Evaluation of a Trunk Injection Technique to Control Grapevine Wood Diseases

Abstract

Vineyard experiments were conducted over five years in the Bordeaux area to evaluate the effectiveness of trunk injections in controlling Eutypa dieback (4 trials) and esca (1 trial). Single treatments were applied in winter 2001 or 2002 using the tree injector StemJect®. Three compounds were tested: two triazole-derived fungicides, propiconazole and difenoconazole, and one elicitor, 2-hydroxybenzoïc acid. Symptomatic vines of two susceptible cultivars, Cabernet Sauvignon and Cabernet Franc, had first been identified in summer in the year before the treatments were started. A disease scale was used to rate the severity of the foliar symptoms. After treatment, disease development was recorded on the same vines in the following years, from 2002 to 2005. Analyses were based on the evolution of foliar symptoms and on the development of wood symptoms (% area of dead wood). This novel procedure made it possible to determine the sanitary status of each vine in terms of three classes of disease severity: remission of symptoms, stability or worsening. No treatment had a significantly durable effect on disease expression irrespective of the site, the compound or the disease studied. Some phytotoxic effects with the triazole fungicides were noticed. Prospects for trunk injections as a means to solve these insidious problems in viticulture are discussed.