Characterization of Trichoderma isolates from southern Italy and their potential use as biocontrol agents against grapevine trunk diseases.

Grapevine trunk diseases (GTD) are one of the most economic important diseases on grapevines causing decline, loss of productivity and eventual death of the vine. In the last decade, the interest by the grape and wine industry in developing and implementing sustainable and biological control practices against diseases, including GTD is raising. Accordingly, the objectives of this study were to i) identify and characterize Trichoderma isolates from southern Italy by morphological and molecular studies and to ii) determine their potential as biocontrol agents against the GTD canker-causing fungi Diplodia seriata, Neofusicoccum parvum and Eutypa lata. A total of 16 Trichoderma isolates from Italy were studied at the Agriculture and Agri-food Canada research centre located in Summerland, British Columbia. Morphological characterization included studies to determine the optimum temperature for micelial growth, which showed to be between 25 and 30°C for all 16 isolates. Multi-locus phylogenetic analyses of the ITS1-5.8S-ITS2, TEF-1α and RPB2 genes revealed six species, including T. atroviride, T. harzianum, T. koningiopsis, T. longibrachiatum, T. paraviridescens, and T. spirale. The antagonistic capabilities of all Trichoderma isolates were screened against D. seriata, N. parvum, and E. lata in vitro via dual culture assay. Results revealed all 16 isolates to provide more than 50% mycelium growth inhibition for D. seriata, 14 isolates for N. parvum and 6 isolates for E. lata. The best performing isolates acroos all three species were selected to further screen in plant their potential as BCA via a detached cane assay (DCA) under controlled growth chamber conditions. Chardonnay dormant canes were pruned and inoculated with 50 ul of a 106 spores/ml of each Trichodrma sp. Then, a 50 ul of a 105 conidia/ml of D. seriata and N. parvum and an approximate 105 mycelial pieces/ml of E. lata were used to challenge the treated pruning wounds 24h, 7d and 21d after treatment. DCA results will be presented and discussed. This study aims to provide alternative sustainable control solutions against GTD