Plant disease最新文献

{"title":"First record of natural infection by <i>Chondrostereum purpureum</i> on Rhododendron in North America.","authors":"Elisa Becker, Simon Francis Shamoun","doi":"10.1094/PDIS-02-25-0303-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0303-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Chondrostereum purpureum (Pers. ex Fr.) Pouzar infects many woody plants, including fruit trees, ornamentals, and forest species (Setliff, 2002). Its broad host range and ability to cause silver leaf disease make it a significant concern in forestry and horticulture. Although C. purpureum was found on Rhododendron spp. in the UK, New Zealand, and Nepal, it was unreported in North America (Farr et al. 1996). Rhododendron is the largest genus in the Ericaceae family, comprising over 1,000 species and more than 25,000 cultivars. Introduced to Britain in 1763, R. ponticum naturalized and became invasive in some woodlands (Cross 1975). These shrubs are susceptible to infection by Phytophthora ramorum, which can cause severe disease (Willoughby et al. 2015). Mechanical cutting removes infected material, but stumps frequently resprout. C. purpureum was evaluated to control R. ponticum resprouts. Though less effective than synthetic herbicides, it may serve as an alternative where herbicides are restricted (Willoughby et al. 2015). In January 2010, a C. purpureum specimen was collected on white-flowering Rhododendron in an urban forest (Victoria, BC, Canada; GPS: 48.477244, 123.383991). Thin, undulating, woody bracket-like basidiocarps were found on stem sides and branch crooks. Upper surfaces were brown-grey with whitish hairs; new growth on edges and smooth undersides was purple. Symptoms included discoloured stem lesions and wilting leaves on infected stems. A pure culture was obtained by plating surface-sterilized, discoloured stem wood on acidified PDA. Within 7 days at 20°C, flat, white, cottony mycelia with clamp connections emerged. Guaiacol testing confirmed laccase activity (Stalpers 1978). Purified DNA was amplified with basidiomycete-specific rDNA primers (Gardes & Bruns 1993) and compared via BLASTn (core_nt). Sequences showed 99% identity to C. purpureum voucher strains LE-BIN 2764 (OR475683.1, 631/635 nt) and PDD:91629 (GQ411519.1, 634/641 nt), and were deposited as GenBank KM652470.1. To fulfill Koch's postulates, 3-year-old R. caucasicum × ponticum 'Cunningham's White' stems were cut and inoculated with either C. purpureum (4 plants) or PDA (2 plants) as a control. Two months later, inoculated plants developed symptoms including darkening stems, yellowing and wilting leaves, and browning of leaf tips. By six months after inoculation, infected plants had wilted and died, while control plants remained symptomfree. Subsequent PCR with 'APN1' C. purpureum-specific primers (Becker et al. 1999) confirmed the presence of the pathogen only in infected plants, and not in control plants. This is the first verified North American occurrence of C. purpureum naturally infecting Rhododendron. Following verification of identity and pathogenicity, the culture and an infected stem were deposited at the Pacific Forestry Centre-Forest Pathology Herbarium (DAVFP #29828). This finding expands the known host range of C. purpureum and has important impli","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144033057","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 <i>Pestalotiopsis</i> Leaf Spot of Palms by Fungicides, Plant Hormones, and Biological Agents.","authors":"Muhammad Zunair Latif, Lingguang Kong, Yanke Jiang, Naila Asghar, Amer Habib, ChongChong Lu, Xinhua Ding","doi":"10.1094/PDIS-09-24-1888-RE","DOIUrl":"10.1094/PDIS-09-24-1888-RE","url":null,"abstract":"<p><p>This study investigates fungal leaf spots of palm, an ever-present threat to the nursery and floriculture industry. Fungicides, plant hormones, and biological agents were used to consider their implications for <i>Pestalotiopsis</i> leaf spot disease management in palms. A survey of different locations in Pakistan's Kasur and Faisalabad districts was conducted, collecting data on disease incidence of debilitating leaf spot disease in <i>Roystonea regia</i> (royal palm) and <i>Ravenea rivularis</i> (ravenea palm). Pathogenicity tests were performed on healthy seedlings using <i>Pestalotiopsis</i> sp. The results indicate that the fungicide Flumax with 86.11% growth inhibition of the pathogenic fungus and the biological agent <i>Trichoderma asperellum</i> with 76% growth inhibition have a significant impact in suppressing pathogen growth. Compared with the fungicide or salicylic acid (SA) application alone, the combined application of SA with 50% less fungicide (Flumax) in an integrated program significantly reduced disease severity to 5.9 and 6.2% in royal and ravenea palms, respectively. Our findings highlighted that integrated disease management (IDM) could be crucial in addressing <i>Pestalotiopsis</i> leaf spot disease. Adapting to IDM can improve the aesthetic value and profitability of palms by allowing a reduction in fungicide use while maintaining effective control of the disease.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS09241888RE"},"PeriodicalIF":4.4,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142740168","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 the Species of <i>Pythium</i> Associated with Corn Seedlings in Delaware.","authors":"John T Bickel, Madeline G Henrickson, Alyssa K Betts","doi":"10.1094/PDIS-04-24-0876-RE","DOIUrl":"10.1094/PDIS-04-24-0876-RE","url":null,"abstract":"<p><p>Corn (<i>Zea mays</i> L.) is the top grain crop by hectares grown in Delaware (DE). Increased pre- and postemergence damping-off in corn caused by <i>Pythium</i> species have been observed in recent seasons. To date, no characterization studies have been performed to understand <i>Pythium</i> species diversity in DE. Symptomatic corn seedlings were collected from 33 fields across DE in 2019 and 2020. Isolates were obtained from infected root tissues and identified by molecular sequencing. In total, 14 species were recovered: <i>P. aristosporum</i>, <i>P. arrhenomanes</i>, <i>P. attrantheridium</i>, <i>P. catenulatum</i>, <i>P. dissotocum</i>, <i>P. graminicola</i>, <i>P. inflatum</i>, <i>P. irregulare</i>, <i>P. oligandrum</i>, <i>P. periplocum</i>, <i>P. spinosum</i>, <i>P. sylvaticum</i>, <i>P. tardicrescens</i>, and <i>P. torulosum</i>. The dominant species recovered was <i>P. graminicola</i>, accounting for 66% of the isolates. Five species were screened for fungicide sensitivity to calculate the EC₅₀ of mefenoxam, ethaboxam, and picarbutrazox which are the most commonly used active ingredients to manage species of <i>Pythium</i> in corn seed treatment packages. All species tested were sensitive to mefenoxam and picarbutrazox. For ethaboxam, <i>P. torulosum</i> was the only species with an EC₅₀ value >10 μg ml^-1. Ten species were screened for fungicide sensitivity to mefenoxam, ethaboxam, or picarbutrazox at 18, 21, and 25°C. As temperatures increased, percent inhibition was reduced in 40, 70, and 80% of the species screened for sensitivity to ethaboxam, picarbutrazox, and mefenoxam, respectively. Nine of these species were screened for isolate aggressiveness in greenhouse panels to examine impact on emergence, shoot height, shoot weight, and root weight. While all species were recovered from inoculated roots, <i>P. arrhenomanes</i>, <i>P. attrantheridium</i>, <i>P. spinosum</i>, and <i>P. sylvaticum</i> had the greatest root weight reduction.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS04240876RE"},"PeriodicalIF":4.4,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625823","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>Nigrospora oryzae</i> Causing Basal Rot on Siberian lily (<i>Lilium</i> spp.) Ornamental hybrids in China.","authors":"Ruiqi Zhang, Yiguang Bai, Xinying Hu, Weidong Wang, Lihong Zhou, Xueyan Li, Yingdong Yang","doi":"10.1094/PDIS-03-25-0648-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-03-25-0648-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;&lt;i&gt;Lilium&lt;/i&gt; 'Siberia', is extensively cultivated and has high economical value in China due to its popularity as an ornamental lily. In August 2023, lily basal rot was observed on about 60% of two-year-old plants at the Liaoning Academy of Agricultural Sciences Multiplex greenhouse ( in an area of about 2000 m&lt;sup&gt;2&lt;/sup&gt; ) . Initial symptoms appeared on the base of the bulbs as brown lesions that expanded over time, and later the leaves turned yellow and about one month latter the whole plant died. To isolate