David Owens, Extension Entomologist, owensd@udel.edu
Tree Fruit
As mentioned previously, we did not have any San Jose scale traps out this year. However, if we assume that adult male flight occurred around April 15, then we will have accumulated 600 degree days by the end of next week to begin crawler emergence. Crawlers are active at 600–700-degree days. This is the best time to target them with an insecticide if necessary.
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.