Definition - What does Sunscald mean?
Sunscald is a sunburn on grapes. It can be a challenge in wine regions that have intense sunlight followed by extreme heat spikes and/or hot winds.
Grapes which have been sunscalded will appear discolored, even brown. They may also begin to crack and shrivel. This can cause grapes to rot, leading to the loss of grapes to harvest.
WineFrog explains Sunscald
Not all grape varieties are susceptible to sunscald, but for those which are, precautions and proper canopy management must be taken into consideration.
In order to protect grapes from sunscald, orientation of the vines can be adapted as well as allowing for a full canopy to develop. The trellis system must expose as many leaves as possible.
A proper trellis can help to direct the sunlight and allow for the training of the canopy to protect grapes as much as possible. Touching the grapes during intense hours of sunlight and heat should also be avoided, as it can remove the protective layer of "bloom".