the causal pathogen, tissues were collected from 5 symptomatic plants with basal rot. The infected bulbs were surface-sterilized with 75 % ethanol solution for 30 s after initial rinsing, followed by triple sterile-water washes, specimens were dried aseptically prior to pathogen isolation. Tissue sections 5 mm × 5 mm were transferred from plant lesion margins onto potato dextrose agar (PDA) medium after surface sterilization. Cultures were maintained at 25℃ for pathogen isolation. After 7 days, 3 consistent surface morphology strains(H1, H2 and H3) were prepared based on single spore isolates. After 10 to 15 days, mycelium had fully covered the plates. The hyphae were branched, septate, smooth, hyaline, Conidia were black, solitary, globose or subglobose, glossy aseptate of 8.3 - 11.4 μm × 12.4 - 14.9 μm (n=50) in size, and produced at the tips of hyaline and ampulliform conidiophores. The fungus showed similar morphological characteristics to &lt;i&gt;Nigrospora oryzae&lt;/i&gt; (Wang et al. 2017). For molecular confirmation of the species identity, genomic DNA of three isolates (H1, H2 and H3) were extracted by the CTAB method (O'Donnell et al., 1998), and portions of three genes, the Intemal Transcribed Spacer (ITS) of the ribosomal RNA, the Translation Elongation Factor subunit 1-alpha (TEF1-ɑ) and the beta-tubulin (TUB2) genes were amplified by the PCR using the primers ITS1/ITS4,EF1-728F/EF-2 and Bt-2a/Bt-2b (Wang et al. 2017). A BLASTn analysis showed that the identity of the nucleotide sequences of isolates (H1, H2 and H3) were 99%(500/501bp; 488/488 bp; 495/499bp) for ITS, 99% (461/461 bp;466/467 bp;467/467 bp) for TEF1- ɑ; and 99% (331/333 bp; 376/384 bp; 381/388 bp) for the TUB2 sequences, with &lt;i&gt;N. oryzae&lt;/i&gt; LC2702 in GenBank. The resulting sequences were submitted to GenBank under accession numbers PP203296, PP784618, PP784619 for ITS; PP417827, PP869279, PP886084, for TEF1-ɑ; PP448183, PP869277, PP869278 for TUB2 of isolates H1, H2 and H3 respectively. A neighbor-joining phylogenetic tree showed that the three isolates from Siberian lily clustered with the &lt;i&gt;N.oryzae&lt;/i&gt; clade.Therefore, the isolates H1, H2 and H3 were identified as &lt;i&gt;N. oryzae&lt;/i&gt; based on morphology and molecular evidence. One representative isolate(H1) was used for completing the Koch's postulates. A pathogenicity test was made on 1-year-old healthy Siberia lily bulbs, the bulbs were disinfected, using a sterile needle to prick the base of the bulbs, then t","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144033071","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>Phytophthora nicotianae</i> causing Root Rot on <i>Medicago polymorpha</i> in China.","authors":"Menghuan Tao, Siqi Xie, Bo Yang","doi":"10.1094/PDIS-04-25-0839-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-04-25-0839-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Medicago polymorpha (commonly known as Jin hua cai) is a nutritious and palatable forage and vegetable crop in China. From November 2023 to March 2024, symptoms of root rot and foliage blight were observed on M. polymorpha in a vegetable production base in Nanjing (31.7960°N, 118.8902°E), Jiangsu Province, China. Typical symptoms included water-soaked lesions, brown to dark-brown discoloration of roots, and wilting. Infected plants eventually collapsed and died as the disease progressed. A survey conducted in 0.75 hectares of M. polymorpha fields revealed disease incidence ranging from 20% to 40%. Symptomatic root tissues were surface-sterilized (75% ethanol for 30 s, 1% NaClO for 120 s, rinsed thrice with sterile water), plated on 10% V8 agar amended with 50 mg/L rifampicin and ampicillin, and incubated at 25°C for 3 days. Phytophthora-like colonies with aseptate hyphae were isolated. Twelve pure cultures (PN-1 to PN-12) were obtained by hyphal tipping and grown on V8 medium for morphological characterization, molecular identification, and pathogenicity testing. All isolates produced colonies with loose, fluffy aerial mycelia. Morphological characterization revealed papillate, noncaducous sporangia (35-60 × 30-53 µm; n=30), spherical chlamydospores (21-33 µm; n=30), and ovoid zoospores (6-9 µm; n=30). Three isolates (PN-1 to PN-3) were selected for molecular identification. The internal transcribed