TALL FESCUE/ENDOPHYTE/ANIMAL RELATIONSHIPS


ENDOPHYTE EFFECTS ON PLANTS

Several years ago, scientists in New Zealand found that the Argentine stem weevil would devastate EF, but not EI,  perennial ryegrass.  This insect is not a pest in the United States, but this knowledge is of concern because the endophytes in the two grasses are closely related.

Greenhouse and environmental chamber work at several locations has shown that several inset species prefer and/or develop more rapidly on EF fescue.  Kentucky studies provided evidence that alkaloids in EI fescue are associated with increased resistance to insect feeding.  A greenhouse study in Alabama revealed over three times as many spiral nematodes associated with the roots and soil of EF, than of FI, plants.

A difference in vigor has been observed between EI and EF fescue pastures in some environments.  This has usually been seen only in new plantings, but in stressful environments in Louisiana and Texas (marginal areas for growing fescue), stand loss was greater in established EF pastures.  EI is also more drought tolerant than EF fescue.  Drought tolerance seems to be associated with EI plants having improved osmotic adjustment, greater sugar accumulation, better root growth and more leaf rolling to conserve water.

These finding have important implications.  First, while fescue is regarded as a forage crop which is easy to establish, that may be less accurate when the fescue is EF.  Thus, when planting EF fescue, a producer should carefully follow all establishment recommendations.  Overgrazing of EF fescue should be avoided, especially during the establishment year.  Fields to which EI fescue is only marginally adapted should not he planted to EF fescue.

Experience has shown that if overgrazing, severe drought or other highly stressful coalitions occur, EF fescue will not persist as well as, EI fescue.  However, EF fescue stands at the Auburn University Black Bell Substation have persisted and remained non-infected for over 15 years though separated from infected fields only by a barb oil wire fence.  Despite the need for higher management levels, the opportunities provided by EF fescue are great.
 

SEED PRODUCTION

The cool-season grasses are well adapted to the mild winters and or\harvest season found in the valley, of the Pacific Northwest.  Oregon has thus established a reputation as a dependable supplier of high-quality forage grass seed, and provides that seed for much of the forage production in the U.S.A.

The discovery of the role of the endophyte in reducing performance of animals grazing on tall fescue pastures resulted in the Oregon Department of Agriculture being assigned responsibility for testing and issuing the Oregon Forage Grass Seed Endophyte Test and tag for forage grass seed.

Results from the Oregon Department of Agriculture on endophyte testing of tall fescue seed from 1983-1989 show over 90% of Oregon's tall fescue Contained 5%. of less endophyte.  Of 2,381 tall fescue seed lots tested, representing 111, million pounds of seed, 93% contained 5% or less endophyte-infected seeds.  Of the seed lots tested, 1,271 were public cultivars (Alto, Fawn, Kentucky 31 and Kenhy) and 894 lots comprised 40 proprietary cultivars.  Lots with 5% or less infection received a state endophyte tag for seed bags

STRATEGIES FOR COPING WITH THE ENDOPHYTE

Livestock producers who have, or who plan to establish fescue fields should develop an intelligent "endophyte strategy" based on research findings.  The following is, a review of options available for avoiding or minimizing endophyte effects.

Establishing New Fescue Stands

When planting a new fescue field for livestock in an area where fescue is well adapted, a livestock producer should use non-infected seed, assuming overgrazing of the EF stand will be avoided.

In a sew states, it is required that percent endophyte infection be stated on fescue seed tags. The importance of knowing the level of endophyte infection in seed can hardly be over-emphasized.  The dramatically increased beef production on FF fescue can be expected every year for the life of the stand!

It is highly desirable to plant a legume companion species with fescue, especially with EI fescue.  The optimum approach is to seed tall fescue in late summer/fall, then plant clover in late winter or the following late summer/fall.  Legumes may dominate EF fescue if planted at the same time.  Kentucky research indicates that clover in a EF stand will further increase young animal gains by 0.2 pounds per animal per day.  However, the primary justification for planting a legume with EF fescue is to reduce N fertilizer expense.

White clover, seeded at the rate of 1 to 3 pounds per acre, is the best legume companion in most fescue pastures.  However, red clover, at a rate of 10 to 15 pounds per acre broadcast or 8 pounds per acre drilled, is another good possibility, especially when fields are to be cut for hay.  Other legumes such as birdsfoot trefoil or alfalfa may also be used.

