Komal K. Sekhon,* Alistair H. McKay, Somer L. Magnuson, and Sonet Van Zyl
*California State University, Fresno, 2360 E. Barstow Avenue, M/S VR89, Fresno, CA, 93740 (kmlksekhon@mail.fresnostate.edu)

Sulfur dioxide (SO2) is a reactive fumigant commonly used to prevent postharvest fungal decay in California table grapes. Fumigation with SO2 is highly effective at controlling several postharvest pathogens, including Botrytis cinerea, Penicillium digitatum, and Penicillium expansum. Although highly effective, the use of SO2 is problematic and the table grape industry would benefit if alternative decay control strategies were available. SO2 can lead to injury, bleaching, and general phytotoxicity of table grape skins and can create “off flavors” that can cause adverse reactions to consumers. SO2 is a very strong oxidizer and causes damage to grape storage facilities and can create a hazardous work environment for employees of storage and shipping facilities. SO2 released into the environment may contribute to air quality concerns. To investigate alternatives to SO2 use, we intend to compare the effica­cy of existing and emerging decay management strategies with current SO2 use to determine if alternatives are practical and commercially viable. Factor X is a novel fungicide tested for its efficacy against common postharvest fungal pathogens, such as B. cinerea in table grapes, P. digitatum in citrus fruits, and P. expansum in apples. Pyrimethanil is a registered postharvest anilinopyrimidine fungicide. Fludioxonil is also a registered postharvest phenylpyrrole fungicide. Primary data suggests that Factor X, pyrimethanil, and fludioxonil are more effective than SO2 at controlling fungal decay. All three fungicides were administered in liquid formulations. Commercial use of a liquid fungicide would greatly decrease the environmental impacts on air quality and employee workplace safety SO2 use poses. We foresee significant reportable out­comes from this thesis on the feasibility of current and potential future alternatives to SO2 use and the practicality of implementing these by the California table grape industry.

Funding Support: AgroFresh Solutions, Inc. and Fresno State Department of Viticulture and Enology