spacer (ITS) region of rDNA and the cytochrome c oxidase subunit 1 (COX1) gene were amplified and sequenced (White et al. 1990; Robideau et al. 2011). ITS sequences (GenBank PV077295, PV413032, PV413033) showed 98.6-99.9% identity with P. nicotianae (OR342796.1, KJ494913.1, MT065865.1). COX1 sequences (GenBank PV102957, PV424230, PV424231) matched P. nicotianae (MH760233.1, MT216343.1) with 99.9-100% identity. Pathogenicity of P. nicotianae (PN-1 to PN-3) was confirmed using the mycelial agar plug inoculation method. Briefly, V8 medium containing fresh mycelium was chopped and mixed with vermiculite, and one dish (9 cm diameter) of the mycelium was added to each pot (7 cm upper diameter, 5 cm lower diameter). As a control, sterile V8 medium without mycelium was similarly processed and mixed into vermiculite. Pathogenicity tests for each of the three isolates were conducted in three independent replicates. Seeds of M. polymorpha (cultivar Huaiyang) were soaked in sterilized water for 12 h and then planted in sterilized vermiculite mixed with mycelial pieces (10 seeds/pot). Plants were maintained in a greenhouse at 25°C under a 14 h/10 h light/dark cycle for 14 days. Seed germination commenced four days after planting. Inoculated plants began to exhibit root rot symptoms 10 days post-inoculation, which were morphologically consistent with field-observed symptoms. P. nicotianae was re-isolated from the lesions, while no symptoms were observed in control plants. P. nicotianae has been reported to cause root rot in various crops worldwide, including ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144017457","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>Lasiodiplodia pseudotheobromae</i> causing leaf spot on <i>Millettia speciosa</i> in China.","authors":"Xiaoshan Geng, Qin Liu, YuanYuan Jiang, Rong-Bing Wang, Yuan Qin, Yingying Long, Jie-Ming Pan","doi":"10.1094/PDIS-01-25-0030-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-01-25-0030-PDN","url":null,"abstract":"<p><p>Millettia speciosa Champ (M. speciosa), a member of the Leguminosae family, is extensively cultivated in Guangxi, China, with planting area exceeding 8,000 hectares. The edible tubers of this plant are valued for their antibacterial and antioxidant properties (Luo et al. 2023; Shu et al. 2020). In July 2024, leaf spot symptoms were observed in a plantation in Guilin, Guangxi, China (25°93'N; 111°09'E), affecting over 40% of plants across a 78,230 m2 area. Symptoms began as small, circular, pale-yellow spots that enlarged into irregular, light brown lesions, eventually causing leaf wilt and defoliation. A total of six symptomatic leaves were collected, surface-disinfected with 75% ethanol for 30 s and 1% NaClO for 2 min, rinsed with sterile distilled water (SDW), and cultured on potato dextrose agar (PDA) at 28°C in darkness for 7 days. Seven isolates were obtained through single-spore isolation. Colonies were initially white, becoming greyish-white with dense, fluffy aerial hyphae. Immature conidia were hyaline, ellipsoid and aseptate, while mature conidia were dark brown, one-septate, and had longitudinal striations, measuring 22.8-29.5 µm × 11.2-15.6 µm (n = 50). The morphological features were consistent with Lasiodiplodia sp. (Zhang et al. 2024). To confirm the pathogen, three representative isolates (including N2-1-1, which yielded identical sequences to the other two for the targeted loci) were sequenced for the internal transcribed spacer (ITS), β-tubulin (BT), and translation elongation factor 1-alpha (EF1-α) regions (Wang et al. 2024). The ITS, BT and EF1-α sequences (Genebank accessions nos. PQ637400, PQ654012 and PQ654013) showed high identity to the ex-type strain of Lasiodiplodia pseudotheobromae (CBS 116459), with identities of [ITS: 528/528 bp (100%)] (cf. EF622077), [BT: 452/460 bp (99%)] (cf. EU673111), and [EF1-α: 299/300 bp (99%)] (cf. EF622057), respectively). Based on morphological and molecular data, the pathogen was identified as L. pseudotheobromae. Pathogenicity was tested on one-year-old M. speciosa seedlings by inoculating leaves with 5-mm mycelial plugs, while control leaves received sterile PDA plugs. The experiment was performed with three biological replicates. Plants were maintained in a greenhouse (12/12h light/dark cycle, 25 ± 2°C, 90% humidity). After 7 d, inoculated leaves developed symptoms identical to those observed in the field, while controls remained symptom-free. The fungus was consistently reisolated, fulfilling Koch's postulates. L. pseudotheobromae has previously been reported to cause diseases in strawberry in Florida, plum and Peanut in China (Zhang et al. 2024; Wang et al. 2024, Zhang et al. 2022), but this is the first report of L. pseudotheobromae causing leaf spot on Millettia speciossa in China. This finding provides a basis for further studies on disease management and biology.