Dealing With Existing Infected Stands

Producers with established fescue fields need to carefully assess their situation. Exiling fescue stands should be tested for endophyte infection on a field-by field basis.  Several states now have laboratories for determining endophyte level.  County agricultural agents can provide information regarding cost, sampling methods, and laboratory addresses.

Once the endophyte level in existing fescue pastures is known, a producer can select the best option for dealing with the problem.  The best way to handle one field may not be best for another.  Four general approaches are available.

1. Manage to minimize the effect -
Endophyte effects on animals can be minimized with management practices.  Grazing and/or clipping management that keep, plants young and vegetative will result in better animal performance.  Likewise, if fescue is cut for hay in the boot stage, better annual performance will be obtained than from late-cut hay.

2. Avoid the Endophyte-
Use of other forage species avoids the endophyte. Using EI fescue in spring and use of other grasses or grass-legume mixtures for summer grazing will avoid the endophyte during the summer when fescue forage quality is low.  Because annual performance is adversely affected by consuming EI fescue hay, feeding of hay of another species also can be helpful.

3. Dilute the Endophyte-
The endophyte or its products can be diluted through the use of other feeds in the diet.  Growing legumes with EI fescue is a particularly attractive option.  Many studies have shown greater liveweight gains, and improved (though Sometimes still unacceptable) pregnancy rates when pastures are renovated to include legumes.

4. Kill infected stands and replant
EF seed is now readily available in most areas of the United States where fescue is grown.  Careful consideration should be given to choosing new varieties.  A new variety that is simply "endophyte-free" will be of little or no value if it is not well adapted.  In view of reduced stress tolerance of EF fescue, the area of adaptation may he slightly less than for EI fescue, and a higher level of inconvenient will be required for successful establishment and for long-term persistence.  University trials are a good source of variety information.

In order to prevent later establishment of volunteer infected plants, any El field which is to be replanted should not be allowed to produce seed during the reestablishment year.  Seedhead formation should be prevented by heavy grazing, clipping or chemical application.

Under usual storage conditions, the endophyte will die in seed within one or two years.  Thus, volunteer plants from old seed will usually be EF or have a very low level of infection.  Unfortunately the germination level of fescue seed can drop sharply during long term storage, depending on temperature and humidity conditions. Furthermore, the vigor of seedlings resulting from planting old seed is likely to be reduced.

Methods of replacing EI stands Include:

A. Rotation - Rotating with other crops, followed by seeding EF, is an excellent approach.  There are many options ranging from no-till corn or a summer annual forage such as pearl millet, to longer term rotations involving a perennial such as alfalfa or two or three annual crops.

B. Prepared Seedbed - Certain situations permit destroying the old sod through tillage, preparing a seedbed, and then replanting EF rescue. However, it is often difficult to completely destroy an old fescue sod by tillage.

C. Chemical Kill No-till - Where methods A and B are not feasible, chemical kill of EI fescue followed by no-tillage planting of EF is the only remaining option.  This technique can be used to go directly from EI to EF fescue, or other forage cops can he used in a rotation.  It is critical that chemicals be used effectively, thus killing all the existing EI fescue.  Furthermore, in some cases there may be common bermudagrass or other species, which must also be killed, requiring the use of more than one herbicide or a higher herbicide rate.  Effective sod kill requires attention to label instructions and striving for optimum environmental plant conditions that will permit greatest chemical effectiveness.  Consult state recommendations on chemicals, rates, restrictions and time of application.

Best result from no-till tests have been found with late summer or early autumn seedings of fescue, except in the northern fescue belt where spring seedings are feasible.  Although chemical kill has been satisfactory in spring, summer drought and weed competition often reduce stand, of spring-seeded fescue.

A particularly effective approach is to use no-till plantings of annual forages after killing EI fescue.  For example, EI fescue can be chemically killed in the spring and a summer annual grass can be drilled into the killed sod followed by no till planting of EF fescue in the fall.  Similarly, fescue can be killed in the fall followed by sod planting of winter annuals and, if desired, sod planting of a summer annual grass the next spring.  Use of annual, in this manner "smothers" fescue plants which were not killed, and also reduce, the likelihood of insects in the old fescue sod damaging young fescue seedlings.