Cucurbit downy mildew was confirmed this past week in South Carolina by Clemson Plant Pathologist Tony Keinath. Here are a few comments from Dr. Keinath on downy mildew.
“Cucurbit downy mildew was confirmed on two cucurbit crops in two counties in South Carolina today: on watermelon in Bamberg County and on pickling cucumber in Clarendon County. This means all cucurbit crops (cucumber, cantaloupe, muskmelon, specialty melons, watermelon, and all types of squashes, pumpkins, and gourds) in the state should be sprayed to prevent downy mildew. I have heard there may be temporary, local shortages of downy mildew fungicides. Chlorothalonil and mancozeb are excellent protectants against cucurbit downy mildew. If a field has been sprayed with one of these materials within the last 6 days, it is protected against downy mildew.”
Below are a few photos from Charleston County Agent Zack Snipes that show the symptoms of downy mildew.
Symptoms on the underside of the leaf.
For help identifying and confirming downy mildew, contact your local Clemson Extension Agent. For information on downy mildew fungicide programs, refer back to these two publications:
A map of counties in which downy mildew has been confirmed can be found here.