Strong and persistent sunlight during summer, compounded by soil dryness, may cause leaves and berries of vines to whither. Young grapes are particularly vulnerable if they were previously shaded by leaves and are not yet accustomed to strong UV radiation. The grapes turn pink or brown, dry out like raisins, and become inedible. Some grape varieties are more sensitive than others. When the weather is too hot, be careful not to defoliate too much, if at all, in the grape zone (that is, don't expose the grapes too much). The grapes will colour even when shaded!