Plant disease最新文献

{"title":"Spatial Efficacy and Economic Return Evaluations of Soil Fumigation for <i>Agroathelia rolfsii</i> Management in Florida Plasticulture Tomato Production.","authors":"Roshni Panwala, James Colee, A Malek Hammami, Samuel Martins, Gary E Vallad","doi":"10.1094/PDIS-05-26-0894-RE","DOIUrl":"https://doi.org/10.1094/PDIS-05-26-0894-RE","url":null,"abstract":"<p><p><i>Agroathelia rolfsii</i> (<i>A. rolfsii</i>), the causal agent of southern blight (SB) of tomato, is a soilborne fungal pathogen that produces sclerotia to survive during fallow periods and is commonly managed with pre-plant soil fumigation in commercial tomato production. However, fumigant efficacy against <i>A. rolfsii</i> sclerotia distributed throughout raised bed soil profiles and the economic return of fumigant inputs have not been assessed for currently available fumigant systems. Across four trials, this study evaluated the efficacy of three fumigant treatments against <i>A. rolfsii</i> sclerotia distributed at different soil depths and placements, on SB disease incidence, and marginal economic returns in a plasticulture fresh-market tomato system. Treatments included the grower-standard chloropicrin and 1,3,-dichloropropene (Pic-Clor) applied at the bed base, metam potassium (Kpam) applied in the top half of the bed, and a combination treatment (Pic-Clor+Kpam). Beds treated with Pic-Clor+Kpam saw 2-3% sclerotia survival across all burial depths and placements, compared to the grower's standard, Pic-Clor, which had 11% recovery at 1.5 cm and 5% at 10 cm depths. Across all seasons, Pic-Clor+Kpam and Pic-Clor limited disease incidence below 2% and 4% respectively, compared to 9% for Kpam and 43% for the nonfumigated control. All fumigant treatments returned at least $20,000/hectare more than the nonfumigated control during high disease pressure seasons. Moreover, both Pic-Clor alone and Pic-Clor+Kpam returned $25,0000/hectare, suggesting that the additional cost of Kpam was not justified based on marginal economic return when only considering disease management. While additional bed-top Kpam application does lower surviving inoculum levels and improves SB disease management compared to Pic-Clor alone, the prospect of limiting other pesticidal applications may be needed to justify the additional cost as marginal returns are comparable across systems.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148990825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Colletotrichum kakivorum</i>: A New Pathogen Causing American Ginseng Root Rot in China with Host Range and Fungicide Efficacy Analyses.","authors":"Jiayi Niu, Xile Zhi, Jing Xu, Wang Chunling, Wenqi Li, Jinxin Liu, Xue Zhang, Yonggang Li","doi":"10.1094/PDIS-07-26-1409-SR","DOIUrl":"https://doi.org/10.1094/PDIS-07-26-1409-SR","url":null,"abstract":"<p><p>American ginseng (<i>Panax quinquefolius</i> L., AG) is a high-value medicinal and edible crop widely utilized in traditional and modern healthcare systems. Root rot disease, induced by a complex of diverse phytopathogens, is a major limiting factor hindering the sustainable cultivation of AG. In July 2024, a pathogenic fungal strain was isolated from symptomatic rotted roots of American ginseng and taxonomically identified as <i>Colletotrichum kakivorum</i>. To our knowledge, this represents the first formal report of <i>C. kakivorum</i> causing infection in American ginseng in China. Host range assays conducted on nine medicinal herb species demonstrated that <i>C. kakivorum</i> could infect seven host plants, including ginseng, radix codonopsis, ladybell, dried rehmannia, platycodon, fragrant solomonseal rhizome, and cochinchinese asparagus, but did not infect white peony or heterophyllous falsestarwort. Two fungicides, pyraclostrobin and difenoconazole, exhibited prominent inhibitory effects against the pathogen. Specifically, pyraclostrobin at 0.1 mg·L⁻¹ and difenoconazole at 0.05 mg·L⁻¹ completely inhibited the germination of <i>C. kakivorum</i> conidia. Field inoculation trials further verified that foliar application of 500 mg·L⁻¹ pyraclostrobin and 200 mg·L⁻¹ difenoconazole reduced the disease incidence of American ginseng root rot (AGRR) by approximately 62%. An integrated management strategy, including crop rotation with non-host medicinal herbs combined with fungicide application, was verified to efficiently control American ginseng root rot induced by <i>C. kakivorum</i>. Collectively, these findings provide a fundamental theoretical basis and practical reference for the prevention and management of <i>C. kakivorum</i>-associated root rot in American ginseng seedlings.