Plant disease最新文献

{"title":"Quantifying <i>Clarireedia</i> spp. in creeping bentgrass reveals pathogen concentration increases at a slower rate in tolerant cultivars.","authors":"Glen Groben, Bruce B Clarke, James A Murphy, Patrick Purdon, Ning Zhang","doi":"10.1094/PDIS-02-25-0348-RE","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0348-RE","url":null,"abstract":"<p><p>Dollar spot, caused by fungi in the Clarireedia genus, is among the most economically important turfgrass diseases. One strategy for controlling dollar spot is the use of tolerant cultivars which typically take longer to develop symptoms and have smaller lesion centers compared to more susceptible cultivars. We previously developed a qPCR assay that can quantify the Clarireedia concentration in asymptomatic and symptomatic turfgrass. The goal of this three-year study was to quantify the concentration of Clarireedia in a tolerant and susceptible cultivar of creeping bentgrass (Agrostis stolonifera) throughout the growing season to determine the effect host tolerance has on dollar spot development in the field. Turfgrass samples were collected weekly in 2019, 2020, and 2021 starting the first week of May and ending the second week of August for a duration of 15 weeks each year. The qPCR assay identified significant differences in Clarireedia concentration between the cultivars in both asymptomatic and symptomatic tissue. Linear model analysis showed the tolerant cultivar 'Declaration' always had a lower Clarireedia concentration compared to the susceptible cultivar 'Independence'. This supported our inhibition hypothesis that, although the concentration of Clarireedia required to cause symptoms was similar for both cultivars, the pathogen increased at a slower rate and therefore took longer to develop in a tolerant cultivar. The ability of the qPCR assay to quantify the concentration of Clarireedia in both asymptomatic and symptomatic tissue in the field during the growing season provides a tool for more in-depth epidemiological studies of dollar spot disease in turfgrass.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145207311","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":"Recombinase-aided amplification combined with lateral flow dipstick for the rapid detection of <i>Pyrrhoderma noxium</i>.","authors":"Haiyue Yin, Haoyu Wu, Dianguang Xiong, Huayi Huang, Danyang Zhao, Chengming Tian","doi":"10.1094/PDIS-11-24-2521-SR","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2521-SR","url":null,"abstract":"<p><p>Pyrrhoderma noxium is an entry quarantine tree pathogenic fungus in China which causes severe root rot and the death of many tree species, resulting in huge landscape, ecological and economic losses. P. noxium is a soil-borne plant pathogen, which makes it difficult to observe the symptoms of infected trees in the early stage. In this study, a rapid, specific, and visible detection method for P. noxium was established by integrating recombinase-aided amplification (RAA) with a lateral flow dipstick (LFD), called RAA-LFD. Firstly, we screened out a specific gene of P. noxium, PnEf1, as the target for RAA amplification by using the bioinformatic analysis. Then, a pair of specific RAA primers and a probe with high-efficiency were designed. Finally, the RAA amplification results were visualized with the LFD. The RAA-LFD detection system of P. noxium was performed at 37°C (body temperature) and did not rely on precise instruments. Remarkably, the detection limit of this system was 100 fg/μL and 5.5 copies with P. noxium gDNA as the template, which was significantly superior to the reported methods. Importantly, the examination results could be visualized in about 20 mins with the naked eye, which indicated a promising application in the field detection of P. noxium. In conclusion, the established RAA-LFD detection system of P. noxium was rapid, highly sensitive and specific, easily observed and simply operated, which provides a strong technical support for the early warning and detection of P. noxium in the field.