Farmers with animals in pasture should check for their grass forages for the presence of ergot which can be toxic to cattle, sheep, swine and horses.
“Recent reports of ergot are not unexpected with the cool, wet spring we had,” said Dan Undersander, University of Wisconsin-Extension forage agronomist.
Ergot is a fungal disease that affects wild and cultivated grasses, as well as small grain crops such as wheat, oats, barley and especially rye. It produces a toxin that reduces blood flow in humans, cattle, sheep, swine and horses.
“The effect of ergot is cumulative,” Undersander said. “Poisoning may develop slowly if lesser quantities are eaten regularly.”
In animals such as cattle the first symptom of the alkaloid is lameness, two to four weeks after exposure, as a result of the reduced blood flow to extremities. The reduced blood flow will eventually lead to complete blockage of blood vessels with terminal necrosis of the extremities such as hooves and ears.
If ergot occurs in small grains, modern cleaning equipment may assist in removing sclerotia from grain. However, if sclerotia are broken or are the same size as the grain itself, removal might be difficult and costly. Often, attempted removal of sclerotia from grain will still result in levels above marketable thresholds. Tolerances for ergot sclerotia in harvested grain can be as low as 0.05% by weight.
The fungus only appears in seed heads and is present this year due to late pasture and hayfield harvesting because of wet conditions. Infected grass crops should be harvested to remove fungus infected seedheads and destroyed, not fed to animals or grazed. All infected hay should be destroyed and should not be used for animal bedding.
Undersander provided these tips for managing ergot:
- Rotate crops with at least one year between small grain crops.
- Use crops that are not susceptible to ergot (e.g., soybeans, alfalfa, corn) in years when small grains are not grown.
- Plant seed that is free of ergot sclerotia. Ergot-resistant varieties are not available, but avoid longer-flowering varieties as they tend to be more susceptible to infection.
- Keep weed grasses under control.
- Mow areas adjacent to small grain fields to prevent grasses from flowering and development of ergot in these areas.
- In fields where ergot becomes a problem, consider clean, deep plowing that will bury ergot sclerotia to at least three to four inches, thus preventing sclerotia from germinating. Pastures and hayfield infected should be mowed and harvested to removed seedheads with ergot and then the forage destroyed – do not feed or use for bedding.
For more information about ergot please contact your local county UW-Extension agriculture agent.