The objective of this work was to produce an herbicide by submerged fermentation in a stirred-tank bioreactor and to assess the potential herbicidal in pre-emergence, post-emergence, and in a detached leaves of Cucumis sativus var species. wisconsin (cucumber) and Sorghum bicolor (sorghum) species. Fermentations were carried out in a stirred-tank bioreactor with useful volume of 3L. Stirring rate (40, 50, and 60 rpm) and aeration (1, 2 and 3 vvm) were the variables studied for bioherbicide production. Fermented broth was fractioned with different solvents to identify the molecules produced by the fungus in a multi-dimensional gas chromatograph system. Bioherbicide showed 100% inhibition of germination of both species in the pre-emergence tests. From detached leaves tests were verified yellowish lesions in Cucumis sativus and necrotic lesions on leaves of Sorghum bicolor. Post-emergence test presented variation of the phytotoxicity from 25 to 66% for the species C. sativus and from 32 to 58% by S. bicolor. The metabolites produced by submerged fermentation of Phoma sp. presented activity in pre-emergence, post-emergence, and detached leaves of C. sativus and S. bicolor and it could be an alternative in the future for weed control.

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This study aimed to compare the herbicidal activity of solid formulas obtained by spray drying with conventional liquid formulas containing biomolecules produced by submerged cultivation of the fungus Diaporthe sp. in a stirred-tank bioreactor. The solid formula presented the highest phytotoxicity on plant control (96.7%) and the phytotoxicity was directly related to the concentration of fermented broth in the formula. The use of adjuvant improved the efficiency of the bioherbicide. Dry matters of treatments were lower than the control and this was correlated with an increase in oxidative stress, since the activity of the antioxidant enzymes such as superoxide dismutase and guaiacol peroxidase increased in the treatment with a high level of phytotoxicity. Spray drying technology is a promising tool to concentrate bioherbicide without the loss of bioactive compounds since one of the major challenges in the production of bioherbicides is the low concentration of active ingredients in the fermented broth.

Brazilian growers are facing difficulties to manage the weeds Lolium multiflorum, Conyza sp. and Echinochloa sp. using commercially available agrochemicals in most crops. This study aims to evaluate the use of a bioherbicide based on fermented broth containing secondary metabolites of Diaporthe sp. to control L. multiflorum, Conyza sp. and Echinochloa sp. The bioherbicide activity in preemergence and post-emergence of these weed species and phytotoxicity on soybean, wheat and rice plants were evaluated. In the pre-emergence test using all weed species, the bioherbicide showed 100% control efficiency in comparison with the control group. Phytotoxic symptoms were observed on soybean leaves and horseweed was efficiently controlled using the bioherbicide.

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