Peach Rusty Spot Is Caused by the Apple Powdery Mildew Fungus, Podosphaera leucotricha.

Peach rusty spot, an economically important disease of peach (Prunus persica var. persica), appears as necrotic spots on fruit. The etiology of the disease is still not well understood, although it has long been suspected that the causal agent is the apple powdery mildew pathogen, Podosphaera leucotricha.