Dark leaf spot of cabbage

Alternaria brassicicola

List of symptoms/signs
Fruit  -  lesions: black or brown
Fruit  -  premature drop
Inflorescence  -  blight; necrosis
Inflorescence  -  dieback
Inflorescence  -  lesions; flecking; streaks (not Poaceae)
Leaves  -  abnormal colours
Leaves  -  abnormal leaf fall
Leaves  -  necrotic areas
Seeds  -  lesions on seeds
Seeds  -  shrivelled
Stems  -  discoloration of bark
Whole plant  -  damping off
Whole plant  -  early senescence

Identification
Symptoms of Alternaria Leaf Spot on cabbage may first develop on young plants in seedbeds, where leaf spots, stunting, or damping off may occur. Dark brown to black leaf spots may appear on tissues of any age and vary in size from pinpoint to 2-inches in diameter. The leaf spots enlarge in concentric circles and mature lesions have a bull’s eye type appearance.
The species that occurs most frequently in New York (Alternaria brassicicola) will produce black sooty colored spores within the leaf spots. The black spores easily detach from the leaf if touched and are visible on the leaf surface, fingers and tools.

In addition to cabbage, Alternaria Leaf Spot is common on other cruciferous crops including cauliflower, broccoli, kale, and Brussels sprouts. Symptoms of infection are similar to those that appear on cabbage, including black sooty spores.

Plant Protection Products