Brown propolis, chitosan and acibenzolar-S-methyl inhibit gray mold and induce postharvest defense responses in strawberries.

Botrytis cinerea is the etiological agent of gray mold in strawberries, a disease that is difficult to control and requires excessive fungicide application to avoid potential losses, increasing production costs, and allowing pathogen resistance to emerge. In this scenario, activating the plant's defense mechanisms with abiotic inducers may be a viable and ecological control solution. The objective was to analyze in vitro pathogen conidia growth, sporulation, and germination, as well as in vivo resistance responses by a potential inductor of glyceollin and deoxyanthocyanidin phytoalexins; and to quantify proteins, phenylalanine ammonia-lyase (PAL), total sugars and reducing sugars, and total phenols. The treatments evaluated were brown propolis ethanolic extract (PEE—20, 40, and 60 mL L−1); chitosan (1.0, 3.0, 5.0%) and acibenzolar-S-methyl (ASM—10; 100 and 1000 mg a.i. L−1). At a dose of 20 mL L−1, the propolis ethanolic extract inhibited B. cinerea, while also accumulating glyceollin, deoxyanthocyanidin phytoalexins and subtly eliciting reducing sugars and PAL. Chitosan (1.0 and 3.0%) is also effective at controlling gray mold. At a dose of 100 mg L−1, the standard reference indicator (ASM) was able to reduce the incidence of pathogens in fruits while increasing total sugars and proteins. [ABSTRACT FROM AUTHOR]