Kate Everts, Vegetable Pathologist, University of Maryland; keverts@umd.edu
Downy mildew was confirmed on Tuesday, June 26, 2019 on cucumber from Federalsburg, MD. This is the furthest north the disease has currently been found in 2019. Cucumbers in the region should be protected with a fungicide that is effective on the disease. Initial symptoms are angular water-soaked lesions on the leaves. Preventative applications are more effective than applications made post-infection. Effective materials are listed in the Mid-Atlantic Commercial Vegetable Production Recommendations: http://extension.udel.edu/ag/vegetable-fruit-resources/commercial-vegetable-production-recommendations/
Early symptoms of downy mildew on cucumber.