Vegetable Crop Disease Update – August 5, 2016

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

Downy mildew is active in both Maryland and Delaware on cucumber and cantaloupe (muskmelon). Muskmelon was first reported in the past week.

Powdery mildew is also present on cucurbit crops. Stay on a good fungicide management program.

Late blight is also present in four counties in Maryland, including on the shore adjacent to Delaware. Recent hot weather has slowed the spread of late blight, however as we move into a period of cooler temperatures and longer nighttime dew periods, late blight is likely to increase in prevalence again.

Gummy stem blight on watermelon (Fig. 1A) and melon (Fig. 1B) and anthracnose on watermelon (Fig. 2, note leaf also has gummy stem blight lesions) are also widespread.


Figure 1. Gummy stem blight on watermelon (A) and muskmelon (B)


Figure 2. Anthracnose (and gummy stem blight) on watermelon.