Plant Safety, Horticultural Benefits, and Disease Efficacy of Essential Oils for Use in Organically Grown Fruit Crops: from the Farm to the Consumer
Project Director
Ali Sarkhosh
Year Funded
2020
Award Number
2020-51300-32181
Funded Institution
University of Florida
Grant Program
OREI (Organic Agriculture Research and Extension Initiative)
USDA NIFA Report (alternate)
Project Overview
Laboratory, greenhouse, and field experiments were conducted to evaluate NOP-allowed plant essential oil (EO) products in managing pre- and post-harvest fungal and bacterial diseases that impact organic production of blueberry, peach, avocado, mango, and other temperate and tropical fruits. Products based on thyme oil and tea tree oil were tested for efficacy against multiple pathogens and arthropod pests (scale, thrips, and mites) and crop phytotoxicity.
Essential oils of thyme, oregano, and savory, and commercial organic fungicide products based on thyme or cinnamon oils showed significant activity against several blueberry, peach, avocado, and mango pathogens in lab experiments. However, they were ineffective in preharvest field trials with multiple spray applications; in contrast, a copper fungicide significantly reduced several fungal diseases in mango and avocado. Post-harvest fumigation with thyme oil or immersion in a solution of Thyme Guard slowed the progression of brown rot in peaches, but these treatments sometimes damaged the fruit depending on cultivar and on concentration and duration of treatment.
Farmer Takeaways
(1) Commercially available, NOP-allowed plant essential oil (EO) fungicides include ThymeGuard (thyme oil), Timorex Act (tea tree oil), and Cinnerate (cinnamon oil).
(2) In field trials, copper (Kocide 2000) controlled multiple pathogens of peach, blueberry, mango, and avocado, while EO fungicides were largely ineffective.
(3) Postharvest fumigation with thyme oil or dipping in ThymeGuard solution reduced brown rot of peach, but treatment concentration and duration must be adapted to peach cultivar to avoid damaging the fruit.
(4) Post-harvest nanotechnologies (nanocoatings, encapsulation of active compounds, nanosensors) show promise but need additional research into human health safety.
Project Outputs
Chang, Y., Boukari, W., Riley, S. S., Harmon, P. F., Sarkhosh, A., & Brecht, J. K. (2024). In Vitro Antifungal Activity of White Thyme, Oregano, and Savory Oils Against Five Monilinia fructicola Isolates from the Southeastern United States. Plant Health Progress, 25(3), 262–269.
Gañán-Betancur, L., Crane, J. H., Schaffer, B., Vargas, A. I., Sarkhosh, A., & Gazis, R. (2024). Essential Oils for Managing Anthracnose in Mango (Mangifera indica): Laboratory Results Do Not Translate into Field Efficacy. Plant Disease, 108(10), 3033–3043.
Chang, Y., Harmon, P. F., Treadwell, D. D., Carrillo, D., Sarkhosh, A., & Brecht, J. K. (2022). Biocontrol Potential of Essential Oils in Organic Horticulture Systems: From Farm to Fork. Frontiers in Nutrition, 8.
Chang, Y., Harmon, P. F., Ritenour, M. A., Liu, T., Sims, C. A., Sarkhosh, A., & Brecht, J. K. (2026). Comparison of Thyme Oil Vapor and Thyme Guard Immersion on Peach Postharvest Brown Rot Control.