Pepper (Capsicum annuum L.) is one of the most economically important cash crops in China. In July 2024, leaf spot was observed on pepper cv. ‘Sujiao 5’ in a 1-ha pepper plantation in Hangzhou (30°17′N, 118°52′E), Zhejiang Province. Among eight greenhouses surveyed, 30 plants per greenhouse were inspected. Disease incidence ranged from 10% to 20%. Early symptoms were round, grayish-white lesions. As the disease advanced, lesions expanded into circular spots with grayish-white centers and brown margins, and a grayish-brown mold layer emerged on the lesions. Thirty diseased leaves were randomly sampled from twenty infected plants for pathogen isolation. Under a stereomicroscope, a single conidium from the mold layer on diseased leaves was transferred onto potato dextrose agar (PDA) medium using a sterilized inoculating needle and incubated at 26°C for 7 days. Twenty single-conidium isolates were successfully obtained. After 15 days on PDA, colonies were grayish-green, velvety, with grayish-white margins. On synthetic nutrient-poor agar (SNA), colonies were light grayish-green with sparse mycelium. The conidiophores were solitary, erect, light brown, and septate. Ramoconidia were light brown, cylindrical to obovoid, aseptate, and measured 6.0-15.3 × 2.5-4.3 μm (n = 30). Conidia were light brown, obovoid to limoniform, forming branched chains with one to four conidia per branch, and measured 3.3-5.7 × 2.3-3.3 μm (n = 30). The morphological features were consistent with Cladosporium sp. (Bensch et al. 2015). All 20 single-conidium isolates shared identical colony morphology and conidial characteristics, so three representative isolates were randomly selected for sequencing. The primer pairs ITS1/4 (White et al., 1990), EF728/EF986 (Carbone and Kohn, 1999), and ACT512/ACT783 (Carbone and Kohn, 1999) were used to amplify the partial fragments of the internal transcribed spacers (ITS, GenBank: PZ437871-PZ437873), translation elongation factor 1-α gene (tef1, GenBank: PZ445478-PZ445480), and actin gene (act, GenBank: PZ445475-PZ445477). The sequences of the three isolates were identical at all three loci. BLASTn analysis showed 99% identity with Cladosporium sp. (ITS: OQ629129; tef1: HM148442; act: MT154165). The phylogeny suggests that three isolates were integrated into the Cladosporium tenuissimum clade (ML bootstrap support values/Bayesian posterior probabilities = 93/1). Based on morphology and phylogeny, the isolates were identified as C. tenuissimum. Since all isolates were morphologically and molecularly identical, isolate LJYB-LA1 was selected as a representative strain for pathogenicity testing. The isolate was cultured on PDA at 26°C in continuous darkness for 14 days. Conidia were rinsed with sterile water containing 0.1% Tween-80 and adjusted to 2 × 10
6
conidia/mL using a hemocytometer. Two-month-old pepper plants cv. ‘Sujiao 5’ were each sprayed with 200 mL of conidial suspension; the negative control plants were sprayed with 200 mL of sterile water. The plants were incubated in a greenhouse at 26°C and 85% relative humidity for 48 h. The experiment was repeated three times with five plants per replicate. After 10 days, inoculated plants developed symptoms similar to those observed in the field, whereas control plants remained asymptomatic. The species C. tenuissimum was reisolated from symptomatic tissues and confirmed by morphology and molecular data, confirming Koch’s postulates. The species C. tenuissimum has been reported to infect Hydrangea paniculata in China (Li et al. 2021) and Phaseolus vulgaris in China (Gao et al. 2024). To our knowledge, this is the first report of C. tenuissimum causing leaf spot on C. annuum in China.
Based on morphology and multilocus analyses, the pathogen was identified as C. eragrostidis, and the obtained sequences were deposited in GenBank placed the three isolates within the C. eragrostidis clade.
