Most growers recognize powdery mildew when it occurs on their crops.
But, recently I have had several growers tell me that they have been fighting a powdery mildew problem for weeks and none of the fungicides that they used seemed to control the disease. The reason for the lack of control was that the mildew they were seeing was not powdery mildew, but downy mildew. Powdery mildew infection is easily recognized by the powdery white to light gray-colored spots on leaf, stem, bud or flower tissue. Eventually, the infection can cover the entire leaf or stem. Infected tissues can be stunted, chlorotic, curled, and deformed.