One of the most wide-spread diseases in grape vines is grape leaf roll virus. Two inspect species are the primary vectors for this virus: grapevine mealy bugs and scale. Mealy bugs are small, white, and found under the bark of grape vines while scale are small, dark, and found on the outside of the bark. Both insects can overwinter in the bark of the vines, making these insects excellent vectors for the virus. Movento spray is typically used to control both insects, but the most efficient and effective times to spray are unclear. The abundance and maturity of mealy bugs and scale in vineyards throughout Niagara was monitored to determine ideal timing and concentration of Movento. Three varieties of vines were sampled across four different sites. Bark peels and tape counts were conducted to observe mealy bug and scale life stage and population abundance. The growth stage of the grape vines was also recorded. The data were analyzed to determine optimal spraying time.
It was determined that the optimal spraying times were either before the insects overwintered or after the second generation of their summer life cycle. Furthermore, it was found the spray should be applied during the evening, when bees and other beneficial insects are less active. These results will help grape vine growers effectively deal with grape leaf roll virus and their primary insect vectors.