Plant disease最新文献

{"title":"First report of <i>Clavibacter nebraskensis</i>, causing Goss's bacterial leaf blight on maize (<i>Zea mays</i> L.) in South Africa.","authors":"Sonja Coertze, Beatrix Coetzee, Elaine Basson, Dore de Villiers, Tjitjila Makhura, Diane Mostert, Bernard Slippers, Lindy Rose, Cobus M Visagie, David Read","doi":"10.1094/PDIS-01-25-0164-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-01-25-0164-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Maize is a staple crop in South Africa and an important income source to both smallholder and commercial farmers (Gravelet-Blondin, 2015). Goss's bacterial leaf blight and wilt, caused by Clavibacter nebraskensis (Cn), is a significant maize disease in North America and a quarantine concern in unaffected regions, with seedborne transmission posing a risk of introduction (EPPO, 2024; Osdaghi et al. 2023). From February to April 2024, bacterial leaf blight symptoms, typical of Cn infection, were observed on maize (Zea mays L.) in the North-West, Mpumalanga and Gauteng provinces of South Africa. Lesions were tan, irregular, parallel to veins, with a shellac-like appearance and black water-soaked edges, showing characteristic \"luminous freckles\" when backlit. Symptomatic leaf samples were collected from 6 commercial maize fields. Eight samples from Carletonville and Potchefstroom (total of two fields) were evaluated at the Forestry and Agricultural Biotechnology Institute (FABI) at the University of Pretoria, and another four samples from Delmas, Leslie, and Bapsfontein (total of four fields) were evaluated at Stellenbosch University's Plant Disease Clinic. DNA was extracted either directly from lesions or from cultures isolated from lesions. For direct DNA extraction, cetyltrimethylammonium bromide was used, followed by a Cn specific PCR with primer pair 1184F/R (McNally et al. 2016). Macerates from lesion edges were streaked out onto nutrient broth yeast (NBY) agar. DNA from a single culture, with yellow-orange mucoid colonies, was extracted with a Zymo Quick-DNA Fungal/Bacterial Miniprep Kit (Zymo Research, Irvine, CA, USA), and confirmed as Cn with previously mentioned PCR primers. Simultaneously, macerates from the lesion edges were streaked onto yeast dextrose chalk agar (YDC). Yellow-orange mucoid colonies developed after four day and were purified onto NBY and incubated at 25°C for 4 days. All isolates tested gram-positive, were coryneform, aerobic, and non-spore forming. Genomic DNA was extracted and the suspension amplified using the 27F/1492R primer pair (Lane, 1991), targeting the 16S rRNA gene. The product was sequenced and confirmed as Cn. Cultures are stored in the culture collections at Stellenbosch University Plant Pathology Department (STE-U) and at FABI (CMW and CMW-IA). At both facilities, cell suspensions at a final concentration of 107 cells/mL were used to inoculate the third leaf of V3 / V4 stage maize plants (P1513, Syngenta), by wounding the middle of the main leaf vein and applying a 25µL droplet. Typical Cn symptoms appeared 4 days post inoculation and Cn was reisolated from these lesions and confirmed with PCR to complete Koch's postulates. Four isolates were selected for high-throughput sequencing (NCBI Bioproject: PRJNA1184689). Assembled genomes (NCBI accession: CP173672-CP173675) were analysed on the Type Strain Genome Server (Meier-Kolthoff and Göker, 2019) and confirmed as Cn based on 16S rRNA and Genome Blast","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143710890","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":"First Report of <i>Taraxacum kok-saghyz</i> Rodin Root Rot Caused by <i>Alternaria tenuissima</i> in Heilongjiang Province, China.","authors":"Guoen Ao, Qinqin Nie, Xiaoyu Chen, Juanying Wang, XuChu Wang","doi":"10.1094/PDIS-12-24-2759-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-12-24-2759-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;&lt;i&gt;Taraxacum kok-saghyz&lt;/i&gt; Rodin (TKS) is a perennial herb of the Asteraceae family, which is an important natural rubber supplement crop (Yang et al., 2023). In May 2023, a severe root rot