the catalyst for an effective program. A mandated financial structure has to be in place. We have all of this in our system.

    Wyoming's land status consists of 62.7 million acres, of which 42.5 million (68 percent) acres are range and permanent grass pasture. Elevation ranges from 13,804 feet to 3,125 feet. One can see that grazing lands are one of our most important renewable resources for wildlife and domestic animals, and provide for a multitude of benefits for outdoor recreation. To protect and preserve our natural resources, it was critical that we worked together to achieve a common goal. We had to be organized to do the job and provide leadership and coordination in developing education and awareness programs. We had to convince private, state and federal landowners and the general public that noxious weeds (undesirable plants) were in fact invading our valuable rangelands. The term "grazing lands" (private, state or federal) can be misleading when it comes to the general public. The perspective is still out there that grazing lands are only for livestock producers; other valuable uses are not recognized.


    In order to formulate a successful organization, interaction must take place between many organizations. You have to recognize what is available to you and take advantage of it under a coordinated system. In our membership and operating procedures, responsibility and authority are shared by more than one person or group. It may appear to be a complicated system, but really it is not, mainly because the law spells out the functions of each entity. Following is a brief breakdown of our operating system (see Figure 1):

    As for ties with other organizations and state and federal agencies, this is a never-ending list. We attempt to have some kind of affiliation with our own state agencies and organizations. We continue to work with other states, trade associations, federal agencies, and members of Congress. Two examples of this are the Intermountain Noxious Weed Advisory Council (INWAC) and the Western Weed Coordinating Committee (WWCC).

    Weed Control Methods

    Wyoming's Special Management Program (SMP) enacted in 1989, requires an Integrated Management System (IMS) be implemented. In this system the districts may establish management zones, which are geographical areas. The management zones are established with written consent of a majority of the landowners within these zones. The treatment program means the use of an IMS prescribed by the district. Treatment includes both materials and methods used in the IMS. In the SMP the landowner contributes 20 percent and the district pays 80 percent of the overall treatment program. This is a catch 22 program. If a landowner chooses not to sign up for the SMP, the district is still compelled to comply with the other Act and may have to pay for 100 percent of the treatment program. The main thrust of our current program is to get all the districts involved in the SMP.

    Wyoming uses the Weed Management Area (WMA) Concept, which is patterned after the guidelines for Coordinated Management of Noxious Weeds in the Greater Yellowstone Area of Idaho, Montana, and Wyoming. The WMA intensifies and unites individual ownerships or jurisdictions that form land units for mapping, planning, monitoring and managing noxious weed programs. Cooperators in the WMA jointly prioritize weed management efforts based on species or geographical area. Cooperators then work together to manage weeds within the area. Cooperating in a WMA provides proper planning, pooling of resources, and individuals are involved in the decision making process. These programs are just now being implemented in Wyoming.

    The Integrated Management System (IMS) is the planning and implementation of a coordinated, ecologically-based program using all proven methods to prevent, contain and control undesirable plants. This includes, but is not limited to: education; preventive measures; physical methods; biological agents; herbicide methods; cultural methods; and management. We have defined IMS in our own law and in the federal law. Components of IMS are not defined in either law. However, the Intermountain Noxious Weed Advisory Council (INWAC) has published a brochure to define these terms to give the public a general understanding of the IMS. This pamphlet is available upon request. In Wyoming, IMS methods being implemented on grazing lands are:

    One has to understand the initial associated cost in initiating the Integrated Management System is not cheap. Our own state legislators believe in the IMS, but have a problem with the high cost of installing this system. You have to prorate the cost of the IMS over a period of years, the same as you would amortize your equipment or vehicle.

    Lessons Learned

    Once we obtained support and were organized to do the job, success came without complications. The state was hungry for an effective weed control program; individuals with an interest in weed management and college degrees were coming on board; federal agencies were funding their share of the program within reason on federal lands; state support on funding was there; we had an excellent relationship with the University of Wyoming; and we were strictly chemical oriented. We stayed chemical oriented until 1989, and at that time the Special Management Program passed the state legislature, allowing us to start implementing the Integrated Management System. However, from July of 1983 through June of 1993 we provided the University of Wyoming $257,500 in grants to start researching various components of the IMS.

    Any time one has an aggressive program, mistakes and failures are going to occur. It does not make any difference what kind of business you are involved in, it happened to us and it will happen to you. But, we learned from our mistakes and failures and built a more effective program. Failures occur when individuals or organizations lose interest, funding becomes restricted at both the state and federal level, landowner's monetary resources fall short, districts take the program for granted, and some even believe it is a voluntary program. We have some federal agencies that believe they do not have a problem with noxious weeds on grazing lands.

