The cleistothecia are dark brown, globose, with many unbranched appendages. There are multiple asci within each cleistothecium. This genera causes powdery mildew disease on plants such as clover, cucurbits, beans, soybeans, delphinium, hydrangea, zinnia, phlox, aster, crepe myrtle, and tulip poplar.
 
 
 
 

Representative Species

Erysiphe polygoni

causes powdery mildew disease of beans, soybeans, clovers, and other legumes, cabbage, beets, cucumber, cantaloupe, delphinium, and hydrangea.

causes powdery mildew disease on squash, aster, phlox, zinnia, verbena, and hellianthus