Early blight of tomato and potato, Alternaria leaf spot on Bradford pear, Alternaria blight of crucifer, Target spot on tobacco. Alternaria causes leaf spots and blights on numerous plants including vegetables, fruit tress, and ornamentals, as well as blemishes and storage rots of vegetables. Alternaria can be easily isolated from decaying plant material because it readily colonizes dead and weakened tissues as a saprophyte. Lesions are often numerous and quickly enlarge to blight leaf tissue. Lower, older leaves are usually attacked first with the disease progressing upward.
Affected leaves turn yellow and dry up.
Lesions on the stem are sunken and dark. They may girdle young plants at the soil line killing them. Darkly pigmented, short, simple conidiophores form on the surface of infected tissue. Saprophytic Alternaria spp.