First report of causing leaf spot on in China.

(L.) Redouté, a member of the Iridaceae family, is globally well-known for its medicinal value as clearing away heat, detoxifying, detumescence and pain (Qin 2000). In 2021, spots were observed on 40% leaves and about 28 disease index in Wanzhou District (30°32'N; 108°22'E) of Chongqing. Initial symptoms appeared as circular yellow white, sunken spots lesions, and then expanded into irregular lesions, the center of the spots was beige, external layer was light brown and surrounded by yellow halo. Symptomatic leaf tissues (5 × 5 mm) were cut from the infected margin, surface sterilized with 75% ethanol for 1 min, washed with 3% sodium hypochlorite for 3 min, rinsed three times with sterile water, placed on potato dextrose agar (PDA) medium incubated at 25°C for 7 days in the dark, forty isolates with similar morphology were obtained. Three isolates (SG9、SG20 and SG33) was selected for subsequent research. Colonies color changed from beige to light brown color after 14 days on PDA medium. Fungal colonies transformed from beige to brown at the edges after 28 days and light brown on top. Ascomata dark brown, ellipsoidal to globose 116.6 to 253.3 × 89.6 to 172.6 μm in diamensions. Asci stipitate, cylindrical with obtuse ends, and 69.1 to 114.7 × 10.2 to 24.1 μm (n = 30) in size, with eight overlapping linearly biseriate ascospores. Ascospores brown, narrowly fusiform, straight or slightly curved with three transversely septate, slightly constricted at septa, and 9.7 to 12.6 × 27.6 to 32.6 μm (n = 30). These characteristics are consistent with sp. reported by Quaedvlieg et al in 2013. DNA was extracted from representative isolates. The internal transcribed spacer (ITS) region, the large subunit rDNA (LSU), the small subunit rDNA (SSU) and the RNA polymerase II second largest subunit (2) genes were amplified for Polymerase chain reaction (PCR) by used ITS1/ITS4, LR5/LROR, NS1/NS4, and 2-/2- primers (White et al. 1990; Vilgalys et al. 1990; Qi M W. et al. 2008; De G. J. et al. 1992). The sequences were submitted to NCBI GenBank: SG-G9 (ITS, OR701701; LSU, OR701699; SSU, OR701700; 2, OR738464); SG-G20 (ITS, OQ748032; LSU, OQ780728; SSU, OQ780723; 2, OQ779979); SG-G33 (ITS, OQ748033; LSU, OQ780729; SSU, OQ780722; 2, OQ779980). A phylogenetic analysis revealed a 99% similarity to the CBS 603.86 (ITS, KF251182; LSU, GQ387590; SSU, GQ387529; 2, KF252189) sequences. Mycelial agar plugs (5-mm diameter) from a 7-day-old PDA culture of a fungal isolate were placed onto pinpricked leaves of three two-year-old plants. While the sterile PDA plugs inoculated in pinpricked leaves of as controls. Inoculated plants were placed in a greenhouse at 25°C and remained 95±1% relative humidity. The inoculated leaves of treatment developed symptoms after 20 days, whereas no symptoms occurred on controls, fulfilling Koch's postulates. The experiments were repeated three times. The fungus was re-isolated and was identical to original isolate by morphologically and molecularly. As far as we know, can cause diseases on carex plants and has been found in Switzerland. This is the first report of causing leaf spot on in China. Along with recording the occurrence of this disease, plant disease management strategies need to be established to reduce losses.