Seleção in vitro de agentes de biocontrole visando o controle de Fusarium sp.

The objective of this research was to evaluate the in vitro antagonistic action of Bacillus and Trichoderma sp. in the control of Fusarium sp. responsible for damages in plants of Vigna unguiculata (L.) Walp (cowpea). The assay was conducted using the crop pairing technique. The pathogen Fusarium sp. was obtained by the isolation of cowpea plants with symptoms of the disease. The antagonists used were: Bacillus subtilis (LCB 30), B. subtilis (LCB 45), Bacillus sp. (BMH), Bacillus sp. (INV) and Trichoderma sp. Mycelial growth evaluations were performed when the entire surface of the PDA (Potato Dextrose Agar) culture medium was colonized by Fusarium sp. in the control treatment (pathogen cultured in the absence of the antagonist). For the analyzes, a completely randomized design with 5 replications was used. From the results obtained, it can be inferred that the isolates of Bacillus spp. and Trichoderma sp. have the potential as antagonists against Fusarium sp., the isolate Bacillus subtilis (LCB 45) responsible for inhibiting 25% of the mycelial growth, and the treatments with B. subtilis (LCB 30), Bacillus sp. (BMH), Bacillus sp. (INV) and Trichoderma sp., Inhibited 59.4%, 46.5%, 46.4% and 37% growth of the colony diameter of the causal agent of fusariosis in cowpea plants, respectively.Nesta pesquisa, objetivou-se avaliar a ação antagonista in vitro de bactérias do gênero Bacillus e do fungo Trichoderma sp. no controle de Fusarium sp. responsável por danos em plantas de Vigna unguiculata (L.) Walp (feijão-caupi). O ensaio foi conduzido utilizando a técnica de pareamento de culturas. O patógeno Fusarium sp. foi obtido pelo isolamento de plantas de V. unguiculata com sintomas da doença. Os antagonistas utilizados foram: Bacillus subtilis (LCB 30), B. subtilis (LCB 45), Bacillus sp. (BMH), Bacillus sp. (INV) e Trichoderma sp. As avaliações do crescimento micelial foram realizadas quando toda a superfície do meio de cultivo BDA (batata, dextrose, agar) apresentava-se colonizada pelo Fusarium sp. no tratamento testemunha (patógeno cultivado na ausência do antagonista). Para as análises foi utilizado o delineamento inteiramente casualizado, com 5 repetições. Pelos resultados obtidos, pode-se inferir que os isolados de Bacillus spp. e Trichoderma sp. possuem potencial como antagonistas contra Fusarium sp., sendo o isolado B. subtilis (LCB 45) responsável por inibir 25% do crescimento micelial, e os tratamentos com B. subtilis (LCB 30), Bacillus sp. (BMH), Bacillus sp. (INV) e Trichoderma sp., inibiram 59,4%, 46,5%, 46,4% e 37%, o crescimento do diâmetro da colônia do agente causal da fusariose em plantas de V. unguiculata, respectivamente