Rusty Spot of Peach

Rusty spot of peach is characterized by the presence of rust-colored spots that can cover the entire surface of the fruit. The cause of rusty spot is uncertain, although many plant pathologists believe it to be the apple powdery mildew fungus, Podosphaera leucotricha. Many observations have shown that peach orchards with rusty spot are usually next to apple orchards that are infected with powdery mildew.

Symptoms

Rusty spot is recognized only on the fruit. The earliest symptoms on young green fruit appear as small, orange-tan spots. This symptom is due to a change in the color of the fuzz or hairs on the fruit. These first spots may become noticeable three to four weeks after shuck fall. The discolored area enlarges slowly, and the older discolored hairs begin disappearing, leaving a fuzzless, smooth, center spot surrounded by a non-uniform band of orange to tan hairs. Finally, the spots become quite spread out leaving brownish or reddish centers of hard, smooth skin that appear somewhat like a bruise from a limb rub.

For more information, please see Penn State Fruit Pathology.

Penn State Horticulture Department

For more information on this subject, Please visit the College of Agricultural Sciences Publications Web site.

Feel free to forward, post or reprint any of the "Solutions" in their entirely, but please credit http://www.solutions.psu.edu/ as the original source of information, and please do not change the content.