Anthracnose disease, caused by Colletotrichum species, poses a significant threat to global litchi production, yet the molecular mechanisms governing host resistance remain poorly understood. To dissect the genetic basis of anthracnose resistance, we employed a comparative transcriptomic approach using two contrasting cultivars: 'YuJinQiu' (DR, disease-resistant genotype) and 'BaiTangYing' (DS, disease-susceptible genotype). Field evaluations and controlled infection assays demonstrated evident phenotypic divergence, with DR exhibiting delayed disease progression and 43.7% smaller lesion areas compared to DS at 72h post-inoculation (hpi). Time-resolved RNA sequencing (0-72 hpi) revealed genotype-specific transcriptional dynamics, where DR displayed fewer differentially expressed genes (DEGs; 819-1457) compared to DS (5195-5735), suggesting a more targeted and efficient defense response. Functional enrichment analyses highlighted rapid activation of innate immunity pathways in DR, including pattern-triggered immunity, MAPK signaling, and jasmonic acid/ethylene biosynthesis, whereas DS prioritized cell wall modification and compensatory secondary metabolic processes. Weighted gene co-expression network analysis (WGCNA) pinpointed three modules tightly linked to anthracnose resistance, enriched for receptor-like kinases (RLKs), nucleotide-binding leucine-rich repeat (NLR) proteins, and phenylpropanoid biosynthesis genes. Hub regulators, including WRKY transcription factors (e.g., WRKY33), ubiquitin ligases, and pathogenesis-related proteins (PR1, PR5), were identified as central coordinators of defense signaling. Strikingly, DR exhibited sustained upregulation of effector-triggered immunity markers, particularly nucleotide-binding leucine-rich repeat (NLR) genes, and early accumulation of phytoalexins, correlating with pathogen suppression. Experimental validation via qRT-PCR confirmed the reliability of transcriptomic data. Our study unravels the multilayer regulatory network underlying litchi anthracnose resistance, providing not only a mechanistic model of cultivar-specific responses but also a robust gene toolkit for accelerating the development of resistant cultivars through marker-assisted breeding.

Glomerella leaf spot (GLS) and apple bitter rot (ABR), collectively associated with over 20 Colletotrichum species, are two distinct diseases that cause substantial losses in apple production. In this study, phylogenetic analysis of 177 isolates collected across five provinces in northern China identified four species within the Colletotrichum gloeosporioides species complex (CGSC), namely C. aenigma, C. fructicola, C. gloeosporioides and C. siamense. C. siamense was the dominant agent of ABR (68.8%) whereas C. aenigma was the primary cause of GLS (76.9%), a pattern distinct from pathogen populations in the American continents. Fungicide profiling of the 177 isolates revealed that 41.2% of isolates showed high-level resistance to the quinone outside inhibitor (QoI) fungicide pyraclostrobin, largely attributable to the G143A mutation in the cytb gene. In contrast, sensitivity to the DMI fungicide difenoconazole remained largely unaltered. Inter- and intraspecific variation in fungicide tolerance was evident, with C. aenigma exhibiting significantly greater tolerance to both pyraclostrobin and difenoconazole compared to C. siamense. Further screening of nine additional fungicides identified prochloraz, fluazinam, penthiopyrad, and cyprodinil as highly effective against pyraclostrobin-resistant isolates. This study reveals the diversity of Colletotrichum pathogens of apple in northern China and highlights a critical need for fungicide resistance surveillance in production, and provides useful information for mitigating QoI fungicide resistance based on rational fungicide rotation.

Cotton (Gossypium spp.) is a major cash crop in India, with Rajasthan being one of the key producing states, though it is heavily affected by fungal diseases such as anthracnose that can severely reduce yield. Accurate identification of Colletotrichum species causing anthracnose is essential, requiring integrated morphological and molecular approaches due to their taxonomic complexity. In the present study, a roving survey was conducted during Kharif 2021–22 in different cotton-growing regions of Rajasthan to assess the occurrence of anthracnose incidence on cotton (Gossypium hirsutum L.) caused by Colletotrichum gossypii. A total of five diseased samples showing typical symptoms such as leaf lesions and boll spots were collected for isolation and detailed examination. The results revealed that the disease was endemic in all surveyed regions. The maximum mean disease severity was recorded in Hanumangarh district (42.25%), followed by Sri Ganganagar district (38.00%). Among the five isolates, isolate RJCG-3 was found to be the most virulent. The pathogen produced hyaline, smooth-walled, falcate to curved conidia with brownish to yellowish acervuli. The length and width of conidia varied from 20.25–28.92 µm and 3.35–3.91 µm respectively in different isolates. The fungal colony exhibited dull white to greyish-white mycelial growth on PDA medium and recorded maximum radial growth (90.00 mm) with profuse sporulation on the seventh day after inoculation.

