Biological control of Fusarium wilt on common beans by in-furrow application of Trichoderma harzianum

Abstract

Two field trials were conducted during the summer and winter seasons of 2010 to evaluate the effect of biocontrol agents against Fusarium wilt of common bean. Treatments included six Trichoderma harzianum isolates applied in planting furrows at 1.2 × 1012 conidia/ha, and one seed treatment with carboxin + thiram. Non-treated and infested plots served as control. Three T. harzianum isolates, CEN287, CEN290 and CEN316, reduced Fusarium wilt incidence and disease severity in the summer trial; incidence averaged 43.9 and 82.4 % in effective treatments and infested control plots, respectively. During the winter season, four isolates, CEN290, 1306, CEN316 and CEN287, reduced wilt incidence by 22.4, 26.7, 41.2 and 51.3 %, respectively, compared to the infested control (92.8 %) and fungicide-treated seeds (85.8 %). In general, ranking of treatments were similar whether incidence or severity was evaluated. However, CEN287 and CEN316 were ranked as the most effective isolates in both seasons. Crop yield-related variables were not affected by the treatments. Fusarium oxysporum population in soil was positively associated with disease incidence and severity, and negatively associated with grain number per pod and 100-grain mass in the summer experiment. In the winter trial, increasing densities of Trichoderma spp. in soil were correlated with increased 100-grain mass and number of grains per pod. The results highlight the value of in furrow applications of biocontrol agents for managing Fusarium wilt of common bean.