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145200715","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":"Control of major plum postharvest diseases by apple thinning by-product extracts.","authors":"Ricardo Lima de Souza, María B Pérez-Gago, Almudena Bermejo, Davide Spadaro, Lluís Palou","doi":"10.1094/PDIS-07-25-1589-RE","DOIUrl":"https://doi.org/10.1094/PDIS-07-25-1589-RE","url":null,"abstract":"<p><p>Fresh Japanese plums are highly perishable and susceptible to postharvest diseases caused by fungal pathogens. Current management strategies rely on synthetic fungicides, raising concerns about resistance and sustainability. Immature-thinned apples (ITA), an underutilized agricultural by-product, are rich in polyphenols with potential antifungal properties. This study evaluated the potential of ITA ultrasound-assisted extracts of the cultivars 'Gala', 'Golden Delicious', and 'Opal' for controlling plum postharvest diseases. Extracts were chemically characterized for total polyphenol content and total antioxidant activity, with chlorogenic acid (CGA) and phloridzin (PH) identified as major compounds, especially in 'Gala' extracts. In in vitro tests, all three extracts inhibited the radial growth of <i>Botrytis cinerea</i> and <i>Monilinia fructicola</i> by more than 90%, but none of them reduced the growth of <i>Rhizopus stolonifer</i>, <i>Penicillium expansum</i>, and <i>Geotrichum candidum</i> by more than 80%. In in vivo trials with plums artificially inoculated, treated 2 or 24 h later, and stored either at 20 ºC for 6 days or at 1 ºC and 90% RH for 4 weeks, all three extracts reduced the incidence of gray mold and brown rot by up to 90 and 85%, respectively. These reductions on cold-stored plums were up to 87 and 71% after a shelf-life period of 4 days at 20 ºC, with no significant differences between apple cultivars. This high curative activity highlights the potential of ITA extracts as sustainable, natural bio-based alternatives to synthetic chemical fungicides for stone fruit postharvest decay control, while aligning with circular bioeconomy principles through the valorization of agricultural waste.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145200759","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":"Mancozeb, copper, sulfur, phosphite, and <i>Bacillus subtilis</i> enhance the efficacy of DMI fungicides for managing Cercospora leaf spot of sugar beet.","authors":"Austin Kyle Lien, Ashok Kumar Chanda","doi":"10.1094/PDIS-06-25-1192-RE","DOIUrl":"https://doi.org/10.1094/PDIS-06-25-1192-RE","url":null,"abstract":"<p><p>Cercospora leaf spot (CLS), caused by <i>Cercospora beticola</i> Sacc., remains a major foliar disease of sugar beet (<i>Beta vulgaris</i> subsp. <i>vulgaris</i> L.) worldwide. Increasing prevalence of resistance to demethylation inhibitor (DMI) fungicides also constrain effective management practices. The efficacy of commercially available DMI fungicides (prothioconazole, tetraconazole, difenoconazole plus propiconazole, and mefentrifluconazole) was evaluated when tank-mixed with broad-spectrum partners including mancozeb, copper, sulfur, potassium phosphite, sodium bicarbonate, and <i>Bacillus subtilis</i>. Field trials were conducted in 2020 and 2021 in Northwest Minnesota. All DMI fungicides suppressed CLS relative to the nontreated control, and mixtures with select partners significantly enhanced disease control and sucrose yield. Notably, mancozeb and copper consistently improved outcomes when combined across multiple DMIs, while sulfur, phosphite, and <i>B. subtilis</i> exhibited improved outcomes in specific pairings. Fungicide efficacy varied by combination, emphasizing the importance of tank mix partner selection. These findings demonstrate that strategic tank mixes can enhance CLS disease suppression and improve sucrose yield outcomes in sugar beet.