The period of time when overwintering leafroller (LR) larvae are most susceptible to the new insecticides overlaps with the beginning of the codling moth (CM) egg laying period. Some new insecticides will kill overwintering leafroller larvae as well as codling moth eggs that are laid on top of the insecticide residues.
When these materials are applied between 250 and 375 CM degree-days since January 1 (75 and 200 DD after biofix), the CM eggs that are laid on top of their residues are killed. Because these early eggs are killed, significant egg hatch is delayed until approximately 525 DD since January 1 (350DD after biofix). This allows a delay in subsequent larvicide applications, which can result in better larval control.
(PMTP Team, WSU-TFREC)