    Barriers to More Effective Management of Noxious Weeds

    I do not see any realistic barriers to management of noxious weeds as it pertains to private and state grazing lands. The federal government administers approximately 52 percent of the land in Wyoming. You might say we are only carrying out half of a program. Barriers to more effective management of noxious weeds are:

    1. Policy and leadership
    2. Funding
    3. Awareness education, and technology
    4. Low priority and interest
    5. Cooperation, coordination, and communication

    We have one federal agency that believes they do not have a problem with noxious weeds on range lands and we are not the only state in a dogfight with federal agencies failing to prioritize and implement effective weed management programs. Okanogan County, Washington, has one federal agency that apparently does not realize the negative impact spotted and diffuse knapweed have on the native or natural ecosystem. It is obvious that Section 15, the Management of Undesirable Plants on Federal Lands, means nothing to this agency in that area. If we had more weed specialists or weed scientists within the federal system, incidents like this one would not happen.

    However, in all fairness to the federal agencies, I do believe we are starting to address these issues and break down some of the barriers. The new legislation enacted by Congress on the "Management of Undesirable Plants on Federal Lands" is going to set the standards. In 1989, the USDA/Forest Service in cooperation with the USDI/Bureau of Land Management, and the Intermountain Noxious Weed Advisory Council, sponsored a workshop to focus on the goal of strengthening intergovernmental coordination and cooperation to improve the effectiveness of weed management programs. The Western Weed Coordinating Committee (WWCC) has since carried on this forum for cooperation.

    Questions and Answers

    Q: Are we absolutely sure that the insects brought in for biological control won't adapt to live on other, more desireable plants?

    A: Rich Malecki: When I started out on my loosestrife work, I was real skeptical about this, too. Basically, the entomologists and other people involved in biological control are extremely thorough. The insects we looked at in Europe were screened using 50-60 different test plants. A list of these plants was sent around the country to botanists and different groups to satisfy their concerns. We tested all the plants in the loosestrife familiy in North America and a large selection of wetland plants. Then there were the agricultural crop plants that were required by APHIS. In addition to test conducted in Europe, we screened any questionable plants again with insects in the U.S. under quarantine. In the case of the insects we were bringing in, a couple of them did have some questionable plants that they fed on. That caused some concerns in Canada and the U.S, so we spent an extra year and actually took these plants from the U.S., sent them to Europe and established them in the middle of loosestrife stands. In Europe, the insects ate all the loosestrife plants, but didn't touch the others. There's a limit to how convincing you can be, but in this case, there's rigorous testing and an environmental assessment was prepared that went to the TAG. You're never going to be absolutely, 100 percent sure, but its a thorough process, and I feel pretty secure in the procedures and protocol that have been developed to date.

    A: Chuck Jarecki: I'd like to make a couple of comments on biocontrol. That's kind of the buzzword and chemicals are not as much as they used to be. 20 years ago, we were all told, "You guys hang tough and the bio work is coming on strong and in the '90s we'll see a way to control these weeds and you won't have to be patronizing Dow and all the other guys." Well, I'm still waiting. I'm looking mainly at what the time lag is. We've been 25 years on spotted knapweed bio research. First, we stole some bugs from the Canadians. They're a fly that lays an egg on the flower that forms a gall which reduces seed production. Great guys! We thought we're on our way, this bio is going to be a snap. All you've got to do is get a few more things. Well, we found out a few things about these seed heads with the galls in them. The mice like to store them away for winter feed. So you've got a natural predation on the gall fly. All right, we've got what looks like 10 insects that are going to work on spotted knapweed, that's one every 2.5 years. Now, we've got weeds coming out the gazoo that nobody's even started on yet. So we get the knapweed kinda half ways under control and 4 or 5 others are going to take it's place that nobody's even started to work on. So, I guess that if I look at the future 100 years down the road, what we may have is a mosaic of what we consider today to be noxious weeds that will be fighting amongst themselves with insects on them trying to keep them under control to some extent, so our rangelands will be a bunch of naturalized aliens. It's a grim scenario, but I think we have to look at the worst case analysis. It scares the hell out of me as a land manager. I'll be long gone and so will everyone else in the room, but it can be very serious for the future of grazing lands in North America.

