Abstract:To elucidate the control efficacy of Trichoderma against maize sheath blight, eighteen Trichoderma isolates were obtained from the maize rhizosphere in the suburb of Ya’ an,Sichuan Province,and tested . The suppression rates of mycelial growth of Rhizoctonia solani by the Trichoderma isolates were 39.44％-84.98％ on dual culture. The suppression rates of mycelial growth of R.solani were 13.48％-85.81％ on the PDA plates contained ferment filtrates of the Trichoderma isolates. But when the filtrates were autoclaved, inhibition activities against R.solani were decreased. Three Trichoderma isolates T8,T13 and T2,which were identified as T.harzianum, T.longibrachiatum, T.aureoviride, respectively, were selected for field experiment. The efficacies of solid culture of T8,T13 and T2 against maize sheath blight were 62.75％, 64.48％, 68.52％, respectively, which were better than that of Jinggangmycin (49.68％). However,the efficacies of fluid ferment filtrate of isolate T13 was only 40.07％, lower than those of the solid culture. After application of solid culture of T8,T13 and T2 yields significantly increased for 29.77％,43.37％ and 54.21％, respectively.