Fundamental to the effective management of codling moth in Washington State orchards has been the use of a simple predictive model to time the first spray of the season. Growers use traps to determine the start of moth activity (Biofix) and then accumulate 250 degree days (DD) to allow time for moths to mate, lay eggs, and for eggs to start to hatch. The first spray for the second generation is timed at 1250 degree days. Additional sprays are then usually timed based on the length of spray residue effectiveness. Twenty years ago growers sprayed Guthion at 21-day intervals; today, […]