The four described Alternaria diseases of citrus include: (i) Alternaria Mancha foliar de los citricos is caused by A. limicola Simmons & Palm. Isolation, Pathogenicity, and Partial Host Range of Alternaria limicola, Causal Agent of Mancha Foliar de los Citricos in Mexico. MARY E. PALM, USDA-ARS. Alternaria Rot Worldwide, Alternaria species can cause four distinct diseases of citrus: Alternaria leaf spot of Rough Lemon, mancha foliar de los citricos, and.
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In the later stages of the disease, the corky tissue can fall out, forming craters or pockmarks on the surface of the fruit. Leaf aoternaria initial foliar lesions occur on young tissue as small brown to black spots that develop prominent yellow halos.
Alternaria fruit lesions can crack around the outer edge, giving a moat-like appearance. Rain events or sudden changes in relative humidity also favor spore release. Although the spores are airborne and carried by winds, alternaria brown spot is often spread among groves on nursery stock transported by humans. Alternaria is extremely common on certain cultivars of tangerines while citrus canker is uncommon on alteenaria cultivars.
Fact Sheet: Alternaria | Citrus Diseases
The disease is likely found in other countries that produce susceptible cultivars. The fruit rind responds to infection by forming a barrier of corky tissue that erupts from the surface. Alternaria is spread by airborne spores. Citrus Diseases March, idtools.
Dancy tangerine hybrids [‘Minneola’ tangelo ‘Honeybell”Orlando’ tangelo, ‘Sunburst’, ‘Nova,’ and ‘Lee’] and ‘Murcott’ ‘Honey’ tangerine frequently altenaria fruit infections of alternaria brown spot. During the packing process, the tops of alternaria lesions may be lopped off, making visual identification difficult.
A fungal toxin is produced that can cause necrosis and chlorosis along the veins extending from lesions.
Spores are produced on older lesions formed on wilted twigs and mature leaves. Even the leaf contributes to the inoculum.
Grapefruit and lemons may also be affected. Fruit – young fruit lesions occur on immature fruit for 4 months post petal fall and cause slightly sunken dark spots with yellow halos.
Alternaria limicola – Wikipedia
Some spores come from fruit lesions but they are not a major inoculum source. On more mature fruit, lesions can vary from small specks to large pockmarks. Lesions are flat and visible on both sides on the ctiricos. Older lesions have a brittle paper-like texture in the middle of the lesions.
Lesions expand into irregular or circular necrotic areas which can involve large portions of the leaf, especially on highly susceptible cultivars like ‘Minneola’. Early fruit drop is common, especially if infection has occurred shortly after petal fall.
This tool is part of the Citrus Resource. Alternaria brown spot fruit lesions are easily confused with citrus canker.