Gummy stem blight is currently confirmed in multiple locations in northwest and northeast Florida. Recent high humidity and high temperatures have been ideal for gummy stem blight throughout the northern part of the state. It is a highly destructive foliar fungal disease of watermelon and can cause yield losses of more than 50 percent.
A common early-stage symptom of gummy stem blight is necrotic lesions to the margin of the leaves, which can be seen in the photo above.
For disease management, it is critical to use clean transplants, followed by use of protective and systemic fungicides in rotation, depending upon existing weather conditions, and stage of the crop.
Based on research trials conducted in Florida and other southeastern states, the 2015 UF Watermelon Spray Guide was developed as a quick-use information source, which provides potential options for disease management.