disease was observed in TKS during cultivation in Harbin (45°75'N, 126°66'E), Heilongjiang Province, China. Field surveys indicated a disease incidence of approximately 10% within the 450 m&lt;sup&gt;2&lt;/sup&gt; cultivation area (500 TKS seedlings), with symptoms including leaf wilting, stunted growth, root necrosis, and plant mortality. To isolate its pathogen, nine symptomatic root segments (about 1 cm) were randomly sampled from three diseased plants and surface sterilized in 2% NaClO for 30 s, rinsed three times with sterile distilled water, and then incubated on potato dextrose agar (PDA) supplemented with 30 mg/L streptomycin at 28 °C in darkness for 3 days. Nine isolates with similar colony morphology were obtained from nine diseased root segments by mycelial tip separation. All isolates exhibited cottony colonies on the PDA medium, initially gray-white and then turned into dark gray, with the reverse side becoming black. On potato carrot agar medium, the conidia of these isolates are oval, brown in color, simple or form unbranched chains, and have 1-4 transverse septa and 0-2 longitudinal septa; they measured 10.23 to 30.57 μm in length and 5.48 to 9.96 μm in width (n = 50), exhibiting morphological characteristics consistent with members of the genus &lt;i&gt;Alternaria&lt;/i&gt; (Simmons et al., 2007). Three isolates (GURF-01, GURF-02, GURF-03) were randomly selected from different plants for further study. These isolates were molecularly characterized by amplifying the internal transcribed spacer (ITS), RNA polymerase II second largest subunit (&lt;i&gt;RPB2&lt;/i&gt;), translation elongation factor 1-α (&lt;i&gt;TEF&lt;/i&gt;), 18S small subunit rDNA (&lt;i&gt;SSU&lt;/i&gt;), 28S large subunit rDNA (&lt;i&gt;LSU&lt;/i&gt;), &lt;i&gt;Alternaria&lt;/i&gt; major allergen (&lt;i&gt;Alt-a1&lt;/i&gt;) and glyceraldehyde 3-phosphate dehydrogenase (&lt;i&gt;GAPDH&lt;/i&gt;) regions by ITS1/ITS4, fRPB2-5f/fRPB2-7cR, EF1-728F/EF1-986R, NS1/NS4, LR0R/LR5, Alt-for/Alt-rev and gpd1/gpd2 primers (Lawrence et al., 2013; Woudenberg et al., 2015; Li et al., 2023), respectively. BLASTn search revealed that ITS (PQ182566, PQ180345, PQ182567), &lt;i&gt;RPB2&lt;/i&gt; (PQ740537 to PQ740539), &lt;i&gt;TEF&lt;/i&gt; (PQ196801 to PQ196803), &lt;i&gt;SSU&lt;/i&gt; (PQ180346 to PQ180348), &lt;i&gt;LSU&lt;/i&gt; (PQ180349 to PQ180350), &lt;i&gt;Alt-a1&lt;/i&gt; (PQ196798 to PQ196800) and &lt;i&gt;GAPDH&lt;/i&gt; (PQ287275 to PQ287277) sequences of these isolates showed 99% to 100% identity with &lt;i&gt;A. tenuissima&lt;/i&gt; (ON514229, KC584435, KC584693, KC584567, KC584311, ON548915 and ON528099). A phylogenetic tree was constructed showing that GURF-01, GURF-02 and GURF-03 clustered with &lt;i&gt;A. tenuissima&lt;/i&gt;. The above three isolates were used for test pathogenicity in the 3-month-old TKS plants with three repeats. The test groups were inoculated with 50 mL spore suspension (10&lt;sup&gt;6&lt;/sup&gt; spores/mL) while distilled water was supplied for the control","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143710905","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":"First Report of '<i>Candidatus</i> Phytoplasma pruni'-Related Strain and '<i>Candidatus</i> Phytoplasma asteris'-Related Strain Associated with North American Grapevine Yellows of Cultivated Grapevines in Minnesota.","authors":"Sara Bratsch, Bo Min Kim, Michelle Grabowski, Stefano Costanzo","doi":"10.1094/PDIS-02-25-0232-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0232-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Surveys for exotic plant pests conducted during July and August of 2023 and 2024 across 20 vineyards in 12 counties throughout Minnesota, USA, revealed that less than 2% of the approximatively 3000 vines inspected (&lt;i&gt;Vitis&lt;/i&gt; spp., hybrid grape varieties) exhibited symptoms suggestive of phytoplasma yellows disease. Observed symptoms included yellowing of leaf lamina, downward rolling of leaf margins, and necrosis of leaf margins. To investigate a potential association between these symptoms and phytoplasmas, two symptomatic plants were selected in August of 