Plant disease最新文献

{"title":"Effects of <i>Phytophthora</i> species on seed germination and seedling survival and performance in five sweet chestnut varieties.","authors":"Ana Díaz Zúñiga, Amira Tiefenbacher, Iva Franić, Susann Dittkrist, Quirin Kupper, Beat Ruffner, Sven Ulrich, Simone Prospero","doi":"10.1094/PDIS-01-26-0083-RE","DOIUrl":"https://doi.org/10.1094/PDIS-01-26-0083-RE","url":null,"abstract":"<p><p>The oomycete genus <i>Phytophthora</i> includes numerous pathogens, some causing severe tree diseases. In forestry, their impact is usually assessed on adult trees, while their effects on seed germination and seedling development-crucial phases in forest regeneration-remain poorly investigated. Here, we tested the effects of the two main causal agents of ink disease in sweet chestnut, <i>P. cinnamomi</i> and <i>P. x cambivora</i>, along with three other <i>Phytophthora</i> species commonly found in European sweet chestnut forests (<i>P. plurivora</i>, <i>P. cactorum</i>, <i>P. cryptogea</i>), on seed germination and seedling development of five Swiss sweet chestnut varieties, which we genetically characterized using microsatellite markers. A total of 180 seeds of each variety were sown in soil substrates artificially infected with different <i>Phytophthora</i> species and incubated for 11 weeks in a climate chamber. Seed germination, seedling survival and seedling performance (height, root length, above and below ground dry biomass) were then assessed. While <i>P. cinnamomi</i> had a significant negative effect on seed germination in all sweet chestnut varieties, no effect was observed for <i>P. cactorum</i>. The remaining <i>Phytophthora</i> species exhibited variety-dependent effects. After successful germination, chestnut seeds of all varieties showed a high probability of surviving and developing into seedlings, except when exposed to <i>P. x cambivora</i> and especially <i>P. cinnamomi</i>, which killed all seedlings. <i>Phytophthora cryptogea</i> and <i>P. plurivora</i> significantly impacted seedling performance in specific varieties. Our study shows that soilborne <i>Phytophthora</i> species can strongly reduce seed germination and, in the case of <i>P. cinnamomi</i> and <i>P. x cambivora</i>, seedling survival in sweet chestnut. In infested stands, this may hinder the recruitment of future tree generations and threaten the long-term persistence of sweet chestnut populations.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149025608","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":"A Comprehensive Review of Bacterial Leaf Spot (<i>Xanthomonas</i> spp.) Host Resistance in Pepper (<i>Capsicum</i> spp.).","authors":"Mohit Jain, Deepa Jaganathan, Bhabesh Dutta, Anuj Sharma, Jeffrey B Jones, Bala Rathinasabapathi, Amol Nankar","doi":"10.1094/PDIS-05-26-0927-FE","DOIUrl":"https://doi.org/10.1094/PDIS-05-26-0927-FE","url":null,"abstract":"<p><p>Bacterial leaf spot (BLS) is one of the most destructive diseases of pepper (Capsicum spp.) worldwide, causing significant yield and quality losses under warm and humid conditions. The disease is caused by multiple Xanthomonas species, whose rapid evolution continues to challenge effective management. This review synthesizes current knowledge on BLS in pepper, including pathogen taxonomy, global distribution, and the historical progression of disease research and resistance breeding. We summarize advances in the identification and deployment of resistance loci, including major race-specific genes, as well as recessive resistance genes and quantitative resistance sources, and highlight the development of molecular markers supporting resistance breeding programs. We further integrate findings from transcriptomic, proteomic, metabolomic, and microRNA (miRNA) studies to elucidate the multilayered defense responses of pepper to Xanthomonas infection. Collectively, these multi-omics approaches indicate that effective resistance is governed by coordinated regulation of defense signaling pathways (e.g., salicylic acid, jasmonic acid, and ethylene), activation of resistance genes (including Bs2, Bs3, and related loci such as bs5 and bs6) and defense-associated transcription factors (e.g., WRKY), differential accumulation of defense-related proteins involved in stress responses, and metabolic reprogramming involving secondary metabolites. Finally, we outline key knowledge gaps and future priorities for developing durable and broad-spectrum resistance to BLS in pepper.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149017720","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":"Proposal for a new standard area diagram to quantify the severity of orange rust in sugarcane.","authors":"Maria Roselane Alves Oliveira, Humberson Rocha Silva, Willams José Oliveira, Djalma Euzébio Simões Neto, Adriano Francis Dorigan, Felipe Dalla Lana, André Angelo Medeiros Gomes","doi":"10.1094/PDIS-08-26-1550-SR","DOIUrl":"https://doi.org/10.1094/PDIS-08-26-1550-SR","url":null,"abstract":"<p><p>Orange rust (Puccinia kuehnii), a fungal disease of major concern in the sugarcane industry, can reduce the productivity of susceptible sugarcane varieties by up to 50% in many sugarcane-producing countries. The use of a standard area diagram (SAD) enhances the assessment of rust severity, improving the accuracy and consistency of disease quantification by evaluators. The present study aimed to develop and validate a new SAD for assessing the severity of orange rust in sugarcane. The SAD was constructed from symptomatic leaves collected in the field, with severity levels of 0, 1.5, 3.8, 7.3, 12.9, 20.7, 31.5, 44.4, and 63.2%. Validation was conducted with 30 evaluators with no prior experience, divided into two groups of 15. Disease severity was estimated from 100 leaf images, initially without the use of a SAD and subsequently with the aid of a SAD. One group used the proposed SAD, while the other used an old SAD for orange rust assessment. The proposed SAD reduced inter-evaluator variability, showed lower systematic bias, and had narrower limits of agreement, although Lin's concordance correlation coefficient (CCC, ρc) remained low, suggesting that factors beyond the SAD itself - such as the intrinsic complexity of orange rust symptoms and evaluator-related factors - may influence visual assessment accuracy. Analysis of bias parameters showed significant reductions in location (u) and scale (v) biases, indicating higher reproducibility and accuracy of the proposed SAD.