A probably new Rebstock disease, which started in the late 20th century Austria and Germany occurred (for the first time in 2002 massive and nationwide). The name Zweigelt disease (which unfortunately has become common in the meantime) resulted from the fact that apparently, above all, the grape variety Zweigelt was affected. However, all other varieties have also been infected (with slightly different symptoms), so this name is somewhat misleading. Sensitive and susceptible varieties to this disease are next to Zweigelt Blauburger. Green Valtellina. Pinot Noir. Rotgipfler. St. Laurent and Zierfandler,
The first symptoms appear with the veraison (Maturity onset). All of a sudden, the berries go limp, shrink or wither grapes, On the grape skeleton are - in contrast to the quite similarly effective stem necrosis - no visible damage. Early detection is more possible with red wine grapes because individual areas of a grape do not completely color (see above). This partial damage mostly affects the top of the grape and is similar to that in South Tyrol, particularly with the Vernatsch variety ( Schiava Grossa ) occurring, called "speed camera" form of the pedicle paralysis. Ultimately, the berries shrink like raisins, but remain on the green grape structure for a long time. On individuals exaggerated Leaf discolouration also occurs. This damage pattern is similar to that Esca disease, which leads to confusion.
The causes are still unclear bacteria. virus or others microorganisms could not be proven as a reason. As causes phytoplasmas supposed. So far, it is only certain that it is a physiological disorder in the metabolism of the vine is. The main reason for this disorder appears to be insufficient supply of certain nutrients (The main cause is lack of potassium suspected) or to be unbalanced between certain nutrients.
Furthermore, extreme environmental situations of the vine also seem like water stress during the growth cycle or contribute high yields over a long period of time. However, due to other circumstances, a (classic) wilting of grapes can occur that has nothing to do with the disease described above. These are, for example, the stalks already mentioned, as well as weather-related drought. sunburn and hailstorm, See also a list of all diseases and pests below Vine enemies,