Antagonistic potential of Bacillus velezensis S26 endospores against gray mold in grapevines

Botrytis spp. are cosmopolitan pathogens that affect various crops worldwide. Gray mold has led to substantial economic losses in viticulture, both in the field and the postharvest phase. Conventional strategies for managing fungal diseases, such as chemical control, negatively impact the environment and human health, prompting the development of eco-friendly products and biopesticides. The study aimed to evaluate the inhibitory potential of Bacillus velezensis strain S26 endospore suspensions against Botrytis spp. in two grapevines cultivars: Niagara branca (Vitis labrusca L.), a table grape variety, and Moscato giallo (V. vinifera L.), a variety used in winemaking. To this end, bacterial antagonism was assessed in leaf discs, grape berries, and vine plants. In addition, an experiment was performed to evaluate bacterial colonization and its impact on grape berry quality of Niagara branca. The findings demonstrated that both fresh and stored endospore suspensions of B. velezensis S26 effectively suppressed the pathogen. In the colonization assay, the bacterium exhibited growth in grape berries even in the presence of the pathogen, and applying the bacterial suspension did not compromise grape quality. Therefore, B. velezensis S26 stands out as a pivotal bioagent for controlling gray mold in field and postharvest grapes.