Pesky powdery mildew may have been hit or miss for much of 2022, but wine, raisin and table grape growers know better than to let their guard down going into the 2023 season. Additionally, Botrytis remains a threat to grapes, especially with any heat headed into harvest.

We recommend following these tips when prepping for next year’s potential pests:

• Scout for powdery mildew before harvest. Powdery mildew in grapes prefers warm temperatures, which have been largely absent this summer. Though cooler days delayed disease development, it is still there. Powdery mildew also thrives in high humidity, which festers in vineyard leaf canopies.
  • Before harvest is a good time to check canes for infection level and evaluate prior to or just after harvest to see if a dormant application will be needed to reduce inoculum for the next season. For powdery mildew control, Miravis® Prime fungicide is an ideal resistance management tool for a fully-charged defense against both powdery mildew and Botrytis. With a residual that is 10-15% longer than conventional chemistries, Miravis Prime offers broad spectrum control when used in an integrated pest management spray program.
• Assess mealybug infestations and plan treatments accordingly. Mealybugs have been confirmed in grapes this season, so a post-harvest evaluation of the problem can provide direction for future treatment. With water supplies and commodity prices low, some growers cut insecticide rates to save money. Others treated early for what has been a later-than-usual infestation this season. If mealybugs are present, build residual control with an application of the soil-applied neonicotinoid, Platinum® 75 SG. Platinum insecticide can also be factored into 2023 plans as an early application where needed.
• Use full insecticide and fungicide rates to prevent more pest problems. While it is tempting to cut rates to save money, using labeled rates at the appropriate time is the only way to minimize escapes and maximize crop yield and quality. Cutting rates increases the risk of having to make a second application, so rolling the dice does not provide much return. Crop advisors can also help growers select appropriate products and product rates to delay any resistance concerns.

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