2024 from two distinct vineyards for further analysis. Petiole tissue DNA extracts were initially tested using a phytoplasma-specific real-time PCR assay (Hodgetts et al. 2009), which confirmed the presence of phytoplasma DNA in both symptomatic plants. Subsequently, the samples underwent semi-nested PCR amplification targeting the phytoplasma 16S rRNA gene, using primers P1/16S-SR followed by P1A/16S-SR (Deng and Hiruki 1991; Lee et al. 2004). The resulting amplicons were cloned and sequenced. No amplicon was produced from an asymptomatic grapevine DNA sample included as a test control. Analysis of the 16S rRNA gene sequences revealed that each plant was infected by one of two distinct phytoplasma strains, designated MN450 and MN466. Representative sequences obtained from the two samples exhibiting interoperon heterogeneity were deposited in the GenBank database under accession numbers: PQ889195 (&lt;i&gt;rrnA&lt;/i&gt;) and PQ889196 (&lt;i&gt;rrnB&lt;/i&gt;) for strain MN450, and PQ889197 (&lt;i&gt;rrnA&lt;/i&gt;) and PQ889198 (&lt;i&gt;rrnB&lt;/i&gt;), for strain MN466. Sequence analysis using the online phytoplasma classification tool &lt;i&gt;i&lt;/i&gt;PhyClassifier (Zhao et al. 2009) showed that the 16S rRNA gene sequences from MN450 shared 1491/1495 bp (99.73%) and 1492/1495 bp (99.80%) identity (&lt;i&gt;rrnA&lt;/i&gt; and &lt;i&gt;rrnB&lt;/i&gt;, respectively) with that of the ''&lt;i&gt;Ca&lt;/i&gt;. Phytoplasma pruni' rrnA' reference strain (GenBank JQ044393), identifying MN450 as a ''&lt;i&gt;Ca&lt;/i&gt;. Phytoplasma pruni' rrnA'-related strain and possibly representing a new subgroup within the 16Sr group III. For MN466, the 16S rRNA gene sequences shared 1471/1482 bp (99.26%) and 1469/1482 bp (99.12%) identity (&lt;i&gt;rrnA&lt;/i&gt; and &lt;i&gt;rrnB&lt;/i&gt;, respectively) with that of the '&lt;i&gt;Ca&lt;/i&gt;. Phytoplasma asteris' reference strain (GenBank M30790), and identifying the phytoplasma as a '&lt;i&gt;Ca&lt;/i&gt;. P. asteris'-related strain belonging to subgroup 16SrI-A. To further characterize the two phytoplasma strains, the &lt;i&gt;secY&lt;/i&gt; gene was PCR amplified from the DNA extracts as described by Lee et al. (2010). The obtained amplicons were cloned and sequenced, and representative &lt;i&gt;secY&lt;/i&gt; gene sequences were deposited in GenBank under accession numbers PQ899621 (MN450) and PQ899622 (MN466). BLASTn searches against the NCBI core nucleotide database revealed that the &lt;i&gt;secY&lt;/i&gt; gene sequence for MN450 exhibited 100% identity (1614/1614 bp) with '&lt;i&gt;Ca&lt;/i&gt;. P. pruni' (GenBank KM268860). Similarly, ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143710886","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":"Systematic exploration, evaluation, and application of significant loci for Fusarium head blight resistance in wheat.","authors":"Peng Jiang, Lei Wu, Chang Li, Yongchao Hao, Yi He, Peng Zhang, Hongwei Wang, Xu Zhang","doi":"10.1094/PDIS-10-24-2115-RE","DOIUrl":"https://doi.org/10.1094/PDIS-10-24-2115-RE","url":null,"abstract":"<p><p>Fusarium head blight (FHB), a serious disease in wheat, causes significant reductions in grain yield and quality worldwide. Marker-assisted selection can provide an effective tool for improving FHB resistance. Although many quantitative trait loci associated with resistance to FHB have been reported, few loci are currently available in breeding programs. The middle and lower reaches of the Yangtze River in China are areas that historically have experienced FHB epidemics, so that some local varieties may contain some valuable genes providing FHB resistance. In this study, association mapping was performed using 103 local cultivated varieties, and a previous QTL mapping using a recombinant inbred line (RIL) population from two locally popular parents, specifically Ningmai 9 and Yangmai 158, was integrated to identify nine candidate intervals. The corresponding Kompetitive Allele Specific PCR markers associated with FHB resistance were successfully developed and validated in 611 breeding lines. Four loci, namely QFhb.jaas-2D, QFhb.jaas-3A, QFhb.jaas-5A.2, and