2011 Annual Report 1a.Objectives (from AD-416) 1. Develop controlled atmosphere treatments for postharvest pest control on perishable commodities. A) Develop semi-commercial scale storage and ultralow oxygen combination treatment for control of western flower thrips on head lettuce. B) Develop semi-commercial scale storage and ultralow oxygen combination treatment for control of western flower thrips on broccoli. C) Develop controlled atmosphere treatment for control of mealybugs and black widow spiders on table grapes. D) Develop ultralow oxygen treatment for control of vine mealybug on grape rootstocks. 2. Develop pure phosphine funigant treatments for highly perishable commodities. A) Develop fumigation treatment with pure phosphine for control of western flower thrips on lettuce, broccoli, asparagus, and strawberries. B) Develop fumigation treatment with pure phosphine for control of lettuce aphid and leafminer on lettuce. C) Develop fumigation treatments with pure phosphine for control of mealybugs and spiders on table grapes. 1b.Approach (from AD-416) The minimum duration of pre-treatment cold storage needs to be determined in order to reduce the overall duration for completing ULO treatment and make it possible for pre-export ULO treatments. Effectiveness of ULO treatments for thrips control and their effect on postharvest quality of lettuce needs to be determined in large-scale tests. Oxygen consumption rates and oxygen demands by lettuce need to be determined in large-scale trials for commercial application. Efficacy and safety of ULO treatment for control of western flower thrips on broccoli. 3.Progress Report A. Continued the ongoing study to develop phosphine fumigation treatment to control of light brown apple moth (LBAM). Significant progress was made to control eggs, the most tolerant life stage to phosphine, using oxygenated phosphine fumigation. Research is continuing to determine effective oxygenated phosphine fumigation to control all life stages of LBAM. B. Continued the ongoing study on ultralow oxygen (ULO) treatment for control of bulb mites on flower bulbs and tubers. Significant progress has been made in finding an effective treatment to control bulb mites. The study is ongoing to develop safe and effective ULO treatment for bulb mite control on flower bulbs. The treatment, if successful, will provide an environmentally friendly alternative treatment for bulb mites and economic benefits to horticultural industries. 4.Accomplishments 1. Low temperature oxygenated phosphine fumigation for controlling lettuce aphid. Postharvest pest control on perishable commodities such as lettuce is essential. Phosphine is a post-harvest fumigant. A researcher at USDA-ARS in Salinas, CA, found that oxygen significantly increases phosphine toxicity against lettuce aphid. Phosphine fumigation under 60% oxygen reduced treatment time from 3 days to 30 hr at low temperature. The shorter oxygenated phosphine fumigation was tested successfully in a pallet-scale trial with chilled head lettuce under an insulation cover for controlling lettuce aphid. The treatment did not adversely affect lettuce quality and achieved complete control of the insect, and provides an economical alternative to fixed, low temperature fumigation chambers for conducting low temperature phosphine fumigation. Review Publications Liu, Y. 2010. Recent advances in development of ultralow oxygen treatment for postharvest pest control on perishable commodities. Stewart Postharvest Review. DOI: 10.2212/spr.2010.3.9. Liu, Y. 2011. Low temperature phosphine fumigation of pre-chilled iceberg lettuce under insulation cover for postharvest control of western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae). Journal of Asia-Pacific Entomology. 14:323-325. Liu, Y. 2011. Semi-commercial ultralow oxygen treatment for control of western flower thrips, frankliniella occidentalis (thysanoptera: thripidae), on harvested iceberg lettuce. Postharvest Biology and Technology. 59: 138-142.