Effects of preharvest application of Acibenzolar-S-methyl and Potassium Silicate on postharvest diseases and fruit quality of Blueberries

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

Submitted to: PhytoFrontiers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Postharvest fruit rot diseases limit the storage and shelf life of blueberries. Alternaria rot and gray mold caused by the fungal pathogens Alternaria alternata and Botrytis cinerea, respectively, are the two major postharvest diseases of blueberries grown in California. Fungicide resistance in these two pathogens is prevalent and thus results in the failure of chemical control. Searching for alternatives to synthetic fungicides is needed. Acibenzolar-S-methyl (ASM) and potassium silicate (PSi) can serve as plant resistance inducers to trigger plant responses to diseases. In this study, we conducted a 3-year field study to evaluate the effects of preharvest application of ASM and PSi on the development of postharvest diseases and fruit quality of blueberries. Blueberry plants were treated with ASM and PSi in the field, and fruit were harvested at commercial maturity and stored in a cold facility. After a 4-week cold storage, fruit were assessed for decay development. We found that the preharvest use of ASM and PSi had no or limited effects on postharvest diseases and fruit quality of blueberries.

Technical Abstract: Blueberries are highly perishable and susceptible to storage spoilage, especially fruit rot diseases caused by fungal pathogens. Alternaria rot and gray mold caused by Alternaria alternata and Botrytis cinerea, respectively, are the two major postharvest diseases of blueberries grown in California. We conducted a three-year study to evaluate the effects of preharvest application of Acibenzolar-S-methyl (ASM) and potassium silicate (PSi) on Alternaria rot and gray mold on blueberry fruit inoculated with the pathogens after harvest, naturally occurring fruit rots, fruit-to-fruit spread of gray mold during cold storage, and fruit quality. After a 4-week cold storage on inoculated fruit, all fruit developed rots regardless of treatments applied in the field; on non-inoculated fruit, ASM significantly reduced % of decayed fruit compared to the nontreated control in 2023 but not in 2021 and 2022, and PSi significantly reduced % of decayed fruit compared to the nontreated control in 2021 and 2023 but not in 2022. However, the magnitude of reduction in disease incidence was low to modest. There were no significant differences in fruit quality attributes among the treatments, except that ASM-treated fruit had a higher soluble solid and a lower titratable acidity compared to the non-treated fruit in 2022, but the magnitude of differences was small. Our results suggest that preharvest use of ASM and PSi had no or limited effects on postharvest diseases of blueberries.