QFhb.jaas-6D, proved to be significantly related to FHB resistance in addition to Fhb1, and they could provide good resistance to FHB in the absence of Fhb1; the combination of multiple loci could produce a more stable resistance. These five markers were then applied in 211 breeding lines, and many resistance lines were obtained with different combinations of resistance loci. Additionally, QFhb.jaas-3A proved to be a highly selected locus, and eight differential genes in its interval were identified by genome and transcriptome analysis. This study provides additional gene resources and materials that could be used in FHB resistance breeding in wheat.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143710876","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":"Bittersweet Challenges: Postharvest Disease Management in Sugarbeet and Sweetpotato.","authors":"Carlos Morales, Kelly Avila, Usha Bhatta, Malick Bill, Collins Bugingo, Maria Camila Buitrago Acosta, Hunter Collins, Sandesh Dangi, Linda Hanson, Carly Hendershot, Shyam L Kandel, Jack Mecklin Mascarenhas, Rachel P Naegele, Camilo Parada-Rojas, Lindsey Thiessen, Sarah Jane Pethybridge, Kirsten Pollok, Jaime F Willbur, Lina Quesada-Ocampo","doi":"10.1094/PDIS-10-24-2214-FE","DOIUrl":"https://doi.org/10.1094/PDIS-10-24-2214-FE","url":null,"abstract":"<p><p>Root crops like sugarbeet and sweetpotato possess an aggregated value that sets them apart from other crops. This aggregated value includes not only their economic importance but also their high nutritional content, which can enhance global food security. However, the economic and nutritional value of these crops is significantly compromised by postharvest diseases, presenting major socio-economic challenges. Postharvest diseases, caused by various fungal and bacterial pathogens, affect crops during field growth, harvest, handling, and storage. Addressing these challenges requires improving several key aspects of disease management that are often lacking in postharvest pathosystems. These aspects include but are not limited to diagnostic methodologies, cultural practices, chemical control, host resistance, and pathogen monitoring among others. Emerging technologies and strategies from various fields offer promising solutions to these challenges. In this manuscript, we review new approaches to address common challenges in postharvest diseases of sugarbeet and sweetpotato. This review highlights important considerations for the implementation, modification, and creation of new approaches to maintain or increase the value of these commodities, which are threatened by postharvest diseases.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143710862","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":"Efficacy of pruning-wound protectant fungicides for the management of <i>Botryosphaeria</i> canker and dieback of apple trees in Maule region, Chile.","authors":"Adrián Vinicio Valdez-Tenezaca, Mauricio A Lolas, Fernanda B Núñez, Bernardo Antonio Latorre, Lizel Mostert, Francois Halleen, Enrique Ferrada, Gonzalo A Díaz","doi":"10.1094/PDIS-11-24-2427-RE","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2427-RE","url":null,"abstract":"<p><p>Botryosphaeria canker and dieback is an important fungal disease caused by Botryosphaeriaceae spp. that affects the productivity of apple orchards in Chile and worldwide. In the field, studies on the management of this disease are focused on the protection by fungicides applied on pruning wounds. However, in Chile, information about the protection and efficacy of fungicides on apple trees against twig and branch pathogens is scarce. Therefore, in this study, we evaluated the efficacy of fungicides to control fungal trunk pathogens causing Botryosphaeria canker and dieback in apple trees using in vitro, glasshouse, and field trials. Isolates of Diplodia mutila, D. seriata, Neofusicoccum arbuti, and Lasiodiplodia theobromae obtained and characterized previously in Chile from apple trees with canker and dieback symptoms were used in this study. In vitro tests showed that benomyl, fluazinam, difenoconazole, and tebuconazole exhibited