Plant disease最新文献

{"title":"Endophytic <i>Pseudomonas</i> isolates elicit genotype-dependent resistance-, tolerance-, and susceptibility-associated responses in the wheat-flag smut pathosystem.","authors":"Aili Tao, Camilo Ayra-Pardo, Tan Wang, FaHu Pang, Siliang Huang","doi":"10.1094/PDIS-04-26-0820-RE","DOIUrl":"https://doi.org/10.1094/PDIS-04-26-0820-RE","url":null,"abstract":"<p><p>Flag smut (FS), caused by Urocystis tritici, remains difficult to manage, and little is known about how endophytic bacteria influence the balance between resistance and tolerance across diverse wheat genotypes. Although endophytic bacteria are increasingly explored as sustainable disease-management tools, their effects on FS outcomes and grain yield remain poorly understood. Here, we evaluated two endophytic Pseudomonas sp. strains (8-2 and 58-1-1), originally isolated from healthy winter wheat plants, for their capacity to modify FS incidence and grain yield across 14 winter wheat varieties spanning a wide range of intrinsic resistance. Seed inoculation enhanced aboveground growth in the tested variety, but disease incidence and grain yield responses varied markedly among genotypes. In most varieties, bacterial inoculation reduced FS incidence and increased grain yield, consistent with resistance-associated outcomes. In contrast, several host-strain combinations exhibited unchanged or increased disease incidence while maintaining or improving yield, indicating tolerance-associated responses. A smaller subset showed increased disease incidence accompanied by yield loss, revealing genotype-specific susceptibility outcomes. Together, these results demonstrate that the two Pseudomonas sp. strains do not uniformly suppress FS but instead differentially shape host responses to infection in a host genotype-dependent manner, giving rise to distinct resistance-, tolerance-, and susceptibility-associated phenotypes. Recognizing these distinct response phenotypes is essential for evaluating endophytic bacteria as agents of FS management.</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":"149025606","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":"Occurrence and sequence diversity of apple hammerhead viroid in major apple-producing regions of northern China.","authors":"Kaijie Li, Xudong Fan, Fang Ren, Yuxin Hao, Guojun Hu, Yafeng Dong","doi":"10.1094/PDIS-05-26-0986-RE","DOIUrl":"https://doi.org/10.1094/PDIS-05-26-0986-RE","url":null,"abstract":"<p><p>Apple hammerhead viroid (AHVd) is an emerging pathogen with a global distribution in apple-growing regions. To clarify its occurrence and distribution in northern China, long non-coding RNA (lncRNA) sequencing combined with RT-PCR was employed to screen 502 apple samples from commercial orchards in Hebei, Liaoning, Inner Mongolia, Shandong, and Shaanxi. AHVd was detected in 34.7% of samples, with infection rates ranging from 25.6% to 37.5% across the five provinces. Notably, 93.7% of AHVd-positive samples were co-infected with multiple viruses, with one extreme case harboring ten distinct pathogens. Quantitative RT-PCR revealed that AHVd accumulation was significantly higher in branch phloem than in leaves or fruit peels. Phylogenetic analysis demonstrated that Chinese AHVd isolates formed a distinct monophyletic group (Group II), although varieties clustered with Italian, Canadian, and German lineages. Sequence analysis identified nucleotide variations exclusively localized within stem-loop I, including a 5-nt deletion and a 10-nt insertion, without disrupting the conserved rod-shaped and highly branched secondary structure. These findings elucidate the epidemiology, genetic diversity, and tissue-specific distribution of AHVd in northern China, providing a foundation for improved diagnostic protocols and management strategies.</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":"149025605","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":"Effects of Climate and Cropping Systems on Perithecial Production by <i>Fusarium asiaticum</i> and <i>F. graminearum</i> sensu stricto.","authors":"Yan Yan Ru, Shuna Xie, Jing Sun, Bao Ye Li, Xin Tao Wang, Bing Li, Hao Zhang, Jun Jie Hao","doi":"10.1094/PDIS-04-26-0688-RE","DOIUrl":"https://doi.org/10.1094/PDIS-04-26-0688-RE","url":null,"abstract":"<p><p>The two dominant Fusarium head blight (FHB) pathogens in China (3-acetyl-deoxynivalenol chemotype of <i>Fusarium asiaticum</i> [<i>F. asiaticum</i> 3ADON] and 15-acetyl-deoxynivalenol chemotype of <i>F. graminearum</i> sensu stricto [<i>F. graminearum</i> 15ADON]) display distinct geographic distributions with different cropping systems. The effects of climate and cropping systems on perithecial production by these two pathogens were examined at four sites annually over three years (five locations in total). Within each year, perithecial production by <i>F. asiaticum</i> 3ADON and <i>F. graminearum</i> 15ADON on inoculated stalks (rice and maize in 2017; maize only in 2020 and 2023) decreased from south (Yancheng in 2017; Xinyang in 2020 and 2023) to north (Zhumadian, Xuchang, and Xinxiang in all three years), with significant differences among sites (P < 0.01). Production on