Sustainable management of grapevine trunk diseases

Abstract

Grapevine trunk diseases (GTD) occur wherever grapes are grown and are considered the main biotic factor reducing yields and shortening vineyards’ lifespan. Currently, no product is available to eradicate GTD once grapevines are infected. Therefore, prophylactic strategies based on pruning wound protection and ‘remedial surgery’, the only eradication method based on the elimination of infected wood and renewal of the vine by means of new canes or suckers, are the only effective strategies available. The Canadian grape and wine industry focusses on a sustainable production and thus, looking for alternatives to chemicals for disease management is a top priority. The objectives of this study were to develop sustainable control strategies in British Columbia (BC) based on i) the use of locally-sourced Trichoderma spp. as pruning wound protectants and ii) the implementation of ‘remedial surgery’ under BC climatic conditions. Three native Trichoderma spp. from BC were used to complete field trials during two growing seasons to determine their potential biocontrol activity against the GTD fungi Diplodia seriata and Neofusicoccum parvum. Results showed Trichoderma-based treatments developed in our laboratory to provide a high pruning wound protection for up to 60 days after treatment. Furthermore, these treatments performed better or similarly when compared against both chemical and biological products registered in other countries. ‘Remedial surgery’ trials were conducted in ‘Chardonnay’, ‘Pinot Gris’ and Pinot Noir’ for six years in BC. Results showed treated (renewed) vines to come back into production one year after treatment. Renewed vines showed higher yields than untreated controls after two years and yield was shown to be more than double at the end of the trial in renewed vines. These studies show sustainable management of GTD to be possible and further studies should focus on their full implementation in BC.