Cucurbit Downy Mildew Update

Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland;

Downy mildew on cucumber was confirmed in Caroline County, MD on Tuesday, June 28. The cucumber crop should be covered with a fungicide that targets downy mildew. Cantaloupes and other melons should be sprayed for downy mildew also, because the strain that infects cucumber can also infect these crops.


Watersoaking of cucumber leaf with downy mildew.

Growers of watermelon, pumpkin, squash, and other cucurbits should make sure their crop has been covered with a protectant fungicide. We have not yet seen downy mildew on anything but cucumber. However I’m especially concerned about downy mildew on watermelon because downy mildew is widespread on watermelon in North Carolina and the recent weather and spore transport trajectories have put the mid-Atlantic region under risk for epidemic spread. Scout your fields aggressively.


Upper and lower surface of downy mildew infected watermelon leaf.