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.
Abstract
Jackfruit (Artocarpus heterophyllus Lam.) is an economically important fruit tree widely cultivated in tropical and subtropical regions (Gupta et al. 2023). In July 2025, a leaf spot disease was observed on jackfruit trees in Zhanjiang, Guangdong Province, China. Diseased leaves initially developed small brown necrotic spots that gradually enlarged and coalesced, resulting in leaf yellowing and premature defoliation. Field surveys indicated that the disease was present in approximately 25% of the surveyed orchards. Symptomatic leaf tissues collected from diseased plants were surface-disinfested in 70% ethanol for 30 s, followed by 1% sodium hypochlorite for 1 min, rinsed five times with sterile distilled water, and plated onto potato dextrose agar (PDA). After incubation at 28°C in the dark for 5 days, 16 fungal isolates with similar morphological characteristics were obtained. Colonies exhibited an average radial growth rate of 17.1 ± 1.6 mm day⁻¹. Conidiophores were septate, pale brown, simple, smooth, straight to slightly curved, exhibiting sympodial proliferation and often bearing clusters of conidia at the apex. Conidia were solitary, ellipsoidal to oblong, straight or slightly curved, pale to dark brown, mostly 3-distoseptate, with a conspicuously darkened median septum and paler terminal cells. Conidia measured 16.3–30.9 × 5.6–11.2 μm (mean ± SD = 21.8 ± 4.9 × 8.1 ± 1.6 μm, n = 50), consistent with descriptions of Curvularia eragrostidis. For molecular identification, the internal transcribed spacer region (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and translation elongation factor 1-alpha (TEF1-α) genes of three representative isolates (LNU-16, LNU-17, and LNU-18) were amplified using primer pairs ITS1/ITS4 (White et al. 1990), GDF/GDR (Templeton et al. 1992), and EF1-983F/EF1-2218R (Rehner and Buckley 2005), respectively. The obtained sequences were deposited in GenBank (ITS: PZ528505–PZ528507; TEF1-α: PZ538484–PZ538486; GAPDH: PZ538487–PZ538489). BLASTn showed 100% ITS identity with C. eragrostidis TD4.2 (OR135782), 100% GAPDH identity with C. eragrostidis RU1 (PQ442766), and 99.77% TEF1-α identity with C. eragrostidis CD15 (MK886803). Maximum-likelihood analysis of concatenated ITS, GAPDH, and TEF1-α sequences placed the three isolates within the C. eragrostidis clade. Based on morphology and multilocus analyses, the pathogen was identified as C. eragrostidis (Gan et al. 2018). Pathogenicity tests were conducted on healthy detached jackfruit leaves. Leaves were surface-disinfested with 0.1% sodium hypochlorite and rinsed three times with sterile distilled water and allowed to air dry. A conidial suspension (10⁶ conidia mL⁻¹) prepared from a 12-day-old culture was sprayed onto leaves. Control leaves received sterile distilled water. Ten leaves were used for each treatment, and the experiment was repeated twice. Inoculated leaves were maintained at 25°C and 80–85% relative humidity. Seven days after inoculation, brown lesions surrounded by chlorotic halos developed on all inoculated leaves and were similar to those observed under field conditions, whereas no symptoms were observed on control leaves. The fungi reisolated from the inoculated leaves were identified as C. eragrostidis through morphological examination and sequence analyses of ITS, GAPDH, and TEF1-α, thus fulfilling Koch’s postulates. To our knowledge, this is the first report of Curvularia eragrostidis causing leaf spot on jackfruit in China. This finding expands the known host range of C. eragrostidis and provides a basis for future studies on disease epidemiology and management.