The present study investigated the leaf blight disease of Sweet flag (Acorus calamus L.) during the cropping seasons of 2019–20 and 2020–21. Field observations showed that all five tested varieties (Nagireddigudem, Munipalli, Gaddipalli, Aihagaripalli and Symbolia) were susceptible, with maximum disease severity recorded between February and March. The highest disease severity was recorded on Nagireddigudem (37.87 %) in 2019–20 and Munipalli (39.54 %) in 2020–21. The pathogen associated with the disease was identified morphologically as a Colletotrichum species, producing white to grey cottony mycelium, hyaline cylindrical conidia, melanised septate setae and dark brown appressoria. Pathogenicity tests confirmed symptom reproduction within 10-12 days post-inoculation. Molecular characterisation through Internal Transcribed Spacer (ITS) sequencing and phylogenetic analysis further confirmed the pathogen as Colletotrichum siamense (GenBank Accession: MT672519). For the management of disease, five isolates of Trichoderma as a bioagent and five botanical extracts were tested against the pathogen, along with a check. In vitro evaluations demonstrated significant inhibition of the pathogen by all Trichoderma isolates, with T5 (TriK5) showing the highest suppression (53.5 %). Among botanical extracts, Withania somnifera exhibited the maximum inhibition (57.4 %), whereas the fungicides carbendazim and copper oxychloride provided the highest suppression at 100 % and 67.4 %, respectively. The study confirms C. siamense as the causal agent of leaf blight in A. calamus and identifies potential biocontrol, botanical and chemical options for disease management.

Ipê trees (Bignoniaceae), mainly belonging to the genus Handroanthus, are widely used in urban landscaping and reforestation programs in Brazil. Anthracnose, typically associated with species of Colletotrichum, represents one of the major diseases affecting ipê seedlings and ornamental trees. However, the etiological agents involved have not yet been fully clarified using modern phylogenetic tools. In this study, we identified Colletotrichum species associated with anthracnose in ipê trees from Pernambuco, Brazil. A total of 22 isolates were obtained from symptomatic leaves of Handroanthus impetiginosus and H. chrysotrichus. Species identification was based on multilocus phylogenetic analyses using CAL, GAPDH, GS, and TUB2 loci. The isolates were assigned to three species: Colletotrichum siamense, C. tropicale, and C. karsti. Colletotrichum siamense was the most prevalent species (50%), followed by C. tropicale (36.3%), while C. karsti represented 13.7% of the isolates. Pathogenicity tests confirmed that all isolates were pathogenic to both ipê species, producing typical anthracnose symptoms. Aggressiveness differed between hosts, with H. impetiginosus showing higher susceptibility, as indicated by larger lesion development, whereas H. chrysotrichus exhibited lower disease aggressiveness. Thus, our findings represent the first multilocus-based identification of Colletotrichum species causing anthracnose in ipê trees, providing new insights into the diversity and epidemiology of this disease in urban environments.

