Tall fescue (Festuca arundinacea Schreb.) is a perennial forage grass that is now found growing in much of the southern half of Iowa. Its introduction was primarily for forage but is now also commonly used in turf, athletic fields, and soil erosion management applications.
Tall fescue has a lot of favorable traits. It is persistent, adapted to a variety of soil conditions, is compatible in mixtures with other grasses and legumes, can be harvested as hay or grazed, and has a March through early November growing season, making it the grass of choice for use in "stockpiled" or "fall-saved" forage for winter grazing pastures.
Unfortunately, much of the tall fescue growing in Iowa contains an internal fungus called an endophyte that produces alkaloids that can cause physiological problems in animals eating the forage.
The fungus is present in stems, seedheads, and the leaf sheath that wraps the stem. Alkaloids are found throughout the plant but in lower concentration in leaf blades and highest in the stems, seedheads, and seed. The presence of the endophyte is actually a benefit to the plant. Some of the alkaloids contribute to the plant's stress tolerance, vigor, and ability to resist diseases and insects. The undesirable alkaloid(s), including the ergovaline type, function as blood vessel restrictors in the animal and can be detrimental to livestock production and reproduction.
A first step in managing the tall fescue endophyte is to clip seedheads in early June to prevent animal ingestion of the plant parts with the highest concentration of alkaloids. Clipping seedheads is also the first step in a more comprehensive stand eradication and renovation. Additional intermediary fescue management steps are to introduce legumes into the stand and move livestock to nonfescue fields during the hottest summer months. Testing for the presence of the endophyte in existing stands is also a useful management practice that can indicate what percentage of the fescue plants in the pasture are infected and what further management steps may be needed. Mid- to late summer is the best time to test for the fescue endophyte. Extension crop and livestock specialists should be able to help you find a fescue endophyte testing lab.
This article originally appeared on pages Page 1-2 of the IC-494(12) -- May 31, 2005 issue.