Black spot leaf disease is a physiological plant disorder that affects some grape varieties such as Concord.

It is essentially a potassium deficiency that causes the leaves on a vine to turn purple and eventually black as chlorophyll is lost.

Most common being Asterina, Asterinella, Diplotheca, Glomerella, Gnomonia, Schizothyrium, Placosphaeria, and Stigmea.

Black leaf can affect many different plant species during wet, damp climate.

There are a number of remedies used to prevent the spread of black leaf disease, including mixtures of baking soda, soap, vegetable oil, and water.