Cucurbit Downy Mildew Found In SC

Cucurbit downy mildew was found in SC this week in Bamberg, Barnwell, and Calhoun Counties. In each case it was found on cucumbers and for now severity seems low. This is about two weeks earlier than in the past couple years.

Downy mildew symptoms on cucumber. Lesions are often limited by the veins in the leaves.
Dark-colored downy mildew spores developing on the underside of cucumber leaves.

If not already doing so, all cucumber and cantaloupe growers in SC should begin applying protective fungicides to help prevent or manage downy mildew. Ranman tank-mixed with a protectant, such as chlorothalonil or mancozeb, or applications of Zampro are good options for protecting plants prior to symptom development. For more info, see Dr. Tony Keinath’s CDM Management publication.

Alternaria Leaf Blight Common This Year

From Clemson Extension Plant Pathologist Tony Keinath.

During the 2019 Cantaloupe Disease Survey, Alternaria leaf blight has been found in several fields. It was more common in fields that had not been sprayed recently than in fields sprayed on a regular schedule. It also was found in a field rotated only one year out of cantaloupe.

ALB cantaloupe.JPG

Alternaria leaf blight lesions on cantaloupe leaf.

The FRAC Group 11 fungicides (Cabrio, Quadris, Flint) are the recommended fungicides. Although the gummy stem blight fungus is resistant to this group of fungicides, they still are very effective against Alternaria leaf blight on cantaloupe and anthracnose on watermelon.