United Kingdom, United States
Black speck is a non-parasitic disorder of mature cabbage and Chinese cabbage. Lesions are discrete, dark brown or black, and up to 2 mm (1/16 in.) in diameter. Lesion margins are short and often have a narrow, yellow halo. Larger lesions of up to 1 cm (3/8 in.) in diameter may also occur. Lesions may coalesce, resulting in large, dead areas of leaf tissue. Minute specks occur on heart leaves. Symptoms may not occur until cabbage is stored at cool temperatures.
Conditions for Disease Development
This disorder appears to be more severe on tender, lush crops and on crops grown during warm weather. Cool conditions during storage favor development of this disorder.