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144037531","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>Colletotrichum nymphaeae</i> Causing Anthracnose on <i>Ampelopsis grossedentata</i> in China.","authors":"Xuqi Shi, Xiping Long, Dejun Peng, Jiaying Lv, Shan Ye, Zhuhong Yang, Zhong Ding","doi":"10.1094/PDIS-01-25-0001-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-01-25-0001-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;&lt;i&gt;Ampelopsis grossedentata&lt;/i&gt;, known as vine tea, is a perennial woody vine traditionally used for making herbal tea from its tender leaves and stems in southern China (Wu et al. 2023). In recent years, its plantations have been devastated by pathogens such as &lt;i&gt;Pestalotiopsis&lt;/i&gt; and &lt;i&gt;Diaporthe&lt;/i&gt;, significantly impacting the quality of its products (Yuan et al. 2022; Liu et al. 2024). In May 2024, 135 symptomatic samples exhibiting shoot blight, branch dieback, canker, and leaf spot were collected from four tea plantations (approximately 130 acres) in Yongshun County, Tujia and Miao Autonomous Prefecture, Xiangxi, Hunan Province, China. Disease incidence in the tea plantation was almost 100%, with yield reductions varying from 80 to 100%. Samples from the diseased-healthy tissue junction were treated with 75% ethanol for 30 s and then washed three times in sterile water. They were placed on PDA at 25°C in the dark. After 5 d, 34 isolates out of 135 samples with the same morphology were obtained (isolation frequency was 5.9%, 14.3%, 17.2%, and 23.4% from four tea plantations, respectively), with a colony morphology different from &lt;i&gt;Pestalotiopsis&lt;/i&gt; and &lt;i&gt;Diaporthe&lt;/i&gt;, and three isolates (AG-CN-4, AG-CN-5, and AG-CN-6) were selected for further analysis. After 7 d of incubation on PDA, fungal colonies were white to gray, and pale gray to pale orange with black spots on the lower surface. On the 25th day, the surface view showed gelatinous orange conidial masses. The conidia were unicellular, colorless, smooth-walled, straight, cylindrical to cylindrical-clavate with both ends rounded or one end acute, and measuring 6.4 to 13.1 × 2.6 to 5.4 μm (mean 8.3 ± 1.6 × 3.6 ± 0.5 μm, n = 40). Culture and conidial morphology were in concordance with published descriptions of &lt;i&gt;Colletotrichum acutatum&lt;/i&gt; sensu lato (Damm et al. 2012). Sequences of the internal transcribed spacer, β-tubulin, chitin synthase, and glyceraldehyde 3-phosphate dehydrogenase genes from the three isolates were then amplified (Weir et al. 2012) and deposited in GenBank (accession nos. PP922606, PP987161-PP987163, PQ813639-PQ813640, PQ815057-PQ815062). A Maximum Likelihood phylogenetic tree was generated by combining all sequenced loci in MEGA7 (Kumar et al. 2016). Three isolates were classified in the &lt;i&gt;C. nymphaeae&lt;/i&gt; clade with 99% bootstrap support. Both morphological and molecular characteristics confirmed that our isolates were highly similar to &lt;i&gt;C. nymphaeae&lt;/i&gt;. We used Koch's postulates to verify these results. Four two-year-old potted plants were inoculated with spore suspensions (1 × 10&lt;sup&gt;6&lt;/sup&gt; conidia/ml) from each isolate using an atomizer, while control plants were sprayed with distilled water. The plants were maintained in an incubator at 25 ± 1°C, 95 ± 5% relative humidity, and a 14/10 h light/dark cycle. After 7 d, the twigs and leaves inoculated with &lt;i&gt;C. nymphaeae&lt;/i&gt; withered, and some leaves exhibited sunken necrotic lesions with brown ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144028307","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 the Detection of Soybean Vein Necrosis Virus (SVNV) in Peanut in the United States.","authors":"Abdelaal