    A: Rich Malecki: I'd like to add to what Chuck is saying because I agree with him on a lot of this. When I started to work with loosestrife, this was a real prevalent noxious weed as far as wetlands are concerned, and that's my area. We had some preliminary indications that insect agents were available and that there was a good chance for biological control. But it would probably take $1 million to pull this off. That is, to have a natural control mechanism that's going to be long-lasting and hold loosestrife at the levels experienced in Europe and Asia. I'm into my seventh year and we've spent about $700,000, starting with $400,000 in congressional appropriations and the rest obtained in a piecemeal fashion. In the end, it's going to be awful close to that $1 million. That's a lot of money to most researchers. There are a lot of problems associated with biocontrol, but there are also a lot of problems associated with chemical control that we're well aware of. We haven't put the emphasis into biocontrol that we've put in other areas. It needs a lot more stimulus to bring it in as one of the techniques that can be used in an integrated pest managment program. Somebody mentioned funding, and that's a big part of it. You have to be able to allocate a large number of dollars for people to get moving in this direction. The people are there and so is the expertise to follow up on this. The trick is to get onto foreign plant species before they really become problems. But, there has to be a program out there. Right now, there are very few organizations or agencies that are strong in biocontrol. At least I haven't noticed many. I think the new OTA report is a step in the right direction, along with meetings like this one, in making people aware of biocontrol. It's a buzzword that needs to be promoted a lot more.

    Q: Are you talking $1 million total over how many years?

    A: Rich Malecki: Yes. This program went pretty smooth. We've spent $700,000 in 7 years and we're probably talking about another $300,000 over the next 10 years before the insects are really established and we have some measure of control.

    Q: The reality is $100,000 a year over even 15 years isn't really that big a cost. I mean, you're talking about a highly significant problem of controlling something like this, and $100,000 a year doesn't really buy you very much in terms of research. I think you've gotten a lot for your money.

    A: Rich Malecki: Right, but go out and find a plant and try to find $100,000 to study it. Even with big problem species, it's hard to come up with those kind of dollars.

    Q: I don't want to put ARS on the spot, but how much money does it have available for biocontrol purposes?

    A: Jim who?: For all kinds of biological control, all kinds of pests that we deal with--plant pathogens, insects--that's $44 million (???) a year. I should add that one thing we get by on rather cheaply is providing for the base funds for projects, that are provided on a "soft money" basis. We're not talking about salaries and overhead there. One thing I would like to do is draw a little comparison. Let me tell you where I'm coming from. Up until a few months ago, I was a bench scientist out in the field trying to get some of this funding. Now I'm in this realm where I begin to see some of the sources of the funding. It's become clear to me that we in the agricultural and environmental science research area are just dealing with peanuts in terms of the money that's available at the Federal level. We have to find a way to get these people's attention. And that's just in Federal dollars. If we talk about industrial money that's available, it's even larger. We're complaining about trying to find $1 million for 8 or 10 years for a biocontrol agent. How much do you think just one of the run-of-the-mill chemical companies spends to create a herbicide? About $100 million, at last count. And, that's to get to a positions where producers have to spend a lot of money on the product, that pests will eventually tolerate. With a biological control, once it's established and working, it's permanent. We're going after peanuts, in terms of funding, compared to the money that's out there.

    A: Tim Butler: Getting back to the example of tansy ragwort, our economic study that we did reveals that we're getting back $5 million back on our investment per year. I think that's a pretty good return on investment. That didn't include all the money for research, as far as money for screening and some of the other research costs, but it did include money for collection and distribution, and the program costs.

    A: Jim? : I'm not one to say we just need to throw money at these problems, but something needs to be done to elevate the level of funding available to do this research and develop these programs or we're never going to get the kinds of biological controls we need.

    A: George Beck (or Hittle?): I think there's a lot of confusion over biological controls. If you look at them strictly as weed control, you get mired in mud. It may take millions and millions of dollars to screen and bring in the right insects. But this is an ecological process. Biological controls are not the whole answer. However, once the insects are established, and over the course of time, a time that may be long even in terms of the lifetimes of the current generation of workers in the field, the insects increase in effectiveness, whereas herbicides constantly lose effectiveness over time. You have to stand back and look at it as an ecological process, rather than simply as weed control at the moment.

    Also, each weed needs to be dealt with on it's own merits, at least in it's biological control aspects. There are numerous examples of shining success in biological control this century. It's a very complex process. A plant like leafy spurge succumbs much sooner than spotted knapweed to some of the insect predators that have been brought into the U.S. Some of that is our own lack of understanding in the weed science community of how to advance our science. We've been figuring out how to kill this plant, rather than trying to understand the relationships.

