Trichoderma atroviride SC1 induces local and systemic resistance against grapevine downy mildew

Several Trichoderma strains are active against numerous plant pathogens, and therefore used as biocontrol agents (BCAs). The fungal strain T. atroviride SC1 was isolated in northern Italy from decayed hazelnut wood and it is effective against several grapevine pathogens (i.e. Botrytis cinerea, Armillaria mellea, Podosphaera xanthii). T. harzianum T39 can induce systemic resistance in plants, but this capability has not been documented for the grapevine – T. atroviride SC1 interaction. Our aims were to evaluate the efficacy of T. atroviride SC1 against grapevine downy mildew (Plasmopara viticola) and to characterize its mechanism of action. Applications of T. atroviride SC1 conidia activated a local and systemic resistance against grapevine downy mildew severity similarly to T. harzianum T39 treatments. However, the effect of these two Trichoderma strains is weaker than the standard copper treatment. From a practical point of view, Trichoderma spp. can be regarded as a tool to reduced susceptibility of grapevine to downy mildew, rather than an alternative to fungicides, but the integration of resistance inducers is required in order to reach a satisfactory efficacy level