Reaction of Selected Cultivars of Sugar Maple to Anthracnose in North Alabama

Abstract

Anthracnose, caused by the fungus Discula campestris, appeared in a planting of 18 sugar maple cultivars in Cullman, AL (USDA Hardiness Zone 7a). Sizable differences in the timing of disease onset and intensification were noted between sugar maple cultivars. On susceptible cultivars, the appearance of reddish-brown lesions 4 to 10 mm in diameter, sometimes with a tan center and yellow border, in June was followed with the initiation of premature defoliation by mid-July. By early fall, the susceptible cultivars Goldspire, Seneca Chief, and Sugar Queen along with the moderately susceptible cultivars Endowment, Fairview, Flax Mill Majesty, Morton, and Sweet Shadow were defoliated and showed no fall color. In contrast, disease onset was delayed, the level of premature defoliation greatly reduced, and fall color display unaffected on the anthracnose resistant cultivars Autumn Blush, Autumn Faith, Fall Fiesta, and Legacy, all of which would be excellent choices for amenity and commercial landscapes in the Mid- and Upper South. Among the representative cultivars of the four resistance classes, total rainfall and mean temperature influenced premature anthracnose-induced defoliation on the susceptible Sugar Queen and moderately resistant Commemoration, but not on the resistant Fall Fiesta or the moderately susceptible Flax Mill Majesty sugar maples. Accepted for publication 28 November 2016.