Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 20, 2008
Publication Date: June 20, 2008
Citation: Liu, Y. 2008. Pure phosphine fumigation treatment at low temperature for postharvest control of western flower thrips on lettuce, broccoli, asparagus, and strawberries. Journal of Economic Entomology. 101(6):1786-91. Interpretive Summary: The presence of live western flower thrips on exported lettuce, broccoli, asparagus, or strawberries affects export of these products to Taiwan. Low temperature phosphine fumigation treatments were conducted to determine effective treatments against western flower thrips and their impact on postharvest quality of lettuce, broccoli, asparagus, and strawberries. Western flower thrips were found to be very susceptible to phosphine and low temperature fumigation with 250 ppm phosphine for 18 hour was found to be adequate to control the thrips. One day fumigation with 500 and 1000 ppm phosphine at low storage temperature was demonstrated to be safe for lettuce, broccoli, asparagus, and strawberries. Therefore, pure phosphine fumigation at low temperature is promising to be used for quarantine treatment of western flower thrips on the affected fresh commodities.
Technical Abstract: U.S. exported lettuce, broccoli, asparagus, and strawberries often harbor western flower thrips (Frankliniella occidentalis), a quarantined pest in Taiwan, and therefore require quarantine treatment. Pure phosphine fumigation at a low temperature of 2°C was studied as an alternative fumigant to methyl bromide to control western flower thrips. Total thrips control was achieved in 18 hour fumigation treatments with 250 ppm phosphine. One day fumigation treatment with 1000 ppm phosphine was tested on iceberg and romaine lettuce and on broccoli. One day fumigation treatments with 500 ppm and 1000 ppm phosphine were tested on asparagus and strawberries. Visual quality for lettuce, broccoli, and asparagus was evaluated after two weeks of post-treatment storage. Strawberry quality was evaluated immediately after fumigation and after one week of post-treatment 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, pure phosphine fumigation at low temperature was promising for postharvest control of western flower thrips on lettuce, broccoli, asparagus, and strawberries.