the lowest EC50 values with means of 0.08, 0.09, 0.12, and 0.18 μg/mL, respectively. This study demonstrates that infection caused by D. mutila, D. seriata, L. theobromae, and N. arbuti can be significantly reduced using single-sprayed protection of fungicides. The most effective in reducing infection on pruning wounds of apple trees by Botryosphaeriaceae were benomyl (66 to 76%), tebuconazole (47 to 68%), thiophanate-methyl (68 to 71%), boscalid + pyraclostrobin (47 to 63%), fluxapyroxad + pyraclostrobin (54 to 57%), and thiophanate-methyl + tetraconazole (63 to 74%). To our knowledge, this is the first study reporting the control of Botryosphaeriaceae causing canker and dieback in apple trees through the use of commercially available chemical fungicides, with different active ingredients and modes of action.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143710867","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":"Systematic surveillance of Fusarium head blight in the southern region of the Republic of Korea.","authors":"Hosung Jeon, Jung-Wook Yang, Noh-Hyun Lee, Donghwan Shin, Donggyu Min, Nahyun Lee, Seul Gi Baek, Ju-Young Nah, Boeun Kim, Mi-Jeong Lee, In-Jeong Kang, Yul-Ho Kim, Kwang-Hyung Kim, Hokyoung Son, Theresa Lee","doi":"10.1094/PDIS-02-25-0282-SR","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0282-SR","url":null,"abstract":"<p><p>Fusarium head blight (FHB), caused by <i>Fusarium graminearum</i> species complex, is one of the most destructive plant diseases affecting wheat and barley globally. However, effective management methods remain elusive because of limited availability of resistant cultivars. Accordingly, systematic surveillance is one of the key strategies, allowing for prompt responses to emerging outbreaks and supporting the establishment of preventive guidelines for future occurrences. FHB severity in the southern region of the Republic of Korea in 2024 following an outbreak was systematically monitored. A total of 100 wheat (<i>n</i> = 43) and barley (<i>n</i> = 57) fields were assessed for FHB indices and mycotoxin concentrations. A geographical breakdown showed that several regions were heavily impacted by the FHB outbreak, with elevated disease severity exceeding 50%. Furthermore, spatiotemporal analysis of the FHB outbreak revealed relatively high disease severity in 2024, ranging from 3- to 6-fold compared to the previous years, likely influenced by climatic factors. A strong correlation of FHB severity and nivalenol concentrations was also observed, with concerning levels that underscore potential risk for future FHB outbreaks. These findings provide valuable insights into the epidemiology of FHB in the Republic of Korea and will help guide the development of more effective management strategies for FHB and its associated mycotoxins.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143710877","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":"First Report of <i>Phytopythium vexans</i> Causing Root Rot on Norway Spruce (<i>Picea abies</i>) in Tennessee and the United States.","authors":"Pratima Subedi, Cansu Oksel, Prabha Liyanapathiranage, Terri Simmons, Fulya Baysal-Gurel","doi":"10.1094/PDIS-01-25-0157-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-01-25-0157-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Norway spruce (&lt;i&gt;Picea abies&lt;/i&gt;), a pyramidal evergreen conifer, is widely grown as an ornamental tree and a popular choice for Christmas decorations. Three-year-old Norway spruce, grown under field conditions in a commercial nursery in Warren County, Tennessee, exhibited root rot and needle chlorosis in June 2024. The affected roots displayed dark brown to black lesions. Roots were evaluated for disease severity on a scale from 0% to 100%. Disease severity was 40% of the root area affected, while disease incidence was approximately 50% of 50 plants. Symptomatic root tissues were surface disinfected using 70% ethanol and washed twice with distilled water. Then, the symptomatic root tissues were plated on V8-PARPH (V8 juice agar amended with pimaricin, ampicillin, rifampicin, pentachloronitrobenzene, and