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145200710","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":"Development of a Triplex Quantitative PCR System for the Detection of <i>Parastagonospora nodorum</i>, <i>Zymoseptoria tritici</i>, and <i>Pyrenophora tritici-repentis</i> from Wheat.","authors":"Heting Fu, Junye Jiang, Michael Wayne Harding, Kher Zahr, Yalong Yang, Shiming Xue, Ronald Nyandoro, Maria Antonia Henriquez, Lipu Wang, David Feindel, Jie Feng","doi":"10.1094/PDIS-01-25-0003-SR","DOIUrl":"10.1094/PDIS-01-25-0003-SR","url":null,"abstract":"<p><p>A triplex quantitative PCR (qPCR) system was developed for the simultaneous detection of the three most prevalent wheat leaf spot diseases: Septoria nodorum blotch caused by <i>Parastagonospora nodorum</i>, Septoria tritici blotch caused by <i>Zymoseptoria tritici</i>, and tan spot caused by <i>Pyrenophora tritici-repentis</i>. In this system, the primer set for <i>P. tritici-repentis</i> targets a species-specific multicopy genomic region, whereas the primer sets for the other two pathogens target the ribosomal DNA (rDNA) region. The specificity of the system was validated through sequence analysis using the currently available database and by testing against 24 DNA samples from nontarget species. Sensitivity testing on serial DNA dilutions from the three target species demonstrated that the system can detect as little as 2 fg of DNA of each species in a 20-μl reaction. For <i>P. nodorum</i>, the system was capable of detecting DNA extracted from a conidia suspension containing as few as 100 conidia. The system was further evaluated on 145 wheat leaf samples (45 symptomatic and 100 asymptomatic) collected from various fields in Alberta, Canada. At least one of the three pathogens was detected in 112 out of the 145 samples, with <i>P. nodorum</i> and/or <i>P. tritici-repentis</i> identified in 74 of the 100 asymptomatic samples. This triplex qPCR system offers a powerful tool for the diagnosis of wheat leaf spot diseases, surveillance, breeding for disease resistance, and research in epidemiology, population genetics, and host-pathogen interactions.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS01250003SR"},"PeriodicalIF":4.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143639765","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":"Potential for Elite Veneer Poplar on Marginal <i>Phytophthora</i> spp.-Infected Christmas Tree Lands.","authors":"William Henry Kohlway, Caleb Phillip Cothron, Solomon Ghezehei, Angela Chiang, Elizabeth Guthrie Nichols, Justin Whitehill","doi":"10.1094/PDIS-07-24-1558-RE","DOIUrl":"10.1094/PDIS-07-24-1558-RE","url":null,"abstract":"<p><p>The cultivation of Fraser fir (<i>Abies fraseri</i>) Christmas trees in the southern Appalachian Mountains of western North Carolina (WNC) is threatened by the proliferation of Phytophthora root rot (PRR) disease. PRR is primarily caused by the soilborne pathogen <i>Phytophthora cinnamomi</i>. Fraser fir is highly susceptible to <i>P. cinnamomi</i>, which threatens the long-term profitability of the Christmas tree bioeconomy. Therefore, alternative species that tolerate the PRR pathogen and contribute to the rural bioeconomy are needed. For instance, select poplar genotypes produce veneer-quality logs and offer a profitable alternative on infected soils no longer capable of Fraser fir production. However, the resistance, tolerance, or susceptibility of hybrid poplars (<i>Populus</i> spp.) to <i>P. cinnamomi</i> infection is currently unknown. We selected 18 elite veneer clonal <i>P. deltoides</i>, <i>P. trichocarpa</i>, and <i>P. maximowiczii</i> poplar genotypes for <i>P. cinnamomi</i> pathogenicity tests based on prior productivity trials at field sites in WNC. Inoculation of containerized poplar clones was carried out using <i>P. cinnamomi</i>-colonized rice grains. Metrics for poplar growth and physiological traits were collected weekly for 10 weeks after inoculations. Although both <i>P. cinnamomi</i>-inoculated and mock-inoculated poplars survived, <i>P. cinnamomi</i> inoculation significantly impacted the growth of pure <i>P. deltoides</i> crosses. Conversely, <i>P. trichocarpa × P. deltoides</i> hybrids exhibited a greater tolerance to <i>P. cinnamomi</i> inoculations, with no significant growth differences between treatments. These findings support the use of hybrid <i>P. trichocarpa × P. deltoides</i> for veneer production as a potential alternative for Christmas tree farmers impacted by the spread of <i>P. cinnamomi</i>.[Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS07241558RE"},"PeriodicalIF":4.