The first report of anthracnose occurring in the United States came from California in 1916, where it was found on almonds. Significant losses from peach anthracnose were prominent during the late 1940s, especially in the southeastern states. In most years, anthracnose was considered a minor disease of peaches. In the last several years, however, the disease seems to be sporadically reoccurring on fruit. If left unchecked, peach anthracnose can cause serious fruit rot infection.
Peach anthracnose is caused by two species of the fungus, Colletotrichum. It is also known as Glomerella cingulata, the fungus which causes bitter rot of apple. This disease has a very broad host range which includes apple, pear, nectarine, plum, sour cherry, grape, nuts, vegetables, various legumes, herbaceous annuals, and perennials. Because of this wide host range, the disease can become established quite readily.
Anthracnose occurs only on ripe or nearly ripe fruit. The disease begins as lesions characterized by small, brown spots which 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). These larger, sunken anthracnose lesions are firm to the touch and are often covered with concentric rings of salmon-colored spore masses. This salmon-pink, sticky spore mass is a characteristic symptom of anthracnose on peach and other fruits. Fruit rots early in development cannot be differentiated and may be confused with firm rots caused by other pathogens. At this stage, identification is dependent upon laboratory isolations.
The fungus can overwinter on mummified fruit and in cracks and crevices in the bark. The fungus can also overwinter on other host species near the orchard. The increase in the amount of peach anthracnose has been associated with the ground cover, blue lupine, that is planted in peach orchards. Anthracnose is spread by the dispersal of fungal spores that occurs by splashing rain. Warm, moist weather favors disease development (75 to 86 degrees F).
The simplest method to control peach anthracnose is not to let the fruit become overripe. Orchard floor and orchard perimeter management that eliminates leguminous hosts and wild Prunus species should be practiced. The elimination of legumes and wild hosts would decrease the amount of primary inoculum available for infections.
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