hymexazol), and incubated at 25 ± 2°C with 8 h light/16 h dark cycle. Within three days of incubation, colonies with whitish radiate and chrysanthemum flower-like mycelial growth patterns were observed (Fig. 1a). Oogonia were smooth, ranging from filamentous to globose (16.25 ± 1.30 μm in diameter, &lt;i&gt;n&lt;/i&gt;=50) (Fig. 1b and c). Antheridia were cylindrical, elongate attached to the oogonia (Fig. 1c). Sporangia were subglobose (16.48 ± 1.74 × 22.05 ± 1.26 μm, &lt;i&gt;n&lt;/i&gt;=50) with papilla (Fig. 1d and e) that are characteristic of &lt;i&gt;Phytopythium vexans&lt;/i&gt; (Ghimire and Baysal-Gurel, 2023; Thao et al. 2020). Pathogen identity was confirmed by sequencing specific genetic markers amplified from genomic DNA extracted using DNeasy PowerLyzer Microbial Kit from 7-day-old pure cultures of the isolates (FBG8275 and FBG8276). The genetic markers for the ribosomal internal transcribed spacer (ITS), the large subunit (LSU), and mitochondrial cytochrome c oxidase subunits I (&lt;i&gt;CoxI&lt;/i&gt;) and II (&lt;i&gt;CoxII&lt;/i&gt;) were amplified and sequenced using the primer pairs ITS1/ITS4 (White et al., 1990), NL1/NL4 (Baten et al. 2014), OomCoxI-Levup/Fm85mod (Robideau et al., 2011), and Cox2-F/Cox2-R (Hudspeth et al., 2000), respectively. The ITS, LSU, &lt;i&gt;CoxI&lt;/i&gt;, and &lt;i&gt;CoxII&lt;/i&gt; sequences of isolates FBG8275 and FBG8276 (ITS: PQ723098 and PQ723099; LSU: PQ723103 and PQ723104; &lt;i&gt;CoxI&lt;/i&gt;: PQ728046 and PQ728047; &lt;i&gt;CoxII&lt;/i&gt;: PQ728048 and PQ728049) matched 754, 673, 612 and 563 base pairs, respectively with the corresponding &lt;i&gt;P. vexans&lt;/i&gt; sequences MK011115, OQ754108, GU133478, and AB468910, with 100% identity. The pathogenicity test was performed on 1-year-old Norway spruce plants grown in a 1-gal container (3.8 liter) to fulfill Koch's postulates. The plants were drench-inoculated (100 ml/plant) once with a mycelial slurry (two plates of 7-day-old culture/liter) of the isolates FBG8275 and FBG8276 (five plants per isolate). Five plants were drenched with pathogen-free agar slurry to serve as control. The study was conducted in a greenhouse condition (23°C to 25°C and 70% relative humidity). Two weeks after inoculation, dark brown to black lesions appeared on the roo","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143710894","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":"Rapid Detection of <i>Xanthomonas fragariae</i> in Strawberry Using Species-Specific Primers Based on Comparative Genomics.","authors":"Sai Wang, Peihong Wang, Weixue Liao, Xiaohui Liu, Mingyan Ouyang, Sisi Lin, Rongpeng Lin, Zhengyin Xu, Gongyou Chen, Bo Zhu","doi":"10.1094/PDIS-11-24-2299-RE","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2299-RE","url":null,"abstract":"<p><p><i>Xanthomonas fragariae</i> poses a significant emerging threat to global strawberry production. The success of surveillance strategies and quarantine measures in controlling its international spread depends heavily on the availability of rapid and reliable in-planta detection tools. Polymerase chain reaction (PCR) is the preferred method for detecting systemic infections due to its high sensitivity, specificity, and ease of use. However, despite the availability of several PCR and real-time quantitative PCR methods, many face issues with analytical specificity. Given the ongoing global evolution of <i>X</i>. <i>fragariae</i> and the emergence of new variants, there is a critical need for adaptable detection methods. In this study, we designed a specific primer pair (XfOG4-F/XfOG4-R) through comparative genomic analysis of 660 genomes from the <i>Xanthomonas</i> genus. This primer set targets a region uniquely and consistently present in all eighty-one <i>X</i>. <i>fragariae</i> genomes available on NCBI. We validated the primer pair's specificity using colony PCR with both target <i>X</i>. <i>fragariae</i> strains and non-target <i>Xanthomonas</i> strains. Detection sensitivity was assessed using PCR and qPCR on isolated DNA and bacterial cell suspensions, both in vitro and in artificially inoculated strawberry leaves. The qPCR method demonstrated sensitivity 100 times higher than standard PCR. Additionally, the PCR test successfully detected the pathogen in extracts from naturally infected strawberry crown samples collected on farms. The new primer set showed improved analytical specificity over previously reported primers, offering a valuable tool for detecting <i>X</i>. <i>fragariae</i>-infected plants in future field surveys.