Main symptoms

 

  • Foliage and leaves

The Vine Winding, as its name suggests, causes the edge of the leaves to roll up to the underside of the leaf blade (figures 8 to 14).

- On red grape varieties, the leaves located on the lower part of the twigs turn red in more or less large spots due to the accumulation of anthocyanins, while the main veins remain green (figures 1 to 4) and the blade thickens . The reddening becomes progressively general in the limbus (Figures 7 to 14). Note that at the end of the season the affected leaves turn brown and die off.

- On white grape varieties, a diffuse yellowing gradually appears on the leaves in the same way. It is rather difficult to differentiate these discolorations from other symptoms, such as those of deficiency or phytoplasmosis (Figures 15 to 17). On these grape varieties, the disease is therefore more insidious and can go unnoticed.

Note that the incubation period of the disease lasts more than ten months.

  • Effects on the vine

Without being fatal, this virus reduces the fertility and vigor of the vine, and therefore the grape yield. It causes a delay in the maturity of the berries which can take several weeks, which impairs the development of polyphenols. The intensity of the symptoms varies according to the grape varieties, the prevailing viral species and the climatic conditions of the year, in particular. GLRaV-2 (genus Closterovirus ) can also be responsible for graft incompatibility problems, with degeneration of the scions.

  • Diagnostic confusion

Confusion of diagnosis can occur with damage of green leafhopper , as well as with symptoms of flavescence dorée , black wood , even with those of certain deficiencies (K, Mg and B), etc. Discolorations caused by green leafhopper are clearly demarcated by leaf venation, while those caused by leaf curl are more gradual. In addition, the main veins that remain green are typical of leaf curl, unlike the symptoms of phytoplasmas. We therefore advise you to have your diagnosis confirmed by a specialized laboratory capable of carrying out the appropriate analyzes: biological indexing, ELISA or PCR tests.

Last change : 04/20/21
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