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Be On Alert for Downy Mildew in Cucurbits

June 14, 2019
this agronomic image shows downy mildew in cucurbits

The Cucurbit Downy Mildew Forecast reported downy mildew in the Southeast region, particularly SC and GA.

According to Clemson University Extension, downy mildew is an aggressive water mold common in cucurbits that destroys plant foliage. The pathogen overwinters on crops growing in the south where cucurbits don’t freeze, and in the spring travels north through the air on wind currents. This disease thrives in mild, wet weather as rainwater, dew, or fog washes spores out of the air onto plant leaves. After infection, downy mildew can continue to spread even in dry weather if temperatures stay above 60°F.

As downy mildew infects the plant, yellow to brown lesions appear and quickly spread on leaves causing them to curl. If the leaves are stunted enough, this could cause yield reduction or even plant death. Lesions also appear on the underside of the leaf which is usually covered in fluffy, brownish-purple “down,” which are masses of pathogen spores.

It is important to apply fungicides preventively to protect against the threat of downy mildew. We recommend using Orondis® Opti fungicide, which combines 2 modes of action to help growers combat an outbreak of this quick-spreading infection. With excellent rainfastness and no known cross-resistant to other fungicides used in management of water mold diseases, Orondis Opti used as part of a disease control program gives you increased protection from downy mildew.

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