    A case in point is diffuse or spotted knapweed and the seedhead project. When weed scientists became involved in the diffuse knapweed issue, we found that it was no wonder the seedhead project didn't work very well. I'm not saying that weed scientists have all the answers, but working with entomologists, weed scientists understand a lot about what the plant is doing that can help understand how the insects can work better. The models that we developed to describe what was going on in that plant community definitely indicate that if you want to bring down the population of weeds, you need something that attacks the mature weed, not seed production. The same thing likely can be said about any seedhead predator on a biennial plant. That's not necessarily true of an annual plant. We shouldn't overemphasize the importance of biological controls, but we don't need to oscillate too far in the other direction, either.

    A: John Randall: I agree with what George is saying. The problem I see is actually one of human psychology. I've seen a slide of a farm field with musk thistle in 1965 and the same shot in 1980, when the thistle was gone. You have to constantly show that shot to farmers to remind them of how effective biological control was for musk thistle. That's part of the problem with the success of biocontrol. In the West, we don't think about musk thistle, that's not a problem and that program is of historical interest. But we don't think about how we're saving $50 million a year, we don't remember that, but it's true. So that investment that was made long ago, we don't think about how valuable that is. The same is true of the programs Randy Westbrooks was proposing where we try and exclude plants, and if we do get them in this country, hit them hard right away. Those success stories, no one has ever heard about, so we don't value them appropriately. The same is true on a small scale. If one of TNC's stewards on one of our preserves yanks up the first weed that comes in, he doesn't right a story telling us how much damage he's prevented for 5 cents worth of work, but it's true. We're just not very good at thinking of these preventative actions that way.

    Q: I'll be able to verify this in about a month, I think. There's a least one seed catalog that sells purple loosestrife. Isn't there some kind of control so that if a plant is a noxious weed, it can't be sold?

    A: Rich Malecki: Purple loosestrife is not on the Federal noxious weed list. It's probably on about 17 State lists. Some States have quarantines that prevent it from being sold in their State.

    Q: Tim Butler showed a list of the goals and objectives of the Western Weed Coordinating Committee. One of them was to identify barriers. What barriers have you identified along the line and what have been the resolutions?

    A: Tim Butler: That's an ongoing process. Some of the things that we've been working on have been better working relationships with Federal agencies. There have been some problems as far as implementing Section 15 of the Federal Noxious Weed Act and developing agency policies within different agencies. We're working along lines to strengthen those ties and working with some of our committe members to resolve some of those things. I think we will have a lot of other things in the future as the committee gets stronger and as we sit down and work to identify some of these areas to really focus on. I think that the report out by the Office of Technology Assessment brings out some barriers that are currently in place that we need to be working more on as far as the importation of plant materials and nonindigenous plant materials into the U.S.

    A: Janette Kaiser: In the State of Oregon alone, Federal agencies get money on a fiscal year basis according to a five-year plan. We're working on the FY95 budget right now. So we can't respond to emergence of new infestations unless that money was pulled out of existing budgets. The WWCC pointed out that this was problem. One of the things we in the Forest Service figured out was a way to channel money to the State department as a cooperator. They can take money for long-term emergency response. The committee was also pointed out that the Forest Service National Forest plans often didn't reflect the goals and objectives of the State regarding noxious weeds. We've moved toward common goals.

    Concluding Comments

    Deen Boe
    Forest Service, USDA
    Past-President, Grazing Lands Forum

    I want to reiterate the mission of the Grazing Lands Forum. That is to seek to improve cooperation, by increasing knowledge, understanding and awareness of grazing lands. "Grazing lands" is a very broad term. Some folks have it tangled up with only livestock grazing or only in the West. An individual who works here in the Hall of States walked by this morning and was curious about our meeting. When we told him what we were doing, he said "I guess that doesn't affect us, there are no grazing lands in the Northeast." He works for the Northeast Governor's Association, so I guess we have a little education yet to do here in the Northeast.

    The Forum process promotes an ongoing exchange of information and viewpoints about selected grazing land issues. I hope we've moved a little bit in that direction in this meeting, our eighth Forum. I know one of the things we try to do is provide opportunity to increase your own networking. That's the reason the breaks were as long as they were. I know I've made three or four contacts here that are important to me, and I hope the rest of you have been successful in that way. We hope to serve as a catalyst for some future actions and facilitate some technology transfer. On thing I didn't hear much about today is "ecosystem management". I did hear a lot about "integration" and "partnerships" and "cooperation" that fit into it. A lot of what's been talked about today are basic tenets of ecosystem managment. Maybe that's something we need to look at in a future Forum.

