2010 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.
A. Started research to develop phosphine fumigation treatment to control of light brown apple moth. This is a part of joint project involving ARS, APHIS, and UC Davis in developing alternative treatments for light brown apple, which became an emerging pest quarantine problem for exported fresh products to Mexico. Significant progress was made, and complete control of larvae and pupae of LBAM was achieved. Research is continuing to find most effective treatment for LBAM eggs (NP 308 component 2, Problem Statement 2C).
B. Efforts were made to determine effective control of grape mealybug eggs with low temperature phosphine fumigation following research started in 2009. Due to problems related to rearing of grape mealybug on grape plants, availability of eggs for testing often became a problem. However, several tests were conducted and more tests will be conducted in the future (NP 308 component 2, Problem Statement 2C).
C. Significant progress was made in controlling grape mealybug eggs using controlled atmosphere (milestone 1C). Sulfur dioxide was found to cause quality reduction to some grapes at high concentrations in certain CA and SO2 combination treatments. On the other hand, ultralow oxygen (ULO) in combination with 50% CO2 was more effective than ULO treatment without CO2. As a result, the research effort was shifted to ULO+CO2 combination treatment and complete control of all life stages of grape mealybug was achieved. The research is continuing to confirm the complete control of all life stages of grape mealybug as well as safety to grape quality (NP 308 component 2, Problem Statement 2C).
D. Ultralow oxygen treatment was studied for control of bulb mites. Bulb mites need to be controlled on exported flower bulbs and tubers and there is no effective fumigation treatment. Current treatment of dipping in pesticide solution generates hazardous waste which is costly to dispose. The preliminary study showed that ultralow oxygen treatment was effective in controlling bulb mites at moderate temperature. Research is continuing to develop safe and effective ULO treatment for bulb mite control on flower bulbs. The treatment, if successfully developed, will provide an environmentaly friendly alternative treatment for bulb mites and economic benefits to horticultural industries (NP 308 component 2, Problem Statement 2C).
Low temperature phosphine fumigation of chilled lettuce under insulation cover. Low temperature phosphine fumigation has been demonstrated to be a safe and effective alternative to methyl bromide fumigation for control of western flower thrips on fresh commodities, including lettuce for export to Taiwan. Its commercial use is, however, hindered by the lack of low temperature fumigation infrastructure. ARS Researchers at Salinas, CA successfully developed a method of fumigating pre-chilled lettuce under an insulation cover for control of western flower thrips. The method was demonstrated to be safe and effective in semi-commercial pallet scale tests, and provides an economical alternative to fixed, low temperature fumigation chambers for conducting low temperature phosphine fumigation for control of the pest on lettuce. The method also has potential to be used to control other phosphine-susceptible insects.
Oxygen increases toxicity of phosphine to insects. Phosphine is a slow acting fumigant in controlling insects and treatment time can last over 10 days for some insects. For low temperature phosphine fumigation of fresh commodities, treatment is even longer as toxicity of phosphine decreases at lower temperatures. Shortening treatment would increase turn over time of fumigation chambers and reduce fumigation cost. Researcher at USDA-ARS in Salinas found significant synergistic effects of oxygen in increasing toxicity of phosphine against all life stages of various insects and resulted in significant reductions in treatment time for pest control. The synergism may have significant practical implications in developing more effective and shorter fumigation treatment for postharvest pests especially for low temperature phosphine fumigation on perishable commodities.
Liu, Y., Bettiga, L.J., Daane, K.M. 2010. Ultralow oxygen treatment for control of Planococcus ficus (Homoptera: Pseudococcidae) on grape rootstocks. Journal of Economic Entomology. 103: 272-276.