Cantaloupe (Cucumis melo L.) is a commercially important fruit crop that is widely cultivated in Thailand. In June 2025, anthracnose disease was observed on cantaloupe during postharvest storage at 25–32°C and 70–75% relative humidity over a period of 3 to 7 days in Chiang Mai Province, Thailand. The disease incidence was 15% to 20% among 100 fruits per pallet box. The symptoms appeared as small, water-soaked lesions on the fruit surface that expanded over time, becoming depressed and dark brown to black spots. In advanced stages, the lesions coalesced, leading to extensive fruit rot, and pink to orange spore masses developed on the lesions under humid conditions. Two fungal isolates (SDBR-CMU752 and SDBR-CMU753) with similar morphology were obtained from lesions using the single conidial isolation method (Choi et al. 1999). Colonies on potato dextrose agar (PDA) reached 80–85 mm in diameter after 1 week of incubation at 25 °C. The colonies were white to pale gray, cottony in texture, with the reverse side appearing pale orange to pale brown. Both isolates produced asexual structures after 1 week at 25 °C on PDA. Light conidial masses were observed. Conidiophores were hyaline, septate, and clavate to cylindrical in shape. Conidiogenous cells were also hyaline, clavate to cylindrical, measuring 15–20 × 3–5 μm (n = 50). Conidia were subcylindrical to oblong, rounded tips, guttulate, and sized 10–20 × 4–5 μm (n = 50). The morphological characteristics of the present isolates align with those of Colletotrichum species within the Colletotrichum gloeosporioides species complex. This species complex contains plant pathogens associated with anthracnose diseases and other diseases afflicting various crops (Jayawardena et al. 2021; Suwannarach et al. 2025). The internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), β-tubulin (TUB), actin (ACT), and calmodulin (CAL) regions were amplified using the primer pairs ITS1/ITS4, GDF1/GDR1, T1/Bt2b, ACT-512F/ACT-783R, and CL1C/CL2C, respectively (Weir et al. 2012; Jayawardena et al. 2021). The resulting sequences were deposited in GenBank under accession numbers PX533053 and PX533054 for ITS, and PX582285 to PX582292 for the other four gene regions. A maximum likelihood tree constructed from concatenated ITS, GAPDH, TUB, ACT, and CAL sequences placed the two isolates within the C. siamense clade. To confirm pathogenicity, healthy commercial cantaloupe fruits (Cu. melo) from the market were surface disinfected by 0.1% NaClO for 5 min, rinsed three times with sterile distilled water, and wounded (Nuangmek et al. 2019). Conidia were collected from 2-week-old cultures on PDA and suspended in sterile distilled water. Fifteen microliters of a conidial suspension (1 × 106 conidia/ml) were dropped onto the wounded fruits. Mock inoculations were performed using sterile distilled water as a control. Each treatment was conducted with ten replications and repeated twice. The inoculated fruits were stored individually in sterile plastic boxes at 25°C with 70 to 80% relative humidity. After 7 days, all inoculated fruits exhibited brown to dark brown lesions, while control fruits remained asymptomatic. Colletotrichum siamense was consistently reisolated from the inoculated tissues on PDA and identified to complete Koch's postulates. Cantaloupe fruit is commonly affected by fungal pathogens such as Alternaria, Colletotrichum, Didymella, and Fusarium species (Nuangmek et al. 2019; Giménez-Santamarina et al. 2025). Prior to this study, C. siamense was known to cause anthracnose on several fruit crops worldwide, including avocado, culinary melon, mango, papaya, and strawberry among others (Talhinhas & Baroncelli 2023; Suwannarach et al. 2025), but has not been reported in cantaloupe fruit. To our knowledge, this is the first global report of C. siamense causing postharvest anthracnose on cantaloupe fruit. The outcomes will contribute to guiding epidemiological studies and further developing improved management approaches for the disease.

Colletotrichum species cause bitter rot (BR) in apples, with symptoms typically manifesting at harvest or during storage. The efficacy of chemical control is limited, and the use of fungicides may lead to the selection of resistant isolates. As a sustainable alternative, biological control using Bacillus spp. has been used for diseases caused by Colletotrichum spp. This study evaluated the effects of B. subtilis, B. velezensis, and B. amyloliquefaciens on conidial germination (CG), mycelial growth (MG), and suppression of BR in apples. The impact of these bacterial strains on MG of five Colletotrichum species (C. chrysophilum, C. limetticola, C. melonis, C. nymphaeae, and C. siamense) was assessed. For B. velezensis, currently under development as a biocontrol product, both the biomass and supernatant fractions were evaluated and compared with the commercial formulations Serenade (B. subtilis) and Duravel (B. amyloliquefaciens). For postharvest control of BR, 'Gala' apples were treated with bacterial suspensions or fungicides and subsequently inoculated with conidia from three Colletotrichum isolates. Captan, dithianon, and metiram + pyraclostrobin served as chemical standards. All the tested Bacillus strains significantly inhibited MG across the Colletotrichum species evaluated. B. velezensis biomass reduced both CG and MG of C. nymphaeae and C. chrysophilum. Metiram + pyraclostrobin inhibited more than 98.2% of CG, while B. amyloliquefaciens achieved 63% inhibition of CG of C. chrysophilum. All fungicides reduced the incidence of BR by over 75% while B. amyloliquefaciens and B. subtilis variably reduced incidence of the disease depending on the isolate, experiment, and concentration.

