Podosphaera leucotricha (Ellis & Everh.) E. S. Salmon
Distribution: Widespread; the disease occurs wherever powdery mildew of apple occurs.
Lesions show as discolored fuzz in circular, tan to orange blemishes that are approximately 3 to 5 mm in diameter.
Megan Kennelly, Cornell Univ.
Lesions begin as small, circular, tan to orange blemishes approximately 3–5 mm in diameter. The discoloration is due to discoloring of the fuzz on the fruit (A). As lesions enlarge, the interior, reddened fuzz is shed. At this point, lesions appear green and smooth, surrounded by a tan to orange halo. Lesions may continue to expand and may coalesce with other lesions to form larger smooth patches of infection. Eventually, lesions stop expanding, harden, and turn orange-brown.