Early Season Sprays for Grapes – Facts for Fancy Fruit

Early Season Sprays for Grapes

There are some potential pest and disease problems that require early season sprays. Phomopsis is a major problem on many grape varieties in the Midwest. Mancozeb should be applied starting at 1-3 inch shoots and repeated each 7-10 days, especially prior to a predicted rain event. Evaluations of delayed-dormant fungicide applications for management of this disease shows that liquid lime sulfur, Sulforix, and fixed copper (copper hydroxide) have proven to be most effective. A single application at bud swell can provide a significant degree of Phomopsis control (a 50 to 60 percent decrease in disease severity on the grape leaves as well as clusters), but will not reduce the need for the standard recommended fungicide sprays for Phomopsis control during the growing season. It is important to recognize that sanitation is part of a Phomopsis management plan. Prune out dead canes and stubs as much as possible since they are the main sources of Phomopsis spores.

Anthracnose is a less common disease, but one that we are seeing more frequently. Vidal,  Frontenac and Marquette as well as several Eastern table grapes are very susceptible to anthracnose. Delayed-dormant lime sulfur or Sulforix sprays are very effective against anthracnose. While sulfur and copper can be toxic to certain varieties, there is minimal chance of phytotoxicity if the products are applied just prior to bud break (at the bud swell stage).

Grape Flea beetle and climbing cutworm can be problems in vineyards. Grape flea beetle is most common in Indiana. Scout vineyards for this pest and its damage, holes eaten into swelling buds. If more than 4% of the buds show damage, apply an insecticide to prevent further damage. Carbaryl (Sevin) is generally recommended.

See the 2018 Midwest Fruit Pest Management Guide (https://ag.purdue.edu/hla/Hort/Pages/sfg_sprayguide.aspx ) for a complete discussion of grape pest management.

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