The disease progresses during the period of potato vegetation, and infected leaves turn yellow and either dry out or fall off the stem. Initial infection occurs on older leaves, with concentric dark brown spots developing mainly in the leaf center. solani is attributed to premature defoliation of potato plants, which results in tuber yield reduction. Stem lesion of Alternaria solani On potatoes Mature lesions are typically covered by a black, velvety mass of fungal spores that may be visible under proper light conditions. solani invades at the point of attachment to the stem as well as through growth cracks and wounds made by insects, infecting large areas of the fruit Fruit spots are similar in appearance to those on leaves – brown with dark concentric circles. Basal girdling and death of seedlings may occur, a symptom known as collar rot.
Seedlings can develop small, dark, partially sunken lesions which grow and elongate into circular or oblong lesions. Stem lesions are dark, slightly sunken and concentric in shape. As the disease progresses, symptoms may migrate to the plant stem and fruit. Under favorable conditions (e.g., warm weather with short or abundant dews), significant defoliation of lower leaves may occur, leading to sunscald of the fruit. Both the area around the leaf spot and the entire leaf may become yellow or chlorotic. These leaf spots resemble concentric rings - a distinguishing characteristic of the pathogen - and measure up to 1.3 cm (0.51 inches) in diameter. solani generally occur on the oldest leaves and start as small lesions that are brown to black in color. solani include leaf spot and defoliation, which are most pronounced in the lower canopy. melongena L.), bell pepper and hot pepper ( Capsicum spp.), and other members of the family Solanaceae. "Bullseye" patterned leaf lesion of Alternaria solani Hosts and symptoms Īlternaria solani infects stems, leaves and fruits of tomato ( Solanum lycopersicum L.), potato ( S. solani is also present in most potato production regions every year but has a significant effect on yield only when frequent wetting of foliage favors symptom development. solani is generally not an issue in the less humid Pacific or inter-mountain regions. solani is problematic in tomato production areas east of the Rocky Mountains and in the midwest, however, A. Early blight can also be caused by Alternaria tomatophila, which is more virulent on stems and leaves of tomato plants than Alternaria solani. Primary methods of controlling this disease include preventing long periods of wetness on leaf surfaces and applying fungicides. If uncontrolled, early blight can cause significant yield reductions.
Despite the name "early," foliar symptoms usually occur on older leaves. The pathogen produces distinctive "bullseye" patterned leaf spots and can also cause stem lesions and fruit rot on tomato and tuber blight on potato. Martin, (1882)Īlternaria solani is a fungal pathogen that produces a disease in tomato and potato plants called early blight. solani Neerg., (1945)Īlternaria solani (Ellis & G.
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