Plant disease最新文献

{"title":"Potential of the Small Molecules Piperidine and Pyrrolidine Against Copper-Resistant <i>Xanthomonas perforans</i>, Causal Agent of Bacterial Spot of Tomato.","authors":"Ketsira Pierre, Qingchun Liu, Mustafa Ojonuba Jibrin, Jeffrey B Jones, Shouan Zhang","doi":"10.1094/PDIS-04-24-0929-RE","DOIUrl":"10.1094/PDIS-04-24-0929-RE","url":null,"abstract":"<p><p>Bacterial spot of tomato (BST), caused by <i>Xanthomonas perforans</i>, is an economically important disease of tomatoes in Florida. Because of the heavy reliance on copper-based bactericides for control of BST, copper-resistant strains of <i>X. perforans</i> are widely distributed in Florida, leading to reduced efficacy of copper-based bactericides for disease control. There is a need for alternative chemical control strategies to effectively manage this disease in tomato production. In this study, two small molecules, piperidine and pyrrolidine, were evaluated for their efficacy against the copper-resistant <i>X. perforans</i> strain GEV 485 in laboratory, greenhouse, and field experiments. In in vitro experiments, piperidine and pyrrolidine at concentrations as low as 2 and 16 mg/liter, respectively, significantly (<i>P</i> < 0.001) reduced bacterial populations within 4 h of incubation compared with the untreated control, whereas Kocide 3000, the grower copper-based bactericide standard, at 0.9 and 2.1 g/liter (full label rate) did not significantly reduce bacterial populations. When tested as foliar sprays in the greenhouse, pyrrolidine at 128 mg/liter significantly (<i>P</i> < 0.001) reduced disease severity compared with the untreated control, with an equivalent efficacy to Kocide 3000 (copper hydroxide at 2.1 g/liter). Kocide 3000 at 1.0 g/liter, in combination with piperidine at 64 mg/liter and pyrrolidine at 64 and 128 mg/liter, significantly improved the efficacy in disease control compared with untreated controls and Kocide 3000 at 1.0 g/liter alone. In field trials, both small molecules demonstrated equivalent or superior efficacy to ManKocide (copper hydroxide + mancozeb) against <i>X. perforans</i> compared with the untreated control. This study demonstrated for the first time the potential of piperidine and pyrrolidine for controlling BST.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS04240929RE"},"PeriodicalIF":4.4,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142505830","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":"Nectriaceae Species Associated with Root Rot of Nursery and Young <i>Eucalyptus smithii</i> Trees in Uruguay with <i>Ilyonectria charruensis</i> as Novel Species.","authors":"Franco De Benedetti, María Julia Carbone, Pedro Mondino, Sandra Alaniz","doi":"10.1094/PDIS-05-24-1052-SR","DOIUrl":"10.1094/PDIS-05-24-1052-SR","url":null,"abstract":"<p><p>Forestry constitutes an important agronomical activity in Uruguay, involving the cultivation of exotic trees mainly for cellulose pulp production with <i>Eucalyptus</i> species<i>.</i> Over the last decade, <i>E. smithii</i> emerged as a species of interest for cellulose pulping. However, its rapid expansion has coincided with high mortality rates among young trees ranging from 5 to 85%, especially during the first and second summer after plantation. Disease surveys conducted on nine <i>E. smithii</i> commercial fields and three nurseries in southern and eastern Uruguay yielded a collection of 25 isolates from <i>E. smithii</i> root rot belonging to the Nectriaceae family. In this study, we aimed to identify and characterize these isolates employing phenotypical and molecular studies and to assess their pathogenicity on <i>E. smithii</i> seedlings. Based on morphological features, the Nectriaceae isolates were subdivided into two groups, one resembling <i>Calonectria</i> (<i>n</i> = 15) and the other <i>Cylindrocarpon</i>-like (<i>n</i> = 10). DNA sequences of the partial histone H3 (<i>his3</i>), actin, calmodulin, RNA polymerase II second largest