Preharvest application of fungicides to control postharvest diseases of blueberries in California

Authors: Xiao, Chang-Lin; Saito, Seiya

Submitted to: Acta horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Postharvest fruit rot diseases limit the storage and shelf life of fresh blueberries. Gray mold caused by Botrytis cinerea and Alternaria rot caused by Alternaria alternata are the two major postharvest diseases of blueberries in California. The blueberry industry needs tools to extend storage of blueberries. In this study, we evaluated the effectiveness of preharvest application of fungicides to control these postharvest diseases of blueberries. On the inoculated fruit, certain fungicides significantly reduced disease incidence and severity, while for the naturally occurring postharvest diseases, the effectiveness of some fungicides varied with trial year. The limitation of preharvest application of fungicides for the control of postharvest diseases in stored blueberries is discussed.

Technical Abstract: Gray mold and Alternaria rot caused by Botrytis cinerea and Alternaria alternata, respectively, are the two major postharvest diseases affecting stored blueberries in California. A four-year field study was conducted to evaluate the effectiveness of preharvest application of fungicides to control these postharvest diseases of blueberries. Over the course of the four-year study, ten different fungicides were tested. Depending on the fungicide labels, each fungicide was applied once to the blueberry plants 1 to 7 days prior to harvest. The harvested fruit were carefully packed into clamshells (170-g fruit each) and then stored at 0-1°C for 4 to 5 weeks for decay development. The treatments were evaluated for their effects on naturally occurring postharvest diseases, the fruit-to-fruit spread (nesting) of gray mold during the storage, and decay on the fruit artificially inoculated with either B. cinerea or A. alternata. On the inoculated fruit, certain fungicides significantly reduced disease incidence and severity, while for the naturally occurring postharvest diseases, the effectiveness of some fungicides varied with trial year. The limitation of preharvest application of fungicides for the control of postharvest diseases in stored blueberries is discussed.