Biocontrol of Grey Mold on Strawberry Fruit by Bacillus spp. and Study of the Mechanisms Involved

Abstract

<p>Grey mold, caused by the fungus <em>Botrytis cinerea</em>, is one of the most prevalent diseases affecting strawberry plants (<em>Fragaria ananassa</em>). The objective of this study was to assess the antagonistic effect of 5 bacterial strains belonging to the genus <em>Bacillus </em>spp<em>.</em> (BA1, BF2, BB3, BI3, and BO4) against <em>B. cinerea</em>, tested both <em>in vitro</em> and <em>in vivo</em> on strawberry fruits. The strains exhibited antifungal activity against <em>B. cinerea</em> under <em>in vitro</em> conditions, both through direct confrontations and antibiosis tests, as well as through the effect of organic compounds. Strain BO4 could inhibit mycelial growth by 62.92% through direct confrontation and 64.58% through the secretion of volatile organic compounds. Additionally, the strain BF2 demonstrated a high antibiosis effect (74.64%) compared to the control at a concentration of 25%. Treating fruits with the bacterial suspension and culture filtrate of the 5 studied strains controlled grey mold growth <em>in vivo</em>, as indicated by low severity indices in strawberries treated with strains BI3, BF2, and BA1, marked by percentages of 24.44%, 24.44%, and 37.78%, respectively, for preventive treatment. The difference in the effectiveness of various strains depended on the treatment mode; preventive treatment proved to be more effective compared to curative treatment.</p>