subunit, translation elongation factor 1-alpha (<i>tef1</i>), and β-tubulin (<i>tub2</i>) genes were amplified for <i>Calonectria</i>, as well as partial <i>his3</i>, <i>tef1</i>, <i>tub2</i>, and internal-transcribed spacer and intervening 5.8S (<i>ITS</i>) gene regions for the <i>Cylindrocarpon</i>-like group. Based on phylogenetic analysis and phenotypical features, three species were identified and characterized: <i>Calonectria pauciramosa</i> (<i>n</i> = 15), <i>Dactylonectria novozelandica</i> (<i>n</i> = 2), and a novel taxon which we describe here as <i>Ilyonectria charruensis</i> sp. nov. (<i>n</i> = 8). The pathogenicity trials revealed that isolates from the three species significantly reduced both shoot and root dry weights of inoculated <i>E. smithii</i> seedlings compared with control plants.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS05241052SR"},"PeriodicalIF":4.4,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142351990","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 tobacco root rot caused by <i>Fusarium oxysporum</i> and <i>Fusarium solani </i>infection in Northeast China.","authors":"Yuzhe Wang, Jiaming Bai, Jianquan Zhou, He Huang, Haiyang Lan, Aiwei Qi, Shengchun Wang, He Liu, Yuanhua Wu","doi":"10.1094/PDIS-12-24-2562-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-12-24-2562-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Tobacco root rot caused by &lt;i&gt;Fusarium&lt;/i&gt; spp. infection results in significant losses to tobacco production. The disease is primarily prevalent in southern and central China, particularly in Fujian, Shandong, and Shanxi (Qiu et al. 2018). In July 2023, tobacco samples (n=10) exhibiting root rot symptoms were collected from Maodianzi Town (40.67°N, 124.62°E; cv. Liaoyan 21) and Qingyishan Town (40.68°N, 124.62°E; cv. Liaoyan 21) in Kuandian, Liaoning Province, China. The disease incidence in the surveyed fields reached approximately 60% to 70% based on the five-point sampling method. The symptoms exhibited blackening and rotting of the main root, stem base, and sparse fibrous roots. To isolate and identify the pathogen, the diseased tissues (2 × 2 mm) were cut from the edge of root lesions, treated with 75% alcohol rinsed with sterile water, and then incubated on potato dextrose agar (PDA) medium at 28 ℃. A total of 21 isolations were obtained through the single-spore isolation method. The experiment was conducted in a laminar flow cabinet and replicated three times. Two morphological types were observed among the colonies and spores of these strains. One type exhibited white, fluffy colonies. Large conidia were sickle-shaped, slightly rounded at both ends, and mostly had two to five septa (16.2×2.1 μm). Small conidia were spindle-shaped to ovate (8.2×2.3 μm) and generally had one septum (Qiu et al. 2024). Another type showed colonies with pink and slightly purple hues, and the spores were sickle-shaped, slightly curved spores with pointed somewhat ends, small conidia were mostly without septa or one septum (15.1×2.0 μm), and large conidia were unequally septate or sickle-shaped (39.4×4.2 μm), mostly with three to five septa (Sang et al. 1998). The mycelia of both fungal isolates had a small number of branches. Two isolates (GF11, GF12) were selected from two different morphologies, and subjected to DNA extraction using the CTAB method (Sagar et al. 2014). Sequencing analysis of the two strains was performed using the nuclear ribosomal internal transcribed spacer region (&lt;i&gt;ITS&lt;/i&gt;, GenBank accession no. PQ608542 and PQ608543), translation elongation factor (&lt;i&gt;TEF-1a&lt;/i&gt;, PQ671287 and PQ671288), and the second largest subunit of RNA polymerase II &lt;i&gt;(RPB2&lt;/i&gt;, PQ671289 and PQ671290) (O'Donnell et al. 2000, 2015). Upon comparison with NCBI database sequences, the &lt;i&gt;ITS&lt;/i&gt; and &lt;i&gt;EF-1α&lt;/i&gt; sequences of strain GF11 were found to exhibit a maximum homology of 100% with the corresponding sequences