The Colletotrichum magnum complex includes the species C. brevisporum, C. liaoningense, C. magnum (previously named Glomerella magna), and C. okinawense, among others, which are emerging as hazardous pathogens of cucurbits, tropical fruits, peppers, and legumes. Numerous spreads have been reported in tropical and subtropical areas, including the Yucatan Peninsula of Mexico, Eastern Brazil, Southern China, Thailand, and South Korea. C. magnum complex species can not be identified by simply observing disease symptoms, and GAPDH and TUB2 gene sequencing is strictly necessary for the identification to the species level. C. brevisporum can synthesize unique metabolites, including brevianthrones, nalgiovensin, and methoxy-nalgiovensin, and volatile organic compounds (VOCs), which strongly differ from other Colletotrichum species. C. magnum can secrete a variety of hydrolytic enzymes and oxidoreductases, which may participate in plant tissue degradation. C. magnum complex species have been identified co-infecting crops together with other pathogenic fungi; however, there is no study available regarding how C. magnum complex species interact with other microorganisms. Studies regarding the potential toxicity of C. magnum complex metabolites and their use as bioherbicides are lacking. C. magnum complex control strongly relies on the application of toxic fungicides, such as thiophanate methyl, captan, chlorathalonil, and copper salts. However, various non-commercial alternative agents, including sodium silicate, mango kernel polyphenols, Bonellia fammea extract, and Mentha piperita essential oil-containing chitosan coatings, also provided competitive control efficacies. Overall, accurate information regarding the yield losses caused by C. magnum complex species and their virulence factors is lacking, hindering the advancement of the research field.

Anthracnose, caused by Colletotrichum species, is a major disease of avocado (Persea americana) that significantly reduces fruit quality and export potential in Chile. Colletotrichum species associated with this disease were identified and their pathogenicity to avocado was assessed. In the summer of 2018, healthy fruits (n = 1,335) were sampled from three commercial groves located in the Metropolitan, O’Higgins and Valparaíso regions of Chile, and from a non-commercial grove and local markets. Fruits were stored until symptoms developed, indicating anthracnose incidence in commercial groves ranging from 10 to 50%. A total of 146 fungal isolates were obtained from symptomatic fruit and were initially identified as Colletotrichum spp. Fifty representative isolates were further identified through multilocus phylogenetic analyses. Ten species belonging to four species complexes were identified. Colletotrichum cf. cigarro was the most frequent taxon (n = 17), followed by C. pyricola (n = 9), C. gloeosporioides (n = 6), C. jiangxiense (n = 5), C. karsti (n = 4), C. anthrisci (n = 3), C. brassicicola (n = 3), C. laurosilvaticum (n = 1), C. fructicola (n = 1), and C. perseae (n = 1). Pathogenicity tests reproduced anthracnose symptoms in inoculated fruits, whereas control fruits remained symptomless, and revealed differences in virulence among isolates and species. This study provides the first report of C. brassicicola, C. laurosilvaticum and C. pyricola as causal agents of avocado anthracnose, highlights the diversity of Colletotrichum species in Chilean avocado groves, and provides insights for improved management strategies for avocado anthracnose.

