Solar radiation and heat

Plants, and in particular vines, generally withstand strong light and high temperatures well, if they occur gradually; on the other hand, sudden thermal variations are generally much more dangerous. Indeed, high heat increases the phenomenon of evaporation, disorganizes cellular structures and destroys proteins.

• Sun burns

Sunburns are quite common in plants, as in vines. They appear on the herbaceous parts at temperatures above 42 ° C, and in particular the usually shaded organs. We can thus observe partial desiccations of the leaves , the blade of which turns brown and necroses over more or less extensive areas. On berries , it is essentially the side most exposed to the sun that is affected. Thus, a reddish brown lesion appears on one side of the fruit, subsequently the entire berry can dry out. If the stress is high, the cluster whole is affected.
Note that this non-parasitic disease seems more serious in very stony or light-colored soils and in plots particularly exposed to solar radiation. 

• Water stress

During hot weather, the vines can also be confronted with water stress which will result in leaf curl and leaf blade browning. If the lack of water is high, leaf necrosis may occur.

Note that sprinkler irrigation is a technique (when it can be implemented) which allows the temperature in the vineyard to be lowered.