Grape Pest Management – Facts for Fancy Fruit

Grape Pest Management

Grapes across the state are post bloom a week or more. As berries reach 3 to 5 weeks post bloom they become naturally resistant to infection by black rot and powdery mildew fungi. So our spray program can relax a bit. Growers normally extend to a 14 to 21 day schedule supported by regular scouting. At that time we can begin to focus on leaf diseases such as downy and powdery mildew. Downy is likely to be a big problem this year because it favors hot, humid conditions, exactly what we’ve been experiencing. There are a number of excellent fungicides specifically for downy mildew as well as older products such as Captan and phosphorous acid products. Scout your most susceptible varieties twice a week and make an application as soon as any downy mildew lesions are noted.

Another concern is insect pests. Japanese beetles have emerged and adults are present throughout the state. We had very high populations this past year so there is potential for Japanese beetles to cause problems again this year. Sevin has been the standard for treatment for a number of years, but its label requirements for REIs of 2 to 6 days make its use impractical for some growers. There are several options including Assail, Brigade, Danitol, etc. Check the spray guide for a list and check the labels for other restrictions. I’ve also noticed quite a bit of leaf phylloxera and potato leaf hopper damage. A well timed insecticide application can take care of multiple pests.

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