maize stalks was higher than on rice stalks at the same site in 2017, the only year when both stalk types were evaluated. On maize stalks, no significant differences were observed in 2017 or 2023 (P > 0.05), whereas in 2020 production was markedly lower, and differed significantly between species (P < 0.01). Correlation and stepwise regression analyses identified average daily temperature from stalk placement to investigation (TEM) and average daily relative humidity in mid-March (RH3m) as the key factors affecting perithecial production on inoculated maize stalks. Pathogen composition on naturally diseased wheat spikes and crop residues revealed that <i>F. asiaticum</i> 3ADON dominated (≥83.3%) in wheat-rice rotation fields south of the Huai River, whereas <i>F. graminearum</i> 15ADON was prevalent (≥71.4%) in wheat-maize rotation fields north of the Huai River. Inoculated stalks displayed no consistent differences in perithecial production between the two species. This is inconsistent with their natural distribution patterns. Therefore, under equivalent initial colonization levels, temperature, relative humidity, and precipitation from mid-January (stalk placement) to mid-April (wheat flowering) do not drive the geographic distributions of <i>F. asiaticum</i> 3ADON and <i>F. graminearum</i> 15ADON by influencing perithecial production on crop residues.</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":"149025648","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":"Effect of nucleic acid extraction methodology and PCR chemistry on the detection of '<i>Candidatus</i> Phytoplasma pruni' in sweet cherry.","authors":"Sarah Cowell, Scott Harper","doi":"10.1094/PDIS-05-26-0875-SC","DOIUrl":"https://doi.org/10.1094/PDIS-05-26-0875-SC","url":null,"abstract":"<p><p>Early and accurate detection of 'Candidatus Phytoplasma pruni' is essential for the control of X-disease in Prunus species, but this is made difficult by pathogen biology and the ability to consistently recover nucleic acids, both of which increase the likelihood of false negatives. Here we examined the latter, using high- and low-titer infected sweet cherry (P. avium) samples to compare three tissue disruption methods, four nucleic acid extraction chemistries, and four PCR chemistries. Results showed that method selection had minimal impact on high-titer samples but significantly affected low-titer detection. Bead-beating disruption consistently outperformed rotary and manual grinding, yielding lower Cq values and more reliable amplification. Among extraction methods, CTAB-based protocols provided the highest nucleic acid recovery and detection sensitivity, particularly when paired with bead beating. Column- and magnetic bead-based kits performed less consistently, especially with low-titer samples, where false negatives were frequent. PCR chemistry also influenced results, although RT-qPCR did not significantly improve sensitivity over qPCR. Importantly, commonly used host internal controls failed to reliably indicate pathogen detection success, as high-abundance targets masked poor extraction efficiency. Cumulatively these data suggest the need for optimizing diagnostic protocols to ensure capture of low-concentration pathogens to avoid false negatives.</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":"149025410","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 dissection of seedling resistance to septoria nodorum blotch resistance in a nested association mapping panel derived from synthetic hexaploid wheat lines and bread wheat.","authors":"Anil Karmacharya, Dhondup Lhamo, Han-Chang Chang, Jason Fiedler, Timothy L Friesen, Justin D Faris, Shengming Yang, Yong Q Gu, Steven S Xu, Zhaohui Liu, Xiaofei Zhang","doi":"10.1094/PDIS-01-26-0156-RE","DOIUrl":"https://doi.org/10.1094/PDIS-01-26-0156-RE","url":null,"abstract":"<p><p>Septoria nodorum blotch (SNB), caused by the necrotrophic fungal pathogen Parastagonospora nodorum, is a major foliar disease of wheat (Triticum aestivum) that significantly reduces grain yield and quality. In this study, we evaluated a modified nested association mapping (NAM) population for SNB resistance. This population consisted of 276 BC1F8 progenies derived from crosses between four synthetic hexaploid wheat (SHW) and ten hard red spring wheat (HRSW) varieties/lines. We screened the population using two P. nodorum isolates (Sn4 and Sn2000) and three necrotrophic effectors (SnToxA, SnTox1, and SnTox3). Genome-wide association studies using the 90K SNP markers identified 32 significant marker-trait associations (MTAs) across nine chromosomes, including nine markers associated with isolate responses and 23 with effector sensitivity. While several markers co-localized with known genes such as Tsn1 (5BL), Snn2 (2DS), Snn3 (5BS), and Snn7 (2DL), we also identified novel loci that expand our understanding of SNB resistance. Of the nine isolate-associated MTAs, the resistance alleles were contributed by different parents: four came from SHW, one from HRSW, and four from both parental types. Nine progeny lines exhibited resistance to both isolates and insensitivity to all tested effectors, indicating broad-spectrum and effective resistance. The SHW lines SW91 and SW93, as well as HRSW cultivars 'Bolles' and 'Linkert', and their progenies consistently showed increased resistance compared to other backgrounds. These lines, carrying novel SNB resistance loci derived from cultivated emmer and Aegilops tauschii, provide valuable germplasm for improving SNB resistance in wheat breeding programs.