This worrying disease, caused by phytoplasmas (bacteria with no cell wall), is also known as “grapevine yellow”. It leads to the death of the vine stock and is incurable.
This disease is spread due to a Grape Leafhopper (Scaphoïdeustitanus), which is present in several areas in France and is getting close to our region.
Indeed, contaminated areas have been found in the South of the Ardèche and Drôme, in the Rhône, Savoieand in the region around Die.
The bacteria develop by area, passed on from vine stock to vine stock by the leafhopper.
It may join a parcel of land through the planting of contaminated vines, often from industrial vine nurseries or by the arrival on a vine stock of a leafhopper carrying the disease.
Contamination by migration of leafhoppers from a distant area remains however less frequentand it is essential to avoid bringing a contaminated plant to a healthy area.
It is a quarantine disease which has been the subject of a compulsory fight since 1987, associating chemical treatments against the grape leafhopper and the destruction of contaminated vines.
Preventive actions do however exist and the Appellation is already using them.
As from 2020, it will be compulsory, according to the specifications of A.O.C. Cornas, to sterilise any planted vine stock before it is planted. This 45-minute treatment in warm water kills the phytoplasma.
- Moreover, a group of wine growers (from the 2 AOC ST PERAY and CORNAS), along with the Fédération Régionale de Défense contre les OrganismesNuisibles (Regional Federation for Defence against Pests) is in charge of inspecting the whole vineyard over a period of 3 years. This procedure enables a rapid and efficient reaction in the event of symptoms discovered on the vines.
- Finally, the Appellation is negotiating with the Prefect so that these measures may be extended beyond the perimeter of the AOC(private individuals, abandoned vines, wild vines on the edge of the Rhône, etc.).
The wine growers of the Appellation are thus uniting to delay and reduce as much as possible the need to use chemical insecticides. It is a question both of protecting the vineyard and preserving biodiversity.