Cucumber scouts in Ontario identified downy mildew symptoms in a cucumber field. Given the early start to the 2021 cucurbit downy mildew season, growers and scouts are encouraged to inspect all fields for CDM, regardless of the crop stage.
“Look for angular “water-soaked” lesions on the older leaves. These lesions are often most noticeable in the morning, and may simply look like the dew has been slow to dry. The angular shape of the lesions is characteristic. Later in the day, new lesions will begin to dry and turn yellow-to-tan. Under humid conditions, grey mildew hyphae with enbedded spores may be visible on the lower leaf surface.”