Bioherbicidal action of Phoma dimorpha fermented broth on seeds and plants of Senna obtusifolia 1

ABSTRACT The weed Senna obtusifolia causes severe damages to pasture areas in Brazil, due to its high production and seed spread. This study aimed to evaluate the bioherbicidal action of Phoma dimorpha fermented broth in the pre-emergence and post-emergence of S. obtusifolia. The experimental design was completely randomized, with two treatments, one with and other without the application of the fermented broth. The bioherbicidal effects were measured in bioassays of pre-emergence (germination percentage), detached leaves (phytotoxicity) and post-emergence (phytotoxicity, plant height and fresh plant mass). The application of the fermented broth provided a pre-emergence bioherbicidal action, inhibiting the seed germination in 100 %. In detached leaves, it caused leaf necrosis and death on the ninth day after the application. In the post-emergence, this application caused moderate symptoms, such as leaf spots and reduction in the weed plant size. It was concluded that the P. dimorpha fermented broth has a potential herbicidal action and, therefore, represents an alternative in the development of bioproducts for a sustainable weed control in pastures.