Arvind Kumar

Fan leaf degeneration is a viral disease of grapevines (Vitis vinifera L). It is primarily caused by the Grapevine fanleaf virus (GFLV). This disease leads to significant yield losses, reduced fruit quality, and can shorten the lifespan of grapevine plants.

Fan leaf degeneration, manifests in grapevines with distinct visual symptoms. These include leaf distortion, yellow mosaic, vein banding, and small, deformed leaves. Additionally, plants may exhibit shoot abnormalities like short internodes and fasciation, along with overall growth inhibition.

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Fanleaf degeneration is a significant viral disease that primarily affects grapevines (Vitis vinifera) and is caused by the Grapevine fanleaf virus (GFLV), a member of the Nepovirus group. The disease is characterized by distinctive symptoms such as fan-shaped, malformed leaves with distorted veins, shortened internodes, poor bud break, and irregular shoot growth. These abnormalities lead to a reduction in fruit set, poor berry quality, and considerable yield losses, sometimes up to 50–80% in severely affected vines. The virus is mainly transmitted by the soil-borne nematode Xiphinema index, although it can also spread through infected planting material like grafts and cuttings. While the primary economic impact is on grapevines, some related plants and weeds can act as alternative hosts without showing significant symptoms. Effective management of fanleaf degeneration involves the use of certified virus-free planting materials, nematode control strategies, removal of infected vines, and proper soil management practices. The disease poses a major threat in all key grape-growing regions globally, including Europe, North and South America, Australia, and South Africa, making vigilant monitoring and control essential for sustainable viticulture.

Preventive measures for fanleaf degeneration in grapevines focus on minimizing the introduction and spread of the Grapevine fanleaf virus (GFLV) and controlling its nematode vector, Xiphinema index. The most effective strategy is to use certified virus-free planting materials, ensuring that both rootstocks and scions (plantlets) are free from infection. Managing nematode populations is equally critical and can be achieved through soil fumigation, crop rotation with non-host plants, and the use of nematicides where appropriate. Planting nematode-resistant rootstocks offers additional protection by reducing virus transmission. Regular monitoring of vineyards for early symptoms, combined with molecular diagnostic tools like PCR, helps in detecting and containing infections early. Rogueing infected vines, maintaining strict sanitation of tools and equipment, and controlling weeds and alternate hosts that may harbor the virus or nematodes further help limit the disease’s spread. Additionally, selecting planting sites with healthy, well-drained soils can reduce the risk of nematode infestation. Implementing these integrated preventive approaches is essential for sustaining healthy and productive vineyards in regions susceptible to fanleaf degeneration.