🦠 Black rot (grape)

Black rot is a grape disease caused by a fungus. The berries first get brown spots, then shrivel and turn into hard black raisin-like mummies. The crop from the affected bunches is lost.

The fungus likes warmth and moisture. It overwinters on leftovers of leaves and berries, and in spring and summer spreads with spores during rain. In wet years the disease develops especially fast. So warm weather and frequent rain are a warning sign for a grower.

Black rot is counted among the diseases of the vine. Downy mildew likes similar conditions: it also loves damp. To protect a vineyard, growers remove infected remains, open up the vines by trimming extra shoots, and apply protective products when needed.

The fungus is mainly found in areas with warm, humid summers. In dry climates the damage is much smaller. For growers this is one of the main reasons to check the vines after every rain.