Pest News: Downy Mildew Outbreak on Cucumbers in Southeast North Carolina

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Cucurbit downy mildew was reported today (June 4, 2013) in Wayne County, North Carolina and confirmed by the Quesada Lab and the Plant Disease and Insect Clinic at NCSU. The disease appears to be just starting and only 1% of the field was affected at less than 1% severity. Immediate action to protect cucurbit crops in NC is recommended. Typically cucumbers, watermelons and melons are more susceptible to the disease than squash and pumpkin, nonetheless; all cucurbits could be at risk especially if environmental conditions are conducive to disease.

For more information about the disease and how to control it see factsheets in english and spanish produced by Dr. Lina Quesada-Ocampo and Dr. Kelly Ivors at the Department of Plant Pathology. Control recommendations are also available in the Cucurbit downy mildew IPM pipe website, where you can also register to recieve text, email and/or phone alerts when new disease outbreaks are reported.

If you think you have cucurbit downy mildew in your cucurbits please contact your local Extension Agent and send photos and/or physical samples to the Plant Disease and Insect Clinic. If cucurbit downy mildew is confirmed in your samples by an expert, please make sure a report is sent to the Cucurbit downy mildew IPM pipe website.

Control strategies are provided in the factsheets for commercial growers. Homeowners can use gardening fungicides that contain chlorothalonil as an active ingredient. Organic growers can use copper-based products to slow down disease progression.

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Cucurbit downy mildew symptoms on cucumber (Photo, Gerald Holmes, Valent USA Corporation, Bugwood.org)

Cucurbit downy mildew symptoms on cucumber (Photo, Gerald Holmes, Valent USA Corporation, Bugwood.org)