H A Shehata, Kassie Conner, Edward Sikora, Amanda L Strayer-Scherer, Kathleen Martin","doi":"10.1094/PDIS-01-25-0209-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-01-25-0209-PDN","url":null,"abstract":"<p><p>During the screening of peanuts (Arachis hypogaea L.) for tomato spotted wilt virus (TSWV) in 2024, 36 plant samples expressing symptoms of tomato spotted wilt were collected from three locations in Alabama: Brewton Agricultural Research Unit (BARU), Brewton, AL; Wiregrass Research and Extension Center (WGREC), Headland, AL; and Gulf Coast Research and Extension Center (GCREC), Fairhope, AL. Foliar necrosis symptoms, not typically associated with TSWV, were also observed in all samples (Supplemental Figure 1). Symptoms varied from moderate light brown to severe dark necrosis along the midveins and lateral veins. Samples were tested for four orthotospoviruses: TSWV, groundnut ringspot virus (GRSV), tomato chlorotic spot virus (TCSV), and soybean vein necrosis virus (SVNV) using ELISA (Agdia Inc, U.S.A.). All samples were positive for TSWV and negative for both GRSV and TCSV; however, one sample tested positive for SVNV (BARU 4). SVNV was previously reported not to infect peanuts (Zhou and Tzanetakis 2013). The 36 samples were subjected to RT-PCR using specific primers for the nucleocapsid (N) protein of SVNV (Shehata et al. 2024). Twenty-four of 36 samples were positive for SVNV (12 from BARU, two from WGREC, and 10 from GCREC). The amplified bands showed lower intensity than the positive control, possibly indicating a low titer of SVNV, which may explain the negative ELISAs. Following the manufacturer's instructions, these bands were cloned using the CloneJET PCR Cloning kit (ThermoFisher Scientific) and sent for Sanger sequencing. The resulting SVNV-N sequences were submitted to GenBank under accessions PQ821900-905. The sequences demonstrated 98.19% nucleotide (nt) and 96.75% amino acid (aa) identities with SVNV from Tennessee (GCF_004789395.1). Nine conserved amino acid mutations were identified compared to the TN strain, resembling those found in soybeans (Shehata et al. 2024). Additionally, RT-PCR was also utilized for TSWV-N detection (Martin et al. 2024), and 26 samples tested positive (12 from BARU, three from WGREC, and 11 from GCREC), which confirmed the presence of both SVNV and TSWV in positive samples (Supplemental Table I). Further research is necessary to investigate co-infection between SVNV and TSWV, potential genome reassortment, and its mechanisms to understand the interactions between these viruses. These interactions could adversely impact legume production in Alabama, valued at $315 million in 2023 (soybean and peanut, USDA 2023). Since both TSWV and SVNV are transmitted by tobacco thrips (Frankliniella fusca) (Keough et al. 2016; Hameed et al. 2022), this is likely how SVNV was introduced to peanuts. This constitutes the first report on the detection of SVNV in peanuts in the United States, suggesting that SVNV has been adapting to new hosts since its discovery (Tzanetakis et al. 2009; Zhou et al. 2018).</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144018349","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 Bacterial leaf Blight Disease of Rice Caused by <i>Xanthomonas oryzae</i> pv. <i>oryzae</i> in Kenya.","authors":"Everlyne Nganga, Laurent Brottier, Camille Blasco, Gabriel Boulard, Florence Auguy, Boris Szurek, Joseph Bigirimana","doi":"10.1094/PDIS-10-24-2096-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-10-24-2096-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a devastating disease of rice crops which can lead to yield losses ranging from 20 to 30% and as high as 50% (Mew 1987). BLB was first reported in Japan in 1884 and is now prevalent in most of the rice-producing countries in Asia. In Africa, Xoo was first reported in Mali and Cameroon (Buddenhagen et al., 1979) and later in many West African countries. Recently, BLB also appears to be spreading in East Africa with reports in Tanzania (Schepler-Luu et al., 2023) and in Madagascar (Raveloson et al., 2023). In June 2023, typical symptoms of BLB such as water-soaked areas and yellowish lesions along the leaf margins and tips were observed on rice plants in the coastal region of Kenya. Five rice fields of the Taita Taveta County with an incidence of 