In a wet year like this, conditions are right for ergot infection; ergot is a fungus with the Latin name of Claviceps purpurea. The current humidity coupled with the warm temperatures will convert the state of Missouri into an incubator. And this month, ergot, which is a surface pathogen, will thrive; "ergot bodies" will begin to appear in grass seedheads; the best way to describe the appearance of ergot bodies, they look like mouse droppings.
Worldwide, ergot infection is most common in small grains, such as rye. In our state, infection occurs most often in tall fescue; this is simply because Missouri has so many acres of tall fescue.
Ergot produces toxic compounds called ergot alkaloids. These alkaloids are similar to ergovaline, the ergot alkaloid frequently reported in toxic tall fescue. These alkaloids cause ergot poisoning. Ergot poisoning symptoms in livestock are similar to symptoms of fescue toxicosis—lameness, heat stress, and poor production. Because of the similarity between these two disorders, many producers will phone up their extension offices to report "fescue foot," even though they are probably seeing ergot poisoning.
Management to prevent ergot poisoning is straightforward. Avoid feeding infected seedheads to livestock. This means clipping if the seedheads are infected. If hay is made, producers should be aware that at least half of the alkaloid concentration will remain. This is true even if the hay is field cured and stored for more than a year.
Occasionally, producers will feed screenings from a seed conditioner. If this occurs, producers must check the screenings to ensure no ergot is present. Ergot bodies in seed screenings are highly concentrated, as expected when the seed is cleaned. Therefore, these screenings are highly toxic, enough in some cases to kill the calves being fed.
After seed are removed, the pasture will be free of ergot infection for at least one more year.
REVISED: October 11, 2011