Esca is a severe vascular disease of the grapevine for which there is no cost-effective cure. Vines eventually die because of deficient sap flow and must be replaced at a high cost. Researchers from France investigated whether there are cultivar differences in the expression of foliar symptoms and vine dieback resulting from esca disease. They also investigated whether it’s possible to group these varietal differences according to genetic heritage.
Project layout
46 Grape varieties from a common experimental garden were investigated over seven years. The incidence and severity of foliar symptoms and dieback (apoplexy and mortality) were recorded. Grape varieties and observations were compared. All vines received identical treatment and environmental input to eliminate other influencing factors.
Results
- Varieties showed differences in foliar symptom expression from 0% to 26%.
- These differences in foliar symptom expression endured across multiple seasons and correlated well with dieback incidence.
- Varieties with higher water use efficiency showed fewer esca symptoms on leaves.
- Varieties with high dieback incidence included Chenin blanc, Mourvèdre, Tempranillo and Riesling.
- Cabernet Franc, Grenache noir, Semillon and Pinot noir showed moderate dieback incidence.
- Low dieback incidence was recorded in Merlot, Shiraz, Chardonnay and Petit Verdot.
Examples of various foliar phenotypes for esca on different Vitis vinifera cultivars grown in a common garden experimental vineyard
A-C: white-berried cultivars (A) Muscadelle; (B) Chasselas; (C) Viognier. D-F: red-berried cultivars (D) Alvarinho; (E) Pinot noir; (F) Cabernet franc. Note that the disease status of a vine is determined by phenotyping the entire shoot, not just individual leaves. This image is reproduced in its original format as permitted by the open access policy of Oeno One.
Variability of susceptibility to esca foliar symptoms and dieback among grapevine cultivars for the period 2017 to 2023
(A) Mean incidence of esca foliar symptoms for the 46 cultivars monitored. Bars and error bars represent the means ± SEM, and the grey triangles indicate the cumulative incidence over the seven years; (B) Range of severity of esca foliar symptoms in symptomatic plants only (mean ± SEM). The severity index, which ranged from 0 to 5, is described in Supplementary Material 2; (C) Range for the incidence of plant dieback. Light grey corresponds to plants with one apoplectic arm (total dehydration of the canopy). Red corresponds to plants with one dead arm. Dark grey corresponds to totally unproductive plants (apoplexy or death on both arms). Grapevine cultivars are ordered according to the mean incidence of foliar symptoms presented in (A). White-berried cultivars are shown in light yellow and red-berried cultivars are shown in dark purple. This image is reproduced in its original format as permitted by the open access policy of Oeno One.
Significance of the study
Although esca is not the only dieback causing vascular disease, it is important to recognise and be aware of possible varietal differences in susceptibility to esca dieback. This could be a consideration when cultivar choices must be made during new vineyard establishment in high humidity/rainfall areas. Pruning shear sanitation should also be a priority in more susceptible varieties. Pruning techniques that limit the size of pruning wounds and manage dieback into the permanent vascular tissue should be applied, especially in these varieties, to lengthen their economic lifespan.
Reference
Gastou, P., Destrac Irvine, A., Arcens, C., Courchinoux, E., This, P., van Leeuwen, C., & Delmas, C. (2024). Large gradient of susceptibility to esca disease revealed by long-term monitoring of 46 grapevine cultivars in a common garden vineyard. OENO One, 58(2). https://doi.org/10.20870/oeno-one.2024.58.2.8043
Image: Wikipedia