    On behalf of the members of the Grazing Lands Forum, I wanted to thank all the speakers who presented material here today. I think we had some outstanding speakers today and a good cross-section of opinion across the whole topic. Of course, I want to thank the audience. This is the largest turn out we've had. Earlier Forums weren't designed for a large group, but this Forum was designed to attract a crowd. The participation at this Forum was excellent.

    I want to thank the program committee for an excellent job of planning and carrying out this Forum, which contributed so much to it's success. I also want to express our thanks to the Society for Range Management, National Capitol Chapter, and particularly Greg Hendricks, for helping with the physical arrangements.

    Top of Page


    David B. Hannaway
    Associate Professor
    Department of Crop & Soil Science
    Oregon State University
    Corvallis, Oregon 97331-3002

    A workshop on "Innovative Systems for the Use of Forage/Grassland/Rangeland" was held at the Airlie House Conference Center in Virginia on September 22-24. This workshop was organized by Walt Wedin and Preston Jones and was sponsored by the Cooperative State Research Service (CSRS). I bring the conference to your attention to report on what happened there and enlist your individual and collective support in the conference follow-on activities.

    Attending were about 60 scientists, organization representatives, and industry leaders from a wide spectrum of interest areas. One of the exciting things about the conference was the linkages that were forged between groups that traditionally have not met together. I see similar linkages going on in the Grazing Lands Forum. The participants explored ways of broadening the base and public information/knowledge on the importance of forage/grassland/rangeland for all Americans. The workshop was organized with three interfaces of concentration with three working groups in each interface:

    One of the outcomes of the Airlie Workshop will be a traditional proceedings issued by CSRS that describes the educational and research priorities and needs for grasslands, rangelands, and conserved forages. The proceedings are scheduled for publication in March of 1994.

    For more information about the workshop or the proceedings, contact:

    Walt Wedin (project coordinator)
    phone: 612-625-9261
    fax: 612-625-1268
    email: kessl001@maroon.tc.umn.edu


    J. Preston Jones (CSRS)
    phone: 202-401-6627
    fax: 202-401-4888
    email: jones@csrs.esusda.gov

    Today, however, I also wanted to brief you on two non-traditional or innovative outcomes of the conference; an electronic mailing group and a brochure. The mailing group is a way to network scientists and other individuals interested in grasslands. I invite any of you who are interested and have an Internet (computer) address to get connected to that network. The grasslands mailing group on Internet can be contacted through email at:


    To subscribe or for further information about the mailing group, contact:

    David B. Hannaway
    phone: 503-737-5863
    fax: 503-737-1589
    email: david.hannaway@oregonstate.edu


    Robert Lucey, President
    Northeast Pastures Management Coordination Committee
    Cornell Univ. - Emerson Hall
    Ithaca, NY 14853
    Phone: (607) 255-1765
    Fax: (607) 255-2106

    Deen Boe, Past President
    USDA - Forest Service
    P.O. Box 96090
    Auditor's Building
    Room 601 RP-E
    Washington, DC 20090-6090
    Phone: (202) 205-1460
    Fax: (202) 205-1096

    Greg Hendrix, Second Vice President
    Soil Conservation Service, USDA
    P.O. Box 2890, Room 6142
    South Agriculture Building
    Washington, DC 20013
    Phone: (202) 720-0436
    Fax: (202) 720-2646

    Dan Undersander
    Executive Secretary
    American Society of Agronomy
    1575 Linden Drive
    353 Moore Hall
    University of Wisconsin
    Madison, WI 53706-1597
    Phone: (608) 263-5070
    Fax: (608) 262-5217

    Ralph Heimlich, First Vice President
    USDA-Economic Research Service
    1301 New York Avenue, N.W.,
    Washington, D.C. 20005-4788
    Phone: (202) 219-0431
    Fax: (202) 219-0029


  • Deen Boe, Forest Service, USDA, Co-Chair
  • Ralph Heimlich, Economic Research Service, USDA, Co-Chair
  • Faith Campbell, Natural Resources Defense Council
  • Jim Clawson, Agronomy and Range Science Department, UC-Davis
  • Greg Hendricks, Soil Conservation Service, USDA
  • Janette Kaiser, Forest Service, USDA
  • Ken Krupa, Economic Research Service, USDA
  • Bob Lucey, Northeast Pastures Management Coordination Committee
  • Greg Ruhle, National Cattlemen's Association


  • Ralph Heimlich, Economic Research Service, USDA
  • Dan Undersander, American Society of Agronomy, University of
  • Wisconsin-Madison


    Last updated November 29, 1995.