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148990773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatiotemporal Dissection of the Infection Response to Bacterial Soft Rot in Non-heading Chinese cabbage.","authors":"Meiling Lyu, Xueli Zheng, Xiaowen Zhang, Bingfeng Xie, Junjie Zhu, Yun Su, Tianyang Song, Yucen Qiu, Yu Zeng, Xinxin Xie, Yixuan Wu, Nuo Chen, Yujun Bu, Rongfang Guo","doi":"10.1094/PDIS-03-26-0558-RE","DOIUrl":"https://doi.org/10.1094/PDIS-03-26-0558-RE","url":null,"abstract":"<p><p>Bacterial soft rot caused by Pectobacterium brasiliense (Pbr) leads to substantial yield losses in cruciferous vegetables, including non-heading Chinese cabbage (pak choi, Brassica rapa subsp. chinensis). This study employed an integrated physiological and multi-tissue transcriptomic approach to decipher the infection response strategies of pak choi against Pbr. Age-dependent resistance was detected, with susceptibility decreasing as plants matured. In susceptible four-week-old plants, Pbr infection induced oxidative stress, characterized by the accumulation of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), and activated a multi-layered response system involving key antioxidant enzymes (SOD, POD, CAT, APX) and phenylpropanoid pathway enzymes (PAL, PPO). Transcriptome profiling revealed a tissue-specific division of response labor. Petioles, the primary infection site, mounted a response characterized by a bidirectional reprogramming of the ribosomal pathway and activation of sulfur metabolism, including the upregulation of cysteine synthesis genes (cysC, cysK). In contrast, leaves implemented a resource-reallocation strategy, involving broad suppression of photosynthesis and hormonal rebalancing-specifically, upregulation of JA repressors (JAZ) and downregulation of the SA signaling component NPR1. Furthermore, we identified an infection-induced transcriptional regulatory network mediated by transcription factors (e.g., MYB, WRKY, AP2-EREBP, NAC), and weighted gene co-expression network analysis (WGCNA) pinpointed hub TFs in infection-associated and health-associated modules. Our findings provide a comprehensive framework for age-dependent and tissue-coordinated infection response in pak choi, offering valuable genetic targets for breeding resistance against bacterial soft rot.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148990886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prevalence of Foliar Diseases on Muskmelon (<i>Cucumis melo</i> var. <i>melo</i>) in South Carolina.","authors":"Anthony P Keinath, Patrick Gerard, Robert Last","doi":"10.1094/PDIS-05-26-1019-RE","DOIUrl":"https://doi.org/10.1094/PDIS-05-26-1019-RE","url":null,"abstract":"<p><p>Muskmelons (Cucumis melo var. melo) grown in the eastern United States are affected by several foliar diseases caused by fungi and an oomycete. The objective of this survey of muskmelon production regions in South Carolina was to determine the prevalence of foliar diseases on spring crops to refine fungicide recommendations. In total, 34 fields from 21 growers in 10 counties were sampled using stratified cluster sampling. A total of 20, 20, and 40 diseased leaves were collected in each field in 2019, 2020, and 2021, respectively, along four transects forming a square of 1225 or 2,500 m2. After collection, disease symptoms were confirmed by identifying the genus of any cucurbit pathogens producing reproductive structures in lesions on leaves during >16 h incubation at 100% relative humidity. Based on estimates of probability of pathogen occurrence among diseased leaves across years, Alternaria, Cercospora, Phoma, Stagonosporopsis, and Podosphaera had an approximately equal estimated probability of occurrence, ranging from 0.082 to 0.168. Estimated probabilities of occurrence of foliar symptoms caused by manganese toxicity (0.056) were similar to estimated probabilities of pathogens among diseased leaves. Pseudoperonospora cubensis was found on two leaves on one farm in 2019. Pathogens were less likely to occur on leaves from fields receiving one or two fungicide applications within the two weeks prior to sampling than on leaves from fields not treated with fungicides. Fungicide recommendations for muskmelon grown in the eastern United States should include fungicides with efficacy against Alternaria leaf blight.