Institution of the Agricultural Research and Higher Education
Abstract
Tunisian table grape production has significantly increased since two decades due to vineyards regional
expansion and yield improvement. But, since several years, decline symptoms on Vitis vinifera have
been recorded in some areas. A study case of a vineyard in Naassen area (near to Tunis) was chosen to
investigate the disease origin and the physiological, biochemical, and histological modifications
associated with vine decline. The investigation revealed characteristic symptoms on leaves, old and
young shoots similar to decline symptoms of Grapevine Trunk Diseases. Based on cultural
characteristics, laboratory investigations revealed the presence of Phaeomoniella chlamydospora and
Phaeoacremonium spp., Diplodia seriata and Botryosphaeria dothidea, from root and shoot samples,
respectively. These fungi are known as the main pathogens responsible for the Esca, Black dead arm
and Excoriose. Molecular analysis confirmed the identification of Diplodia seriata. Beside
morphological alterations on leaves and shoots, symptomatic vines presented significant reductions of
30 and 20% in trunk diameter and bud break rate, respectively, and delayed spring growth compared to
healthy ones. Furthermore, roots and stems from declined vines contained 3 times more starch than
those from asymptomatic ones. Decline survey revealed a heterogeneous dispersion of symptoms in the
vineyard in accordance with water supply. The vines along the edge of vineyards are usually less
watered and show more decline symptoms. Decline dynamics in time and space scales have to be
considered in order to develop effective management strategies