Xiang Lu, Chumiao Chen, Yunzhi Bai et al.· Plant Disease· 0 citations
Strain AB3-4 featured brownish-green centers, white peripheral mycelium, darker central reverse fading radially, and based on morphology and phylogenetic pattern, AB3-4 was identified as Alternaria sp.
Qirui Zhang, Hai-Jiao Yang, Zhong-Shun Mao et al.· Plant Disease· 0 citations
Chinese chives (Allium tuberosum Rottler ex Spreng.), an economically important aromatic vegetable, are widely cultivated worldwide. In May 2025, a severe leaf rot disease was observed on Chinese chives in Mile (24.45°N, 103.4°E), Yunnan Province, China. Following consecutive days of rain and high humidity, symptoms first appeared on young leaves. These symptoms manifested as progressive necrotic rot that extended from the middle section toward both leaf apices and bases. Field surveys revealed that over 75% of surveyed plants exhibited typical rot symptoms. To identify the causal agent, we collected 10 diseased plant samples. After surface cleaning, the samples were cut into 5 × 5 mm tissue segments. These segments were then surface-sterilized with 75% ethanol for 1 min, and rinsed three times with sterile distilled water. The tissues were transferred to potato dextrose agar (PDA) medium and incubated at 25 °C in the dark for 3 days. Following purification of the putative pathogen, ten isolates displaying consistent morphological characteristics were obtained. One of these isolates, designated as JC9, was selected for further characterization. Isolate JC9 cultured on PDA at 25 °C for 5 days produced abundant non-septate aerial hyphae. Pseudoconidia were spherical to ovoid in shape. Sporangia displayed morphological heterogeneity, encompassing ovoid forms with laterally positioned papillae and limoniform forms bearing short pedicels possessing prominent papillae. The mean sporangial length and width were 55.1 μm and 25.5 μm, respectively. Occasionally, empty sporangia exhibiting direct apical germination were observed. Chlamydospores were globose, occurring either terminally or intercalarily, with a mean diameter of approximately 28 μm. Collectively, these morphological features align closely with the established diagnostic criteria for Phytophthora heterospora (Scanu et al. 2021). For molecular identification, three gene regions were selected for amplification: the internal transcribed spacer (ITS), translation elongation factor 1-alpha (TEF1), and beta-tubulin (β-TUB). These markers are widely adopted for Phytophthora species identification and phylogenetic analysis, and are recommended for multi-locus phylogenies (Kroon et al. 2004). Amplifications were performed using the primer pairs ITS4/ITS5 (White et al. 1990), ELONGF1/ELONGR1 and F-βtub1/F-βtub2r (Kroon et al. 2004), respectively. The sequences were deposited in GenBank under accession numbers PZ266852 (ITS), PZ242888 (TEF1), and PZ242889 (β-TUB). Phylogenetic analyses — conducted under both maximum likelihood and Bayesian inference frameworks and based on concatenated alignments of the three loci — demonstrated that isolate JC9 formed a highly supported monophyletic clade (100% bootstrap support; posterior probability = 1.0) with reference strains of Phytophthora heterospora within the Phytophthora palmivora species complex. This clade was phylogenetically distinct from the Phytophthora palmivora sensu stricto lineage, thereby confirming the taxonomic assignment of isolate JC9 to Phytophthora heterospora. Pathogenicity tests were conducted by inoculating individual leaves of potted Chinese chive ( Allium tuberosum) plants with 5 µL zoospore suspension (1 × 10⁶ spores/mL) of JC9. The zoospores were harvested from PDA cultures using sterile water. Control leaves were treated with an equal volume of sterile distilled water. Each treatment comprised 30 healthy leaves with three independent biological replicates. All plants were maintained in a controlled greenhouse at 28 ℃ under a 12-h photoperiod (12-h light / 12-h dark). Sterile water was sprayed once daily to maintain persistent high humidity for pathogen infection. Three days post-inoculation, lesions identical to field symptoms developed on inoculated leaves, whereas control leaves remained asymptomatic. A pathogen strain morphologically and molecularly identical to isolate JC9 was successfully re-isolated from symptomatic leaf tissue, confirming Koch's postulates. Leaf rot of Chinese chives (Allium tuberosum) caused by Phytophthora heterospora has recently become a serious disease during the rainy season in Mile, significantly affecting local production and causing economic losses. As a major Chinese chive production area in southwest China, Mile features a subtropical monsoon climate characterized by high temperatures, abundant rainfall, and prolonged soil wetness during the rainy season — environmental conditions highly favorable for Phytophthora heterospora, a fungus-like oomycete pathogen known to thrive in warm, humid environments with distinct wet periods. These climatic and edaphic factors collectively facilitate the pathogen’s infection, colonization, and dissemination in chive fields. To date, this disease has not been reported in other Chinese chive-growing regions. Primary transmission pathways include infected seedlings and pathogen-contaminated soil; under field conditions, rain splash serves as the dominant mechanism for short-distance dispersal. This study provides a fundamental basis for early diagnosis, rapid detection, and integrated management of this emerging leaf rot disease.
