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Notice of Ergot in Grasses

June 7, 2002
Weather conditions this spring have been extremely conducive for the development of ergot. Jim Morrison, Crop Systems Educator at the Rockford Extension Center, reports that ergot is being found in cool-season grasses and in brome. Ergot is a disease that is most frequently found in grasses along fencerows and, of course, in pastures.

Ergot is a fungal disease of the seed head and can infect around 200 species of wild and cultivated grasses and open-pollinated small grains such as rye. The fungus Claviceps purpurea is the most common incitant of ergot. The fungus infects the seed head during flowering, and a prominent black sclerotium develops instead of a seed. The sclerotia are larger than seed and a little curved.

Ergot sclerotia in grass head. (Photo by L. Ribbing.)

They are not difficult to see in the least.

Infested grasses are a serious concern in a pasture situation because the fungus produces a very potent mycotoxin. The mycotoxins are a serious health risk not just to animals but to humans as well. As a result, grain that exceeds market tolerance of ergot is discounted in value because of the toxicity risk. Ergot poisoning primarily affects cattle that ingest the ergoty grass heads or the cleanings from contaminated grain. Ergot sclerotia contain numerous toxic alkaloids (including LSD). One of the most common symptoms of ergot poisoning is constriction of blood vessels in the extremities. This results in lameness, hoof sloughing, and ear and tail tips falling off. Anyone enamored of the alkaloids in the ergot sclerotia should consider that the effects on humans are just as gruesome as on ruminates. There is a long history of the effects of ergot poisoning (also known as St. Anthony's fire) of humans who unknowingly ingested the sclerotia in bread made from infested rye flour.

Grasses should be thoroughly inspected before grazing this year. This disease is extremely easy to control in grasses; you just need to mow prior to seed head development. For cultivated rye this obviously is not an option, and the crop should be inspected and the seed well cleaned.--Suzanne Bissonnette

Author: Suzanne Bissonnette

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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