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148983180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Brefeldin A, an effector of <i>Ascochyta medicaginicola</i>, mediates virulence.","authors":"Xunfeng Chen, Yanxiu Pan, Yanru Lan, Zhibiao Nan, Peng Gao, Qiuyan Song","doi":"10.1094/PDIS-06-26-1240-RE","DOIUrl":"https://doi.org/10.1094/PDIS-06-26-1240-RE","url":null,"abstract":"<p><p>Alfalfa spring black stem, caused by Ascochyta medicaginicola, severely affects global alfalfa production. This study isolates and identifies brefeldin A (BFA) from pathogen fermentation products and demonstrates its strong phytotoxicity. BFA inhibits leaf photosynthesis and seed germination in a dose-dependent manner at concentrations ≥10-4 mol. Significant variation in BFA sensitivity is observed among cultivars, with 'Longdong' showing the highest susceptibility and 'Spyder' displaying relative resistance. LC-MS/MS analysis detects BFA in naturally infected plants, confirming its presence during disease development. BFA treatment increases leaf relative electrolyte leakage, reduces chlorophyll content, and induces chloroplast structural damage, including shrinkage and disintegration of grana lamellae. Furthermore, BFA enhances defense-related enzyme activities and alters the expression of 953 genes. Gene set enrichment analysis reveals that photosynthesis pathways are significantly down-regulated, whereas defense responses are up-regulated. These results identify BFA as a key virulence effector and provide a basis for disease-resistant breeding and ecological management of spring black stem disease.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148983069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Whole-genome characterization and phylogenetic placement of <i>Fusarium oxysporum</i> f. sp. <i>vasinfectum</i> isolates.","authors":"Catherine Danmaigona Godsent-Ogbe, Eun-Gyu No, Lin Zhang, Terry Wheeler, Jane K Dever, Ping He, Libo Shan","doi":"10.1094/PDIS-11-25-2248-RE","DOIUrl":"https://doi.org/10.1094/PDIS-11-25-2248-RE","url":null,"abstract":"<p><p>Fusarium wilt of cotton, caused by Fusarium oxysporum f. sp. vasinfectum (<i>Fov</i>), remains a persistent threat to cotton production worldwide. Among the known races, <i>Fov</i> race 4 and its extra-virulent variants cause particularly severe losses in Upland cotton. Although several Fov genome assemblies have been assigned to races, the genomic diversity and evolutionary relationships among pathogenic and non-pathogenic isolates associated with cotton outbreaks remain poorly understood at the whole-genome level. This study addressed these gaps by generating and comparing high-quality genome assemblies of four Fusarium isolates collected from Texas cotton fields: two pathogenic (TX17-24 and TX18-9) and two non-pathogenic (TX17-6 and TX18-6). Draft assemblies were generated using Oxford Nanopore long reads and polished with Illumina reads. Comparative genomic analyses showed that pathogenic isolates possessed larger genomes and more conserved orthologous families, whereas non-pathogenic isolates contained more unique genes. Analyses of predicted secreted effectors, transposable elements, and carbohydrate-active enzymes further distinguished pathogenic and non-pathogenic lineages, suggesting roles in virulence adaptation and genome plasticity. Phylogenomic analyses using k-mer-based, assembly- and alignment-free methods incorporated all available long-read <i>Fov</i> genomes and revealed substantial genetic diversity within races 1 and 4, clustering isolates into multiple sublineages. These findings show that <i>Fov</i> race diversification is underestimated when based on traditional classification schemes and may be shaped by host specialization, geographic separation, or horizontal gene transfer. This work advances our understanding of the genomic diversity and evolutionary dynamics of <i>Fov</i> and establishes a foundation for improved race identification and characterization of Fusarium wilt pathogenesis in cotton.