2010 Annual Report 1a.Objectives (from AD-416) Develop low temperature phosphine fumigation treatment for control of lettuce aphid, leafminer, and western flower thrips on exported lettuce. 1b.Approach (from AD-416) Small-scale fumigation treatments using different phosphine concentrations and durations at a low temperature will be conducted to determine effective treatment to control each insect species. Selected fumigation treatments will be tested on commercial iceberg and romaine lettuce determine effects on postharvest quality of lettuce. Large pallet-scale fumigation treatment will be conducted to verify efficacy and safety of selected low temperature phosphine fumigation. Additional research will be conducted to determine suitability of using a phosphine generator for fumigation at low temperature and to find an economical way to conduct low temperature phosphine fumigation to control western flower thrips on lettuce. 3.Progress Report Laboratory studies were conducted to determine effective low temperature phosphine fumigation treatments for lettuce aphid and pupae of the leafminer, Liriomyza langei, two quarantine pests on exported lettuce to Japan. Successful controls of lettuce aphid and the leafminer were achieved in 3-day and 2-day treatments, respectively. Research is continuing to optimize treatments and determine their safety to lettuce quality. A semi-commercial pallet scale low temperature phosphine fumigation method was successfully developed to treat pre-chilled lettuce under an insulation cover to control western flower thrips, a quarantined pest in Taiwan. The treatment has potential to be developed as an economical alternative to fixed low temperature chambers to conduct low temperature phosphine fumigation for control of pests that are susceptible to phosphine. The method can also be used on existing chambers, containers, or sealable structures by lining them with proper insulation materials. (NP 308 component 2, Problem Statement 2C).