Designation (French Sécheresse, also drought stress) for the condition of a vine that is lacking from various causes 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 harms as well as too much. A certain (mild) water stress can even be beneficial for the quality because of the lower yield. Essentially, two interacting components play a role in the water supply of the vine. That's it Water storage capacity of the soil in the root area and the humidity in the atmosphere. Particularly negative is the coincidence of strong transpiration (evaporation) over the stomata of the leaves (see under evaporation ) and low soil moisture. Too dry soil can be partially compensated in cold weather by a sufficient humidity.
The vine is in this case in the process of photosynthesis less moisture over the leaves to the air. A balance can also be made by artificial irrigation However, this is usually not allowed in Europe for quality wines. The water stress symptoms on the vine are flabby or withered tendrils and later too leaves, In case of acute water stress, it may cause chlorosis (yellowing of the leaves) and necrosis (wither of the leaves) come. If the lack of water occurs at the beginning of the growth period, this leads to bad fruit set and subsequently to small berries. Water stress can also be caused by animal pests (such as nematodes or phylloxera ) or caused by vine diseases damaged and thus impaired roots. A small amount of water stress can also have a positive effect on the quality of the wine due to the lower yield. See under abscisic acid and irrigation as well as under climate,