of &lt;i&gt;F. oxysporum&lt;/i&gt;, while the &lt;i&gt;RPB2&lt;/i&gt; sequence showed a maximum homology of 99.66%. For strain GF12, its &lt;i&gt;ITS&lt;/i&gt;, &lt;i&gt;EF-1α&lt;/i&gt;, and &lt;i&gt;RPB2&lt;/i&gt; sequences were determined to have maximum homologies of 100%, 99.72%, and 99.55% respectively with the corresponding sequences of &lt;i&gt;F. solani&lt;/i&gt;. According to Koch's postulates, GF11 and GF12 were used for pathogenicity testing. Nicotiana tabacum cv. K326 were cultivated at the 26°C growth cham","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143812125","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 Leaf Anthracnose on <i>Calathea orbifolia</i> Caused by <i>Colletotrichum siamense</i> in China.","authors":"Surapong Khuna, Sinang Hongsanan, Tanapol Thitla, Weiqian Meng, Ning Xie, Gang Liu","doi":"10.1094/PDIS-12-24-2723-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-12-24-2723-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Peacock plant (Calathea orbifolia [Linden] H. A. Kenn.) is grown in China as a valuable houseplant. In September 2024, leaf anthracnose was found on this plant in a field in Shenzhen (22°35'55\"N, 113°59'21\"E), Guangdong Province, China. The area investigated was ~900 m2 and included ~300 plants. Disease incidence was ~70% of 100 plants. Disease severity per plant was 20 to 60% necrotic lesions on the leaf. The initial symptoms were brown spots with a yellow halo. The spots enlarged, elongated, irregular, 0.5 to 9 × 0.2 to 4 cm, and leaves withered and died. Ten symptomatic leaves were collected for pathogen isolation. Small pieces (5×5 mm2) of lesion margins were surface sterilized in 1% NaClO for 1 min, 70% ethanol for 30 s, rinsed in sterile distilled water, placed on PDA, and incubated at 25°C. After 3 days, fungal colonies were purified on PDA using the single hyphal tip method. Three fungal strains (MBSZU 24-004 to MBSZU 24-006) with similar morphology were obtained from different plant samples with an isolation frequency of 75%. Colonies on PDA were white, 30 to 35 mm in diameter after 3 days at 25°C, then grayish white with cottony mycelia, the reverse pale yellow after 1 week. All strains produced asexual structures. Setae were dark brown, 43.2 to 169.4 × 2.1 to 4.3 µm, a cylindrical base, and an acuminate tip. Conidiophores were septate, hyaline to pale brown, and branched. Conidiogenous cells were hyaline, cylindrical to ampulliform, 10.3 to 32.3 × 2.2 to 4.4 µm. Appressoria were oval to irregular, dark brown to black, 6.2 to 18.9 × 5.7 to 10.1 µm. Conidia were one-celled, hyaline, smooth-walled, cylindrical, ends rounded, guttulate, 9.5 to 20.6 × 3.6 to 6.2 µm (n = 100). Morphologically, all strains resembled the C. gloeosporioides species complex (Weir et al. 2012). The ITS, ACT, CAL, CHS-1, TUB2, GAPDH, and ApMat genes were amplified using primer pairs ITS5/ITS4, ACT-512F/ACT-783R, CL1C/CL2C, CHS-79F/CHS-345R, T1/T22, GDF1/GDR1, and AMF1/AMR1 (Silva et al. 2012; Weir et al. 2012), respectively. Sequences were deposited in GenBank (ITS: PQ550808 to PQ550810; ACT: PQ558623 to PQ558625; CAL: PQ558629 to PQ558631; CHS-1: PQ558632 to PQ558634; TUB2: PQ558626 to PQ558628; GAPDH: PQ558635 to PQ558637; ApMat: PQ777471 to PQ777473). Maximum likelihood phylogenetic analyses of the combined seven genes identified all strains as C. siamense. To test pathogenicity, both wounded and unwounded healthy leaves were used in this experiment. All leaves were wiped with 0.1% NaClO and then rinsed with sterile water. Conidia suspensions (15 µl of 1 × 106 conidia/ml) of all three strains grown on PDA at 25°C for 2 weeks were placed on all samples using the attached leaf assay. Control leaves were mock-inoculated with sterile distilled water. Each treatment had 10 replicates and was repeated twice. Plants were placed at 25°C and 80 to 85% relative humidity. After 10 days, both wounded and unwounded inoculated leaves exhibited brown lesions with