An insect with the strange name of "Scaphoideus titanus" roams our vineyards. Were it not for the severity of its actions, one might find its name almost romantic. However, Scaphoideus titanus, also known as the grapevine leafhopper, has an unfortunate tendency to suck the sap from plants, causing the death of the vegetation.
This disease, called flavescence dorée, has been present in Tessin since 2004, in the canton of Vaud since 2015, and in Valais, in the Fully region, since October 2016.
It is now clearly established that global warming is one of the causes of the disease's spread. However, we also know that the use of contaminated rootstocks, grafts, or scions is also a factor in the dissemination of the disease from one region to another.
For any new planting or for the replacement of missing vines, it is extremely important to use only healthy and certified vine plants! In Switzerland, flavescence dorée is among the quarantine diseases subject to mandatory reporting under the federal Plant Protection Ordinance. Therefore, the circulation of Vitis plant material by a nursery must be accompanied by a compliant phytosanitary passport bearing the ZP-d4 symbol.
The first symptoms appear in the vineyard from August onwards. They are visible until leaf fall. Infested leaves are rigid, abnormally colored, and their edges curl downwards. For white grape varieties, the leaves show yellow discoloration; for red grape varieties, the leaves turn red. The clusters dry out or wither, and the wood does not lignify.
Flavescence dorée is a pernicious and destructive disease. Insecticide treatment is currently recommended to eradicate the leafhopper in regions where its presence is confirmed. Affected vines will be uprooted and destroyed. Another disease, Bois noir, present in Valais since 1991, causes the same symptoms and can mask the detection of flavescence dorée. Only laboratory analysis can determine the origin of the affliction.
The cantonal agricultural service has set up training courses for winegrowers to recognize the symptoms of flavescence dorée and Bois noir. From September onwards, winegrowers are now required to survey the entire vineyard in search of diseased vines, which must be immediately uprooted. This is an essential step to preserve our viticultural heritage.
Source: Valais Cantonal Department of Agriculture
