Fig 1.
Symptoms expressions in Esca-infected Cabernet Sauvignon grapevines.
(A) Grapevine showing tiger-stripe leaf symptoms associated with the chronic form of Esca. (B) Longitudinal section of an Esca-infected grapevine. Note the large area occupied by necrotic tissue (NT) and white rot (WR). (C) Longitudinal section of an asymptomatic grapevine in which most of the tissue is non-necrotic (NNT).
Table 1.
Notation table presenting the status of the 16-year-old Cabernet-Sauvignon cultivar (Vitis vinifera L.) sampled in 2015 and 2016.
In the table, (-) stands for asymptomatic cordons and (+) stands for cordons that expressed Esca-foliar symptoms.
Fig 2.
Percentage of necrosis and white rot in the trunk wood (T) and cordons (C) of asymptomatic (A) and symptomatic (S) grapevines.
Fig 3.
Comparison of daily sap flow densities and whole plant transpiration in asymptomatic and symptomatic Cabernet Sauvignon grapevines.
(A) Mean maximum daily sap flow densities in asymptomatic and symptomatic grapevines during the week preceding the onset of Esca-foliar symptoms. Data represent transpiration values under non-limited light conditions, i.e. recorded between 10:00 a.m. and 4:00 p.m. Error bars represent SE and a different number of stars for a given date indicates a significant difference between asymptomatic and symptomatic grapevines at p<0.05. (B) Mean daily transpiration in asymptomatic and symptomatic grapevines. Data were separated to reflect days “before” (red squares) and “after” (black circles) the apparition of the foliar Esca symptoms. Error bars represent SE. (C) Mean daily transpiration in asymptomatic and symptomatic grapevines. Data were separated to reflect days with high (black symbols) and low (blue symbols) maximum vapour pressure deficit (VPD), and to represent days “before” (squares) and “after” (circles) the apparition of the foliar Esca symptoms. Error bars represent SE.
Fig 4.
Evolution of stomatal conductance and leaf transpiration in asymptomatic and symptomatic Cabernet Sauvignon grapevines.
(A) Average stomatal conductance in asymptomatic and symptomatic grapevines. (B) Average foliar transpiration in asymptomatic and symptomatic grapevines. The first Esca-foliar symptoms were observed on July 13th (stage 76 on the BBCH scale). Error bars represent SE and a different number of stars for a given date indicates a significant difference between asymptomatic and symptomatic grapevines at p<0.05.
Fig 5.
Evolution of water potentials in asymptomatic and symptomatic Cabernet Sauvignon grapevines.
(A) Predawn leaf water potentials, (B) stem leaf water potentials, and (C) midday leaf water potentials in asymptomatic and symptomatic grapevines. The first Esca-foliar symptoms were observed on July 13th (stage 76 on the BBCH scale). No data were recorded for predawn water potential on June 22nd (A) and for leaf water potential on July 21st (C) due to bad weather conditions. Error bars represent SE. The different number of stars indicates a significant difference between asymptomatic and symptomatic grapevines at p<0.05.
Table 2.
Impacts of the grapevine trunk disease Esca on hydraulic conductance of whole-vine (Kvine) and leaf (Kleaf) of Cabernet-Sauvignon cultivar (Vitis vinifera L.).
Values shown are means from three different sampling dates where gas exchanges and water potentials were measured concurrently (from the end of flowering to berry ripening). Different letters within a row indicate a significant effect at p<0.05.
Fig 6.
Elemental and isotopic analysis of leaf, cordon and trunk samples collected from symptomatic and asymptomatic grapevines.
(A) Percentage of carbon and (B) percentage of nitrogen in leaves, cordons and trunks of symptomatic and asymptomatic grapevines. (C) Oxygen isotope discrimination (δ18O) in leaves and (D) carbon (δ13C) isotope discrimination in leaves, cordons and trunk of symptomatic and asymptomatic grapevines. For each type of measurement, non-necrotic samples were used. White Error bars represent SE and a different number of stars for a given tissue indicates a significant difference between asymptomatic (white columns) and symptomatic (black columns) grapevines at p<0.05.