yellow","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143812124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic dissection of powdery mildew resistance in emmer wheat WL509 via bulked segregated RNA sequencing.","authors":"Yaoxue Li, Ningning Yu, Hongxing Xu, Lige Geng, Yanmin Qie, Xueqing Liu, Xusheng Sun, Jiangchun Wang, Qingguo Xin, Jiadong Zhang, Dongming Li, Lilong Jiang, Yuting Liang, Yuli Jin, Pengtao Ma","doi":"10.1094/PDIS-02-25-0366-RE","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0366-RE","url":null,"abstract":"<p><p>Emmer wheat (Triticum dicoccum, 2n = 4x = 28, AABB), as the ancestral species of common wheat, is a crucial gene donor for improving common wheat against powdery mildew, a destructive wheat disease worldwide. Cultivated emmer wheat accession WL509 exhibits broad and high level of resistance to powdery mildew. Using inheritance analysis, bulked segregated RNA sequencing (BSR-Seq) and molecular markers detection, we identified a dominant gene, tentatively designated PmWL509, and mapped it to 757.2-776.4 Mb interval on chromosome arm 2AL based on the reference genome of wild emmer (v2.0). PmWL509 was then mapped to the Pm4 locus using linked and diagnostic markers of Pm4. Homologous cloning and sequence alignment revealed that PmWL509 shares identical amino acid sequences with Pm4a but exhibits distinct resistance spectra and expression patterns. To explore potential regulatory mechanisms and key genes controlling resistance, 1,024 DEGs between resistant and susceptible bulks were annotated and analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. Six DEGs in the mapping interval and three pathogenesis-related (PR) genes were screened and evaluated by qRT-PCR when invaded by the Blumeria graminis f. sp. tritici (Bgt) isolate E09, and the result indicated that two DEGs TRIDC2AG078910 and TRIDC2AG081650 and two PR genes PR5 and PR9 could be considered to play a key role in the resistant pathway of PmWL509. The diagnostic marker JS717/JS718 was confirmed to be available for efficiently transferring PmWL509 into different wheat backgrounds.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143812126","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":"Viral Detection in Phalaenopsis Orchids Using High-Throughput Sequencing and One-step Multiplex RT-PCR.","authors":"Jing Huang, Ying Chen, Xiao Zhu, Chuan Li, Huazhen Hu, Jie Zhang, Jie Hu, Shanshan Zhao, Shuai Zhang, Qun Hu, Jianguo Wu, Jing Zou","doi":"10.1094/PDIS-11-24-2417-SC","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2417-SC","url":null,"abstract":"<p><p>Phalaenopsis orchids are highly valued ornamental plants but are susceptible to viral infections that significantly reduce their commercial value. Traditional detection methods for virus infecting phalaenopsis are limited in efficiency and scope. In this study, we employed high-throughput sequencing (HTS) to identify viruses present in 82 samples from three major phalaenopsis cultivars-'Ama' (Phalaenopsis amabilis), 'Haojili' (Phalaenopsis haojili) and 'Hongfuqitian' (Phalaenopsis hongfuqitian)-in Fujian Province, China. We identified six positive-sense single-stranded RNA (+ssRNA) viruses, including odontoglossum ringspot virus (ORSV) and tobacco mosaic virus (TMV), which are well-known to infect orchids, as well as four viruses not previously reported in phalaenopsis globally: tomato mottle mosaic virus (ToMMV), pepper mild mottle virus (PMMoV), plum pox virus (PPV) and tobacco etch virus (TEV). ORSV exhibited the highest detection rate at 86.59%, followed by TMV at 34.15%. The detection rates of ToMMV, PMMoV and PPV were 4.88%, 3.66% and 2.44%, with TEV having the lowest detection rate at only 1.22%. Co-infection was prevalent, with 37.80% of samples infected by two or more viruses. We designed specific primers and developed a one-step multiplex reverse transcription polymerase chain reaction (mRT-PCR) detection method optimized for these six viruses, achieving high specificity and efficiency. This method was validated using additional diseased samples, confirming its practicality for rapid virus detection. Our findings enrich the understanding of the phalaenopsis virome and within-host virus diversity and provide a valuable tool for early diagnosis and management of viral diseases, contributing to improved quarantine measures and control strategies in phalaenopsis cultivation.