Vine mealybug populations can be harder to treat than other mealybug species that growers are familiar with.
Grape growers are seeing increasing issues with vine mealybug populations due to the breeding habits of the pest. Cooperative Extension Specialist Kent Daane says the bug can have several generations in one season which not only promotes the spreading of populations, but also makes them hard to treat. Daane adds that the pest also can also be found all over the plant, making product coverage a challenge.
More About Treatments
From the UC IPM website: If vine mealybug is found in a vineyard, treatment is recommended. However, the level of treatment varies greatly depending on the region, type of grape, and harvest date:
•Coastal regions only have two to three generations of vine mealybug per year, compared to five to seven in the lower San Joaquin Valley.
•Table grapes have no allowance for mealybugs in the cluster, while wine grapes can tolerate low levels.
•Harvest dates vary widely in table grapes. Fruit from a Flame Seedless vineyard, harvested on the first of July, is less susceptible to damage than fruit in a neighboring Crimson Seedless vineyard, which might be harvested in October.
Due to the complexity of these and other factors, such as biological control, decisions about the level of mealybug control need to be made on a vineyard-by-vineyard basis. Read more from UC IPM.