Plant disease最新文献

{"title":"Characterization of Bean Common Mosaic Virus Isolates Infecting Three Leguminous Bean Crops from South and Southeast Asia.","authors":"Shimul Das, Sridhar Jarugula, Basavaraj Bagewadi, Amer Fayad, Alexander V Karasev, Rayapati A Naidu","doi":"10.1094/PDIS-05-24-1113-SR","DOIUrl":"10.1094/PDIS-05-24-1113-SR","url":null,"abstract":"<p><p>Bean common mosaic virus (BCMV) is causing economically important diseases in leguminous crops worldwide. In this study, BCMV isolates from country bean (CB; <i>Lablab purpureus</i>), yard-long bean (YLB; <i>Vigna unguiculata</i>), and rajma bean (RB; <i>Phaseolus vulgaris</i>) collected from Bangladesh, Nepal, and Cambodia were characterized. Samples that tested positive for BCMV in serological assays were subjected to high-throughput sequencing to generate near-full-length genome sequences. In pairwise comparisons of the polyprotein open reading frame, 13 BCMV isolates from Bangladesh, Cambodia, and Nepal showed sequence identity of 92.1 to 98.8% at the nucleotide and 94.2 to 99% at the amino acid level among themselves and with corresponding sequences of BCMV reported previously. In phylogenetic analyses using the global BCMV sequences, they segregated into five distinct lineages, with RB isolates from Nepal clustering with US1/NL1-clade of common bean isolates from different countries, YLB isolates aligning with blackeye cowpea strain sequences reported from China, and CB isolates from Nepal and Bangladesh clustering with soybean isolates from China. One YLB isolate from Nepal was identified as a putative recombinant. None of the BCMV sequences aligned with isolates representing the RU1 or PStV clades. In grow-out tests, seed samples from local markets showed a 14.3 to 38.1% transmission efficiency rate of BCMV with CB seed lots and 9.5 to 33.3% with YLB seed lots.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS05241113SR"},"PeriodicalIF":5.4,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141996324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Multiplex RT-qPCR Assay for Simultaneous Detection of Cucurbit Viruses from Individual Whitefly and Plant Samples.","authors":"A Abdul Kader Jailani, Mathews L Paret","doi":"10.1094/PDIS-09-23-1964-RE","DOIUrl":"10.1094/PDIS-09-23-1964-RE","url":null,"abstract":"<p><p>Whiteflies (<i>Bemisia tabaci</i>) are a significant pest of cucurbits and vector many viruses, leading to substantial economic losses. Modern diagnostic tools offer the potential for early detection of viruses in the whiteflies before crop production. One such tool is the multiplex reverse transcriptase quantitative PCR (RT-qPCR) probe-based technique, which can detect multiple targets in a single reaction and simultaneously quantify the levels of each target, with a detection limit of 100 copies per target. In this study, a multiplex RT-qPCR-based detection system capable of identifying one DNA virus and three RNA viruses in whiteflies-cucurbit leaf crumple virus (CuLCrV), cucurbit chlorotic yellows virus (CCYV), cucurbit yellow stunting disorder virus (CYSDV), and squash vein yellowing virus (SqVYV)-was developed. To ensure the reliability of the assay, an internal gene control as the fifth target to monitor false-negative results was incorporated. This newly developed molecular diagnostic tool possesses several advantages. It can detect up to five desired targets from a single whitefly RNA sample, even at concentrations as low as 1 ng/μl. To evaluate its sensitivity, we conducted experiments using serially diluted cloned plasmids and in vitro transcribed RNA transcripts of the target viruses. We also assessed the specificity of the assay by including aphid-transmitted viruses and other viruses known to infect cucurbits. The diagnostic method successfully detected all five targets simultaneously and allowed for the quantification of up to 100 copies using a mixture of healthy RNA and in vitro transcribed RNA. Our aim with this study was to develop a highly specific and sensitive one-step multiplex RT-qPCR system for the simultaneous detection of viruses transmitted by whiteflies in cucurbits. This system offers significant advantages for early detection, enabling prompt control measures to mitigate the further spread of viral infections and reduce yield losses. Additionally, we demonstrated the ability to simultaneously detect mixed viruses (CCYV, CYSDV, CuLCrV, and SqVYV) in individual whiteflies and quantify the number of viral copies carried by each whitefly. The multiplex RT-qPCR assay outperforms currently available techniques for detecting many samples at a given time and can be effectively utilized for early monitoring of plant viruses in individual whiteflies and symptomless plants.