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143649889","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>Pythium deliense</i> Causing Cottony Leak on Pickling Cucumber Fruit in South Carolina, USA.","authors":"Anthony P Keinath, Virginia DuBose, Phillip Carnley, Robert Last, Curt Colburn, Xiao Yang","doi":"10.1094/PDIS-04-25-0855-SR","DOIUrl":"https://doi.org/10.1094/PDIS-04-25-0855-SR","url":null,"abstract":"<p><p>Cottony leak, a soft rot on fruit of cucurbit crops, is a concern for pickling cucumber (Cucumis sativus cv. Gershwin) growers in South Carolina and other states. Fruit with typical symptoms and signs of cottony leak were sampled from five commercial fields in 2022 and 2023. Most isolates (28) recovered from symptomatic fruit were identified as Pythium deliense, and the remaining five isolates were P. aphanidermatum, based on sequences of the mitochondrially encoded cytochrome c oxidase subunit 1 gene. P. deliense also was recovered from stem lesions on two seedings. In pathogenicity tests, P. aphanidermatum was more virulent on pickling cucumber fruit of cv. Kirby, whereas P. deliense was more virulent on seedlings of cv. Gershwin. Recovery of Pythium spp. from symptomatic fruit was greater (P = 0.05) in fields cropped to peanut (Arachis hypogea) or soybean (Glycine max) (83.3 ± 7.6% of fruit), hosts of P. deliense, than to coastal Bermudagrass (Cynodon dactylon) (55.0 ± 11.7% of fruit), a nonhost, two years prior to planting cucumber. Planting crops that are nonhosts of P. deliense for two years before pickling cucumber may help to reduce the incidence of cottony leak. This is the first report of P. deliense as a causal agent of cottony leak on cucurbit fruit.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145200626","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":"Etiology and Epidemiology of Branch Dieback and Fruit Blight and Necrosis of English Walnut in France.","authors":"Marie Belair, Adeline Picot, Cyrielle Masson, Marie-Neige Hébrard, Marie Debled, Aude Moronvalle, Benjamin Richard, Sylvie Tréguer, Léa Morvant, Amandine Henri-Sanvoisin, Yohana Laloum, Gaétan Le Floch, Flora Pensec","doi":"10.1094/PDIS-07-25-1494-RE","DOIUrl":"https://doi.org/10.1094/PDIS-07-25-1494-RE","url":null,"abstract":"<p><p>English walnut (Juglans regia L.) is an economically important fruit crop worldwide and ranks second in France in terms of cultivated area, following apples. This study presents the first comprehensive investigation into the etiology and fungal community analysis associated with dieback symptoms in walnut trees in France, where this disease has been increasingly reported since 2015. Both symptomatic and asymptomatic twigs and husks were collected from 12 commercial walnut orchards located in the two primary production regions from 2020 to 2022. Several fungal species-among Botryosphaeriaceae, Colletotrichum, Diaporthe, and Fusarium taxa-were consistently isolated from symptomatic husks and twigs. Among these, Botryosphaeria dothidea and Colletotrichum godetiae were significantly associated with symptomatic husks, and Diaporthe eres and Fusarium juglandicola with symptomatic twigs, as confirmed by ITS2 metabarcoding sequencing. Additionally, Neofusicoccum and Diaporthe were significantly associated with warm and dry years, unlike Colletotrichum. Following pathogenicity assays on twigs and fruits, N. parvum emerged as the most aggressive species. These results suggest a complex interplay of factors influencing disease dynamics, further compounded by potential interactions among the main pathogenic species. Notably, in twigs, we found that the prevalence of D. eres was negatively correlated to that of N. parvum while the association between D. eres and F. juglandicola was the most frequent one, suggesting both competitive and facilitative interactions. This research underscores the importance of understanding the fungal pathobiome and its interactions in the development of walnut tree diseases.