Cucurbit Downy Mildew
Cucurbit downy mildew was reported June 17th in watermelon in Nash County, NC. The first report in NC earlier this month was on cucumber in Duplin County.
Cucurbit downy mildew affects the leaves of all commercial cucurbits (cucumber, cantaloupe, squash, watermelon, pumpkin, etc.). See recommendations below from the previous newsletter.
Growers are advised to scout for the disease and initiate preventative sprays immediately, especially if the weather is going to be cool and wet.For a preventative spray program, products like chlorothalonil and mancozeb are good broad spectrum protectants that can be rotated. Products like Gavel (contains mancozeb), Tanos, and Zampro can be tank mixed with these, as appropriate. Applications should be made every 7 days on cucumber, every 10 days on other cucurbits.After disease is confirmed, growers are advised to switch to and rotate between Ranman and Previcur Flex in tank mixes with chlorothalonil or mancozeb. These tank mixes can also be rotated with Orondis Opti by itself (contains chlorothalonil). Apply every 5 days in cucumber, every 7 days in other cucurbits.