Protection of Grapevine Pruning Wounds against Eutypa lata by Biological and Chemical Methods

Eutypa dieback, caused by the fungus Eutypa lata, is a serious disease of grapevines that infects mainly through pruningwounds. The aim of this study was to evaluate the in vitro efficacy of fungicides from various chemical groups againstE. lata, as well as the in vivo efficacy of the most effective fungicides and selected bacterial and fungal antagonists ofE. lata, in grapevine pruning wound protection trials. In vitro studies revealed that flusilazole, tebuconazole, benomyl,fenarimol and myclobutanil were the most effective fungicides to inhibit mycelial growth of E. lata. Two field trialswere conducted, one subjected to artificial inoculation and the second to natural infection only. In the first, benomyl,flusilazole and commercially available Trichoderma harzianum-containing products and an experimental Bacillussubtilis strain were applied to fresh pruning wounds. Two Cabernet Sauvignon vineyards were pruned in August2001 and 2002 and immediately treated and inoculated with a spore suspension of E. lata one day later. Isolationswere made from the treated pruning wounds after 12 months to assess the effectiveness of the treatments. Thefungicides benomyl and flusilazole were the most effective treatments, although the Trichoderma treatments T77 andTrichoseal spray caused a significant reduction in E. lata infection. In a second trial, pruning wounds of CabernetSauvignon, Sauvignon blanc, Red Globe and Bonheur were treated with the Trichoderma products Vinevax (=Trichoseal spray) and Eco77 (= T77) in August 2005 and 2006, subjected to natural infection only and evaluatedafter seven months. Vinevax and Eco77 not only reduced E. lata, but they also reduced the incidence of othergrapevine trunk disease pathogens.