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Euphrates poplar (Populus euphratica Oliv.) constitutes about 61% of the global poplar population, thriving in arid regions of western China (Wu et al. 2023). It plays a crucial role in maintaining ecological balance, securing oasis agriculture, and driving socio-economic progress in the region. During a June 2023 investigation in the P. euphratica forest within the Hotan area of Xinjiang (37°20'21″N, 79°21'15″E), over 12% of the P. euphratica trees displayed branch withering symptoms. The affected trees exhibited cracked bark, trunk decay, darkened coloration, and an eventual black coal-smoke-like appearance. Fungal spores were notably present beneath peeling bark on trunks and main branches. The deep ulcers extended longitudinally into the cambium, leading to tree mortality. In some cases, lateral spread into the sapwood caused dark discoloration of vascular tissue. Twenty diseased branches from various locations were collected and 5-10 mm2 lesions were excised from the edges. These were then surface-disinfected with 75% ethanol for 30 s and 1% sodium hypochlorite for 2 min. After three rinses with sterile distilled water, excess moisture was removed using sterile filter paper, followed by incubating the samples on Potato Dextrose Agar (PDA) medium. Cultures were subsequently grown at 25 ± 1 ℃ under a 12-h photoperiod for three days, thus resulting in the isolation of 25 fungal strains with similar morphological characteristics. All strains displayed rapid colony growth (40 mm/d). On PDA medium, the mycelium initially presented as a white colony, transitioning to an olive-green to greyish color, finally turning dark-grey to black. Colonies generated mycelia that disintegrated into 0- to 1-septate, cylindrical to round, hyaline to brown arthroconidia, occurring singly or in arthric chains, averaging 8.9 ± 2.1 μm × 4.9 ± 1.3 μm, with a length/width ratio of 1.79. Based on morphological characteristics, the isolates were identified as Neoscytalidium dimidiatum (Penz.) Crous & Slippers (Crous et al. 2006). Molecular characterization involved amplifying the partial internal transcribed spacer (ITS) region and translation elongation factor 1-α (TEF1-α) and β-tubulin (TUB2) genes using ITS1/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn 1999), and BT2a/BT2b primers (Glass and Donaldson 1995). Sequences, available in GenBank (ITS: PP033096, PP033097, PP033098; TUB2: PP032812, PP032813, PP032814; TEF1-α: PP032815, PP032816, PP032817), exhibited 99-100% identity with the epitype N. dimidiatum Arp2-D (ITS, MK813852; TUB2, MK816354; TEF1-α, MK816355). Phylogenetic analysis, employing maximum likelihood and Bayesian inference on concatenated ITS-TEF1-TUB, was constructed using IQ-Tree and MrBayes3.2.7, revealing isolates clustering within the N. dimidiatum clade. Three isolates (HY01, HY02, and HY05) from different collection points were chosen for pathogenic investigation. Pathogenicity testing on one-year-old healthy P. euphratica seedlings involved removing a 4-mm-diameter bark plug using a cork borer. A 3-day-cultured N. dimidiatum plug of the same size was inoculated, with a blank PDA as control. The wound was covered with moistened sterile absorbent cotton and finally sealed with parafilm for three days. Experiments were repeated thrice. Symptoms manifested by day 2 post-inoculation, resembling the original symptoms by day 7. In the control group, plants remained healthy. N. dimidiatum was exclusively re-isolated from lesions on inoculated stems, confirmed as N. dimidiatum through morphological characteristics and sequence analysis, aligning with Koch's hypothesis. To our knowledge, this is the first report of N. dimidiatum inducing stem canker on P. euphratica in China. This pathogen has been reported on many tree hosts including citrus (Alananbeh et al., 2020), common fig (Güney et al., 2022), dragon fruit (Salunkhe et al., 2023), and Almond (Nouri et al., 2018). Therefore our findings will serve as a warning for authorities to a potential threat in China's P. euphratica and other trees cultivation. Thus, further epidemiological studies are essential for devising effective management strategies.

