Oats (Avena sativa) are an important fodder crop in the vast ranges of northern and northwestern China, given the growing demand from livestock. (Yang et al. 2010). In July 2020, diseased leaf samples of cultivar Dingyan-2 were collected from fields near Gonghui Town, Zhangbei County, Zhangjiakou City (41.35° N, 114.55° E). These leaves showed oval to irregular yellowish-brown spots (0.5 to 6 mm in diameter) surrounded by a yellowish halo progressing to form narrowly striped spots fusing into lesions in severe cases. In a disease survey of six fields (about 1.5 ha in total), 35% of the plants were infected with a disease severity ranging from 0 to 20%. To isolate the pathogen, 12 symptomatic leaves (two leaves for each plant) were arbitrarily sampled from different locations across the fields and small pieces (5 mm2) of diseased leaves were excised from the border between diseased and healthy tissue. Excised tissue pieces were surface sterilized by immersion in 75 % ethanol for 30 s, then 1% NaClO solution for 1 min, rinsed in sterilized distilled water three times, and transferred to potato dextrose agar (PDA). Colonies on PDA were 41–46 mm diam in 10 d at 25 °C with surface texture floccose, obverse pale mouse grey to black due to ascomata and aerial mycelium, and reverse pale olivaceous. Asci were ellipsoidal to ovoid, 12–18 × 11–15 μm (av.= 15 ×12 μm; n=30) in spore-bearing part, containing eight irregularly arranged ascospores. Ascospores were 1-celled, dark brown when mature, smooth, ellipsoidal, with attenuated ends, 7.5–8.4 × 4.3–5.5 μm (av.= 8.1 × 5.0 μm; n=50), with an apical or slightly subapical germ pore. These morphological characteristics were consistent with previous descriptions of Canariomyces microsporus (syn. Thielavia microspora, Wang et al. 2019). For molecular identification, genomic DNA (isolate MNK-Y1) was extracted and the internal transcribed spacer (ITS) region and β-tubulin (tub2) were amplified and sequenced by using the primers ITS1 and ITS4 (White et al. 1990) and Btub2Fd and Btub4Rd (Woudenberg et al. 2009). Sequences were deposited in GenBank under accessions MW080329 (ITS) and MW557539 (tub2). Blast search revealed that the ITS and tub2 sequences matched 99.4%, 100% (471 bp out of 474 bp; 648 bp out of 648 bp) with the sequences of the ex-type isolate CBS 276.74 of C. microsporus accession number MH860852.1 and MK926899. Koch’s postulates were proven to confirm the pathogenicity of isolate MNK-Y1. Eight-week-old healthy oat seedlings of cv. Dingyan 2 were grown in the greenhouse, at 15-20 ℃ under 30-40% of relative humidity. Ten oat plants were spray inoculated with a spore suspension (5×105spores/ml; isolate MNK-Y1). Another ten oat plants were sprayed with sterile water as controls. All plants were covered with a transparent glass cover and a black polyethylene bag to maintain relative humidity and dark for two days. After 15 days, all the inoculated plants had developed yellowish-brown spots similar to those observed in the field whereas the control plants sprayed with sterile water remained healthy. The pathogen was reisolated from inoculated plants and identified as C. microsporus based on morphological characteristics and the molecular methods described above. This species has previously been isolated from saline and desert soils as well as from leaves of Thymus (Wang et al. 2019). To our knowledge, this is the first report of leaf spot of oat caused by C. microsporus in China.

