This disease (upper photo) is caused by the fungus Mycosphaerella fragariae (imperfect stage is Ramularia tulasnei). Leaf spot infects leaves, petioles, runners, fruit stalks (pedicels), and berry caps or calyxes. Small, dark purple to reddish-purple, round spots, 1/8 to 1/4 inch in diameter (3 to 6 millimeters), appear on the upper leaf surfaces. The center of the spots soon become tan or gray and eventually almost white, while the broad margins remain dark purple. Later in the season, dark specks (sclerotia and/or perithecia) may be seen in the older lesions. Indistinct, tan or bluish areas form on the underleaf surface.