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS09231964RE"},"PeriodicalIF":5.4,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141564060","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":"Pathotype Identification and Host Resistance Evaluation of Clubroot in Zhejiang Province, China.","authors":"Yi Zhang, Wenfeng Gong, Yingying Gao, Kun Zhao, Fangzhan Wang, Yapei Liu, Mei Zhang, Xiaolin Yu","doi":"10.1094/PDIS-12-23-2748-SR","DOIUrl":"10.1094/PDIS-12-23-2748-SR","url":null,"abstract":"<p><p>Clubroot, caused by <i>Plasmodiophora brassicae</i>, is a globally destructive soilborne disease affecting cruciferous plants. In this study, the predominant pathotypes of <i>P</i>. <i>brassicae</i> in six cities within Zhejiang Province were identified using the Williams and European clubroot differential (ECD) systems. A phylogenetic analysis of <i>P</i>. <i>brassicae</i> isolates infecting cruciferous crops worldwide was conducted using MEGA, and their ITS2 secondary structures were predicted through the ITS2 database. Accessions of <i>Brassica rapa</i>, <i>B</i>. <i>oleracea</i>, <i>B</i>. <i>juncea</i>, and <i>Eruca sativa</i> Mill. were employed to assess clubroot resistance. The results revealed that the prevalent pathotypes in Zhejiang Province were pathotype 1, ECD20/31/12 and ECD24/16/30; pathotype 3, ECD20/15/4; pathotype 8, ECD16/0/0 and ECD24/0/0; and pathotype 2, ECD16/15/15. Isolates from distinct genera of Brassicaceae formed separate branches in the evolutionary tree. Moreover, isolates of <i>Brassica</i> crops from Zhejiang Province exhibited homology with those from other global regions, a finding corroborated by their ITS2 secondary structure. Approximately 80 and 95% of <i>B</i>. <i>rapa</i> and <i>B</i>. <i>juncea</i> crops displayed susceptible phenotypes for pathotype 8, ECD16/0/0, whereas approximately 60% of <i>B</i>. <i>oleracea</i> crops exhibited resistance. Furthermore, three <i>Brassica</i> crop accessions showed significant variation in resistance to the pathogen, both among morphological and geographical origin groups. This study contributes to understanding the distribution of diverse <i>P</i>. <i>brassicae</i> pathotypes in different regions of Zhejiang Province and facilitates the identification of <i>Brassica</i> crops with potential disease resistance suitable for cultivation in the province.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS12232748SR"},"PeriodicalIF":5.4,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141856183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic Analysis of Stripe Rust Resistance in the Chinese Wheat Cultivar Luomai 163.","authors":"Zimeng Li, Chan Yuan, Shunda Li, Yu Zhang, Bin Bai, Fangping Yang, Pengpeng Liu, Wei Sang, Yong Ren, Ravi Singh, Pingan Liao, Caixia Lan","doi":"10.1094/PDIS-06-24-1195-RE","DOIUrl":"10.1094/PDIS-06-24-1195-RE","url":null,"abstract":"<p><p>Stripe or yellow rust (YR) caused by <i>Puccinia striiformis tritici</i> (<i>Pst</i>) is an important foliar disease affecting wheat production globally. Resistant varieties are the most economically and environmentally effective way to manage this disease. The common winter wheat (<i>Triticum aestivum</i> L.) cultivar Luomai 163 exhibited resistance to the <i>Pst</i> races CYR32 and CYR33 at the seedling stage and showed a high level of adult plant resistance in the field. To understand the genetic basis of YR resistance in this cultivar, 142 F₅ recombinant inbred lines (RILs) derived from cross Apav#1 × LM163 and both parents were genotyped with the 16K SNP array and bulked segregant analysis sequencing. The analysis detected a major gene, <i>YrLM163</i>, at the seedling stage associated with the 1BL.1RS translocation. Additionally, three genes for resistance at the adult plant stage were detected on chromosome arms 1BL (<i>Lr46/Yr29/Pm39/Sr58</i>), 6BS, and 6BL in Luomai 163, whereas Apav#1 contributed resistance at a quantitative trait locus (QTL) on 2BL. These QTL explained YR disease severity variations ranging from 6.9 to 54.8%. The kompetitive allele-specific PCR (KASP) markers <i>KASP-2BL</i>, <i>KASP-6BS</i>, and <i>KASP-6BL</i> for the three novel loci <i>QYr.hzau-2BL</i>, <i>QYr.hzau-6BS</i>, and <i>QYr.hzau-6BL</i> were developed and validated. <i>QYr.hzau-1BL</i>, <i>QYr.hzau-2BL</i>, and <i>QYr.hzau-6BS</i> showed varying degrees of resistance to YR when present individually or in combination based on genotype and phenotype analysis of a panel of 570 wheat accessions. Six RILs combining resistance alleles of all QTL, showing higher resistance to YR in the field than Luomai 163 with disease severities of 10.7 to 16.0%, are important germplasm resources for breeding programs to develop YR-resistant wheat varieties with good agronomic traits.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS06241195RE"},"PeriodicalIF":4.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141760236","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, Pathogenicity, and Fungicide Sensitivity of <i>Colletotrichum</i> Species Associated with Anthracnose on Italian Ryegrass in Southwestern China.","authors":"Lingling Xu, Zhiting Xu, Jiaqi Liu, Huawei Cui, Jiahui Long, Longhai Xue, Chunjie Li","doi":"10.1094/PDIS-01-24-0206-RE","DOIUrl":"10.1094/PDIS-01-24-0206-RE","url":null,"abstract":"<p><p>Italian ryegrass (<i>Lolium multiflorum</i> L.) is widely cultivated as an important forage grass worldwide because of its high nutritional value and good palatability. Anthracnose caused by <i>Colletotrichum</i> species was a common and new emerging disease of Italian ryegrass. In this study, 88 <i>Colletotrichum</i> isolates were collected from diseased leaves of Italian ryegrass planting regions in Sichuan, Chongqing, and Guizhou provinces of southwestern China between 2019 and 2022. By the pure culture technique, 15 representative single-spore isolates were obtained for further study. Multilocus phylogenetic analysis coupled with morphological features showed that these isolates were finally identified as six new record species: <i>C. cereale</i> of the <i>C. graminicola</i> species complex, <i>C. fioriniae</i> and <i>C. nymphaeae</i> of the <i>C. acutatum</i> species complex, <i>C. boninense</i> and <i>C. citricola</i> of the <i>C. boninense</i> species complex, and <i>C. nageiae</i>. Pathogenicity tests indicated that all species could induce anthracnose symptoms; of these, <i>C. cereale</i> was more invasive than other species, followed by <i>C. fioriniae</i>, <i>C. nageiae</i>, <i>C. citricola</i>, and <i>C. boninense</i>; <i>C. nymphaeae</i> was the weakest pathogenic species to Italian ryegrass plants (<i>P</i> ≤ 0.05). Fungicide sensitivity assays showed that iprodione, propineb, and oxime·tebuconazole had strong inhibitory effects on the mycelial growth of six <i>Colletotrichum</i> species; in addition, azoxystrobin and fludioxonil also significantly inhibited the mycelial growth of <i>C. nymphaeae</i> and <i>C. fioriniae</i>, respectively. These results provide the basis for the diagnosis and detection in the field, pathogen identification, and management of anthracnose on Italian ryegrass.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS01240206RE"},"PeriodicalIF":4.4,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141760237","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 paprika as a natural host plant for tomato chlorosis virus in Korea.","authors":"Hae-Ryun Kwak, Dong-Wan Kang, Hee-Seong Byun, Bongchoon Lee, Inyoung Han","doi":"10.1094/PDIS-08-24-1697-PDN","DOIUrl":"10.1094/PDIS-08-24-1697-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Paprika (&lt;i&gt;Capsicum annuum&lt;/i&gt; var. grossum (L.) Sendtn.), also called bell pepper or sweet pepper, is a valuable greenhouse crop that is mostly consumed as fresh fruit in Korea. In 2022, it was cultivated on 726 ha in Korea and 82,042 tons were produced (KOSIS, 2023). In April 2023, interveinal chlorosis and yellowing were observed on the lower and middle leaves of greenhouse paprika in Jinju and Haman, South Korea, and many whiteflies (&lt;i&gt;Bemisia tabaci&lt;/i&gt;) were present. The