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143812142","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>Pectobacterium versatile</i> causing aerial stem rot on potato crops in Mexico.","authors":"Jose Luis Valdez-Lopez, Edel Pérez-López, Carlos Ignacio Mora Zamudio, Jesus Mendez-Lozano, Edgar Antonio Rodríguez-Negrete, Maria Elena Santos-Cervantes, Norma Elena Leyva-Lopez","doi":"10.1094/PDIS-02-25-0423-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0423-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;In February 2023, potato (Solanum tuberosum L.) plants (cv. Fianna) exhibiting symptoms of aerial stem rot (water-soaked and brown lesions on the stem) were observed in a field in the Guasave Valley, northern Sinaloa, Mexico with an incidence of approximately 40%. Ten symptomatic stem fragments from five diseased plants were disinfected, plated on crystal violet pectate (CVP) medium, and incubated at 28°C for 24 h (Hélias, 2012). Single colonies that formed cavities were selected for further analysis. Five representative isolates, showing biochemical and morphological characteristics consistent with Pectobacterium spp. (Palafox et al., 2024), were chosen. These characteristics included catalase activity, pectinolytic activity, Gram-negative bacilli morphology, absence of oxidase activity, and non-fluorescence on King's B medium. DNA extraction was performed according to the protocol of Chen and Kuo (1993), with minor modifications. The recombinase A (recA) gene was amplified by PCR using primers described by Waleron et al. (2002) for members of the former Erwinia genus. BLASTn results of the recA sequences obtained from the isolates (accession numbers: PQ788255-PQ788259) showed 100% identity and coverage with the Pectobacterium versatile type strain 14A (accession number: CP034276.1). Two isolates were selected as representatives for further analysis. Multi-locus sequence analysis (MLSA) of concatenated sequences (1789 bp) from the genes dnaX (PQ788260 and PQ788261), dnaJ (PQ788262 and PQ788263), and gyrB (PQ788264 and PQ788265) was conducted as described by Mainello-Land et al. (2024) on MEGA version 11 (Tamura et al., 2021), comparing sequences with those of Pectobacterium species type strains. Both isolates from northern Sinaloa clustered with the P. versatile 14A strain, supported by a bootstrap value of 100%, confirming their taxonomic identity as P. versatile. The pathogenicity of both isolates was evaluated by inoculating bacterial suspensions (10 mM MgSO₄, OD600 = 0.8, approximately 10⁸ CFU/mL) into the stems of 5-week-old potato plants (cv. Fianna). Three plants per isolate were inoculated, along with negative control plants, and plants treated with sterile 10 mM MgSO₄ as a separate control. The plants were maintained at 28°C with 80% relative humidity. Three days post-inoculation, symptoms of aerial stem rot-including decay, blackening, and tissue liquefaction-were observed in the inoculated plants, while the negative control and sterile solution-treated plants remained asymptomatic. To fulfill Koch's postulates, bacteria were re-isolated from symptomatic tissues as cavity-forming colonies on CVP medium. The identity of the re-isolated strains was confirmed by PCR using specific primers for P. versatile designed by Su et al. (2023). The experiment was performed in duplicates, and the results were consistent across replicates. To our knowledge, this study provides the first report of P. versatile as the causal agent of potato aeria","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143812123","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 