2011 Annual Report 1a.Objectives (from AD-416) Conduct basic and commercial tests to determine the effectiveness of PH3, PH3+CO2, and modern compressors to control Hessian fly in single or combined treatments, and the effect of postharvest hay handling practices on Hessian fly mortality in the laboratory and field. 1b.Approach (from AD-416) Hessian fly will be reared in the greenhouse at the USDA, ARS, Parlier and Manhattan. Basic fumigation tests will be conducted in the facilities provided by the ARS in Parlier and the National Hay Association in California, Oregon, and Washington. Laboratory dose-response fumigation tests will determine the effect of temperature, exposure time, and PH3 or PH3+CO2 dosage on Hessian fly mortality, and establish a treatment schedule. Large-scale fumigation tests at hay handling facilities will confirm the efficacy of a proposed PH3 or PH3+CO2 fumigation schedule as a quarantine treatment. Bale compression tests at hay handling facilities will be used to determine the effect of compressors on mortality of Hessian fly puparia. Large-scale compression tests will be used to confirm the efficacy of bale compression alone or in combination with fumigation as a quarantine treatment. Basic tests will determine the effect of postharvest drying and bale curing on Hessian fly mortality. Data will be provided to The National Hay Association in support of market access for hay exports from the western U.S. 3.Progress Report This Trust Agreement supports Objective 3 of the parent project. The goal of the research is to develop quarantine strategies to control Hessian fly in exported hay. Field drying hay in windrows and compression of harvested hay in modern compressors to produce compact export bales were found to cause high levels of mortality of Hessian fly, a pest of regulatory concern in hay exported from the western states to Asia. The findings support the systems approach to pest control and the concept that the occurrence of Hessian fly would be negligible in harvested and processed, exported hay bales. Cooperator activity has been monitored by the use of written reports, technical meetings, email, and telephone conversations.