Anthracnose fruit rot and leaf blight caused by Colletotrichum species, are significant diseases affecting pecan in the subtropical regions of China. From 2018 to 2021, disease surveys were conducted in the provinces of Zhejiang, Anhui, Shandong, Yunnan, Jiangsu, Sichuan, Jiangxi, and Guangxi, leading to the isolation of 108 Colletotrichum isolates from symptomatic samples. Species identification was performed through multigene phylogenetic analysis of the ITS, ACT, CAL, GAPDH, TUB2, and CHS-1 DNA regions. The isolates were classified within the C. gloeosporioides, C. acutatum, C. gigasporum, and C. orchidearum species complexes, with over 52% belonging to the C. gloeosporioides complex. Twelve Colletotrichum species were identified: C. fructicola (n=48), C. fioriniae (n=18), C. siamense (n=15), C. gloeosporioides (n=5), C. nymphaeae (n=5), C. aenigma (n=4), C. jiangxiense (n=4), C. henanense (n=2), C. gigasporum (n=2), C. conoides (n=1), C. sojae (n=1), and C. cliviicola (n=1). Pathogenicity tests via point inoculations confirmed that C. fioriniae, C. fructicola, and C. siamense showed higher virulence. In wound inoculation assays, leaves inoculated with C. fioriniae, C. conoides, C. fructicola, C. siamense, and Colletotrichum sp. developed larger lesions (diameters ranging from 4.0 to 8.3 mm) compared to those inoculated with C. gigasporum, C. jiangxiense, C. sojae, C. nymphaeae, C. cliviicola, and C. henanense (lesion diameters from 2.0 to 2.5 mm). The prevalence and diversity of Colletotrichum species associated with pecan anthracnose varied among the eight provinces, with relatively greater diversity observed in Yunnan, Jiangsu, Zhejiang, and Anhui. C. fructicola (50.3 %) was the most prevalent species across most pecan-growing regions studied in China, followed by C. fioriniae (15.5 %). This study provides the first report of C. conoides, C. aenigma, C. henanense, C. jiangxiense, C. gigasporum, C. sojae, and C. cliviicola infecting Carya illinoinensis in China.

Diversity and pathogenicity of Colletotrichum species associated with tea anthracnose in Nyingchi, Xizang, China

Pathogen Identification via Multilocus Phylogenetic Analysis and Resistance Evaluation in <i>Vitis</i> Germplasm

Application of thermostable chitinase I168L in the control of anthracnose on avocado and evaluation of cross-infection ability of Colletotrichum species

Colletotrichum species associated with anthracnose of Camellia oleifera in Jiangxi Province, China

Colletotrichum species are major plant pathogens and emerging opportunistic human pathogens. Due to their vast genetic diversity, existing diagnostic tools often suffer from narrow specificity or labor-intensive workflows. In this study, we developed a rapid, universal, and highly sensitive genus-specific real-time PCR assay utilizing a TaqMan MGB probe targeting the conserved 28S rDNA region. The assay demonstrated exceptional specificity, with no cross-reactivity against closely related fungal taxa or common co-occurring pathogens. The method exhibited high sensitivity, achieving a limit of detection (LOD) of 680 fg of genomic DNA. Furthermore, the assay was successfully validated using simulated environmental samples, where it accurately identified Colletotrichum within complex fungal communities. By providing a robust platform for genus-level screening, this methodology significantly enhances the efficiency of phytosanitary inspections and clinical diagnostics, facilitating timely biosecurity interventions and therapeutic decisions.