disease incidence was 30-40% on five farms (approximately 4.5 ha) in the two areas. The typical symptoms and presence of whiteflies in greenhouses indicated potential infection by the whitefly-transmitted crinivirus, tomato chlorosis virus (ToCV). Six samples collected from symptomatic plants were examined by leaf dip using transmission electron microscopy (TEM) and revealed filamentous virus particles about 800 nm long. To confirm the TEM results, six symptomatic paprika leaf samples were subject to RT-PCR using the specific primers ToCV-M-4F and ToCV-M-4R to detect ToCV (Choi, 2023). All tested samples were positive for ToCV. To confirm the presence of other viruses and obtain the complete genome sequences, one of the six ToCV-positive samples (ToCV-PAP-JJ6) was subject to high-throughput sequencing (HTS). Total RNA was extracted from symptomatic leaves using the RNeasy Plant Mini Kit (QIAGEN, Germany) and a transcriptome library was generated using the TruSeq Stranded Total RNA LT Sample Prep Kit (Illumina, San Diego, CA, USA) according to standard protocols. HTS was performed on an Illumina NovaSeq 6000 system (Macrogen, Korea). De novo transcriptome assembly of the 85,668,854 reads with Trinity software (r20140717) yielded 817,303 contigs of 201 to 38,987 nucleotides (nt). BLASTn and BLASTx analysis of the contigs against the NCBI viral reference database showed that three large contigs were virus sequences, two of which were homologous to ToCV-RNA1 and -RNA2 and one to bell pepper alphaendornavirus (BPEV). The ToCV-RNA1 (genome 8,594 nt, 11,212 mapped reads, mean read coverage 196.2 times) and ToCV-RNA2 (genome 8,242 nt, 40,122 mapped reads, mean read coverage 734.9 times) contigs showed 100% coverage and 99% base pair matching (8,583/8,594 and 8,233/8,242, respectively) with known genome sequences of ToCV-RNA1 (MG813908) and ToCV-RNA2 (KP114534) isolated from tomato in Korea (Lee et al. 2018). The sequences were deposited in GenBank as isolates ToCV-PAP-JJ6 RNA1 (OR865222) and ToCV-PAP-JJ6 RNA2 (OR865223). The BPEV contig (genome 14,728 nt, 2,928,519 mapped reads, mean read coverage 15,012.4 times) was detected at very high read depth and RT-PCR for BPEV confirmed that all six samples were coinfected with ToCV. BPEV was recently reported in paprika and red pepper in Korea (Jo et al., 2022). The BPEV-infected pepper cultivars have been reported not to produce any symptoms (Escalante & Valverde 2019). ToCV was first reported in tomato greenhouses in Korea in 20","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625837","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":"Virulence Determinants Are Unevenly Distributed Within <i>Streptomyces</i> Species and Strains Causing Potato Common Scab in the Province of Quebec, Canada.","authors":"Adrien Biessy, Mélanie Cadieux, Marie Ciotola, Renée St-Onge, Jochen Blom, Martin Filion","doi":"10.1094/PDIS-04-24-0744-RE","DOIUrl":"10.1094/PDIS-04-24-0744-RE","url":null,"abstract":"<p><p>Potato common scab is an important bacterial disease afflicting potatoes around the world. Better knowledge of the local <i>Streptomyces</i> spp. populations causing this disease is key to developing durable control strategies. In this study, we isolated 230 <i>Streptomyces</i> strains from scab-infected potato tubers harvested from commercial potato fields located across the province of Quebec, Canada. The genetic diversity of this collection was first studied using repetitive element-based PCR fingerprinting, and the genomes of 36 representative strains were sequenced using PacBio's sequencing technology. This enabled us to identify the strains to the species level, to study the distribution of previously characterized virulence-associated genes and clusters, and to explore the repertoires of putative plant cell wall-degrading enzymes. In parallel, the virulence of the 36 strains was evaluated using a potato tuber slice assay. The diversity was higher than previously reported, as 11 phytopathogenic species were found across the province. Among them, <i>S</i>. <i>scabiei</i> and <i>S</i>. <i>acidiscabies</i> were the most abundant as well as the most virulent. Strains belonging to these two species harbored numerous virulence determinants, including the thaxtomin biosynthetic gene cluster. By contrast, most weakly virulent strains lacked this cluster but harbored at least one known virulence determinant. The results obtained suggest that a higher number of virulence-associated genes and clusters in the genome of phytopathogenic <i>Streptomyces</i> spp. are associated with greater virulence. This study contributes to increasing the publicly available genomic resources of scab-causing <i>Streptomyces</i> spp. and expands our knowledge on the diversity and virulence of this important bacterial pathogen.