Cherry blossom (Cerasus serrulata) is a plant with important garden applications. It is a newly introduced exotic plants in the Arar region of Xinjiang, China (40°41'18.19″N,81°43'50.55″E). In October 2022, it was discovered that about 30% of cherry blossoms had a canker disease. The leaves of the sick branches were dired, the branches themselves were damaged, with dark brown color inside. Orange-yellow conidia horns were produced in humid condition. Samples were collected from fifteen trees exhibiting notable symptoms. The diseased junctions of the infected shoots were chopped into small pieces and subjected to surface sterilization by using 70% ethanol for 30s, 1% NaClO solution for one minute, and sterile distilled water three times (Chen et al. 2016). The representative strain YINGHUA-1 was chosen for identification by molecular biology and morphology. After five days of incubation at 26℃ on PDA media, colonies of white fluffy mycelium were produced from the YINGHUA-1 strain. After 25 days of PDA culture, the production of pycnidia was first observed, circular, black. The pycnidia began to produce conidia at 30 days. The conidia was translucent without septum, with a slightly curved single cell and smooth surface. Pycnidia was spherical and flat, with a single black aperture at the top that resembles a nearly round hole, the chamber was made up of several tiny chambers separated by a shared wall, and its diameter ranges from 900-1900 µm. The size of the conidium was 3.7-6.6×1.1-1.9 μm (n=20). The intrinsic transcriptional spacer (ITS), transcriptional elongation factor (tef-1α), and β-tubulin (tub2) gene moieties of rDNA were sequenced using ITS1/ITS4, EF1-728F/EF1-986R, and Bt2a/Bt2b primers, respectively(Zhang et al. 2014). The amplified sequences of ITS region (Accession No. OR855907), tub2 (Accession No. OR865863) and tef-1α (Accession No. OR865864) were deposited in the GenBank. BLAST searches of the sequences revealed 99.59% identity (474/476 bp) of the ITS sequence, 98.63% identity (216/219 bp) of the tef-1α sequence, and 98.55% identity of the tub2 sequence (339/344 bp) with C. ailanthicola CFCC59446 (accessions OR826163, OR832040, and OR832062, respectively.) Phylogenetic analyses were performed with Iqtree v.1.6.12 for maximum likelihood (ML). Confidence levels for the nodes were determined using 1000 replicates of bootstrapping methods. Based on phylogenetic analysis and morphological characteristics, the pathogen was identified as C. ailanthicola. The pathogenicity of C. ailanthicola was confirmed by inoculation of 1-year-old shoots (5 replicates of this experiment). After 7 days, symptoms of inner bark discoloration were visible on xylem of branches and the same fungus was re-isolated from the inoculated shoots, with no lesions on the control shoots. C. ailanthicola is only known from a single host plant, Ailanthus altissima,in China (Fan et al.2020). As far as we know, this is the first report of C. ailanthicola harmings C. serrulata in China.

Korla pear (Pyrus sinkiangensis Yü) is an important commercial fruit tree that originated in China (Zhou et al. 2020). In April 2020, a survey was conducted in Aksu region, Xinjiang (40°55'37"N, 80°28'42"E), China. Some Korla pear trees (>15 years old) exhibited symptoms of branch dieback and branch cankers. Cankers observed on the trunk and branches of the tree were sunken, dark ulcerative lesions sometimes exhibiting signs of stromata erumpent through the bark and exuding yellow to reddish-orange spore tendrils. Of the 180 plants surveyed, 80% were symptomatic. Thirty samples of symptomatic tissues of infected branches were taken to the laboratory. Bark and cortical wood samples containing necrotic and healthy tissue were excised with flame-sterilized scalpels, surface disinfected with 75% ethanol and 1% NaClO, placed on PDA plates, and incubated at 25°C. A total of 30 fungal isolates were obtained. Among them, 28 isolates were identified as Valsa mali var. pyri (Lu. 1992) based on morphological and molecular identification, and two isolates (ALE6T-GP21 and ALE7T-GP23) were identified as Valsa nivea (Hoffm.) Fr. Valsa nivea isolates had a fine villi form mycelium that was initially white, turned grayish-green over time and grew close to the medium surface. Cultures also contained black ostiolate pycnidia in a stroma that consisted of multiple irregular locules. Conidiophores were hyaline, occasionally branched at the bases and (15.50-)16.48-17.94(-18.50)×(1.00-)1.13-1.37(-1.50) μm (n=20). Conidiogenous cells were phialidic and subcylindrical that taper towards the apex. Conidia were hyaline, banana-like and (5.47-)6.13-6.97(-7.64)×(1.02-)1.06-1.20(-1.23) μm (n=10). The molecular characteristics are consistent with the previous description of V. nivea (Adams et al. 2006). The internal transcribed spacer (ITS), transcription elongation