Disease caused by Neofusicoccum parvum in pruning wounds of grapevine shoots and its control by Trichoderma spp. and Xenorhabdus szentirmaii.

Neofusicoccum parvum, is a fungal pathogen and one of the etiological agents of dieback disease in grapevines. The fungus causes deterioration of vines due to vascular colonization and/or production of toxins. We report herein the inhibitory effects of Trichoderma spp. isolates and the antifungal effects of cell-free supernatants (CFS) from Xenorhabdus and Photorhabdus bacteria against N. parvum in agar plates. We also evaluated the effects of the most effective fungi and bacteria against the pathogen in pruning wounds of vine shoots. All isolates of Trichoderma exhibited antifungal activity ranging between 82 and 97.5% at 14 days of post-treatment. All Xenorhabdus and Photorhabdus CFS at 10 and 33% concentrations inhibited mycelial growth with X. szentirmaii PAM 11 and PAM 25 causing the highest inhibition (>74%). In the shoot experiments, T. asperellum IB 01/13 and T. asperellum Quality®, X. szentirmaii PAM 11 (undiluted growth culture and CFS) suppressed the fungus by ≥ 93%. Our study highlights the potential of Trichoderma and X. szentirmaii PAM 11 for use as biofungicides in the management of N. parvum in grapevines. Further studies should be conducted to develop formulations of Trichoderma and Xenorhabdus that enhance stability in shelf-life and increase the efficacy of N. parvum control in grapevines under field conditions.