South Africa Wine Technical Yearbook 2025

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Millerandage of bunches on infected vines.

TABLE 1. Cultivar sensitivity to fanleaf virus. Tolerant cultivars

Sensitive (still productive)

Very sensitive

Agiorgitiko

Shiraz

Muscadel

Alicante Bouchet

Macabeu

Chenin blanc Chardonnay

Bourboulenc

Clairette Blanche

Sauvignon blanc Grenache blanc/noir

Ugni blanc

Tannat Terret noir Rousanne Petit Manseng

index also remains imperative over the lifetime of a block. In high-risk areas, the use of tolerant cultivars should be a serious consideration. Although limited data is available on the use of rootstocks that suppress the virus, it does show promise as a possible strategy in problem areas. Sound viticultural practices, like disinfecting pruning equipment with a bleach solution (one part bleach to nine parts water), must be applied to prevent mechanical transmission of the virus. In cases where infected vineyards are uprooted, as much of the plant material as possible should be removed, especially the roots. It is a good practice to let the soil lie fallow for at least seven to 10 years before establishing a new vineyard, or to plant a crop that is not a host for Xiphimena index. 

Certain rootstocks show suppression of the virus and can present possible benefits for the management of fanleaf virus: RS3 (Ramsey crossed with Schwarzmann), UCD GRN 1, Nemadex and VR 039-16 (the last-mentioned three rootstocks are all Muscadinia Rotundifolia crossed with Vitis vinifera compatible rootstocks). These rootstocks are mentioned in the literature as rootstocks with potential suppression against fanleaf. None of these rootstocks are currently available on a commercial scale in South Africa. Management and control The most important control measure against the fanleaf virus is to start with certified, virus-free plant material, and also to establish new plantings on nematode-free soil. Control of nematodes, especially Xiphinema index, is critically important – both before establishment and during the establishment phase. Regular sampling for Xiphinema

Reference https://www.wineland.co.za/grapevine-fanleaf-virus/

For more information, contact Hennie Visser at henniev@vinpro.co.za.

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TECHNICAL YEARBOOK 2025