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS04240744RE"},"PeriodicalIF":4.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141724161","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":"Comparison of rDNA-ITS Sequences, Vegetative Compatibility, Biological Characteristics, and Thifluzamide Sensitivity of <i>Rhizoctonia solani</i> AG-3 PT, TM, and TB Subgroup Isolates Collected from Potato and Tobacco in China.","authors":"Mengxiao Liu, Tianbo Liu, Yu Yang, Qian Li, Haiyan Mao, Xinchun Li, Fenglu Wang, Jingtao Zhao, Yuanhua Wu, Chong Zhang","doi":"10.1094/PDIS-07-24-1407-RE","DOIUrl":"https://doi.org/10.1094/PDIS-07-24-1407-RE","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Potato black scurf and tobacco target spot are significant agricultural diseases primarily caused by &lt;i&gt;Rhizoctonia solani&lt;/i&gt; AG-3, which is further classified into PT (potato type), TM (tomato type), and TB (tobacco type) subgroups, with the naming of these subgroups originally indicating their respective infection hosts potato, tomato, and tobacco. This study determined the subgroup classification of 129 &lt;i&gt;R. solani&lt;/i&gt; AG-3 isolates recovered from tobacco leaves exhibiting target spot disease in major tobacco-cultivating regions of China, as well as 80 &lt;i&gt;R. solani&lt;/i&gt; AG-3 isolates obtained from potato stem cankers and tuber sclerotia in Liaoning, Jilin, and Heilongjiang provinces, and Inner Mongolia autonomous region of China. Sequence analysis of the internal transcribed spacer (ITS) regions revealed that all potato isolates belonged to the &lt;i&gt;R. solani&lt;/i&gt; AG-3 PT subgroup, whereas the tobacco isolates were classified into TM and TB subgroups. Specifically, 51 strains from the northeast (Liaoning, Jilin, and Heilongjiang provinces) belonged to the TM subgroup, while the others belonged to the TB subgroup. Phylogenetic analysis indicated a closer relationship between AG-3 TM and AG-3 PT compared to AG-3 TB. Population genetic analysis highlighted distinct genetic variations among the subgroups, with the AG-3 TB subgroup isolates exhibiting fewer ITS1 variable sites and the AG-3 PT subgroup displaying a higher number of ITS2 variable sites. Furthermore, comparisons were made regarding macroscopic vegetative interactions, biological characteristics, pathogenicity to potato and tobacco, and susceptibility to thifluzamide among the three subgroups. The results indicated no macroscopic somatic interactions among the subgroups, with the highest frequency of somatic incompatibility observed within AG-3 PT, followed by AG-3 TM, and AG-3 TB. Additionally, the three subgroups differed in colony color, sclerotium morphology, production time, and distribution location on potato-dextrose-agar (PDA) medium, with AG-3 TM being the least likely to produce sclerotia. Regarding temperature, optimal growth conditions varied among the subgroups. Regarding pathogenicity, the AG-3 PT subgroup strains were more pathogenic on tobacco and potato stem bases compared to the AG-3 TB subgroup, whereas the AG-3 TB and TM subgroup strains were more pathogenic on leaves. Notably, AG-3 TM exhibited remarkable virulence towards both the stem base and leaves. The AG-3 PT subgroup strains exhibited the highest susceptibility to thifluzamide, with a susceptibility baseline of 0.037±0.013 mg·L&lt;sup&gt;-1&lt;/sup&gt;, followed by the AG-3 TM subgroup strains with a baseline of 0.111±0.034 mg·L&lt;sup&gt;-1&lt;/sup&gt;, and the AG-3 TB subgroup strains with a baseline of 0.137±0.035 mg·L&lt;sup&gt;-1&lt;/sup&gt;. This study contributes to a deeper understanding of the biology and etiology of the three subgroups of &lt;i&gt;R. solani&lt;/i&gt; AG-3, providing a valuable theoretical basis for the scientific control