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148983217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Symptomatology and Host Range of <i>Clavibacter</i> Species Associated with Small Grain Cereals.","authors":"Nastaran Zamani, Asma Rahmanzadeh, Anne Vidaver, Ebrahim Osdaghi","doi":"10.1094/PDIS-05-26-0881-RE","DOIUrl":"https://doi.org/10.1094/PDIS-05-26-0881-RE","url":null,"abstract":"<p><p>Bacterial mosaic of small grain cereals is caused by five Clavibacter species, i.e., Clavibacter davisi, Clavibacter rahimiani, Clavibacter tessellarius, Clavibacter vidaverae, and Clavibacter zhangzhiyongii. While taxonomic range of the causal agents has only recently been investigated, biological features and host range of the pathogens remain unexplored. In this study, phenotypic features, symptomatology, and host range of the five Clavibacter species were evaluated. The host range assays were performed on seven small grain cereals' species, i.e., barley, maize, millet, oat, sorghum, triticale, and wheat under controlled greenhouse conditions. The five Clavibacter species showed considerable differences in colony color and morphology on agar-based culture media. The range of field symptoms induced by Clavibacter species under field conditions expands beyond mosaic patterns and yellowing, including necrotic lesions and leaf desiccation. Whereas water-soaking and oozing were not observed in the bacterial mosaic infections. Under greenhouse conditions, symptoms were similar to those recorded in the field. Clavibacter tessellarius strains were the most aggressive agents with the widest host range, infecting all evaluated plant species except maize. Clavibacter rahimiani and Clavibacter zhangzhiyongii strains induced noticeable symptoms only on sorghum and oat plants, while Clavibacter vidaverae and Clavibacter davisi did not induce any symptoms on oat and millet. Sorghum plants became infected with all strains of the five Clavibacter species, while only Clavibacter tessellarius strains infected millet plants. These findings provided novel insight into the biology of bacterial mosaic pathogens and highlighted the importance of precise symptomatology of the disease in the field surveys and quarantine inspections.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148983304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Antagonistic microorganisms against Verticillium wilt in yellow-fleshed kiwifruit and their effect on Bruno rootstock physiology.","authors":"Daniel Ardiles-González, Arturo Calderon-Orellana, Juan G San Martín, Braulio E Ruiz, Inés Eradia Figueroa, Hector Garcia, Ernesto Antonio Moya-Elizondo","doi":"10.1094/PDIS-04-26-0706-RE","DOIUrl":"https://doi.org/10.1094/PDIS-04-26-0706-RE","url":null,"abstract":"<p><p>Verticillium wilt, caused by <i>Verticillium nonalfalfae</i> MLST2, is an emerging disease affecting yellow-fleshed kiwifruit in Chile, and effective management strategies are currently unavailable. This study evaluated the biocontrol potential of antagonistic microorganisms against <i>V. nonalfalfae</i> MLST2, their interaction with different kiwifruit rootstocks, and their effects on plant physiological performance. Six <i>Pseudomonas protegens</i> and six <i>Bacillus velezensis</i> isolates were screened <i>in vitro</i>, and the most effective strains were subsequently evaluated with Trichoderma harzianum RGM3510 under controlled conditions. <i>B. velezensis</i> BcB1 and <i>P. protegens</i> C025 showed the highest in vitro inhibition of mycelial growth (46.2 and 40.2%, respectively). However, disease suppression in planta depended strongly on the rootstock genotype. Among the evaluated rootstocks, Z5Z6 consistently exhibited the lowest wilt severity, whereas <i>P. protegens</i> C025 significantly reduced disease development compared with the inoculated control. In contrast, <i>B. velezensis</i> BcB1 failed to suppress disease and, in some rootstocks, increased wilt severity. Although cumulative disease severity in Bruno plants was not significantly reduced by the biological treatments, <i>P. protegens</i> C025 produced disease levels comparable to the non-inoculated control. Moreover, treatments containing <i>P. protegens</i> improved stomatal conductance and photochemical reflectance index, indicating lower physiological stress associated with pathogen infection. These results demonstrate that the success of biological control against <i>V. nonalfalfae</i> MLST2 is determined by the interaction between antagonistic microorganisms and rootstock genotype, highlighting <i>P. protegens</i> C025 in combination with the Z5Z6 rootstock as a promising strategy for the integrated management of Verticillium wilt in kiwifruit.