Idesia polycarpa, a deciduous tree in the Salicaceae family, is used for oil and timber (Wu et al. 2019). In August 2025, a field survey at an I. polycarpa nursery in Zunyi City, Guizhou Province (27.9° N, 106.9° E) revealed leaf disease on seedlings, with 50% disease incidence (n=1000). Early symptoms were small light yellow spots, expanding into irregular brown to black lesions with dried margins, necrotic areas, and defoliation. Lesion edges were yellowish, centers grayish-brown to blackish-brown. Twenty diseased leaves were randomly selected from five plants. Tissue pieces (5 mm × 5 mm) from lesion margins were disinfected with 3% sodium hypochlorite for 30 s and 75% alcohol for 1 min, rinsed with sterile distilled water, placed on PDA medium, and incubated at 28℃ for five days. Three morphologically similar strains, HB-1, HB-2, and HB-869, were isolated. On PDA at 28℃ in the dark, colonies were white on the obverse and light yellow on the reverse. The texture was velvety to floccose; the aerial mycelium was well-developed, dense, and fluffy, evenly covering the entire plate. Acervuli were black, spherical to subspherical, 0.15-0.97 mm in diameter, and embedded in the mycelial layer. All isolates produced asexual structures, with black setae measuring 37.7–39.5 μm × 4.7–4.9 μm, having a cylindrical base and a gradually tapering tip. Appressoria were ellipsoidal, dark brown, measuring 6.90–11.26 μm (mean = 8.14 ± 1.26 μm) × 5.08–7.94 μm (mean = 6.50 ± 0.92 μm) (n = 50). Conidiophores were colorless to light brown, septate, and branched. Conidia were slender ovoid, colorless, unicellular, aseptate, and smooth-walled, with rounded ends and containing oil globules, measuring 8.24–13.24 μm (mean = 11.50 ± 1.35 μm) × 4.51–5.18 μm (mean = 4.87 ± 0.22 μm) (n = 50). Cylindrical, rounded-end conidia were observed, matching the morphology of C. fructicola (Khuna et al. 2025). For identification, representative isolate HB-869 was subjected to multi-locus sequence analysis using ITS, CHS-1, and GAPDH, with primers ITS1/ITS4, CHS-79F/CHS-345R, and GDF/GDR, respectively (Weir et al. 2012). BLAST searches revealed that the ITS (GenBank: PX992721), CHS-1 (PZ094120), and GAPDH (PZ094121) sequences of HB-869 showed 98.89%, 100%, and 98.57% identity to those of the C. fructicola ex-type strain ICMP 18581 (JX010165, JX009866, and JX010033, respectively). Based on morphological and molecular evidence, HB-869 was identified as C. fructicola. For pathogenicity assay, ten 1-year-old I. polycarpa seedlings, approximately 40 cm tall, were selected. Leaves were inoculated by sterile needle-pricking. Five plants received 5 mL of HB-869 conidial suspension (1×10⁶ conidia/mL), while five control plants received sterile distilled water. All were incubated at 25 °C, 70% RH, under a 12 h light/dark cycle. The assay was independently repeated three times. At 14 days post-inoculation, typical anthracnose symptoms appeared on inoculated plants, consistent with field observations, while controls remained asymptomatic. The re-isolated pathogen was identified by morphology and ITS, CHS-1, and GAPDH sequences, fulfilling Koch’s postulates. C. fructicola infects diverse hosts, including Epimedium sagittatum (Hou et al. 2024). Given the economic importance of I. polycarpa, this finding expands the known host range of C. fructicola and offers valuable insights for disease diagnosis and management. This is the first report of anthracnose on I. polycarpa caused by C. fructicola in China.
Lanxin Sun, Cheng-Xu Wu, Zaihua Yang et al.· Plant Disease· 0 citations
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
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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.
Apricot (Prunus armeniaca L.) is an important fruit crop produced worldwide and is widely cultivated in China (Guo et al. 2010). In July 2025, a severe fruit rot disease was observed on apricot trees in an orchard located in Harbin, Heilongjiang Province (126.68°E, 45.72°N). Based on a random survey of 30 plants, the incidence of the disease was estimated to be 32%. At the initial stage of pathogen infection, dark brown lesions appeared on the fruit surface, accompanied by a grayish-brown floccose mycelial layer. As the disease progressed, the pathogen invaded the fruit interior, causing browning and softening of the flesh and hindering fruit ripening. The entire fruit eventually rotted and completely dehydrated, forming dark brown mummified fruits that remained attached to the branches. Tissues from lesion margins were surface-disinfested, plated on potato dextrose agar (PDA), and incubated at 25°C in the dark. Hyphal tips were subcultured for purification and eleven isolates were obtained. Based on morphological observation and ITS sequencing, all eleven isolates were preliminarily identified as Nothophoma sp. Representative isolates (strains PN2 and PN7) were selected for pathogenicity tests. Seven-day-old mycelial plugs from the colony margins were used as inoculum to inoculate healthy apricot fruits attached to branches, with blank PDA plugs serving as controls. The fruits were surface-disinfested with 75% ethanol and subjected to two inoculation methods: wounded (punctured 8–10 times with a sterilized insect needle) and non-wounded. Apricot fruits wound-inoculated with strains PN2 and PN7 exhibited typical disease symptoms consistent with those observed in the field. Pure cultures with morphological and cultural characteristics identical to the original inoculated strains were reisolated from the lesion margins of symptomatic fruits. Conidia of strains PN2 and PN7 were ovoid to ellipsoid, smooth, aseptate, hyaline to olivaceous, and measured 5.3–7.1 × 3.7–4.4 μm. On PDA, colonies initially grew radially, with a pale yellowish-brown center and white cottony margins; the texture was dense in the center and sparse at the edge. Colony color later deepened to dark brown, becoming a dense, thick, cottony mat, with both color and texture showing obvious maturation. These characteristics were consistent with previous descriptions of Nothophoma spiraeae (Zhang et al. 2020). PCR amplification of genomic DNA of the two strains was performed for the nuclear ribosomal Internal Transcribed Spacer (ITS), Large Subunit Ribosomal (LSU), β-tubulin (TUB), and RNA polymerase II second largest subunit (RPB2) gene regions using primer pairs ITS1/ITS4 (White et al. 1990), LR0R/LR7 (Vilgalys et al. 1990), Bt2a/Bt2b (Glass et al. 1995), and RPB2-5F2/RPB2-7cr (Liu et al. 1999), respectively. The amplified products were sequenced, and eight high-quality sequences were obtained. All sequences were deposited in GenBank (ITS, PZ263778 and PZ263779; LSU, PZ263776 and PZ263777; TUB, PZ334562 and PZ334563; and RPB2, PZ334561 and PZ307118). BLAST homology analysis showed more than 99.6% identity with N. spiraeae and its closely related species Nothophoma quercina. Phylogenetic analysis revealed that strains PN2 and PN7 clustered with N. spiraeae. Nevertheless, N. spiraeae and N. quercina cannot be clearly separated using the selected molecular markers owing to insufficient phylogenetic resolution between these two species. Combining the phylogenetic data and morphological characteristics obtained in this study, the pathogen was tentatively identified as N. spiraeae. To the best of our knowledge, this is the first report of N. spiraeae causing fruit rot on P. armeniaca. This study supports prediction and management of this new apricot disease to lower economic losses in apricot production.
