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.
Low temperature phosphine fumigation using a QuickPHlo-R phosphine generator from United Phosphorous Ltd was tested to determine safety to both romaine and head lettuce. This type of phosphine generator has been suggested to produce pure phosphine and may be suitable to fumigate fresh commodities. Both one day and three day treatments for control of western flower thrips and lettuce aphid respectively were conducted. Phytotoxicity was however, found in both one day and three day treatments. The phosphine generator therefore is not suitable for postharvest pest control on harvested lettuce.
Phosphine fumigation treatments of romaine and head lettuce for control of lettuce aphid were conducted to verify efficacy and safety. In addition, pallet-scale fumigation of pre-chilled lettuce under an insulation cover and high oxygen level to control lettuce aphid was conducted. The treatment was successful and has the potential to be developed as an economical alternative to fixed low temperature chamber fumigation for control of both lettuce aphid and leafminer.