Classification of wine grape cultivars according to their susceptibility to Botrytis cinerea: importance of fruit maturity

Abstract

Botrytis cinerea causes one of the most serious diseases in grapevines namely Botrytis Bunch Rot (BBR). A classification of different grapevine cultivars (cvs.) according to their susceptibility to B. cinerea is an essential management indicator in Integrated Pest Management. Although such classifications are available, they are based mostly on professional experience rather than experimental results. The aim of this study was to compare and classify different wine-grape cvs.according to their susceptibility to B. cinerea and to study the influence of fruit maturity on this classification. Between 2011 and 2015, three field trials were carried out under two contrasting climatic and cropping conditions, in Chile and France, including 13 common cvs. Both incidence and severity of the disease were evaluated at harvest and indices of susceptibility (SI) and maturity (FMat) were calculated on a per-site basis. The significant differences in disease incidence and severity observed among cvs. led to a similar susceptibility classification in both countries, despite the contrasting climatic conditions and cropping practices. Cabernet Sauvignon, Cabernet Franc, Grenache Noir, Petit Verdot and Mourvèdre were the most resistant cvs., whereas Gewürztraminer and Sauvignon Blanc were the most susceptible ones. Moreover, an exponential and positive relationship was established between SI and maturity. These findings might be of interest for choosing cultivars more resistant to B. cinereain order to reduce the number of specific anti-Botrytis fungicide applications.