Biological control of frogeye leaf spot of soybean caused by Cercospora sojina with indigenous strains of bacteria

SIMONETTI E; CARMONA MA; SCANDIANI MM; GARCÍA AF; LUQUE AG; CORREA O.S; BALESTRASSE KB

LETTERS IN APPLIED MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012

0266-8254

Aims: Assessment of biological control of Cercospora sojina, causal agent of frogeye leaf spot (FLS) of soya bean, using three indigenous bacterial strains,BNM297 (Pseudomonas fluorescens), BNM340 and BNM122 (Bacillus amyloliquefaciens). Methods and Results: From cultures of each bacterial strain, cell suspensions and cell-free supernatants were obtained and assayed to determine their antifungal activity against C. sojina. Both mycelial growth and spore germination in vitro were more strongly inhibited by bacterial cell suspensions than by cellfree supernatants. The Bacillus strains BNM122 and BNM340 inhibited the fungal growth to a similar degree (I 52–53%), while cells from P. fluorescens BNM297 caused a lesser reduction (I 32–34%) in the fungus colony diameter. The foliar application of the two Bacillus strains on soya bean seedlings, under greenhouse conditions, significantly reduced the disease severity with respect to control soya bean seedlings and those sprayed with BNM297. This last bacterial strain was not effective in controlling FLS in vivo. Conclusions: Our data demonstrate that the application of antagonistic bacteria may be a promising and environmentally friendly alternative to control the FLS of soya bean. Significance and Impact of the Study: To our knowledge, this is the first reportof biological control of C. sojina by using native Bacillus strains.