Efectividad de aislados microbianos como agentes de biocontrol de Sclerotinia sclerotiorum en frijol

Abstract

Common bean is the second crop in importance in Mexico. This crop is susceptible to be attacked by various plant pathogens such as fungi, viruses or bacteria, which can cause significant losses in agricultural productivity. Sclerotinia sclerotiorum is a soil borne fungus that causes the disease known as white mold in common bean, and can germinate myceliogenic and carpogenically, depending on the environmental conditions. Conventionally, this fungus is controlled with synthetic fungicides. Alternative strategies, such as the use of antagonistic microorganisms may be beneficial in the long term since the risks of developing resistance to the pathogen is reduced, as well as the negative effects on the environment and human health. Preliminary work in our laboratory identified three native microbial isolates (105, 150 and OX32) which showed antagonist properties to S. sclerotiorum in vitro conditions. In this study, we evaluated the effect of these antagonists on the infection of S. sclerotiorum in common bean detached leaves and flower, as well as carpogenic germination of sclerotia. The results indicate that 0X32 isolate inhibited infection by ascospores in common bean flowers and myceliogenic germination of sclerotia in soil, 105 and 150 isolates inhibited mycelial growth in bean leaves and the production of apothecia from sclerotia in treated soils. Based on this work, one of the objectives of the present study was to test the effect of selected microbial isolates on the incidence of white mold in bean crop in field conditions. However, it was not possible to adequately assess the effectiveness of the different isolates on the incidence of white mold disease under field conditions since the disease was poorly manifested during the bioassay. Additional work will be needed to know how effective the bacteria isolates are in the field. The use of native antagonists could become a useful strategy to control S. sclerotiorum spreading.