fumigant and non-fumigant nematicides for <i>Belonolaimus longicaudatus</i> management in potato.","authors":"Zane Joseph Grabau, Chang Liu, Pablo A Navia Gine, Rebeca Sandoval-Ruiz","doi":"10.1094/PDIS-12-24-2626-RE","DOIUrl":"https://doi.org/10.1094/PDIS-12-24-2626-RE","url":null,"abstract":"<p><p>Belonolaimus longicaudatus (sting nematode) is a yield-limiting plant-parasitic nematode in Florida potato production. Fumigation using 1,3-dichloropropene (1,3-D) at 66 kg a.i./ha is a common practice for managing sting nematode, but effective alternatives are needed. Therefore, the objective of this study was to test the efficacy of alternative nematicides and nematicide rates against sting nematode in potato production. A preliminary field trial was conducted in 2022 followed by small plot field trials in 2023 and 2024 in northeast Florida. Treatments in repeated trials included preplant fumigation of 1,3-D at (1) 33, (2), 50, or (3) 66 kg a.i./ha; metam potassium at (4) 125 or (5) 293 kg a.i./ha; (6) a combination of 1,3-D at 33 kg a.i./ha and in-furrow oxamyl; in-furrow (7) oxamyl or (8) fluopyram; and (9) untreated control. Any treatment with fumigation reduced sting nematode population densities relative to untreated control at 6 weeks after planting, and, generally, at harvest. The common practice of 1,3-D at 66 kg a.i./ha remained the most consistent treatment for mitigating damage from sting nematode. 1,3-D at 50 kg a.i./ha or the combination of 1,3-D at 33 kg a.i./ha and oxamyl were consistently better than untreated control, but not as consistent at improving yield as 1,3-D at 66 kg a.i./ha. 1,3-D at 33 kg a.i./ha or metam potassium had inconsistent impacts on yield. Among metam potassium rates, 125 kg a.i./ha had similar efficacy as 293 kg a.i./ha, but was more cost effective. Standalone fluopyram or oxamyl did not improve sting nematode management. In summary, the common practice of 1,3-D at 66 kg a.i./ha was the most consistently effective treatment against sting nematode in potato, but other nematicide treatments also had efficacy.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143812067","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 karstii</i> Causing Anthracnose on <i>Stephania epigaea</i> in China.","authors":"Yimeng Li, Tong Xu, Jin Li, Jingyi Wang, Chunju Liu, Xian Dong, Jia Hong Dong, Pengzhang Ji, Lei Zhang","doi":"10.1094/PDIS-02-25-0297-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0297-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;The perennial herbaceous vine Stephania epigaea Lo, known as Di Burong in Chinese, is generally used as an anti-inflammatory and analgesic drug, as well as an ornamental plant (Dong et al., 2018). In May 2024, symptoms resembling anthracnose were observed on S. epigaea plants in an herbal nursery (33 m2, approximately 400 plants) in Kunming, Yunnan Province (24°33' 59.21\" N, 99°55' 43.71\" E), China, with an incidence rate of 75%. The disease initially occurred as small, round brown spots on the leaf margins, which later expanded into irregular lesions. The centers of these lesions were dark brown with yellow edges. To isolate and identify the pathogen, 0.5 × 0.5 mm sections of diseased leaf tissue were sterilized by dipping them in 75% ethanol for 30 s, then in 1% NaCIO for 180 s, followed by three rinses in sterile water. The samples were then cultured on potato dextrose agar (PDA) in the dark at 28 °C for 3 days. The fungal isolates were purified using the single-spore purification method, and 10 isolates with similar morphological characteristics were obtained. The colonies on PDA were initially white, changing to a grayish-white color over time. The ascomata were dark brown, spherical, and either on the surface or partially immersed in the PDA. The conidiophores were smooth, septate, branched, and hyaline to light brown. The conidia were cylindrical, aseptate, hyaline, and smooth, with dimensions