First Report of Powdery Mildew Caused by Erysiphe quercicola on Quercus mongolica in Korea

Abstract

Mongolian oak (Quercus mongolica Fisch. Ex Ledeb), belonging to family Fagaceae, is mainly distributed in Asian countries including China, Japan, Korea, and Mongolia. From August to November 2016, a powdery mildew was observed on Q. mongolica on the Chilgap mountain located in Chungcheong nam-do and in a garden of the Chonnam National University, Gwangju, Korea. Diseased leaves showed irregular necrotic lesions on both sides. Two voucher specimens were deposited at the Environmental Microbiology Laboratory Fungarium, Chonnam National University, Gwangju, Korea, (EML-QMPW1, EML-QMPW2). Conidiophores were erect, 55.5–108.5 μm long and composed of 1 to 2 cells. Foot-cells of conidiophores were cylindrical. Conidia were formed singly, obovoid to ellipsoid, ends subtruncate, and measured 28.0–38.5 μm × 15.5–23.0 μm with a length/width ratio of 1.5 to 2.2. The morphological characteristics were consistent with the description of Erysiphe quercicola (Takamatsu et al. 2007; Lee et al. 2011). To confirm the morpho...