Biological control of Corynespora cassicola and Drechslera tritici-repentis

Chemical control is the most widely used method for disease management in significant crops such as soybeans and wheat. However, for a few years biological control has gained prominence. Thus, we evaluated the antagonism of bacteria Pseudomonas fluorencens, Pantoea aglomerans, and Bacillus sp. on the phytopathogens Corynespora cassiicola and Drechslera tritici-repentis, previously isolated from soybean and wheat leaves, respectively. The experiments were carried out under controlled conditions at the Phytobacteriology Laboratory of the Faculty of Agronomy and Veterinary Medicine (FAVM), University of Passo Fundo (UPF), Rio Grande do Sul, Brazil. The treatments were: T1: P. Fluorencens + pathogen; T2: P. aglomerans + pathogen; T3: Bacillus spp. + pathogen, and T4: pathogen (control). In each experiment (C. cassiicola and D. tritici-repentis), a completely randomized design with six replications was used. The data were submitted to linear regression analysis, obtaining the daily increase rate (slope). The final time data was submitted to the ANOVA, and the means were compared by the Tukey test (P < 0.05). P. fluorescens, P. agglomerans, and Bacillus sp. reduced mycelial growth by 74 and 87% of C. cassiicola and D. tritici-repentis, respectively. Although this study was carried out under in vitro conditions, it can serve as a basis for other biological control studies, especially about the management of leaf spots caused by C. cassiicola and D. tritici-repentis, under field conditions.