of 10.0 to 16.7 × 5.2 to 6.9 μm (average 13.5 × 6.0 μm, n = 30). A 24-hour slide culture (Cai et al., 2009) of the conidia suspension revealed solitary appressoria that were light to dark brown, nearly spherical to oval, and smooth-walled to undulate, with dimensions of 6.8 to 10.5 × 4.7 to 10.0 μm (average 8.7 × 6.7 μm, n = 30). To further characterize the pathogen, isolate SeF03 was randomly selected for further testing. Total genomic DNA was extracted using the cetyl trimethylammonium bromide method, and the nuclear ribosomal internal transcribed spacers (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), histone 3 (HIS3), actin (ACT), and calmodulin (CAL) genes were amplified using the primer pairs ITS1/ITS4 (White et al., 1990), gpd1/gpd2 (Berbee et al., 2019), CYLH3F/CYLH3R (Crous et al., 2006), ACT-512F/ACT-783R (Carbone and Kohn, 1999), and CL1C/CL2C (Weir et al., 2012), respectively. BLASTn homology search showed that the ITS (PQ963009), GAPDH (PV021394), HIS3 (PV021395), ACT (PV021396), and CAL (PV021397) sequences of SeF03 were 100, 98.81, 100, 98.15, and 100% identical to Colletotrichum karstii strain CBS 128500 (JQ005202, JQ005289, JQ005463, JQ005550, and JQ005723), respectively. A phylogenetic tree of Colletotrichum species was built based on concatenated nucleotide sequences of ITS, GAPDH, HIS3, ACT, and CAL using the maximum likelihood method with the Tamura-Nei model. SeF03 and C. karstii clustered on the same branch. Morphological and molecular characteristics also confirmed that SeF03 was identical to C. karstii. Pathoge","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143812122","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":"Assessment of seed treatments for management of pathogens causing seed rot, seedling damping-off, and seedling root rot in alfalfa (<i>Medicago sativa</i> L.).","authors":"Leta Larsen, Melinda R Dornbusch, Carla Hines-Snider, Deborah Samac","doi":"10.1094/PDIS-05-24-1147-RE","DOIUrl":"https://doi.org/10.1094/PDIS-05-24-1147-RE","url":null,"abstract":"<p><p>Seed rot and damping-off of alfalfa (Medicago sativa L.) is caused by a soilborne disease complex resulting in thin initial stands of plants with continuing damage during wet soil conditions decreasing forage yields and winter survival. Apron (metalaxyl) and Apron XL (mefonoxam) have been used on alfalfa seeds for decades to reduce damping-off and early season root rot. Although several other anti-oomycete (oomicide) and fungicides are labeled for use on alfalfa seeds, there is little information on their efficacy against specific pathogens or the disease complex. Our objective was to test chemical seed treatments to identify those with broad antimicrobial activity to aid in establishing alfalfa stands where pathogen complexes are present. First, 10 products were tested for mycelial growth inhibition of nine alfalfa pathogens. The two most promising, EverGol Energy and Intego Solo, were active against Globisporangium ultimum, Pythium irregulare, P. sylvaticum, P. paroecandrum, Aphanomyces euteiches, and Phytophthora medicaginis. Protection of seedlings in agar plate bioassays and infested soil assays against G. ultimum and Pythium species by EverGol Energy was like that of Apron XL, while Intego Solo was not effective. The Evergol Energy seed treatment provided modest protection in bioassays with A. euteiches and P. medicaginis for susceptible cultivars, although it did not improve protection for resistant cultivars. Combined seed treatments did not improve seedling health in single pathogen bioassays or experiments with naturally infested field soil with multiple pathogens. Seed treatments with Apron and Apron XL were the most effective in providing partial protection against the disease complex in field soil. These results suggest that greater resistance is needed for managing the disease complex.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143812062","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}