Gummy stem blight (GSB), caused by the fungus Didymella
bryoniae is the most widespread and destructive disease of watermelon in Georgia and the US. Although watermelon suffers the greatest losses from GSB, severe epidemics are observed in
cucumber and cantaloupe each year. Management options for this disease are rotation, deep turning diseased tissue, avoiding irrigating that prolongs leaf wetness, and preventive fungicide applications. Of these management options, application of preventive fungicides is the most effective.
Check out this GSB research from the Georgia Watermelon Growers Association.