Podosphaera leucotricha is a powdery mildew which affects the leaves and stems of Apples (Malus sylvestrs, Malus domestica and cultivars) and Pear (Pyrus communis) and a few related species of shrubs or trees - see Woods et al (2024) for detailed host list.

Podosphaera clandestina may be present on other species of Pear and on Cydonia (Quince).  Phyllactinia mali may be present on Cydonia (Quince)

Malus/Pyrus communis other Pyrus/Cydonia

Photograph the mildew on the host plant, and add host species to the comments for your record.  If recording on Quince or species of Pear other than P communis, microscopic examination may be needed to separate from similar species.

Apples, Pears, Quince and related species