Last year, barley producers in northeast Iowa suffered a serious outbreak of ergot, a fungal disease that can affect any small grain crop and many grass species. The fungus is called Claviceps purpurea, and it produces dark sclerotia in the seed heads of the plant (see photo). These sclerotia overwinter in or on soil and produce spores that infect the flowers.
Although this disease can noticeably reduce yields when very severe, its real threat is poisoning of livestock. The fungus produces toxic alkaloids; as little as 0.1 percent sclerotia by weight in grain can cause symptoms. Initially, animals will reduce feed intake and, subsequently, their weight gain slows down. Milk production also drops. If animals consume larger amounts, more serious effects occur, such as gangrene of tails and hooves, sometimes followed by death of the animal.
Ergot sclerotia and barley grain.
What is the potential for this disease to occur in 1997? An outbreak similar to last year is very unlikely. Weather conditions in 1996 were ideal for the disease. The wet spring was very favorable for the fungus and it prolonged the flowering period of the barley so heads were more susceptible to infection.
Even if spring is wet again, I do not expect to see much ergot. Nevertheless, the possibility does exist, so I would like to review a few possible scenarios.
- In fields where infected barley was harvested last year but now are in alfalfa, there is little to worry about. If the alfalfa lasts two to three years, viability of the sclerotia will be greatly reduced.
- In fields where infected barley was harvested last year and reseeding will take place this year, it would be safer not to plant a small grain crop. Corn, soybeans, or a forage legume would be better choices. If a small grain or forage grass will be planted, the field should have been plowed last fall. If it wasn't, it should be plowed this spring. Burying the sclerotia reduces their survival to one year or so.
- Small grain crops in fields adjacent to infested fields could have ergot infection this year if weather is favorable. However, I think this is a very small risk, especially if the infested fields were tilled last fall.
- Forage grasses grown for hay or pasture that were infected last year could have a recurrence if weather is favorable. The risk can be minimized by cutting hay before heading. This results in better quality hay and the risk of ergot is eliminated.
The key in any situation this year will be to watch for ergot symptoms in the field, so if the disease does develop, grain with high ergot levels will not be fed to animals.
This article originally appeared on page 41 of the IC-478 (5) -- April 21, 1997 issue.