2010 Annual Report 1a.Objectives (from AD-416) To validate and demonstrate areawide management approaches, primarily mating disruption, for the control of navel orangeworm in walnuts grown in the northern region of California’s central valley. 1b.Approach (from AD-416) Management of navel orangeworm in walnuts is predicated on effective suppression of codling moth because this insect provides an opening for early season entry of navel orangeworm. A large-scale effort to use codling moth pheromone to disrupt mating will provide the basis for an indirect non-insecticide management option for navel orangeworm control. Additionally, smaller sub-plots will be treated with a pheromone mating disruption program directly targeting navel orangeworm. As part of this project, movement of navel orangeworm among the different host crops in the Sacramento Valley/north region (primarily walnut and almond) will be assessed in order to determine the parameters that determine success for mating disruption targeting navel orangeworm in walnuts. Part of this research will be conducted in collaboration with Carolyn Pickel, another participant in this areawide project. Documents SCA with UC Berkeley. 3.Progress Report This research contributes to objective 1 of the in-house project. The goal of this project is to demonstrate mating disruption for control of navel orangeworm in walnuts combined with mating disruption to control codling moth in walnuts in the Sacramento Valley. One ARS entomologist based in Parlier, CA is collaborating with one UCCE researcher based in Yuba City and one UC entomologist at UC Berkeley to demonstrate this technique. The pheromone, which disrupts mating of navel orangeworm, is dispensed by aerosol puffers in walnuts, as an adjunct to the existing demonstration of mating disruption in walnuts targeting codling moth. Demonstration sites were selected in cooperation with 14 growers and their Pest Control Advisers, covering more than 2,000 acres. This new technology will be expanded to 5,000 acres in the coming year. Supporting studies assessed NOW larval survival in unharvested almonds and walnuts over the winter in order to develop more accurate monitoring techniques so that the use of puffers could be refined. Additional studies were conducted to document the area affected by each aerosol puffer to enhance control. Cooperator activity was monitored by reports at a stakeholder meeting in August, oral presentations at the annual meeting of the Walnut Board of California, telephone conversations and e-mail.