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145186604","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":"Identification and biological characteristics of <i>Colletotrichum</i> species causing persimmon anthracnose in China and screening of <i>Colletotrichum horii</i> antifungal agents.","authors":"Runyu Li, Luping Cui, Fan Jiang, Li Ziyan, Sadaruddin Chachar, Zhirui Fan, Xu Jidi, Changfei Guan","doi":"10.1094/PDIS-07-25-1564-RE","DOIUrl":"https://doi.org/10.1094/PDIS-07-25-1564-RE","url":null,"abstract":"<p><p>Persimmon anthracnose, caused by a diverse range of Colletotrichum species with genetic variations, poses a significant and widespread threat to persimmon cultivars. This study aimed to identify the causal agents via morphological characterization and multi-locus phylogenetic analysis, investigate their biological characteristics, and evaluate the efficacy of antifungal agents against the most virulent species. Six anthracnose isolates were identified: C. boninense, C. fioriniae, C. horii, C. gloeosporioides s.s, C. fructicola, and C. aenigma. All isolates were pathogenic to persimmon branches and leaves, with C. horii causing the largest leaf lesions and exhibiting strong pathogenicity on branches, resulting in severe infections on persimmon seedling leaves and branches. Beyond determining the pathogenicity of these Colletotrichum spp. on persimmons, this study also investigated the biological characteristics of the six anthracnose fungi, including optimal growth conditions for temperature, pH, light, and medium. The results showed that the optimal temperature for the growth of all six fungi was 25 °C, with no significant variation in the pH values ranging from four to ten. Light conditions significantly influenced sporulation: continuous darkness was most conducive to conidial formation and production, except for C. boninense. Mycelial growth of most species was insensitive to light, while C. boninense grew fastest under continuous light. In vitro screening of sixteen antifungal agents against C. horii revealed that Bacillus subtilis exhibited the strongest inhibitory activity against mycelial growth, followed by carbendazim, imidazole, thiophanate-methyl, pyraclostrobin, and difenoconazole. Field trials confirmed that imidazole, pyraclostrobin, and difenoconazole provided the most effective control of persimmon anthracnose. These findings provide a theoretical basis for understanding the epidemiology and developing management strategies for persimmon anthracnose.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145150352","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":"Characterization of fungicide resistance in <i>Plasmopara viticola</i> isolates from Maryland and Pennsylvania vineyards.","authors":"Shannon Rotella, Jessica Clippinger, Bryan Hed, Michael Campbell, Mengjun Hu","doi":"10.1094/PDIS-11-24-2499-RE","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2499-RE","url":null,"abstract":"<p><p>Plasmopara viticola, the causal organism of grapevine downy mildew, poses a significant threat to Eastern US grape production. In this study, we determined fungicide resistance profiles of vineyards across Maryland and Pennsylvania between 2019 and 2023. A total of 352 downy mildew samples were collected from 27 vineyards and 32 different cultivars and tested for resistance to various fungicides commonly used for downy mildew management at field application rates using whole leaf bioassays. DNA was also extracted and used to confirm known resistance mechanisms to azoxystrobin (G143A) and mandipropamid (G1105S) using Sanger sequencing and PCR-RFLP. Resistance to azoxystrobin, mandipropamid, and phosphorous acids was found throughout all regions tested, with bioassays resulting in 69%, 39%, and 33% of isolates displaying resistance to respective chemicals. In addition, all isolates subsampled and sequenced displayed the G143A mutation regardless of resistance phenotype, indicating bioassays could underestimate the frequency of resistance. Of the 52 isolates tested using PCR-RFLP to confirm the presence of the G1105S mutation, 46 displayed genotypes consistent with their observed phenotypes. This is the first report of resistance to phosphorous acid in North America, which was found to be widespread throughout regions tested and detected as early as 2020. Multi-chemical class resistance was also commonly detected, with 20% of isolates displaying resistance to all three chemicals simultaneously. This study highlights the escalating threat posed by P. viticola to grape production in the Northeast, as rising populations resistant to multiple chemical classes considerably diminish the fungicide options available to growers.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145150393","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}