First Report of Powdery Mildew Caused by Blumeria graminis on Avena sativa in China

Abstract

Oat (Avena sativa) is extensively planted as a fodder crop and most of the production is used for livestock feed in China (Yang et al. 2010). In March 2017, powdery mildew was observed on A. sativa in the Forage Germplasm Nursery (30.47785° N, 103.75878° E) in Xinjin county, Sichuan Province, China. Approximately 40% of plants (about 0.2 ha in total) were affected. The symptoms initially appeared as irregular white mycelial colonies on the adaxial leaf surface. Subsequently, the colonies increased in numbers and size, later covered a large area of leaf and stem. In advance stage of infection, white patches turned into sunken reddish-brown lesions on leaf surface and eventually caused leaf death. The hyphae were flexuous, septate, branched, and 2.6 to 7.6 μm (n = 20) wide. The well developed appressoria on the hyphae were observed with diameter between 3.2 and 6.3 μm (n = 10). Conidiophores were unbranched and cylindrical with swollen bases, measuring 6.3 to 13.2 × 23.4 to 67.5 μm (n = 20), and borne verti...