| Pesticides

Flavescence dorée threatens vineyards in Switzerland

Studies indicate that the neighboring forest may act as a reservoir for the disease

07.03.2025 | 14:10 (UTC -3)

Cultivar Magazine

When infected with flavescence dorée, grapevine leaves become brittle, curl toward the underside of the leaf, and may turn yellow, red, orange, or purple - Photo: Agroscope

Flavescence dorée, a disease caused by phytoplasma Candidatus Phytoplasma vitis, is advancing on vineyards in the canton of Ticino, Switzerland. And causing concern among winegrowers. Transmitted by the insect Scaphoideus titanus, known as the American grapevine leafhopper, the disease has no effective treatment and leads to the death of infected plants.

Researchers at the Swiss center of excellence for agricultural research, Agroscope, have been investigating the disease for years. Initially, its spread was thought to be exclusively an agricultural problem.

However, recent studies indicate that the neighboring forest may act as a reservoir for the disease. Abandoned vines in old vineyards end up taking root and growing on trees in the forest, serving as a source of infection.

Since 2016, a collaboration between Agroscope and the Swiss Institute for Forest, Snow and Landscape Research (WSL) has been analyzing this dynamic. At thirteen test sites, researchers collected wild grapevine leaves and transmitting insects for laboratory analysis.

The results confirmed that wild grapevines are affected by the same pathogens as cultivated grapevines. Furthermore, the genetic material of the pathogens was identified as identical in both types of grapevines.

The American vine leafhopper is the main vector of flavescence dorée - Photo: Agroscope — The American vine leafhopper *Scaphoideus titanus* is the main vector of flavescence dorée - Photo: Agroscope

The project also revealed that other insects, such as the oriental leafhopper (Orientus ishidae), can also carry phytoplasma, making the spread of the disease even more complex.

According to Marco Conedera, project coordinator for the WSL, the fact that forests serve as a reservoir for the pathogen explains why traditional control measures have not been sufficient to contain the advance of flavescence dorée.

Currently, disease control is based on the use of insecticides, eradication of infected vines and planting of certified pathogen-free seedlings. However, proximity to forest areas can compromise the effectiveness of these strategies. Removing wild vines appears to be a promising alternative to prevent the disease from spreading to new wine-growing regions in Switzerland.

More information can be found at doi.org/10.1007/s42161-024-01775-0