Ramie (Boehmeria nivea), native to China, is a natural fiber-yielding crop. The ramie fibers are long, pure white in color, silky in texture, and highly durable and hygroscopic (Angelini and Tavarini 2013). In May 2025, anthracnose symptoms were observed on 10% of cultivated ramie plants in a 10-ha field, Dazhou City (30.86°N, 107.33°E), Sichuan Province, China. Leaf tissues adjacent to and including lesions were excised, superficially disinfected with 70% ethanol for 20 s and 1% NaClO for 40 s, and washed with sterile distilled water at least five times. The disinfected tissues were incubated on PDA amended with streptomycin sulfate (50 mg/L) in the dark at 25 ℃. Two or three days later, hyphal tips from the edges of growing colonies were transferred to fresh PDA plates. Three representative isolates, G21, G22, and G23, showed identical morphological characteristics. The colonies exhibited cottony aerial mycelia on SNA plates. The upper and lower surfaces of mycelia were initially grayish-white and gradually became brownish-white. Setae were observed on the hyphae. Asci were 60.5 ± 5.4 × 13.7 ± 1.5 µm in size (n = 20), eight-spored, fasciculate, and clavate. Ascospores were 24.2 ± 3.6 × 5.1 ± 0.7 µm in size (n = 30) and slightly curved with obtuse to slightly rounded ends. Meanwhile, colonies produced abundant conidia, which were unicellular, hyaline, aseptate, smooth-walled, straight, cylindrical and rounded at both ends, measuring 18.1 ± 1.5 × 5.5 ± 1.2 µm (n = 30). These morphological characteristics match those of Colletotrichum species (Liu et al. 2022; Xue et al. 2020). Three isolates were properly preserved in our lab. All the isolates were further identified by sequencing rDNA internal transcribed spacer (ITS) regions, actin (ACT), beta-tubulin (TUB2), histone3 (HIS), chitin synthase (CHS) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes, using primer pairs ITS1/ITS4, ACT-512F/ACT-783R, T1/Bt2b, CYLH3F/CYLH3R, CHS-79F/CHS-345R and GDF1/GDR1 (Liu et al. 2022), respectively. BLASTn searches indicated our ITS (PX090878-PX090880), ACT (PX092338-PX092340), TUB2 (PX092341-PX092343), HIS (PX092350-PX092352), CHS (PX092344-PX092346) and GAPDH (PX092347-PX092349) sequences showed 99.48-100% identity to the corresponding sequences of C. reniforme LC8230 (MZ595847.1, MZ664145.1, MZ673968.1, MZ673867.1, MZ799290.1, and MZ664110.1). Based on concatenated ITS, ACT, TUB2, HIS, CHS, and GAPDH sequences, the constructed phylogenetic tree of Colletotrichum species confirmed that our isolates were C. reniforme. In the pathogenicity test, healthy leaves of ramie seedlings were sprayed with conidial suspension (1 × 105 conidia/mL) of G21, with controls treated with sterile dH2O. Each treatment was incubated in a greenhouse (at 25°C under 90% relative humidity and a 12/12 h light/dark cycle). The experiment was repeated three times. Ten days after inoculation, anthracnose symptoms appeared on inoculated leaves, while controls remained healthy. Koch's postulates were fulfilled by re-isolation of C. reniforme from diseased leaves, based on morphology and molecular methods described above. C. gloeosporioides (Wang et al. 2010) and C. higginsianum (Wang et al. 2011) were previously reported as causal agents of anthracnose on ramie. To our knowledge, this is the first report of C. reniforme causing anthracnose of ramie worldwide. Our study will assist in monitoring the diversity of infectious agents causing ramie anthracnose in China.

The excessive use of pesticides poses significant environmental and health risks. A real-time disease detection system can help mitigate this issue by identifying early infections and applying treatment only to affected areas. Building on the work of (P. P. Than), who conducted an exhaustive study on chilli anthracnose and the pathogenicity of Colletotrichum species, we utilize disease severity and spread indicators to enhance dataset annotation. Specifically, we classify infection levels based on affected areas, enabling precise disease detection. In this paper, we evaluate our method on a dataset of 6010 images, implementing a three-class classification system to determine the severity of fruit infections. This classification aids in calculating the optimal pesticide quantity required for specific areas. We assess the performance of YOLOv8 and YOLOv9 models in detecting infection levels, even in cases of minor disease spots. Among them, YOLOv8 demonstrated superior accuracy, achieving a mean average precision (mAP) of 92.7%, compared to YOLOv9’s 83.5%. The proposed method reduces pesticide usage by enabling targeted treatment and containment of infected areas. Furthermore, this enrichment improves plant disease understanding, optimizes workflows, and supports more informed decision-making in precision agriculture.