and","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625742","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 of Pine Ghost Canker in Southern California Urban Forests.","authors":"Marcelo I Bustamante, Karina Elfar, Carlos Carachure, Adam Adaskaveg, John N Kabashima, Christopher Shogren, Akif Eskalen, Shannon Colleen Lynch","doi":"10.1094/PDIS-08-24-1718-SR","DOIUrl":"https://doi.org/10.1094/PDIS-08-24-1718-SR","url":null,"abstract":"<p><p>Pine ghost canker is a recently described disease affecting multiple pine species in urban forests of Southern California. Symptoms include wedged cankers with irregular margins and cryptic discoloration on cross-sections of branches, which can lead to severe dieback and potentially tree death. In this study, we identified and characterized five <i>Neofusicoccum</i> species (<i>N. luteum</i>, <i>N. mediterraneum</i>, <i>N. parvum</i>, <i>N. stellenboschianum</i>, and <i>N. vitifusiforme</i>) as the primary etiological agents of pine ghost canker. These pathogens were consistently isolated from multiple symptomatic pine samples (<i>n</i> = 41) and identified by morphology and phylogenetic analyses using four DNA barcodes (rDNA ITS, <i>tef1</i>, <i>tub2</i>, and <i>rpb2</i>). Pathogenicity was confirmed on healthy branches of 15-year-old Monterey pines, where the five <i>Neofusicoccum</i> species, caused vascular lesions that were not significantly different in length. Secondary fungi (<i>Diaporthe</i>, <i>Diplodia</i>, <i>Neopestalotiopsis</i>, and <i>Pestalotiopsis</i> spp.) were also recovered from symptomatic tissues but did not cause vascular lesions in pathogenicity tests. The optimal temperature for mycelial growth of <i>N. luteum</i> and <i>N. parvum</i> was 30 °C, whereas for <i>N. mediterraneum</i>, <i>N. stellenboschianum</i> and <i>N. vitifusiforme</i>, it was 25 °C. All five species were able to resume growth at room temperature (20 °C) after showing no growth during a 7-day exposure to 5 °C and 40 °C. This study constitutes the first report of <i>N. luteum</i>, <i>N. stellenboschianum</i>, and <i>N. vitifusiforme</i> causing pine ghost canker in California. Environmental factors such as warmer temperatures, irrigation, and pest infestations are discussed as drivers of disease expression in pine trees. Management practices are also proposed.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625745","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":"Pathogen Composition and Fungicide Sensitivity in Rice Spikelet Rot Disease.","authors":"Jiaqi Chen, Xiping Cao, Xiaolong Fu, Mingguo Zhou, Changjun Chen, Xiu-Shi Song","doi":"10.1094/PDIS-09-24-1807-RE","DOIUrl":"https://doi.org/10.1094/PDIS-09-24-1807-RE","url":null,"abstract":"<p><p>Rice spikelet rot disease (RSRD) is an emerging threat to rice crops, with sporadic but severe outbreaks in China in recent years. The composition of its pathogenic fungi has not been consistently identified, and chemical control methods remain unclear. This study aims to characterize the pathogen species responsible for RSRD and develop effective control strategies. Regional variations in disease symptoms and pathogen compositions were analyzed, which led to the identification of six novel pathogens, including Fusarium tanahbumbuense, Alternaria gaisen, Curvularia verruculosa, Curvularia brachyspora, Curvularia muehlenbeckiae, and Curvularia hominis. The pathogenic composition of RSRD exhibited considerable variation across different latitudes within China. Specifically, Alternaria spp. predominated in the Heilongjiang and Liaoning Provinces. Whereas Fusarium spp. and Curvularia spp. were more prevalent in the Hainan and Fujian Provinces. In contrast, Fusarium spp. and Alternaria spp. were the dominant pathogens in the Anhui and Jiangsu Provinces. Furthermore, an assessment of the sensitivity of these predominant pathogens to four chemical compounds was conducted, which led to the identification of potential fungicides for effective disease control. This research provides valuable insights into the pathogenic profile of RSRD across different regions and offers strategic recommendations for fungicide-based management of the disease.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625751","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}