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149017691","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>Bacillus velezensis</i> JB23 suppresses pokkah boeng and other fungal diseases of sugarcane.","authors":"Kaiyuan Pan, Xiaoni Yan, Shuang Wang, Hongtao Jiang, Charles Arthur Powell, Yixue Bao, Ronghui Wen, Muqing Zhang","doi":"10.1094/PDIS-05-26-1024-RE","DOIUrl":"https://doi.org/10.1094/PDIS-05-26-1024-RE","url":null,"abstract":"<p><p>Pokkah boeng and other fungal diseases reduce sugarcane yield and stalk quality in many production regions. In this study, 190 bacterial isolates were obtained from sugarcane tissues and rhizosphere soil and screened for antagonistic activity against Fusarium sacchari. Strain JB23 showed strong inhibition against multiple sugarcane fungal pathogens and was identified as Bacillus velezensis based on colony morphology and multilocus sequence analysis. JB23 suppressed mycelial growth of Fusarium commune, Colletotrichum falcatum, Sporisorium scitamineum, and several additional fungal pathogens. Hyphae exposed to JB23 showed swelling, distortion, irregular branching, and collapse. Under greenhouse conditions, pretreatment with JB23 reduced pokkah boeng disease incidence from 80.33% to 19.45% and reduced disease index from 31.25 to 6.24. Similar reductions were observed under field conditions. JB23 treatment also increased antioxidant enzyme activities, reduced H₂O₂ and malondialdehyde accumulation, and altered phenylpropanoid- and PR-related defense responses, as indicated by PAL activity, ScPR1 expression, and lignin accumulation, while also increasing emergence rate, biomass accumulation, and SPAD values. Collectively, the results demonstrate that B. velezensis JB23 suppresses multiple fungal pathogens associated with sugarcane and reduces pokkah boeng severity under greenhouse and field conditions.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149017652","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":"Dual-target RPA-LFD/RF-RPA combined detection system: A rapid method for detecting the pathogens causing cowpea wilt disease.","authors":"Wanzhen Feng, Danlu Hong, Guo Liang Liao, Lina Yang, Chengdong Yang, Qinghe Chen","doi":"10.1094/PDIS-03-26-0580-RE","DOIUrl":"https://doi.org/10.1094/PDIS-03-26-0580-RE","url":null,"abstract":"<p><p>Cowpea wilt disease, caused by the combined infection of Fusarium oxysporum and Phytophthora vignae, poses a persistent threat to crop yields and food security, driving the need for a dual-target detection method for early warning and informed crop management. This study developed a new method that can simultaneously detect two target pathogens, using multiplex recombinase polymerase amplification (RPA), followed by detection via lateral flow dipsticks (LFD) and real-time fluorescence (RF). The optimized system detects pathogens at 10 pg/mL within 20 minutes, with results visible via test strips or ultraviolet (UV) light. The system demonstrated a 100-fold increase in sensitivity over conventional PCR and reduced the detection time by 40 minutes. Field sample testing confirmed 100% specificity. This dual-target detection method presents a robust field-deployable solution, enabling rapid, sensitive, and equipment-free on-site diagnosis of cowpea wilt disease, which is critical for early prevention and boasts significant potential for practical application.</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":"148990776","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":"Genetic diversity and divergence of global and French populations of <i>Septoria steviae</i>, the causative agent of Septoria leaf spot in <i>Stevia rebaudiana</i>.","authors":"Charles Bastide, Patrick Cosson, Jonathan Gaudin, Carlos Jorge Budeguer, Zoe Le Bihan, Corinne Romiti-Michel, Cecile Hastoy, Dominique Rolin, Luis Ernesto Erazzu, Valerie Schurdi-Levraud","doi":"10.1094/PDIS-02-25-0279-SR","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0279-SR","url":null,"abstract":"<p><p>This study investigates the genetic diversity of worldwide Septoria steviae, the causal agent of Septoria leaf spot on Stevia rebaudiana, focusing on French and Argentine populations. Multi-Locus Sequence Typing (MLST) of five loci (ITS, LSU, CAL, EF1 and ACT) was used to compare the diversity of 14 French and 14 Argentinean new isolates with previously published data from other regions. Phylogenetic analyses based on ITS and LSU loci from 61 isolates from 6 countries confirmed that Paraguayan isolates form a genetically distinct group compared to other populations, highlighting the importance of geographic isolation. A more detailed analysis using five loci in 59 isolates from five countries (France, Argentina, the USA, Paraguay, and Japan) showed significant genetic differentiation between Japanese isolates and those from other countries, with French and Argentine isolates being closely related, suggesting common ancestry or gene flow. Local genetic variation among French isolates was also examined, showing minimal differentiation between nearby sites, but with slight evolutionary divergence observed over time. This suggests a slow rate of genetic evolution in French populations, likely due to shared environmental factors and agricultural practices. The results highlight the role of geographic factors in shaping the genetic structure of Septoria steviae populations, and the importance of continued monitoring of genetic diversity to inform management strategies and breeding programs for disease resistance in Stevia rebaudiana.</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":"148990795","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":"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}