Efficacy and Phytotoxicity of Sulfur Dioxide Fumigation for Postharvest Control of Western Flower Thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), on Select Fresh Fruit and Vegetables

Sulfur dioxide (SO 2 ) fumigation was evaluated for efficacy against western flower thrips ( Frankliniella occidentalis ) and phytotoxicity to four select fresh fruits and vegetables. Western flower thrips were found to be very susceptible to SO 2 fumigation. Fumigations with 0.3 and 0.5% SO 2 for 60 and 30 min, respectively, at a low temperature of 5 °C achieved 100% thrips mortality. Broccoli, bell peppers, apples, and navel oranges with thrips were subjected to 30 min fumigation with 0.3–0.5% SO 2 to verify efficacy and determine potential phytotoxicity. The fumigation resulted in complete control of thrips. Its effects on visual quality of fresh produce varied. The fumigation caused severe discoloration of broccoli. However, the treatment did not have significant effects on the color of other products. No negative impact on visual appearance of bell peppers and navel oranges was observed. However, it caused darkened lenticels on green apples and, therefore, may potentially degrade apple postharvest quality. The lack of phytotoxicity of SO 2 fumigation is likely due to well-developed wax layers on those fresh products. The results of the study suggest that SO 2 fumigation has good potential to be used safely and effectively against sensitive pests on select fresh fruit and vegetables including peppers and citrus fruits.