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 (R) 80 and Span (R) 80, in order to increase phytotoxicity. In step 1, the maximum herbicidal activity (1.23% of the leaves had lesions) was obtained at 25 degrees 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 (R) 80 and Span (R) 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.