Oat (Avena sativa), an important source of crude protein, fiber and crude fat needed for livestock, is increasingly being cultivated in China. In August 2020, leaf spots were observed on oat cv. Bayan 7 plants in an experimental field of 3 ha with a disease incidence of 12% and a severity of 20% in Daqiao Town (26.42°N, 103.22°E), Huize County, Yunnan Province, China. Symptoms mainly consisted of reddish brown spots which were oval to irregularly circular in shape and to 3 to 4 mm in diameter (occasionally confluent). The spots were surrounded by chlorosis involving the affected leaf surfaces, due to the spread of the disease. Infected tissues (10 diseased leaves) of ten different plants were cut into small pieces (5×5 mm) at the junction of disease and healthy tissues, surface-sterilized in 75% ethanol solution for 30 s, 1% NaClO solution for 2 min, rinsed three times with sterilized distilled water, air dried, and transferred to potato dextrose agar (PDA) plates. A total of nine single-spore isolates with similar colony morphologies were obtained. After 7 days, the colonies showed white-to-gray aerial mycelia, and appeared dark brown at the center of the reverse view. Setae were brown, smooth walled, cylindrical at base, rounded at tip, containing 1 to 4 septum, and measured 50 to 190 μm long. Conidia are hyaline, aseptate, cylindrical to spindle, straight to slightly curved, rounded at both ends, and measured 14.5 to 17.5 × 3.6 to 4.1 μm in size (n = 50). Based on the morphological characteristics, the fungal pathogen was identified as being closely related to Colletotrichum americae-borealis (Damm et al. 2014). To further substantiate the identification, the ITS region of rDNA, beta-tubulin (TUB) gene, chitin synthase (CHS) gene and histone H3 (HIS3) gene were amplified by the primers described previously (Damm et al. 2014) and sequenced. Sequences of the representative isolated strain YNC-1 were deposited in GenBank (MZ676033 for ITS, MZ686211 for TUB, MZ686214 for CHS, MZ686217 for HIS3). BLAST analysis showed 99 to 100% identity to C. americae-borealis type strain CBS 136232 (GenBank Accessions: KM105224, KM105504, KM105294 and KM105364, respectively). The four locus datasets were combined by SequenceMatrix 1.8 (Vaidya et al. 2011), and the strain YNC-1 and C. americae-borealis (CBS 136232 and CBS 136855) formed a subclade with 97% bootstrap support. To test pathogenicity, five pots with each containing five 5-week-old oat seedlings (cv. Baiyan 7) were sprayed with the YNC-1 isolate conidial suspension (1 × 105 conidia/ml) while the other five pots were sprayed with sterile water as a control. All plants were kept for 48 h at 100% RH, and then moved to a nursery shelf in a greenhouse maintained at 26/18°C day/night temperatures. After 5 to 7 days post inoculation, reddish brown spots were observed on the inoculated plants and C. americae-borealis was reisolated and confirmed by morphological and molecular features. No disease was observed on control plants. To our knowledge, this is the first report of C. americae-borealis causing leaf spot on oat in China. C. americae-borealis has been reported associated with leaf spot in alfalfa (Li et al. 2021) and licorice (Lyu et al. 2020). The disease can cause a serious threat to oat crops in China and disease management strategies are needed to control its proliferation.

This study was performed to develop tteokgalbi suitable for young-aged individuals by using mudfish and radish greens, major ingredients of Chueo-tang. Mudfish-tteokgalbi (control), in which 15% of the meat and tallow was replaced with mudfish paste, was used while substituting 25 to 100% of the green onions with radish greens. The pHs and sugar contents of the tteokgalbi developed in this study were 6.07-6.28 and 9.94-10.9, respectively, and it was suitable for tteokgalbi sold in the market. Replacing green onions with radish greens while manufacturing tteokgalbi significantly reduced the color (a and b values) and weight loss during cooking compared to the control. Replacing green onions with increasing quantities of radish greens also significantly reduced the adhesiveness of the samples in the texture profile analysis. Although the overall acceptability of the control was the best, the ideal quantity of radish greens as a substitution for green onions appears to be 25-50%. The unique flavor of the supplemented radish greens was indistinguishable in the sensory evaluation and the principal component analysis with an electronic nose. Finally, radish greens were confirmed as a good ingredient for manufacturing tteokgalbi together with mudfish paste.