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Ask Your PCA: What works for mealybug pests in winegrapes?

Issue Date: Jun 8 2022
Cameron Jones Nutrient Ag Solutions, Stockton

Mealybugs are problematic in winegrapes. The main pest is the vine mealybug, but there is also the grape mealybug. The difference between the two is the vine mealybug has more generations, as many as seven to eight per year. By comparison, the grape mealybug has two to three generations annually.

Mealybugs put pressure on the vine by sucking the vascular carbohydrates out. They then move into the bunches and create a sticky, sooty mold. Once the pests infect the vines, they damage the grapes, which can result in yield loss. The mealybug can also cause secondary disease movement, so reducing its populations also reduces pressure from secondary diseases.

Ants are also problematic. They feed off of the sugary secretion produced by the mealybug and, while they don't damage the grapes, they shield them from predatory insects such as wasps or lacewings.

Treatment for mealybugs is difficult because they hide underneath old bark, making it hard to penetrate with sprays.

A foliar insecticide has been the staple product for controlling mealybugs. It is absorbed by the leaves and moves systematically into the phloem and xylem of the plant.

A newer kind of approach has been mating disruption. The pheromone disrupts the males so they can't find the females and mate. Dispensers in the vineyard slowly release the pheromone. Mating disruption impacts the populations, especially in the fall, by preventing breeding and overwintering, which also decreases populations the following year. There is a pheromone that can be sprayed on, too.

The use of predatory wasps is another approach, which has the potential to help combat pests that hide underneath the bark.

Systemic insecticides and pheromones are becoming the go-to controls for combating mealybug populations and disrupting mating cycles.

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