First report of Alternaria alternata causing leaf spot on oat (Avena sativa) in China.
In October 2018, a leaf spot disease occurred widely in oat fields of Maojing Town, Huan county, Qingyang city, Gansu, China. The disease severity was estimated at around 30%. At the beginning of August, the lower leaves were initially infected. The symptoms appeared as small brown spots on the leaves or a dust-colored lesion under the leaf tip, which expanded and appeared as dark brown, oval to irregular necrotic spots surrounded by a yellowish border on the leaves. Twenty leaves with typical symptoms were collected from 10 different plants (two leaves per plant) in the field to isolate and identify the pathogen. Based on morphological characteristics, sequence analysis of nuclear protein-coding genes and pathogenicity tests, the causal agent was identified as Alternaria alternata. This is thought to be the first report of a leaf spot on oats caused by A. alternata in China.