Sunburn

sunburn can damage grapes and is a viticultural term used loosely for a range of conditions. Classical sunburn produces a round halo of burnt skin on the side of the berry facing the sun’s position in the western sky, as damage normally occurs in the afternoon. Such sunburn is due to a combination of bright sunshine, high air temperatures, and low winds, and the so-called ‘hot spot’ can be up to 12 °C/54 °F above air temperature. Berries which were previously shaded from the sun are most sensitive, as their skins have not been conditioned by exposure to sunlight. Sunburn sensitivity is higher for vineyards suffering water stress.