Natamycin as a postharvest treatment to control gray mold on stored blueberry fruit caused by multi-fungicide resistant Botrytis cinerea

Authors: Saito, Seiya; Wang, Fei; Xiao, Chang-Lin

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2022
Publication Date: 2/2/2022
Citation: Saito, S., Wang, F., Xiao, C. 2022. Natamycin as a postharvest treatment to control gray mold on stored blueberry fruit caused by multi-fungicide resistant Botrytis cinerea. Postharvest Biology and Technology. 187. Article 111862. https://doi.org/10.1016/j.postharvbio.2022.111862.
DOI: https://doi.org/10.1016/j.postharvbio.2022.111862

Interpretive Summary: Gray mold caused by the fungus Botrytis cinerea is one of the major postharvest diseases of blueberries in California. Control of postharvest gray mold is generally dependent on the use of chemicals known as fungicides. However, fungicide resistance in B. cinerea can result in the failure of chemical control. Alternatives to conventional chemical fungicides are needed for control of postharvest gray mold. Natamycin, a biofungicide, is registered for postharvest use in certain fresh fruit and it has been demonstrated to be highly effective in controlling various postharvest fungal diseases. In this study, natamycin was evaluated for its efficacy in controlling gray mold on blueberries caused by B. cinerea that are resistant to multiple fungicides as well as the effectiveness in reducing decays in general resulting from natural infections. Our results showed that as low as a quarter rate of the label rate of natamycin significantly reduced gray mold regardless of fungicide resistance. Natamycin also reduced overall fruit decay resulting from natural infections and had no adverse effect on fruit quality. Our results suggest that natamycin can be a promising tool to control postharvest gray mold of blueberry fruit while maintaining fruit quality.

Technical Abstract: Gray mold caused by Botrytis cinerea is one of the major postharvest diseases of blueberries in California. Control of postharvest gray mold is generally dependent on the use of synthetic fungicides. However, multiple resistance to different classes of fungicides is common in B. cinerea populations in various production regions. Alternatives to conventional chemical fungicides are needed to control postharvest gray mold. Natamycin, a biofungicide, is registered for postharvest use in certain fresh fruit and it has been demonstrated to be highly effective in controlling various postharvest fungal diseases. In this study, natamycin was evaluated for its efficacy in controlling gray mold caused by B. cinerea with different fungicide resistance phenotypes as well as the effectiveness in reducing decays in general resulting from natural infections. Our results showed that as low as a quarter rate of the label rate of natamycin significantly reduced gray mold incidence and severity regardless of fungicide resistance phenotypes. Natamycin also reduced overall fruit decay resulting from natural infections and had no adverse effect on fruit quality. Our results suggest that natamycin can be a promising tool to control postharvest gray mold of blueberry fruit while maintaining fruit quality.