The presence of the endophyte Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon, and Hanlin in many tall fescue pastures (E+) and E+ fescue volunteer stands may diminish the biological diversity of soil organisms, insects, plants, birds, and mammals (Clubine, 1995; Matthews, 2000; Palmer, 2001). A 0.61- to 0.74-m wide border around tall fescue pastures, composed of native grasses either with or without legumes, can moderate the effect of E+ tall fescue on wildlife (Clubine, 1995). A border supplies some food and cover for small game, and is particularly effective when the pasture is adjacent to a well-managed forest.
Studies have shown that tall fescue is allelopathic to rape (Brassica napus L.), birdsfoot trefoil (Lotus corniculatus L.), red clover (Trifolium pratense L.), crabgrass [Digitaria ciliaris (Retz.) Koeler], white clover (T. repens L.), sweetgum (Liquidambar styraciflua L.), and loblolly pine (Pinus taeda L.) (Luu et al., 1989; Pederson, 1985; Peters, 1968; Peters and Zam, 1981; Walters and Gilmore, 1976; Wheeler and Young, 1979). These studies did not reveal whether the endophyte or the tall fescue caused the allelopathy, neither did they suggest a mechanism for the observations. In a recent study, both E+ and endophyte free (E-) tall fescue seed extracts exhibited allelopathy to red and white clovers, small white clover (T. nigrescens Viv.), crimson clover (T. incarnatum L.), and subterranean clover (T. subterraneum L.) (Springer, 1996). In general, there is little plant diversity where dense stands of E+ tall fescue occur.