Effects of «Trichoderma» Treatments on the Occurrence of Decline Pathogens in the Roots and Rootstocks of Nursery Grapevines

The growth-stimulating attributes of Trichoderma treatments (dips, soil amendments and drenches with Trichoderma products containing propagules of selected strains of Trichoderma harzianum) in grapevine nurseries, and their effect on the occurrence of fungi in roots and rootstocks of nursery grapevines, in particular fungi causing Petri disease (Phaeomoniella chlamydospora and Phaeoacremonium spp.) and black foot rot (Cylindrocarpon spp.), were compared with quintozene/procymidone treated (standard) vines. Early shoot growth of Trichoderma treated vines was visibly better than that of the control vines. Eight months after planting, at uprooting, percentage take and shoot mass of Trichoderma and standard treated vines were similar, but total root mass was significantly higher for Trichoderma treated vines. Low percentages of Cylindrocarpon spp. were isolated from the rootstocks of treated and untreated vines, while less Petri disease fungi were isolated from rootstocks of Trichoderma treated vines. Markedly fewer fungi were also isolated from the roots of Trichoderma treated vines. Incidences of Petri disease fungi in roots of Trichoderma and standard treated vines were similar, but fewer Cylindrocarpon spp. were isolated from Trichoderma treated vines. These results indicate the potential of Trichoderma treatments in grapevine nurseries for the production of stronger vines with lower Phaeomoniella/Phaeoacremonium and Cylindrocarpon infection levels