Sihan Wang, Wentao Ma, Xinming Lu 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.
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
Ligustrum lucidum, commonly known as Chinese privet, is an ornamental tree widely cultivated in China. In August 2024, a severe leaf spot disease was observed on Ligustrum lucidum in and around Dushan Forest Park (33°04′13″N, 112°35′11″E) in Nanyang, China. Disease incidence reached 59% among 100 surveyed trees, reducing the ornamental value of affected plants. The lesions were initially small, scattered, and pale gray on the adaxial leaf surface, mostly circular to irregular in shape. On the abaxial surface, the corresponding lesions were slightly sunken and light brown. As the disease progressed, adjacent lesions enlarged and coalesced, and the necrotic tissue occasionally detached, producing shot-hole-like perforations. For pathogen isolation, ten symptomatic leaves were randomly collected. Small tissue segments were excised from the margin between healthy and diseased tissues, surface sterilized in 75% ethanol for 30 s, followed by 1% NaClO for 1 min, rinsed twice in sterile water, and plated on potato dextrose agar (PDA) supplemented with 50 μg/ml streptomycin. Plates were incubated at 25°C in darkness. In total, 16 isolates with similar morphological characteristics were obtained. Three representative isolates (DYNZ09, DYNZ17, and DYNZ20) sampled at separate sites were selected for further investigation. Colonies grew slowly on PDA at 25°C, with a growth rate of 3 mm per day. Conidia were light brown and obclavate to cylindrical, measuring 16.3–95.0 × 4.5–10.7 μm (n = 100). These morphological features were consistent with descriptions of Corynespora cassiicola. For molecular identification, genomic DNA of three representative isolates was extracted using the CTAB method. The rDNA internal transcribed spacer (ITS), translation elongation factor 1-alpha (tef1-α), and β-tubulin genes (tub) were amplified using primers ITS1/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn 1999), and Bt2a/Bt2b (Glass and Donaldson 1995), respectively. The obtained sequences were deposited in GenBank (ITS: PX488446–PX488448; tef1-α: PX549115–PX549117; tub: PX549119–PX549121). BLAST analysis showed 99.1-100% identity with sequences of C. cassiicola. Phylogenetic analysis based on concatenated ITS, tef1-α, and tub sequences using the maximum likelihood method (MEGA12) (Kumar et al. 2024) demonstrated that the isolates clustered with C. cassiicola strains. Pathogenicity assays were performed by spraying a conidial suspension (106 conidia ml-1) onto healthy leaves of L. lucidum seedlings (60–80 cm in height). Control plants were treated with sterile water. Inoculated seedlings were maintained in chambers at 28°C and 90–95% relative humidity under a 12 h light/12 h dark photoperiod. At 14 dpi, inoculated seedlings developed foliar symptoms, which were identical to the field observations. Control plants remained symptomless. C. cassiicola was consistently reisolated from diseased tissues, thereby fulfilling Koch’s postulates. C. cassiicola is a well-known pathogen with a broad host range and has been reported to cause diseases on soybean (Lu et al. 2021). C. cassiicola has been reported on other Ligustrum species, including L. quihoui (Yu et al. 2023) and L. × vicaryi (Wang et al. 2013). However, these reports involved different host species. To our knowledge, this is the first report of leaf spot caused by C. cassiicola on L. lucidum in China. This finding provides a basis for accurate diagnosis and future management of Corynespora leaf spot on L. lucidum.
Tan Wang, Zhanying Zhu, Zi-Meng Kou et al.· Plant Disease· 0 citations
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