Antagonistic Effect of Endophytic and Commercial Trichoderma Isolates on Phaeoacremonium minimum, the Causal Agent of Leaf Stripe Disease of Grapevine

Leaf stripe disease (LSD) of grapevine, which was previously known as esca complex disease, is one of the most important and destructive trunk diseases of grapevines.Phaeoacremonium minimum is the principle hyphomycete associated with disease. Chemical control of LSD has proven difficult, meanwhile, application of biological control agents for disease management have been promising. The aim of present study was to evaluate inhibitory potentiol of three Trichoderma species sincluding one commercial product (Trichoderma harzianum T22) and two endophytic isolates, T. longibrachiatum and T. brevicompactum, against four isolates of Pm. minimum with opposite mating type (two MAT1-1 and two MAT1-2 isolates) using dual culture, volatile and non-volatile metabolite assays. The results of this study showed that all three species of the antagonist had significant inhibitory effect on the growth of Pm. minimum, in comparison to the control. In dual culture assay, T. harzianum T22 showed the highest potential in the inhibition of the Pm. minimum growth, with 76.53 percent growth inhibition, in comparison to the two other antagonists. In volatile metabolites assay, significant differences were observed among the antagonists in growth inhibition of the Pm. minimum. In non-volatile compounds assay, T. brevicompactum with 75.46 percent growth inhibition of pathogen, showed the highest control potential in comparison with the other two species. Non-volatile compounds of T. longibrachiatum and T. harzianum T22 showed 46.93 and 17.67 percent inhibition on colony growth, respectively. Evaluation of the inhibitory effects of these antagonists on the opposite mating types of Pm. minimum showed that volatile compounds of T. longibrachiatum were more effective on MAT1-1 (48.74% growth inhibition) compared to MAT1-2 (35.10 growth inhibition). Overall, the results of this study reveal T. brevicompactum as an effective antagonist against Pm. minimum; hence, further evaluation of its biocontrol properties and efficacy in disease control under greenhouse and field condition remain to be studied.