Peach Disease - Anthracnose

Most years, anthracnose, caused by two Colletotrichum species, is considered a minor disease of peach. If left unchecked, this disease that attacks peach fruit can cause serious fruit rot infection.
Peach Disease - Anthracnose - Articles

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Source: University of Georgia Plant Pathology, University of Georgia, Bugwood.org

The first report of anthracnose occurring in the United States came from California in 1916, where it was found on almond.

Significant losses from peach anthracnose were prominent during the late 1940s, especially in the southeastern states. Most years, anthracnose is considered a minor disease of peach. In past years the disease has occurred sporadically on fruit. If left unchecked, peach anthracnose can cause serious fruit rot infection.

Peach anthracnose is caused by two species of fungus Colletotrichum (C. acutatum and C. gloeosporioides). The same fungus causes bitter rot of apple and pear. These fungi have a very broad host range, including apples, pears, nectarines, plums, tart cherries, grapes, nuts, vegetables, various legumes, herbaceous annuals, and perennials. Because of this wide host range, the disease can become established in peach orchards in a short time.

Symptoms

The disease begins as lesions characterized by small, brown spots that become darker, circular, and slightly sunken as they age. Young lesions may be confused with those of brown rot caused by Monilinia species, and Botryosphaeria species (black rot and white rot). At this stage, identification depends on laboratory isolations. In time the lesions become brown and sunken. Large, sunken anthracnose lesions are firm to the touch and are often covered with concentric rings of salmon-colored spore masses. The salmon-pink sticky spore mass is a characteristic symptom of anthracnose on peach and other fruits.

Disease cycle

The fungus overwinters on mummified fruit and in cracks and crevices in the bark. The fungus can also overwinter on other host species near the orchard.

Anthracnose is spread by the dispersal of fungal spores that occurs by splashing rain. Warm, moist weather favors disease development (75-86°F). Once young peach fruit are infected, the fungus grows through the fruit and into the phloem of the twig. The infected twig remains alive throughout the winter and dies in the spring. Once the twig dies, the fungus sporulates on the surface of the twig.

Disease management

Orchard floor and orchard perimeter management that eliminates leguminous hosts and wild Prunus species should be practiced to prevent the spread of disease. Specific chemical recommendations for home gardeners are in Fruit Production for the Home Gardener , and recommendations for commercial growers are in the Penn State Tree Fruit Production Guide. 

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