Aucuba japonica is widely planted in China for landscape use, particularly in gardens and parks. In September–October 2024, leaf blight symptoms were observed on A. japonica in Meicheng Park, Nanyang City, Henan Province (32°59′21″ N, 112°32′54″ E). A subsequent survey across different sections of the park recorded a disease incidence of 39% (n = 100 plants). Initial symptoms consisted of small dark-brown spots on leaves that enlarged into irregular leaf-blight lesions; in severe cases, lesions coalesced and caused defoliation and noticeable aesthetic decline. Diseased leaves (n = 20) were collected and surface sterilized. From each leaf, two lesion margins (3–3 mm²) at the interface of healthy and diseased tissue were excised and placed on potato dextrose agar (PDA). In total, 40 fungal isolates were obtained from symptomatic tissues. Thirty-six isolates showed typical Colletotrichum morphology. Isolates shared similar morphology, and three strains (SJSH09, SJSH12, SJSH23) obtained from symptomatic plants located in different sectors of Meicheng Park were selected for detailed analyses. Colonies on PDA were white to pale gray with a cottony texture, typically exhibiting subtle concentric zoning on the colony surface. Conidia were hyaline, aseptate, smooth-walled, and cylindrical to fusiform, measuring 7.3–22.8 × 2.6–5.3 μm (n = 100), consistent with Colletotrichum morphology (Talhinhas et al. 2023). For molecular identification, five loci—the rDNA internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase ( gapdh ), chitin synthase (chs-1), actin (act), and β-tubulin (tub2)—were amplified from the three strains (Zhang et al. 2023). Sequences have been deposited in GenBank under accession numbers PV636156–PV636158 (ITS), PV641785–PV641787 (gapdh), PV641782–PV641784 (chs-1), PV641788–PV641790 (act), and PV641794–PV641796 (tub2). BLASTn analyses showed that all loci had 99–100% identity to Colletotrichum aenigma reference strains, with no conflicting top hits to other species. A maximum-likelihood phylogeny based on the concatenated dataset (ITS, gapdh, chs-1, act, tub2) and ex-type reference sequences was inferred in MEGA. The three strains formed a clade with the C. aenigma ex-type ICMP 18608, TJ325, and XZC02, clearly distinguishing them from other Colletotrichum species. Morphological and molecular evidence together support identification of all three strains as C. aenigma. Pathogenicity was assessed by spraying conidial suspensions (10⁶ conidia mL⁻¹) onto unwounded leaves of five A. japonica plants; five additional plants were sprayed with sterile water as mock-inoculated controls. Plants were incubated at 28 °C and ~90% relative humidity. 14 days post-inoculation, lesions resembling those in the field developed on all inoculated plants, whereas no symptoms appeared on controls. The pathogen was re-isolated. ITS sequences of these re-isolated were 100% identical to those of the inoculated strains, confirming that the same pathogen were recovered and thereby fulfilling Koch’s postulates. Anthracnose of A. japonica caused by Colletotrichum boninense has been reported previously from Guizhou Province, China (Liu et al. 2022). This is the first report of C. aenigma causing leaf anthracnose on A. japonica. Given the widespread use of A. japonica as an ornamental shrub in urban landscapes, this newly recognized anthracnose disease poses a potential threat to plant health and aesthetic value. Accurate identification provides a basis for reliable diagnosis and for the development of targeted fungicide applications and other management strategies to protect ornamental plantings.

Walnut anthracnose is caused by pathogenic fungi of the genus Colletotrichum. Current detection approaches primarily depend on single-pathogen assays, which frequently fail to identify complex Colletotrichum populations in field environments, often resulting in a high rate of false negatives. To overcome this constraint, we developed a broad-spectrum detection method using recombinase polymerase amplification combined with a lateral flow dipstick (RPA-LFD), enabling rapid detection of Colletotrichum species. Targeting the conserved internal transcribed spacer (ITS) region, we designed specific primers and probes, selecting the optimal set through systematic screening. The assay specifically identified Colletotrichum species without cross-reacting with other walnut-associated fungi. The optimized RPA-LFD detection system exhibited a 10 min reaction time at 39°C and showed distinct sensitivity thresholds, detecting C. fioriniae, C. gloeosporioides, C. godetiae, C. karsti and C. nymphaeae at 10 pg/μL, while achieving 100 pg/μL for C. fructicola and C. siamense. This RPA-LFD system is simple to operate, with high sensitivity and specificity. It enables visual result interpretation and shows broad application potential in walnut anthracnose management.

Colletotrichum spp. cause anthracnose diseases in a wide range of host plants worldwide. However, anthracnose of cacao in Peru has been poorly studied. In August 2022, a phytosanitary survey of cacao plantations in the province of Bagua, Amazonas revealed a high incidence of cacao anthracnose in pods and leaves. Fourteen, Colletotrichum spp. isolates were obtained and morphologically and molecularly identified. The molecular identification was based on a seven-loci concatenated phylogenetic analysis, which supported an accurate phylogenetic identification of three species belonging to Colletotrichum gloeosporioides species complex: C. siamense, C. fructicola, and C. tropicale. Koch’s postulates were fulfilled after inoculation of cacao pods and leaves with conidial suspensions from representative strains of the three species, the development of similar symptoms as those observed in the field, and re-isolation of the strains. The present study enriches our knowledge about the C. gloeosporioides species complex affecting cacao in Peru.