David Owens, Extension Entomologist, owensd@udel.edu
San Jose Scale
A few weeks ago, I discussed San Jose Scale crawler timing. Although we did not have pheromone traps out this year, we can estimate based on previous years and relative apple phenology that male scale would have been active around April 15. If so, crawlers should be active sometime between May 23 and 30; we are looking for 600–700 degree days.
Vineyards
Grape root borer is one of the most damaging insects to vineyards. It is a silent killer of grape vines, tunneling into roots for 2-3 years before emerging from the soil as an adult moth. The only evidence they leave behind is the pupal case right at the soil surface, sometime during the first two weeks of July. Infested vines slowly decline and become less thrifty and may die. Historically, this insect has been controlled by either chlorpyrifos soil drench (no longer an option) or mounding soil up in June to smother pupae. We have been working for a third option: mating disruption. Mating disruption technology uses dispensers to flood the vineyard with high doses of female sex pheromone, confusing males and preventing males from successfully finding the real deal. Females go unmated and the population declines.
Mating disruption technology Isomate GRB Z has just received a section 18 label for use in Delaware, Maryland, Virginia, North and South Carolina, Tennessee and Georgia. The use rate is 100 dispensers per acre, with higher rates (150-200 dispensers) per acre around border rows and end plants. This represents our best means of controlling grape root borer. It may be less effective in smaller vineyards (less than 4 acres), but I think it would still be worth using.