A form of grape rot caused by the mould of the subgenus Penicillium expansum. This is particularly encouraged by warm and humid weather. It prefers ripe berries which have already been attacked by botrytis, have broken seeds due to powdery mildew or have been damaged by harmful birds, wasp damage or mechanical damage (e.g. by hail). The ripe berries turn greenish-grey and get a (first white, later blue-green) pimple-shaped spore system. Even the slightest movement of air causes clouds of spores to rise. Due to the intensely unpleasant taste, even the smallest amounts cause the taste of mould. For this reason, the infested berries must absolutely be sorted out by selection during the grape harvest. Very similar in cause and effect is pink rot, in which the fungal network is whitish to pink in colour. This is caused by the mould Trichothecium roseum. Both fungal diseases are difficult to control, as they only appear as a secondary symptom at maturity. Together with green rot, vinegar rot frequently occurs. Wrong aromas that have been introduced into the wine by rotten grapes are combated by activated carbon. See also under fungi and vine enemies.
Picture left: From farmer Karl - own work, CC BY 3.0 at, Link
Picture right: From H.J. Larsen, Bugwood.org - insectimages, CC BY 3.0, Link
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