5-10% were surveyed, and 10-15 symptomatic leaf samples were collected in each field following a W pattern. Rice varieties were either Saro 5 or Arize 6444, two high productivity rice. 4-5cm long leaf fragments of 45 samples were next processed for bacterial isolation and surface disinfected, rinsed with sterile water, and ground individually in tubes with steel beads using a TissueLyser (Qiagen). Thirty-four round, pale yellow pigmented, and mucoid Xanthomonas-like colonies were obtained upon plating of 30 µl of the leaf powder resuspended in 1mL of sterile water on a semi-selective medium (peptone, 10 g/L; sucrose, 10 g/L; purified bacteriological agar, 16 g/L; glutamic acid, 1g/L; cycloheximide, 25 mg/L; cephalexin, 20 mg/L and kasugamycin, 10 mg/L) 72h after incubation at 28°C. To confirm that the isolates were Xoo, multiplex PCR established for the identification of X. oryzae pathovars was used (Lang et al. 2010). Thirty-two strains resulted in the amplification of two bands characteristic of the Xoo pattern. In addition, 6 of these strains (namely CIX5498, CIX5504, CIX5513, CIX5514, CIX5516 and CIX5539) were subjected to gyrB sequencing using the universal primers XgyrB1F and XgyrB1R (Young et al., 2008). The resulting partial 800 bp gyrB sequences of these 6 strains showed 100% identity (767/767 nt) with that of the PX099A Asian reference Xoo strain (accession CP000967.2). The pathogenicity of these 6 strains and the reference strain PX099A used as positive control was tested on 1-month-old Oryza sativa cv. Komboka plants (n=8 per treatment, 1 repetition). Rice leaves were inoculated by leaf clipping using sterile scissors dipped in the bacterial suspension at an optical density of 0.2. Three weeks after inoculation, plants exhibited typical BLB lesions for each of the six tested strains similarly to that of the positive control, whereas Mock-inoculated plants remained symptomless. Bacteria re-isolated from these diseased leaves yielded colonies that were confirmed as Xoo by multiplex PCR, fulfilling Koch's postulate. All strains isolated in this study are referenced in the CIX collection of the French National Resear","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144006004","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 and Visual Detection of <i>Pyricularia oryzae</i> Using Coupled Recombinase Polymerase Amplification-Lateral Flow Dipstick Assay.","authors":"Yan Du, Jun Yang, Zhongqiang Qi, Junjie Yu, Rongsheng Zhang, Mina Yu, Huijuan Cao, Tianqiao Song, Xiayan Pan, Shuchen Wang, Qin Xiong, Yongfeng Liu","doi":"10.1094/PDIS-08-24-1787-RE","DOIUrl":"10.1094/PDIS-08-24-1787-RE","url":null,"abstract":"<p><p>Rice blast, caused by <i>Pyricularia oryzae</i>, is one of the most destructive fungal diseases in rice, severely impacting rice production worldwide every year. Rapid, accurate, and visual detection of <i>P. oryzae</i> is essential for more effective prevention and control. In this study, we developed a recombinase polymerase amplification-lateral flow dipstick (RPA-LFD) assay to detect <i>P. oryzae</i>. Species-specific RPA primer pairs and probe were designed based on the target gene MGG_15975. The optimized reaction temperature and time were set at 37°C and 25 min, respectively. Specificity analysis showed that the assay could specifically detect <i>P. oryzae</i> isolates from rice, whereas other fungal species or <i>Pyricularia</i> species from grasses were not detected. Additionally, this assay demonstrated high sensitivity, capable of detecting as low as 10^-2 ng/μl of <i>P. oryzae</i> genomic DNA, which was found to be 100 times more sensitive than conventional PCR. Furthermore, using this assay, <i>P. oryzae</i> was effectively detected in diseased leaves in rice fields and could also be identified at an early stage of infection before obvious lesions appeared in artificially inoculated rice seedlings. Therefore, the RPA-LFD assay developed in our study for the detection of <i>P. oryzae</i> is rapid, highly sensitive, and efficient, which has the potential application for early diagnosis of <i>P. oryzae</i> infection in rice fields.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS08241787RE"},"PeriodicalIF":4.4,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142681915","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}