Mow Pastures Now To Maintain Productivity

 EDWARDSVILLE, ILL.
   Ample rainfall this spring has resulted in lush pasture growth. Unless pastures have been intensively managed and heavily grazed, the forage grasses are currently in the process of seed production. Even intensively managed grazing systems will have some areas of the pasture where animals haven’t grazed, and grasses have formed seedheads.
   Because the seedheads are tall, the pastures appear to be lush, green and highly productive. In reality, grasses in the reproductive stage of development are focusing all of their energy on seed production, and producing little or no animal available forage. For maximum pasture productivity, it is important that these seedheads be clipped to return the grass to vegetative growth. An added advantage to removing seedheads is a reduction in the potential for animal health problems.
   Open pollinated forage grasses are highly susceptible to infection by the fungus Claviceps purpurea, which attacks the plant’s flowers and developing seeds. As the infection progresses, the developing grass seeds are replaced by fungal sclerotia, or black “fruiting bodies,” which are the reproductive stage of the fungus. The resulting disease is called ergot. Fungal infection and ergot development is favored by wet, humid, cool conditions during flowering.
    Animal health issues can arise because the Claviceps fungus produces alkaloid toxins which are detrimental when ingested by grazing animals. Ergot poisoning produces a wide range of animal symptoms, which may include hyper excitability, staggering, convulsions, dry gangrene and sloughing of the tips of the extremities (ears, tails, hooves, etc.). The only treatment is to remove the animal from the infected feed source, treat any secondary infections that may occur from tissue loss, and hope for the best.
    Although all of this seems pretty dire, the solution to the problem is relatively easy and inexpensive: Mow the pasture to prevent seedhead formation or remove any seedheads that have already formed. When baling grass hay, always harvest prior to seedhead formation. Most cool-season forage grasses will only attempt to form seedheads one time in the spring. Once clipped, they will remain vegetative for the remainder of the grazing season and ergot poisoning will not be an issue. Δ
ROBERT BELLM: Extension Educator, Crop Systems, University of Illinois