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143710832","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":"First report of <i>Fusarium culmorum</i> and <i>Fusarium avenaceum</i> causing vascular necrosis in European hazelnut branches in Chile.","authors":"Ernesto Antonio Moya-Elizondo, Verónica Retamal, Juan G San Martín, Braulio E Ruiz, María José Lisperguer, Tommaso De Gregorio, Matteo Maspero","doi":"10.1094/PDIS-10-24-2253-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-10-24-2253-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Hazelnut (&lt;i&gt;Corylus avellana&lt;/i&gt; L.) is the second most cultivated nut crop in Chile. Pathogens associated with fungal trunk diseases (FTD) pose a serious threat to this crop, because these fungi colonize the wood causing loss of productivity and eventually death of the plants (Martino et al., 2025). During Spring 2018 and 2020, FTD symptoms such as wood necrosis, vascular discoloration of branches, cankers, and wilted branches were detected in a survey conducted in 24 hazelnut orchards located between Maule and Araucanía regions, Chile (Moya-Elizondo et al., 2023). Wood pieces (3 mm x 5 mm) were removed from the edge of necrotic canker lesions, disinfected with 2% NaOCl, rinsed twice with sterile distilled water, and dried on sterile absorbent paper. Tissue pieces were placed on potato dextrose agar (PDA) supplemented with streptomycin sulphate (200 mg L⁻¹) and incubated at 25°C in darkness for five days. Different fungi were isolated from cankers, but based on morphological characteristics (pale pink or burgundy colonies), &lt;i&gt;Fusarium&lt;/i&gt; spp. were identified in 5.2% of the samples (27/520). Each colony was hyphal-tip purified in a new PDA plate. Macroconidia developed on sporodochia after 30 days of incubation at 25°C on carnation leaf agar. Two morphologically different isolates were analyzed. Colonies of isolate F066 were cottony, dark pink and light pink on the edges when grown on PDA. Macroconidia were hyaline, falcate with rounded apical cells, slightly curved, with 3 to 6 septa (30 to 53 x 5.2 to 6.2 µm). Isolate F094 presented slightly cottony colonies, light pink, and dark pink with pale yellow hues in the central area with macroconidia of similar morphological shape but measuring 36 to 55 x 2.8 to 4.2 µm. In both isolates, chlamydospores and microconidia were absent. The ITS, RPB2, and TEF-1α genomic regions were amplified with primers ITS1/ITS4, 7cf/11ar, and EF1/EF2, respectively (Sandoval-Denis et al., 2018). The ITS (MT640271, PP928999), RPB2 (MT997139, PP934182), and TEF-1α (MT661593, PP934183) sequences were deposited in GenBank, showing 100% similarity with reference sequences of &lt;i&gt;Fusarium culmorum&lt;/i&gt; (Wm.G.Sm.) Sacc. and &lt;i&gt;Fusarium avenaceum&lt;/i&gt; (Corda) Sacc. for ITS: (MK729631, MT463390), RPB2 (GQ915490, MK185027), and TEF-1α (MN044434, KP400709), respectively. To fulfil Koch's postulates, pathogenicity was evaluated in 8-year-old hazelnut plants cv. Tonda di Giffoni in a commercial orchard. A hole of 6.5 mm in diameter was made in healthy branches using an electric drill and an actively growing mycelial disc (5 mm) was placed into five branches per isolate, ensuring contact of the mycelium with the wood. The wounds were sealed with plastic film to prevent contamination and desiccation. Additionally, PDA discs were inoculated as a control. After seven months, branches were cut longitudinally to verify wood necrosis. Inoculation with isolates F066 and F094 resulted in necrotic lesions ranging between 50-125 mm and 3","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143676987","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}