Angular leaf spot, caused by the fungus Pseudocercospora griseola, is a major disease of common bean (Phaseolus vulgaris L.) in Brazil. The objective of this research was to develop an alternative method for controlling this disease based on an aqueous extract of Pycnoporus sanguineus mycelium. It was evaluated the antimicrobial activity of the aqueous extract against P. griseola as well as its activity of resistance induction against angular leaf spot. The role of the plant defense enzymes peroxidase, polyphenol oxidase and β-1,3-glucanase, and the proteins and chlorophyll content was investigated. The experiments in vitro and in greenhouse used extracts from mycelium of P. sanguineus and water, Acibenzolar-S-methyl (ASM: 75 mg/L) and the fungicide azoxystrobin (40 mg/L) were the control treatments. In vitro, the extract of mycelium inhibited the mycelial growth as well as the sporulation and conidia germination of P. griseola. However severity was reduced in 93% and 50% in greenhouse and field respectively. The activities of peroxidase, polyphenol oxidase and the content of proteins and chlorophylls had an increment in plants treated with extract. These results indicate the potential of P. sanguineus for alternative control of the angular leaf spot in bean.
Phaseolus vulgaris; Pseudocercospora griseola; Phaeoisariopsis griseola; alternative control
