The first report of leaf spot disease on Microstegium vimineum caused by Curvularia geniculata in China.
In August 2014, M. vimineum plants with leaf spot disease were observed near a roadside in Shigu Village of Hengyang, Hunan Province, China. Diseased plants at a 5 × 8 m sunny location had lesions on leaves with dark red, often small but dense, elliptical necrotic spots up to 0.1 × 0.3 cm. When leaves had leaf spots, the stalks turned dark red, and spikelets became purple brown and wilted. Disease incidence was up to 50% among natural populations. Field samples of diseased leaves were taken to the Weed Research laboratory, Nanjing Agricultural University (sample no. NAU037153). Fungi were isolated from tissue pieces of symptomatic leaves using standard surface sterilization and single spore isolation technique. Based on morphological characteristics, molecular data (sequence analysis of the internal transcribed spacer and glyceraldehyde 3-phosphate dehydrogenase gene) and pathogenicity tests, the fungi were identified as Curvularia geniculata [Cochliobolus geniculatus]. This is thought to be the first report of leaf spot disease on M. vimineum caused by C. geniculata in China. C. geniculata has potential to provide biological control of M. vimineum in its introduced range in the USA.