Observation on Black Dead Arm in French Vineyards

Abstract

Black dead arm was first identified in French vineyards in 1999. It produces symptoms in the vine wood, causing decline and eventually death. Previously, this disease was confused with esca because of the similarity of the foliar symptoms. Two forms of black dead arm, a mild and a severe form, were observed in French vineyards on Cabernet Sauvignon and Sauvignon. Isolations from 23 vines collected from four vineyards located in three viticultural districts of Bordeaux showed that the main fungi associated with the brown streaks were Botryosphaeria obtusa, B. dothidea and Trichoderma spp. Pathogenicity tests showed that B. obtusa and B. dothidea caused dark lesions on 1- year-old canes. Therefore, these two fungi merit further study to determine their role in causing black dead arm.