Powdery mildew showing up on annuals and perennials

Michigan greenhouse growers of annuals and perennials are being advised to be on the lookout for powdery mildew. Mich. St. Univ. senior district extension horticulture and marketing educator Tom Dudek, who has recently seen disease symptoms on greenhouse crops, said it is critical that the disease be managed by disposal of heavily infected plants into a dumpster or treating the plants quickly if there is a mild infection. He said powdery mildew is a common and difficult problem if not managed effectively.

The disease can occur on all above-ground plant parts and results in white growth on the plant’s surface. Powdery mildew can infect plants even when the relative humidity is low, but epidemics are prompted when relative humidity is high.