Definition - What does Wilt mean?
Wilt is the non-woody part of plants that has lost its rigidity due to the lack of turgor pressure in plant cells. Wilting is triggered by a lack of water in the non-lignified plant cells. Wilt occurs when the rate of water absorption by the plant is less that the rate of water loss from the plant. When a grapevine has wilt, it causes both the stem and the shoot to shrink and lose the water juices inside them. Lack of timely care of a wilt can permanently damage or kill a grapevine.
WineFrog explains Wilt
There are a few trigger points for wilt, but a cause is the lack of water in grapevines. Wilt might be caused by drought like conditions, where the soil moisture drops below favorable conditions. Alternatively, wilt might be a result of a vascular system dysfunction in plant cells due to extremely low temperatures. Studies have also revealed that wilting is caused by saturated soil conditions, high salinity or even due to organisms like fungi or bacteria that cause the vascular system to be clogged.
A wilt in a grapevine reduces the ability of the vine to grow and transpire and thus produce healthy and productive grapes for wine production. Permanent wilting can permanently damage vines, because a wilted vine cannot be grafted into other healthy wine roots or shoots.
The symptoms of wilts are similar to the symptoms of blights in vines, resulting in an ongoing confusion between them amongst winemakers and viticulturists.