Pueraria thomsonii Benth. is a leguminous vine grown in southern China for its edible, starch-rich roots. In May 2025, typical stem base rot was observed on plants in a commercial field of approximately 0.4 hectares in Wuzhou, Guangxi (23°32'12"N, 110°39'29"E), with disease incidence about 30%. Symptoms began as yellowish-brown discoloration on basal stems, turning dark brown with longitudinal cracks, brown dry rot of underlying tissues, and reddish-brown vascular discoloration. Late-stage stems exhibited black, dry, hollow rot; severely infected plants showed reduced branching, leaf thickening, and basal leaf yellowing, leading to death. Symptomatic tissues (5 × 5 mm) from lesion margins were surface-disinfested (75% ethanol 10 s, 2% NaOCl 5 min, rinsed thrice), placed on potato dextrose agar, and incubated at 28°C in darkness. Fifteen isolates were obtained via single-spore purification. Two morphological groups were identified. Group 1 (GG-F1) produced white, floccose colonies with abundant macroconidia: fusiform, slightly curved, 5-6 septate, (45-91) × (2.8-5.5) µm (n=50), with a distinct foot cell and bent apical cell. Group 2 (GG-F2) formed creamy-white to buff colonies with abundant microconidia: hyaline, oval to reniform, aseptate or 1-septate, (5.3-12.5) × (1.6-4.1) µm (n=50); macroconidia were sparse, stout, cylindrical with blunt apex and 3-5 septa. Genomic DNA was extracted from the three isolates using the CTAB method (Sagar et al. 2014). The ITS, EF-1α, and RPB2 regions were amplified and sequenced. BLAST analysis by Fusarioid-ID database (https://www.fusarium.org/page/ID) showed that GG-F1 shared 99.76% (ITS), 99.76% (EF-1α), and 99.85% (RPB2) identity with ex-type strains of Fusarium pseudensiforme (Neocosmospora pseudensiformis, now by Fusarioid-ID database); GG-F2 shared 100%, 99.76%, and 100% identity with Fusarium suttoniana (Neocosmospora suttoniana, now by Fusarioid-ID database), respectively. A multilocus phylogenetic tree confirmed the placements. Sequences were deposited in GenBank (ITS, PZ176910 and PZ176911; EF-1α, PZ196199 and PZ196200; RPB2, PZ196196 and PZ196197). Pathogenicity was tested by brushing conidial suspensions (1 × 10⁶ conidia/mL) onto basal stems of one-year-old healthy P. thomsonii plants, followed by Parafilm wrapping. Controls received sterile water. Each isolate was tested on six plants per replicate, with three replicates. All plants maintained under greenhouse conditions developed typical symptoms 6 days post-inoculation, while controls remained asymptomatic. Re-isolations from symptomatic tissues yielded fungi identical to the original isolates based on morphology and multilocus sequences, fulfilling Koch’s postulates. To our knowledge, this is the first report of stem base rot on P. thomsonii caused by a complex of Fusarium pseudensiforme and Fusarium suttoniana in China. This finding establishes a pathogen complex in kudzu root production regions, providing a basis for disease surveillance and integrated management.
