First Report of Powdery Mildew Caused by Erysiphe quercicola on Acacia auriculiformis in India

Abstract

Earleaf acacia, also known as Australian acacia (Acacia auriculiformis) is planted as a source of firewood and as an ornamental tree. In India, it was introduced as a plantation tree to cover barren lands and hill slopes. During October 2014 to February 2015, severe infection of powdery mildew on earleaf acacia was observed in various localities of Satara District, Maharashtra State, India. Disease symptoms included grayish white circular to irregular patches consisting of epiphytic mycelium and conidia on both surfaces of leaves. As disease progressed, leaves were covered by a gray powdery fungal mass, and older leaves became yellow to brown and dropped prematurely. Infections on pods were not observed. Disease incidence was estimated to be 100%. An examination of diseased tissues using light microscopy revealed amphigenous mycelium, effuse or forming dense patches, persistent, and often causing brownish discoloration of leaves; hyphae were hyaline and smooth, 2 to 6 µm wide with hyphal appressoria solit...