Low temperature phosphine fumigation for postharvest control of western flower thrips (Thysanoptera: Thripidae) on lettuce, broccoli, asparagus, and strawberry.

Abstract

U.S. exported lettuce, broccoli, asparagus, and strawberries often harbor western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), a quarantined pest in Taiwan, and therefore require quarantine treatment. Fumigation with diluted pure phosphine at a low temperature of 2 degrees C was studied to control western flower thrips and to determine effects on the quality of the treated products. Total thrips control was achieved in > or = 18-h fumigation treatments with > or = 250 ppm phosphine. One day fumigation treatment with 1,000 ppm phosphine was tested on lettuce and broccoli. One-day fumigation treatments with 500 ppm and 1,000 ppm phosphine were tested on asparagus and strawberry. Visual quality of lettuce, broccoli, and asparagus was evaluated after 2-wk posttreatment storage. Strawberry quality was evaluated immediately after fumigation and after 1-wk posttreatment storage. For all the products, there were no significant differences between the treatments and the controls in postharvest quality, and there were no injuries caused by the fumigation treatments. Therefore, phosphine fumigation at low temperature was promising for postharvest control of western flower thrips on lettuce, broccoli, asparagus, and strawberry.