Qian Wang, Quan Zeng, G. Shi et al.· Plant Disease· 0 citations
Sesame (Sesamum indicum L.) is an important oilseed crop widely cultivated in China. In August of 2025, wilt symptoms were observed on sesame (cv. Jizhi No. 1, 2, etc.) in a field in Shijiazhuang, Hebei, China. Affected leaves turned yellow and necrotic from the lower to upper portions but remained attached. Longitudinal yellowish-brown lesions occurred at the stem base, with pink sticky sporodochia under high humidity. Infected plants eventually died. Disease index was calculated according to Xu et al. (2026) with minor modifications, ranging from 11.2% (cv. Jiheizhi No. 8) to 55.2% (cv. Jizhi No. 1) across nine plots (250 plants/plot, with three replicates). Symptomatic stems were collected for fungal isolation. Small pieces (5 ⅹ 5 mm) were surface-sterilized (70% ethanol 30 s, 1% NaClO 2 min), rinsed, and plated on PDA at 25°C with 12-h photoperiod for 3-7 days. The single-spore method was used to purify the obtained isolates. Based on morphological and cultural characteristics, combined with ITS sequencing, a total of 48 isolates were preliminarily divided into two groups, with isolation frequencies of 68.8% and 31.2%, respectively. Representative isolates, ZM1 and ZM2, were selected for further study. On PDA, ZM1 colonies reached 70.9±3.3 mm diameter after 7 days, with white to pale-violet aerial mycelia, irregular margins, and purple reverse pigment. Macroconidia were hyaline, slender, straight to slightly curved, foot-shaped basal cell, tapering apical cell, 3–5 septate, 34.3±10.6 × 4.0±0.3 μm (n=200). Microconidia were abundant, hyaline, oval to kidney-shaped, 0–1 septate, 11.9±3.3 × 3.2±0.2 μm (n=200). Chlamydospores absent. ZM2 colonies reached 85.8±1.6 mm diameter after 7 days, with white aerial mycelia, orange reverse pigment, irregular margins. Macroconidia were hyaline, slender, curved, falcate, with foot-shaped basal cell, tapering to hooked apical cell, 1-4 septate, 26.0±8.8 × 4.5±0.7 μm (n=200). Microconidia absent. Chlamydospores were globose to subglobose, in chains, intercalary or terminal, with an average diameter of 10.9±1.6 μm. These traits matched Fusarium species (Leslie and Summerell, 2006). Molecular characterization was performed based on ITS, TEF-1α, and RPB2 (Xu et al., 2026). BLAST analysis revealed that ZM1 showed 100% (ITS and RPB2) and 99.5% (TEF-1α) similarity with F. oxysporum references, and ZM2 showed 100% similarity with F. lacertarum references across all three loci. Multi-locus phylogenetic analysis (ML), based on TEF-1α-RPB2 sequences, confirmed that ZM1 clustered with F. oxysporum (CBS 144134, 97% bootstrap) and ZM2 with F. lacertarum (NRRL20423, 99% bootstrap). All sequences were deposited in GenBank (ZM1: PZ288046/PZ291680/PZ453744; ZM2: PZ288047/PZ291681/PZ453745). Pathogenicity tests were conducted on 1-month-old sesame seedlings (cv. Jizhi No.1). Conidial suspension (1 × 10⁶ conidia/mL, 25 mL/pot) was poured around the stem base and root zone without wounding (ten plants per treatment, twice replicates); controls received sterile water. All plants were covered with plastic film for 24 h, then uncovered and maintained at 25°C, 12-h photoperiod. After 14 days, all inoculated plants exhibited typical wilt symptoms; controls remained symptomless. F. oxysporum and F. lacertarum were reisolated from ZM1- and ZM2-inoculated plants, respectively, fulfilling Koch’s postulates. F. oxysporum is a well-known causal agent of Fusarium wilt on sesame worldwide (Duan et al., 2020). Although less frequent, F. lacertarum was confirmed pathogenic and represents the first report of this species causing sesame wilt in China. F. lacertarum has previously been reported on Sorghum bicolor in North Carolina (Beacorn and Thiessen, 2021) and Casuarina equisetifolia in Brazil (Poletto et al., 2015). The identification expands the host range of F. lacertarum and highlights the importance of monitoring emerging Fusarium species in sesame production.
