This disease, which comes from the Middle East, has long been known in Europe and is the most widespread vine infection. It is caused by the Grapevine leafroll associated virus (GLRaV), which is found in the phloem of the leading tissue settles. The German vine breeder Georg recognized viruses as the cause of the disease Shy (1879-1949). The different virus (Closter viruses) are identified with a number, so far seven different ones have been discovered (GLRaV1-7). The disease manifests itself in Europe starting in July, the symptoms are different vine different degrees. The leaves begin to change color in all shades - red for dark and yellow for white varieties. A narrow strip along the leaf veins remains green. The sorts Blue Portuguese. Cabernet Franc. Chardonnay. Müller-Thurgau. Pinot Noir. Sylvaner and Traminer have the characteristic symptoms, at American vines but they are not visible.
Later, the leaves curl down so that in September they only look like narrow triangles from above. Occasionally, on the sheets too necrosis educated. As a result, diseased vines form shorter and thinner ones shoots out. The flowers are strong Verrieseln, The negative effects include an increased blossom sensitivity, a delay in maturity, a lesser Mostgewicht as well as a Income reduction of 50% and more. The wine is re alcohol content. colour and taste negatively affected. If the for leaf rolling disease and brushwood disease If responsible viruses occur together, the symptoms of the disease can be much stronger.
The spread is through infected documents and scions, as well as virus transmission of mealybugs and Vine mealybugs (of the species Pseudococcus, Planococcus and Pulvinaria). A transmission through nematodes is excluded. The vines are not destroyed, however, and growth of tenderness occurs rather slowly. That is why the dangerous illness is underestimated and fought too late. It is not possible to directly combat the existing crop. Indirect control is achieved through careful control of the propagation stock and exclusive use of healthy planting material. See also under Vine enemies,
Images and source: Maree et al. 2018 - Frontiers in Microbiology