Envision a world where the fresh produce you enjoy is not only free from pests but also retains its quality without the use of harmful chemicals. This vision is becoming a reality thanks to new research on sulfur dioxide fumigation. Sulfur dioxide, widely recognized for its preservative properties, is now being explored as a potent fumigant to control pests on fresh fruits and vegetables. This innovative approach promises to address the growing need for safer and more effective postharvest pest control methods.

Researchers have found an innovative solution for postharvest pest control using sulfur dioxide fumigation. This method, aimed at tackling Western Flower Thrips (WFT), shows promising results while maintaining the quality of various fresh fruits and vegetables. This research, led by Dr. Yong-Biao Liu from the USDA-ARS at the Sam Farr United States Crop Improvement and Protection Research Center, was published in the journal Agriculture.

The study highlights that sulfur dioxide fumigation is highly effective against WFT, achieving complete mortality at specific concentrations and durations. For instance, fumigations with low concentrations of sulfur dioxide for short durations at a low temperature resulted in total thrips mortality. Dr. Liu and his team tested the fumigation on four fresh produce items: broccoli, bell peppers, apples, and navel oranges. The findings revealed that while sulfur dioxide fumigation caused severe discoloration in broccoli, it did not significantly affect the visual quality of bell peppers, navel oranges, and yellow apples, though green apples exhibited some darkened lenticels.

“Western flower thrips are very susceptible to sulfur dioxide fumigation, and our results show that this method can be safely applied to certain fruits and vegetables,” said Dr. Liu. The researchers also noted the advantage of sulfur dioxide fumigation at low temperatures, which reduces the need to raise the temperature of the produce, making it more efficient for postharvest cold storage.

The need for alternative fumigants arises from the phase-out of methyl bromide, which has been largely discontinued due to its ozone-depleting effects. Currently, phosphine and sulfuryl fluoride are the primary alternatives, but both have significant drawbacks, including long treatment times and phytotoxicity issues. Sulfur dioxide fumigation, being a generally recognized as safe (GRAS) compound, presents a greener alternative.

“Given the increasing restrictions on traditional fumigants, sulfur dioxide offers a viable solution for pest control,” Dr. Liu mentioned. However, the study also pointed out that sulfur dioxide fumigation might not be suitable for all types of produce. For instance, broccoli showed severe discoloration due to high sulfur dioxide sorption. This indicates that each fresh product requires specific testing to ensure safe and effective postharvest pest control.

Dr. Yong-Biao Liu’s research provides a framework for future studies to explore sulfur dioxide fumigation’s potential for various other pests and produce. This innovative approach could significantly benefit the agricultural industry by providing a safer and more efficient method for postharvest pest control.

Journal Reference

Liu, Yong-Biao. “Efficacy and Phytotoxicity of Sulfur Dioxide Fumigation for Postharvest Control of Western Flower Thrips, Frankliniella occidentalis.” Agriculture, 2024, DOI: https://doi.org/10.3390/agriculture14020305

About The Author

Dr. Yong-Biao Liu

Research Entomologist

USDA, Agricultural Research Service

Sam Farr United States Crop Improvement and Protection Research Center 

Salinas, California. 

Dr. Liu is a research entomologist at USDA-ARS focusing on development of alternative treatments to replace methyl bromide fumigation for postharvest pest control on fresh and stored products. Dr. Liu’s research resulted in ultralow oxygen treatments for control of thrips, bulb mites, mealybugs, and black widow spiders on harvested lettuce, flower bulbs, grape bench grafts, and table grapes respectively. Dr. Liu developed oxygenated phosphine fumigation method to enhance phosphine toxicity against insects. Dr. Liu also discovered nitric oxide as a potent fumigant under ultralow oxygen conditions for postharvest pest control and developed methods of nitric oxide fumigation to control both pests and microorganisms on fresh and stored products. Currently, Dr. Liu focuses on developing sulfur dioxide fumigation treatments and identifying and developing new fumigants from organic volatile compounds for control of postharvest pests on fresh and stored products. Prior to joining USDA-ARS, Dr. Liu did extensive research in areas of insect biology, insect antifeedant, insect sex pheromone, Bt resistance and resistance management. Dr. Liu published over 100 research articles and patents through his research career.

Education: B. Agri., Beijing Forestry University in 1982; M. Sci. in forestry, Univ. of British Columbia in 1987; Ph.D. in Entomology, Univ. of Maine in 1990.