Abstract

Vicia villosa is widely grown in China as a green manure crop. Investigations conducted in three fields in March of 2018 revealed a leaf spot disease on V. villosa with 25 to 50% incidence in Nanchong City, Sichuan Province, China. Infected leaves displayed irregularly shaped, scattered spots, and black mycelial layers grew on the spots' surfaces in humid environments. Leaves with typical pathological symptoms were photographed and sampled. To isolate the pathogens, the tissues from diseased and healthy junction areas on symptomatic leaves were excised, surface-sterilized, rinsed, and incubated on potato glucose agar (PCA) at 25 °C (Senanayake et al. 2020). Six pure isolates were obtained by single-spore isolation and deposited at the Culture Collection of JZB and CGMCC. The strain numbers of these six pure isolates are JZB3720009-JZB37200011 and CGMCC 3.25122-CGMCC 3.25124. On PCA plate, the colony reached 90 mm in diameter after 7 days at 25 ℃. Aerial hyphae were loose, appearing gray to gray-brown. Conidiophores are hyaline to pale brown, solitary, erect, separated, base with a narrowed basal cell, 22 to 100 μm. The apex of the conidiophores swelled, forming conidiogenous cells. Conidiogenous cells were brown to dark brown, solitary, smooth, slightly curved, subcylindrical, 7.1 to 17.0 × 5.1 to 6.8 µm (average: 12.7 × 5.9 µm, n = 20). Conidia are clustered, smooth-walled, straight, ellipsoid to cylindrical, tapering towards rounded ends, 2 to 3 but mostly 3 septate, basal and apical cells brown, middle cells dark brown with enlarged, 17.0 to 32.0 × 8.0 to 12.0 µm (average: 25.4 × 9.8 µm, n = 50). Morphologically, these isolates resembled species belonging to the genus Curvularia (Marin-Felix et al. 2017). Genomic DNA of the six isolates was extracted using a fungal DNA kit (Cat No.18812; Yeasen, Shanghai, China). The ITS region, gapdh and tef genes were amplified using the primers and procedures described by Raza et al. (2019) The sequences obtained in this