Description (French Sécheresse, also drought stress) for the state of a vine who lack for various reasons water suffers. In extreme cases this can lead to complete annihilation ( apoplexy ) to lead. However, certain grape varieties have one resistance against drought and drought developed. A balanced water balance in a vineyard is very important, too little water hurts as much as too much. A certain (mild) water stress can even be an advantage for the quality due to the lower yield. Essentially, two interacting components play a role in the water supply to the vine. They are Water storage capacity of the soil in the root area and the humidity in the atmosphere. The coincidence of strong perspiration (evaporation) via the stomata of the leaves (see under evaporation ) and low soil moisture. A soil that is too dry can be partially compensated for in cool weather by sufficient humidity.
In this case, the vine gives the process of photosynthesis less moisture from the leaves to the air. Compensation can also be achieved through artificial irrigation done, but this is usually not allowed in Europe for quality wines. The water stress symptoms on the vine are flaccid or withering tendrils and later too leaves, With acute water stress it can lead to chlorosis (yellowing of the leaves) and necrosis (withered leaves) come. If there is a lack of water at the beginning of the growing season, this leads to bad results fruit set and subsequently to small berries. Water stress can also be caused by animal pests (such as nematodes or phylloxera ) or roots that are damaged and thus impaired by vine diseases. A small amount of water stress can also have a positive effect on the wine quality due to the lower yield. See under abscisic acid and irrigation as well as under climate,