Editor: Cesar Escalante                                                                                                

Extension Plant Pathologist

escalac@purdue.edu

812-886-0198

July 17, 2026

For cantaloupe, all Indiana MELCAST stations are currently recommending fungicide spray intervals of approximately 14 days. For watermelon, recommended spray intervals also remain relatively long across Indiana. Most MELCAST stations are currently suggesting spray intervals of 14 days. A few locations, including Ft. Vallonia, Merom Station, and West Lafayette, are reporting slightly shorter intervals of approximately 13 days, reflecting somewhat greater accumulation of EFI values during the past week. Overall, however, MELCAST data continue to support relatively extended fungicide application intervals across the state.

However, I have recently observed gummy stem blight in watermelon sentinel plots at the Southwest Purdue Agricultural Center (SWPAC). Growers should begin scouting fields for symptoms, which may include blighting along leaf margins, brown and decayed leaf petioles, and lesions and exudations on stems. Gummy stem blight can also only affect vines, and these symptoms are often difficult to detect in fields with dense canopies. Regular scouting remains important, particularly as vine growth increases and foliage becomes more difficult to inspect.

If gummy stem blight is detected, fungicide applications should be made as soon as possible. Effective products include Inspire Super®, Miravis®, Monsoon®, Quadris Top®, and Switch®. Additional information on disease management and fungicide recommendations can be found in the Midwest Vegetable Production Guide. Growers are also encouraged to contact me to discuss management options. If you suspect gummy stem blight in your field, I would appreciate the opportunity to visit and collect samples as part of an ongoing study evaluating the genomic diversity and fungicide resistance of gummy stem blight populations in Indiana.

Finally, I would like to invite everyone to attend the SWPAC Vegetable Field Day, which will be held on August 13, 2026 in Vincennes, Indiana. This is a free event, although registration is required. PARP credits will be available for participants. The program will begin at 8:00 a.m. and conclude at midday, with discussions focused on current vegetable research trials and future research priorities for disease management in cucurbit crops. The event will provide an excellent opportunity to discuss challenges and research needs directly with researchers and industry representatives. Lunch will be provided thanks to the generous support of our sponsors: Summit Agro, Agrauxine, and Vive Crop Protection.

If you have any questions or comments, please feel free to reach out.