Grapevine fanleaf virus

Grapevine fanleaf virus (GFLV) is a destructive plant pathogen that causes a serious condition known as infectious degeneration. This viral disease significantly impacts the quality and yield of vineyards globally, making it one of the most economically damaging threats to viticulture worldwide.

The virus is primarily transmitted by the soil-inhabiting ectoparasitic nematode Xiphinema index. These nematodes feed on the root tips of the vines, acquiring the virus from infected plants and transmitting it to healthy ones. The disease can also be introduced to new vineyard blocks through the planting of infected propagation material or rootstocks.

Infected vines exhibit distinct symptoms including fan-shaped leaves with malformed margins and yellow mosaic patterns. Stems show abnormal growth, characterized by shortened internodes and double nodes, which creates a stunted, bushy appearance that drastically reduces the plant's photosynthetic efficiency and fruit set.

Environmental conditions conducive to the spread of the virus are those that favor the survival and mobility of Xiphinema index in the soil. Optimal soil temperature and moisture levels for the vector determine the rate of disease expansion, often leading to patchy spread throughout the vineyard where infected vines appear in clusters.

Control of GFLV is challenging because there is no cure for infected vines. Integrated management relies on:

• Sourcing certified virus-free rootstock and scion wood.
• Testing and treating the soil for nematodes before planting new vineyards.
• Rigorous roguing and destruction of infected vines and their root systems.
• Cleaning and disinfecting pruning equipment to prevent mechanical transmission.