AgWatch

Watch For Ergot In Tall Fescue This Season

 LEXINGTON, KY.
   The ergot fungus, Claviceps purpurea, is a widespread fungus that attacks the flowers of a number of grass species. The ergot fungus infects only the flower parts of certain grasses, and replaces the seed with "ergots". Ergots are survival bodies of the fungus that are easily recognized with the naked eye. They look like dark brown to black, curved miniature cigars measuring 1/8 inch to 3/8 inch. They are longer than grass seed, so they stick out beyond the glumes (Figure 1). If you cut them open, you'll see that they have a gray to whitish interior. These ergots will be evident as the seedheads approach maturity. Tall fescue is commonly affected in Kentucky, though other grass species may also be attacked.
   C. purpurea is related to the fungal endophyte of tall fescue, and both are capable of producing potent toxic alkaloids that affect animal health (and human health, if eaten). This is not a trivial issue; I once was subpoenaed to give a deposition in a case in Kentucky with economic losses of over $2 million, in which ergot was implicated as the cause. And in the past few weeks, there was a case of poisoning of livestock in Wisconsin when bedding composed of ergotcontaminated tall fescue seed hulls was used.
   Management
   Preventing livestock from consuming a significant dose of ergot sclerotia is the only reasonable course of action.
   • Pasture
   If seedheads form, inspect them for ergots. If they are found, mow before turning livestock out into the pasture. Mow the seedheads along the fencerow, as well.
   • Hay
   If the seedheads are dry before harvesting, the ergots will often fall to the ground during cutting/ tedding/baling. However, if the seedheads were still somewhat green when cut, the ergots can remain attached to the seedhead, and will end up in the bale. In harvested hay, ergots constitute a very small fraction of the total forage in the bale. Because of this, the risk from feeding these bales is low. However, repeated feeding of infested hay into a feedbunk can lead to accumulation of the ergots at the bottom of the bunk. Livestock may then consume a high dose of ergots when they feed on this residue.
   • Seed Production
   Where tall fescue is being grown for seed, avoid exposing livestock to the screenings and seed hulls, as these may be contaminated with ergots. Seed-cleaning operations concentrate the ergots and can pose a great hazard if livestock consume them. Δ
Dr. Paul Vincelli is Extension Plant Pathologist with the University of Kentucky at Lexington. 
Figure 1- Ergot sclerotia in seedhead of tall fescue.
 Photo by Steve Patton.

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