Entomosporium Leaf Spot

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Entomosporium Leaf Spot is a disease caused by the fungus Diplocarpon mespili. The fungus effects plants in the Amygdaloideae subfamily of the Rosaceae (rose) family. In Minnesota this includes apple, crabapple, serviceberry and hawthorn. In other areas it includes pear, quiince, loquat, photinia, and pyracantha. The disease is sometimes referred to by a name which includes the species on which it appears, such as Quince Leaf Blight, Hawthorn Leaf Blight, and Leaf Spot of Red Tip Photinia.

Entomosporium Leaf Spot appears in early summer as reddish-brown, angular spots up to 9 ⁄16″ in diameter. In the center of each spot there is a minute black fruiting body (avervuli) that is visible only with a hand lens. As the fungus spreads the spots enlarge and the leaf yellows, leaving green halos around the brown spots. The leaf eventually dies and falls prematurely. Twigs and branches may develop small areas of dead tissue (cankers). The cankers may eventually girdle the twig or branch causing dieback.

Apple, crabapple, serviceberry and hawthorn

Early summer to fall; sporulation in early to mid-July.

Sources

4, 7, 26, 29, 30, 77.