Monitoring and management of grape mealybugs (Pseudococcus maritimus) in Washington state

Mealybugs have been identified as a primary vector of grapevine leafroll disease (GLD) in Washington vineyards. Successful management of this devastating disease in Washington State vineyards will depend upon accurate diagnosis and appropriate management of mealybug infestations. While GLD has primarily been an economic pest in wine grapes only (studies are underway to determine its impact on juice grapes), monitoring juice grape vineyards for mealybug infestations is enabling us to conduct studies on the epidemiology of GLD potentially reducing the disease spread to uninfected vineyards of both types. Dr. Jocelyn Millar, our own renowned PBESA pheromone chemist has supplied us with the sex pheromones for grape mealybug, obscure mealybug, long-tailed mealybug, and vine mealybug and we field deployed them in preliminary tests for their use as tools for monitoring mealybug populations in a series of grower-collaborator vineyards. Fortunately no mealybug males except grape mealybug were captured in any of the traps we placed in over 1,200 acres of Washington vineyards in 2009. In 2010 we continued monitoring grape mealybug populations in both concord juice grapes and wine grapes. Traps were set up at one, four, and eight per 30 acres of vineyard to monitor population densities. Transects were also set up outside the vineyards to determine how far males could disperse. We have also conducted insecticide efficacy trials against mealybugs for the past 11 years. We will cohesively summarize these results.