Cause A fungus, Sordaria sp., that is commonly found in the feces of herbivores. It is not considered a pathogen of grass or other plants. It showed up in Oregon seed fields during 2011 in areas of fields treated with high rates of chicken litter under unusually warm and wet early fall conditions. The fungus produces masses of black ascospores, which can coat leaf blades.
Symptoms Black powdery masses are found on soil surface, stubble, and grass leaf blades and form roundish black patches. A few, up to many, patches can be found. The spores can be wiped off the leaf blades and healthy green leaf blades are apparent underneath.
Cultural control
- Wait for spores to be washed or blown off leaf blades.
- Avoid high rates of chicken manure amendments.