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148983054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-throughput qPCR phenotyping of Verticillium stripe resistance in <i>Brassica napus</i> under natural field infection.","authors":"Mohamed Samir Youssef, Sean Walkowiak, Christian Obermeier, Isobel A P Parkin, Sally Lynne Vail, Robert W Duncan, Harmeet Singh Chawla","doi":"10.1094/PDIS-06-26-1149-RE","DOIUrl":"https://doi.org/10.1094/PDIS-06-26-1149-RE","url":null,"abstract":"<p><p>Verticillium stripe, caused by Verticillium longisporum, is an emerging threat to Brassica napus production in North America, with increasing field incidence and yield loss reported in affected regions. Although visual ratings are useful for rapid field assessment, resistance breeding is constrained by the lack of scalable, objective phenotyping methods that can quantify pathogen colonization across large genotype panels under field conditions. Here, we adapted and validated an established OLG70/OLG71-based SYBR Green qPCR assay within a high-throughput workflow combining freeze-dried hypocotyl sampling and magnetic bead-based DNA extraction to quantify V. longisporum DNA in field-grown B. napus. A panel of 215 B. napus genotypes was evaluated at two naturally infested field sites in Manitoba, Canada. The assay produced robust standard curves across plates, with R² values >0.99, amplification efficiencies of 95-105%, and low intra-plate variability, supporting reliable quantification over a broad dynamic range. Log₁₀-transformed fungal DNA quantities showed strong cross-environment consistency, with genotype rankings largely conserved between sites (Spearman ρ = 0.82). At the Glenlea site, qPCR-derived fungal load was strongly associated with visual Verticillium stripe severity (Spearman ρ = 0.68; R² ≈ 0.44; Kruskal-Wallis P = 1.59 × 10⁻¹⁷), indicating that hypocotyl colonization measured by qPCR captures biologically meaningful variation in disease expression. This scalable qPCR-based platform provides a repeatable, high-resolution phenotype for large-scale germplasm screening and future genetic analyses aimed at improving Verticillium stripe resistance in canola.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148930893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temporal changes in the population structure of the pathogen <i>Globisporangium irregulare</i> in a hydroponic Eustoma production system in Japan.","authors":"Ayaka Hieno, Kazuma Morita, Kayoko Otsubo, Wenzhuo Feng, Haruhisa Suga, Koji Kageyama","doi":"10.1094/PDIS-03-26-0634-RE","DOIUrl":"https://doi.org/10.1094/PDIS-03-26-0634-RE","url":null,"abstract":"<p><p>Temporal changes in the population structure of <i>Globisporangium irregulare</i> were investigated over three years (2015-2017) in a hydroponic Eustoma production system in Fukushima, Japan. The aims of this study were to determine the phylogenetic affiliation of Fukushima isolates, their potential as a source of contamination, and whether any specific molecular types were associated with pathogenic traits. Phylogenetic analyses based on genetic distances revealed that isolates exhibiting an intermediate RAPD DNA group I/II genotype occupied phylogenetic positions between groups I and II, suggesting recombination across lineages. The 2015 population exhibited relatively high genetic diversity, whereas isolates in 2016-2017 were genetically more uniform and often shared identical genotypes across cultivation cycles. These results indicate that pathogen populations were likely maintained within the hydroponic system, probably via infected plant residues, rather than repeatedly being introduced from the surrounding environment. No clear association was detected between molecular type and pathogenicity-related characteristics. Extracellular enzyme activity analysis revealed increased cellulase and xylanase activities with time while a reverse trend was seen in pectinase activity. However, these year-related trends did not correlate with disease severity. Isolates dominant after 2015 showed lower heat tolerance and reduced zoospore productivity compared with the 2015 population. The observed genotype replacement therefore appears to reflect selection for persistence within the hydroponic environment rather than increased virulence, stress tolerance, or dispersal ability. These results suggest that disease management in hydroponic Eustoma production should consider the potential for long-term survival within cultivation facilities and emphasize the importance of sanitation and residue management.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148930817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}