Early blight
| Alternaria solani | |
|---|---|
| Scientific classification | |
| Kingdom: | Fungi |
| Phylum: | Deuteromycetes |
| Class: | Dothideomycetes |
| Subclass: | Pleosporomycetidae |
| Order: | Pleosporales |
| Family: | Pleosporaceae |
| Genus: | Alternaria |
| Species: | A. solani |
| Binomial name | |
|
Alternaria solani Sorauer, (1896) |
|
| Synonyms | |
|
Alternaria allii Nolla, (1927) |
|
Alternaria allii Nolla, (1927)
Alternaria porri f.sp. solani Neerg., (1945)
Alternaria solani (Ellis & G. Martin) L.R. Jones & Grout, (1896)
Macrosporium solani Ellis & G. Martin, (1882)
Alternaria solani is a fungal pathogen, that produces a disease in tomato and potato plants called early blight. The pathogen produces distinctive "bullseye" patterned leaf spots and can also cause stem lesions and fruit rot on tomato and tuber blight on potato. Despite the name "early," foliar symptoms usually occur on older leaves. If uncontrolled, early blight can cause significant yield reductions. Primary methods of controlling this disease include preventing long periods of wetness on leaf surfaces and applying fungicides.
Geographically, A. solani is problematic in tomato production areas east of the Rocky Mountains and is generally not an issue in the less humid Pacific or inter-mountain regions. A. 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.
Alternaria solani infects stems, leaves and fruits of tomato (Solanum lycopersicum L.), potato (S. tuberosum), eggplant (S. melongena L.), bell pepper and hot pepper (Capsicum spp.), and other members of the Solanum family. Distinguishing symptoms of A. solani include leaf spot and defoliation, which are most pronounced in the lower canopy. In some cases, A. solani may also cause damping off.
On tomato, foliar symptoms of A. solani generally occur on the oldest leaves and start as small lesions that are brown to black in color. These leaf spots resemble concentric rings - a distinguishing characteristic of the pathogen - and measure up to 1.3 cm (0.51 inches) in diameter. Both the area around the leaf spot and the entire leaf may become yellow or chlorotic. 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. As the disease progresses, symptoms may migrate to the plant stem and fruit. Stem lesions are dark, slightly sunken and concentric in shape. Basal girdling and death of seedlings may occur, a symptom known as collar rot. In fruit, A. 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. Mature lesions are typically covered by a black, velvety mass of fungal spores that may be visible under proper light conditions.
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Wikipedia