Grapevine fanleaf virus

Grapevine fanleaf virus (GFLV) is a devastating viral disease that causes the condition known as infectious degeneration or fanleaf degeneration. This virus is a major constraint in viticulture, as it severely reduces both the quality and quantity of grape yields globally.

The virus affects all species of the genus Vitis. It is a systemic pathogen, meaning that once a vine is infected, the virus spreads through the entire plant, affecting the vascular system and disrupting the hormonal balance required for normal growth and development.

Symptoms are highly characteristic and often include short internodes, fan-shaped leaf malformations with deep serrations, and yellow mosaic patterns. One of the most detrimental signs is the massive shedding of flowers and berries (coulure/millerandage), leading to thin, irregular clusters with poor fruit quality.

The primary mode of transmission is through soil-dwelling nematodes of the genus Xiphinema, specifically X. index. These nematodes act as vectors, acquiring the virus by feeding on the roots of infected vines and transmitting it to healthy ones. Human activity, such as propagating infected rootstocks or cuttings, is another major factor in long-distance spread.

Management of GFLV is challenging because there is no direct cure for infected vines. Integrated management strategies focus on prevention: establishing vineyards with certified virus-free rootstocks, long-term fallow periods to reduce nematode populations in the soil, using nematicides when necessary, and removing infected vines immediately to prevent the disease from spreading to neighboring plants.