Impact of Oriental Fruit Fly Postharvest Treatments on Avocado

Abstract

The detection in August 2015 of the Oriental Fruit Fly (Bactrocera dorsalis Hendel, Diptera: Tephritidae) in the Redland area in Miami-Dade County, Florida triggered a quarantine that restricted the movement of fruit fly host material in an approximately 99-square mile (256-square kilometer) area. The quarantine affected 4000 acres of fruit bearing commercial avocado groves. Approved post-harvest treatments for B. dorsalis and avocado included in the USDA Treatment Manual were acceptable for immediate certification and movement of fresh avocados from the quarantine area. However, it was unknown if Florida avocados would meet quality standards (US combination grade) after the treatments. Three post-harvest treatments that combine methyl bromide fumigation and cold storage periods were tested on six avocado varieties from Florida. The treatments differed in the durations of the fumigation and cold treatment periods. A seven day transit period at 8.3°C (47°F) was added to account for the time when the fruit leaves the packing house until it is sold by retailers. None of the six varieties had met the US combination grade after the treatments and transit period. Treated fruit exhibited both internal (pulp) and external (skin) damage. Damage was attributed to the fumigation component of the treatment, but the six varieties tolerated the cold portion of the treatment. Damage by fumigation ranged from 26% - 100%. In general, the longer the fumigation period the worse the effect. The need for alternative post-harvest treatments for Florida avocados is discussed.