</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":"149025653","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":"Physiological and transcriptomic analyses reveal the antifungal activity of <i>Simplicillium lanosoniveum</i> filtrate against wheat crown rot pathogen <i>Fusarium pseudograminearum</i>.","authors":"Zhenjie Hu, Yihao Cai, Rongrong Zhai, Youfei Zhao, Yawei Fan, Bo Min, Chenhao Sun, Xingli Zhao","doi":"10.1094/PDIS-04-26-0829-RE","DOIUrl":"https://doi.org/10.1094/PDIS-04-26-0829-RE","url":null,"abstract":"<p><p>Fusarium pseudograminearum (Fp), the predominant phytopathogen responsible for wheat crown rot, severely impairs wheat growth and yield, posing a persistent threat to global wheat production. This study evaluated the biocontrol potential of the fermentation filtrate from the endophytic fungus Simplicillium lanosoniveum FSL-376 against Fp. In vitro, the filtrate exhibited potent antifungal activity, significantly inhibiting mycelial growth, and causing severe morphological abnormalities in both hyphae and spores at low concentrations. Mechanistic investigations revealed that the antifungal action was achieved by disrupting fungal cell membrane integrity [evidenced by increased electrolyte conductivity and malondialdehyde (MDA) accumulation], triggering intense oxidative stress via suppressing the activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and disrupting energy metabolism through the inhibition of hexokinase (HK) and succinate dehydrogenase (SDH) activities. Transcriptomic analysis further revealed multi-target inhibition, characterized by the downregulation of genes involved in transmembrane transport, antioxidant defense, and oxidative phosphorylation. In pot experiments, seed treatment with the FSL-376 filtrate significantly alleviated Fp-induced growth inhibition, restored antioxidant enzyme activities and chlorophyll content in wheat seedlings, and improved root morphology. Notably, the FSL-376 filtrate exhibited no phytotoxicity to wheat seedlings and showed no growth-promoting effect under pathogen-free conditions, indicating its biosafety and pathogen-specific biocontrol efficacy. This study demonstrates that S. lanosoniveum FSL-376 serves as a promising and reliable biocontrol resource for wheat crown rot management, which functions via dual mechanisms of direct antifungal inhibition and enhancement of host plant stress tolerance.</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":"149025735","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":"Detection of SdhB mutations in <i>Botrytis cinerea</i> isolates from strawberry using a High-Resolution Melting (HRM) assay.","authors":"Adrian Israel Zuniga, Nan-Yi Wang, Carolina Suguinoshita Rebello, Mayara Bolognesi, Bruna Balen Forcelini, Natalia A Peres","doi":"10.1094/PDIS-03-26-0492-RE","DOIUrl":"https://doi.org/10.1094/PDIS-03-26-0492-RE","url":null,"abstract":"<p><p><i>Botrytis cinerea</i>, the causal agent of Botrytis fruit rot (BFR), is one of the most destructive pathogens of strawberry. In Florida, BFR management relies heavily on succinate dehydrogenase inhibitor (SDHI) fungicides; however, resistance associated with mutations in the SdhB subunit has increasingly been reported. This study developed and validated a high-resolution melting (HRM) assay for rapid detection of SdhB mutations directly from <i>B. cinerea</i> spores, and evaluated resistance frequencies to fluopyram, isofetamid, and pydiflumetofen across Florida strawberry fields. Two HRM primer sets successfully differentiated SdhB mutations H272R or Y, N230I, and P225F based on distinct melting profiles. The assay detected mutations from spore concentrations as low as 10⁵ spores/ml, without requiring DNA extraction or post-PCR processing. Sanger sequencing subsequently confirmed complete agreement with HRM genotyping results. Among 133 field isolates collected from 2017 to 2022, N230I and P225F were the most frequent mutations, correlating with moderate to high resistance to fluopyram and isofetamid. Resistance monitoring of 1,496 isolates over eight strawberry seasons revealed increasing resistance to fluopyram (44.9-99%) and isofetamid (≤57%), whereas pydiflumetofen resistance remained below 15%. Sequencing of SdhC and SdhD subunits revealed minimal variability and no new target-site mutations. Detached fruit assays confirmed reduced efficacy of isofetamid against isolates harboring N230I. The HRM assay developed here provides a rapid, accurate, and cost-effective tool for detecting and monitoring SDHI resistance in <i>B. cinerea</i> populations in strawberry production systems.</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":"149025384","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":"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}