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.
Symptoms
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.
Disease Cycle
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).
Disease Management
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.
