Documenting Population Fluctuations of Vine Mealybug in Chardonnay Vines Influenced by Environmental Conditions, Insecticide Programs, Vine Phenology, and Weeds

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Virginia Tech


Vine mealybugs (VMB) are a key pest to coastal vineyards in California. They can cause major issues to host plants during all their life stages due to their mouthparts and reproduction. Chardonnay, a highly VMB-susceptible variety at Delicato Family Wines, was chosen for this study to document fluctuations of this pest. Selected commercial blocks had different soil textures, vine phenology, weed types, VMB previous infestation history, topography, mechanical and chemical practices. Block 218A had moderate population levels, with sooty mold. Block 41B had high mealybug populations with some sooty mold but not as much as 218A (it is also a younger block than 218A). Block 96A, the youngest block, had no VMB presence from May-early August 2022 but had one highly infested vine during the last few weeks of August. Pheromone traps were also placed in these blocks to monitor males. When counting numbers in all traps, the trap closest to the highly infested vine in 96A had the most captured males throughout this study. After documenting all findings, it seemed like mealybugs prefer cooler shaded areas especially when temperatures are warm. In conclusion, management of weeds, sanitizing equipment after going into a field, and proper insecticide timing with the use of growing degree days, will assist in having better management of VMB. These practices can reduce the chances of sudden population growth, and continuous reproduction that may lead to sooty mold and possible vectored diseases such as leaf curl and red blotch.