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POSTERS: Biological Control I

P-047 - Evaluation of early-season application of biocontrol Theia (Bacillus subtilis) on crown and root rots of watermelon caused by Phytophthora capsici

Monday, August 4, 2025
3:45 PM - 4:30 PM HST
Location: Exhibit Hall 3
Abstract Text: Phytophthora capsici, an oomycete pathogen, causes stem, root, and fruit rots of pepper and watermelon, two crops which are economically significant to the state of Florida. These diseases are typically treated with conventional fungicides, however there are sustainability concerns associated with the use of these products. The addition of biological controls into disease management strategies could reduce the number or application rates of conventional fungicide applications within a growing season. Given that biologicals function best as preventatives and Florida watermelon growers seek early-season treatments, we evaluated Bacillus subtilis (Theia) as an early-season addition to a standard fungicide rotation for P. capsici management in watermelon. A watermelon trial was conducted in central Florida to evaluate 10 treatments, which included seedling drenches containing Theia applied foliarly one week prior to transplanting, as well as soil drenching with Theia at the time of transplant, followed by a rotation of conventional grower-standard fungicides. Treatments were monitored weekly for disease and resulting data were compared using orthogonal contrast to evaluate their efficacies. This study explores areas of disease management which are of interest to local growers and could reduce the reliance on conventional fungicides.