Jianchao Cui, Yuanzhang Guo, Li-Min He et al.· Plant Disease· 0 citations
Curcuma kwangsiensis, a perennial herb of the Zingiberaceae family, is widely cultivated in southern China for its medicinal roots (rhizomes and tuberous roots). However, disease problems have become increasingly severe with the expansion of cultivation areas. In September 2025, severe root rot was observed in approximately 6.67 hectares of C. kwangsiensis plantations in Guangxi, China, with disease incidence reaching up to 80% in continuous cropping fields. Initial symptoms included leaf yellowing and wilting, followed by plant death. Roots initially developed local necrotic lesions, which gradually expanded into dark brown rot, ultimately leading to complete disintegration of the root system. Typical diseased plants were collected for pathogen isolation and identification. Small root segments (approximately 5 × 5 mm) were excised from lesion margins, surface-sterilized with 75% ethanol for 30 s and 2% NaOCl for 2 min, rinsed five times in sterile water, dried, and placed on potato dextrose agar (PDA) at 28°C in the dark. Six morphologically consistent isolates were obtained. Colonies produced abundant white, fluffy aerial mycelia with white or pale-yellow reverse. Macroconidia were sparse, hyaline, falcate or slightly curved, 1–3 septa, measuring 20.6–42.3 × 3.6–6.1 μm (n=50). Microconidia were abundant, hyaline, falcate, ovoid to reniform, 0–1 septa, 7.2–16.1 × 2.8–6.7 μm (n=50), and formed in false heads on monophialides. Chlamydospores were globose, smooth-walled, single or in pairs, 6.7–8.1 μm in diameter. Based on these morphological characteristics, the fungus was preliminarily identified as Fusarium sp. For molecular identification, genomic DNA of representative isolate Fsu1 was extracted. The internal transcribed spacer (ITS), translation elongation factor 1-α (TEF1-α), and RNA polymerase II second largest subunit (RPB2) genes were amplified using primers ITS1/ITS4, EF-1H/EF-2T, and RPB2-5F2/RPB2-7cR, respectively (O'Donnell et al. 2022). BLAST analysis showed that all obtained sequences shared > 99% homology with Fusarium suttonianum. Specifically, the ITS, TEF1-α, and RPB2 sequences of isolate Fsu1 (GenBank accession nos. PZ176576, PZ211876, PZ211877) shared 100%, 99.89%, and 100% identity to F. suttonianum, respectively. Maximum likelihood phylogenetic analysis based on the concatenated sequences showed that isolate Fsu1 clustered with the type strain of F. suttonianum in the same clade. For pathogenicity test, five healthy C. kwangsiensis seedlings were slightly root-wounded, and 50 mL of spore suspension (1×10⁶ conidia/mL) was inoculated into the soil around roots. Controls were treated with sterile water. All plants were grown in a greenhouse. After 30 days, all inoculated plants developed symptoms identical to field observations, including leaf yellowing, wilting, and dark brown root rot, while controls remained asymptomatic. The fungus was re-isolated from diseased roots and identified as F. suttonianum by morphological and molecular analyses, fulfilling Koch's postulates. F. suttonianum has been reported causing root rot on various plants, including Plukenetia volubilis, Phaseolus vulgaris, and Vigna unguiculata (Delgado-Mera et al. 2025, Sousa et al. 2025). To our knowledge, this is the first report of F. suttonianum causing root rot on C. kwangsiensis in China. This finding provides a foundation for developing effective disease management strategies for C. kwangsiensis production.
