Gummy stem blight disease pressure has been light so far this season in North Florida watermelons. That trend may soon be changing, however.
Bob Hochmuth, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Regional Specialized Extension agent in Live Oak, Florida, confirmed this week that gummy stem blight disease is beginning to become a problem for Florida watermelons.
“The multiple rainstorms over the past several days could certainly set the stage for gummy stem blight to be more active and potentially a major concern if gummy stem blight is already present. Of course, not all fields even have gummy, so, make sure you know the situations in your fields,” said Hochmuth in an email alert on Wednesday.
Gummy stem blight causes lesions on leaves and stems and leads to defoliation. The disease favors warm, wet conditions.
UF/IFAS research rank Inspire Super at the top for gummy stem blight control, but it has a seven-day pre-harvest interval (PHI). It is recommended for growers with seven days before their next harvest.
For those producers who have already sprayed Inspire Super or are less than seven days until the next harvest, Aprovia Top would be a suitable option. Aprovia Top has performed similarly to Inspire Super in most research trials and has a 0-day PHI on the label. The main caution is that both Inspire Super and Aprovia Top have FRAC (Fungicide Resistance Action Committee) group 3 fungicides in their ingredients. It is important to minimize the number of applications of those two in rotation. If gummy stem blight is not present in your fields, then mancozeb and tebuconazole is a good option at a lower cost than the other recommended options above.