Bob Hochmuth, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS Regional Specialized Extension agent in Live Oak, Florida, talks about how downy mildew has impacted North Florida’s watermelon crop this year. He also demonstrates what symptoms look like.
Downy mildew can degrade or destroy the plant’s foliage very rapidly. It thrives in a wet, humid environment, and the fungi need the water on plant tissue to germinate and infect the plant.
Under favorable conditions, severe foliar infection can occur and cause the leaves to curl and eventually die. If the leaves are damaged, they cannot protect and shade the fruit. As a result, the watermelons can develop blisters or sunscald.