Solid-state fermentation for production of a bioherbicide from Diaporthe sp. and its formulation to enhance the efficacy

In this study, a bioherbicide was produced by solid-state fermentation (SSF) using Diaporthe sp. Adjuvants were employed in a formulation to enhance the herbicidal activity towards the target (Cucumis sativus). The study was divided into two steps: (1) the fermentation condition for bioherbicide production was assessed; (2) evaluation of different formulations containing palm oil, Tween® 80 and Span® 80, in order to increase phytotoxicity. In step 1, the maximum herbicidal activity (1.23% of the leaves had lesions) was obtained at 25 °C, moisture content of 50 wt%, supplemented with 10 wt% of corn steep liquor and soybean bran and inoculum density of 15 wt%. In step 2, the formulation containing 8.2 wt% of palm oil, 8.2 wt% of Tween® 80 and Span® 80, resulting in an HLB of 12.8 showed the highest phytotoxicity on the leaves. At this condition, dry matter and height of target were reduced about 36% in comparison with control. Diaporthe sp. has the potential to produce molecules with herbicidal activity and the use of adjuvants enhanced three times its efficiency.