Ergot, caused by the fungus Claviceps purpurea, is a disease that attacks grass hosts and cereals. It is prevalent on rye, and occurs on barley, oats, and wheat. Sufficient quantities of ergot can make feed unsafe for livestock. Ergot contains toxins that can cause poisoning in animals.
Ergot is characterized by the dark purple to black sclerotia, which are hardened, weather-resistant fungal bodies, found in the head of cereals and grasses before harvest. These black bodies may be present in the grain after harvest.
Although there are varieties that are more prone to infection by the ergot fungus, there are no true resistant varieties. There are a few simple ways to reduce ergot. Rotation to a non-grass, deep plowing, planting clean seed, and mowing wild grass before flowering are some common practices to diminish ergot infection.