factor (tef-1α) and β-tubulin (Tub2) gene were sequenced using ITS1/ITS4, EF1-728F/EF1-986R and Bt2a/Bt2b primers, respectively (Zhang et al. 2014). BLAST (Basic Local Alignment Search Tool) searches against the NCBI database revealed that the ITS sequence had 99.83% homology (ON843984.1 and ON843987.1), tef-1α gene had 99.22% homology (MH015266.1 and MH015267.1), and the Tub2 sequence had 99.57% and 100% homologies (KT934364.1 and KT934364.1) with V. nivea sequences. The amplified sequences of ITS region (OK442665 and OK442666), tef-1α (OK510871 and OK510872) and Tub2 (OK510869 and OK510870) were deposited in the GenBank. A phylogenetic analysis was performed using MEGA7 that shows 100% bootstrap support that ALE6T-GP21 and ALE7T-GP23 were V. nivea. A pathogenicity trial was conducted with isolate ALE6T-GP21 inoculated onto 1-year-old shoots of 15-year-old Korla pear trees in Alar city, Xinjiang, China. Five shoots were inoculated by making 5-mm deep wounds using a sterile scalpel then inoculating with a 50 μL conidia suspension (1×106 mL-1). Additionally, five shoots served as the negative control and were inoculated in the same way using 50 μL ddH2O. The trees were kept under ambient conditions. Inoculated branches developed symptoms 18 days post inoculation, whereas the control branches showed no symptoms. V. nivea was re-isolated from the symptomatic areas and the isolate confirmed as ALE6T-GP21 by sequence analysis. Currently, the proven hosts of V. nivea are Populus, Elaeagnus, Juglans, Malus and Salix (Adams et al. 2006; Wang et al. 2020). To our knowledge, this is the first report of pathogenic V. nivea occurring on P. sinkiangensis in the world. It will provide a basis for research into the occurrence, distribution of V. nivea on Korla Pear.

Apple (Malus pumila Mill.) is an important fruit crop in Xinjiang, China. In September 2021, apple tree canker was observed in a 21-year-old commercial apple orchard cv. Fuji in Xinjiang (38°17'51.43"N, 77°9'50.81"E) , northwest of China. Of the 200 plants surveyed, 25% were symptomatic. The diseased trees showed branch dieback and cankers. The cankers observed on the wood were sunken, shriveled, and discolored. After the bark was peeled off, the diseased wood was dark brown, and the necrosis was obvious on the cross-section of the diseased branch. To identify the causal agent, five symptomatic trees were collected and analyzed in the laboratory. Apple wood samples (0.5×0.5 cm) were surface-disinfected with 1% v/v sodium hypochlorite and 75% v/v ethanol, rinsed with sterile distilled water, transferred onto potato dextrose agar (PDA), and incubated in the dark at 25 °C for 5 days. Conidia were induced on sterilized pine needles covered with 2% w/v water agar under near-UV light. The colonies of five isolates were white to gray with sparse aerial mycelium that gradually became dark olive green in the later stage. Conidia were initially hyaline but becoming brown at maturity, 1-septate, oval, rounded at both ends, and with dimensions of 24.9-32.1 × 15.1-21.5 µm (n =50) and the aspect ratio of 1.6. Based on the cultural and morphological features of Phillips (2002), the isolates were identified initially as Diplodia mutila (Fr. : Fr.) Mont. To confirm species identification, genomic DNA was extracted from the representative isolate SC-8A. The primer ITS1/ITS4, EF1-728F/EF1-986R and BT2a/BT2b were used to amplify the rDNA sequences of, respectively, the internal transcribed spacer (ITS), translation elongation factor 1-alpha (EF1-α) gene, and a portion of beta-tubulin (tub2) gene. The nucleotide sequences indicated ≥99% identity to D. mutila (CBS 112553) for three DNA regions. Consensus sequences were deposited in GenBank. as accession numbers OM618108, OM676657 and OM676658 for ITS, EF1-α and tub2, respectively. To fulfill Koch's postulates, pathogenicity tests were performed using isolate SC-8A on one year old branches of cv. Fuji (n=5). Wounds were created in the middle of the branches using a sterilized hole punch (5mm diameter) and were immediately inoculated with mycelial plugs of the same diameter. For the control treatment, sterile agar plugs were used (n=5) in the branches. The inoculated and control branches were wrapped with sterile parafilm. On the 10th day after inoculation, canker lesions appeared on the inoculated branches, but no lesions were observed in the negative control. D. mutila was re-isolated from 100% of the inoculated shoots and was not re-isolated from any of the negative controls, the Koch's postulates were met. Previously, D. mutila has been reported in Canada (Úrbez-Torres et al., 2016), Argentina (Lódolo et al., 2022) and Chile (Díaz et al., 2022) causing Botryosphaeria canker and dieback in apples. To our knowledge, this is the first report of D. mutila causing Botryosphaeria canker and dieback in apple trees in China.