Plant disease最新文献

{"title":"Flutriafol Drench Provides Season-long Protection of Boxwood Plantings Pre-infected by <i>Calonectria pseudonaviculata</i> in the Mid-Atlantic.","authors":"T Michael Likins, Billy Davis, Patrick Anderson, Blake Gillis, Chuanxue Hong","doi":"10.1094/PDIS-12-24-2731-SC","DOIUrl":"https://doi.org/10.1094/PDIS-12-24-2731-SC","url":null,"abstract":"<p><p>Flutriafol drench application on March 7 without and with additional applications at 8- and 20-week intervals all consistently protected boxwood plantings pre-infected by Calonectria pseudonaviculata in two gardens in Richmond, Virginia through November 21. All drench applications were dosed at 2 ml product with 42% flutriafol and delivered in 250 ml solution per 30.5-cm shrub height in both gardens. While providing season-long protection, this drench dose also resulted in significant phytotoxicity on 30.5-cm tall 'Justin Brouwers' boxwood but not on English and common boxwood, which were 1.4 and 1.1 m tall, respectively. Once the phytotoxicity issue is resolved, only a single drench per year may suffice to protect boxwood plantings in the Mid-Atlantic, which would substantially cut the labor cost and minimize the health impacts commonly associated with current fungicide foliar sprays.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143543078","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":"Optimal use of insecticide against the small brown planthopper, <i>Laodelphax striatellus</i>, effectively reduces the damage caused by Rice stripe virus.","authors":"Takuya Shiba, Masahiro Hirae, Yuriko Hayano-Saito, Yasuo Ohto, Hiroshi Uematsu, Ayano Sugiyama, Mitsuru Okuda","doi":"10.1094/PDIS-08-24-1707-RE","DOIUrl":"https://doi.org/10.1094/PDIS-08-24-1707-RE","url":null,"abstract":"<p><p>Rice stripe virus disease is one of the most devastating diseases of rice (<i>Oryza sativa</i>) in East Asia. The causal virus, Rice stripe virus (RSV), is persistently transmitted by the small brown planthopper (<i>Laodelphax striatellus</i>, SBPH). Since there is no effective treatment once rice plants are infected with RSV, it is crucial to prevent RSV infection in rice to minimize the damage. This study evaluated the effect of SBPH control with insecticides applied to the nursery box at transplanting and/or sprayed in the field on RSV infection and yield loss. We found that insecticide application either to nursery boxes or in the field reduced the percentage of diseased plants, the magnitude of damage in diseased plants, and yield loss. The combination of nursery box and field insecticide applications was the most effective at controlling the disease as it provided seamless control of SBPH from transplanting to the initial panicle formation stage. The study results offer a detailed description of the process by which chemical control of SBPH reduces damage caused by RSV. We expect these findings to be useful in developing an integrated pest management system for RSV.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143557253","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 Caused by <i>Colletotrichum fructicola</i> on <i>Tetrastigma hemsleyanum</i> in China.","authors":"Youchao Dang, Meiqin Mao, Jingyi Xu, Fei Xu, Xiaoqing Zhang, Chuan Qi, Bo Zhu, Luping Qin","doi":"10.1094/PDIS-12-24-2728-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-12-24-2728-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Tetrastigma hemsleyanum in the family Vitaceae, is a rare and endangered medicinal plant endemic in China (Ji et al. 2021). In October 2024, leaf anthracnose was observed in Lishui city (118°96'E, 28°13'N), Zhejiang, affecting T. hemsleyanum plantings over an area of 5.3 × 103 m2. Disease incidence ranged from approximately 30 to 60%. Early symptoms were small circular or irregular brown spots of foliage, gradually expanding in size, then coalescing to form large irregular dark brown spots with grayish white centers causing leaves to senesce and resulting in plant death in severe cases. Leaf pieces (5×5 mm) from nine symptomatic leaves were surface disinfected with 75% ethanol for 30 s, 2.5% NaClO for 1 min, rinsed in sterile water three times, dried, placed on potato dextrose agar medium, and cultured in darkness at 28°C for 5 days. Five isolates (THP10 to THP14) were obtained by the hyphal-tip method from the nine leaves. The colonies were olivaceous to dark gray with white margins and cottony mycelium; reverse sides had black centers. Conidia were single, colorless, cylindrical, 13.37 to 17.89 × 3.91 to 5.73 μm (average 15.42 × 5.11 μm; n=50). The morphological characteristics of the isolates overlapped with those of Colletotrichum species within the C. gloeosporioides complex, including C. fiucticola (Weir et al. 2012). The internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), chitin synthase (CHS)，calmodulin (CAL), actin (ACT), and beta-tubulin 2 (TUB2) genes were amplified using ITS1/ITS4, GDF/GDR, CHS-79F/CHS-345R, CL1C/CL2C, ACT-512F/ACT-783R, and T1/Bt2b primer sets, respectively (Weir et al. 2012). Sequences were deposited in GenBank with accession Nos. ITS: PQ571715 - PQ571719; GAPDH: PQ593912 - PQ593916; CHS: PQ593906 - PQ593910; CAL: PQ593900 - PQ593904; ACT: PQ593894 - PQ593898; TUB2: PQ593918 - PQ593922. BLASTn analysis of THP10 sequences had highest matches to the type strain of C. fructicola ICMP 18581 with ITS sequences 100% identical (JX010165; 549/549 bp), GAPDH sequences 99% identical (JX010033; 267/269 bp), CHS sequences 100.00% identical (JX009866; 274/274 bp), CAL sequences 100% identical (JX009676; 731/731 bp), ACT sequences 99% identical (JX009501; 270/272 bp), and TUB2 sequences 100% identical (JX010405; 699/699 bp). A maximum likelihood phylogenetic tree was constructed with the combined sequences data sets using MEGA 11, and the five isolates clustered with C. fructicola (Weir et al. 2012). To test pathogenicity, five isolates of C. fructicola were evaluated, leaves on three healthy 6-month-old potted T. hemsleyanum seedlings were wounded with sterile needles and inoculated with 5 mm diameter mycelial plugs. Sterile PDA plugs served as controls. After inoculation, the plants were incubated at 28°C, 85% relative humidity, with a 12 h photoperiod. The experiment was repeated three times. Symptoms similar to those from the field were observed 21 days after inoculation, whereas control","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143557245","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":"Pyridaben as a novel fungicide against <i>Sphaerotheca fuliginea</i>, the causal agent of cucumber powdery mildew.","authors":"Jing Jin, Ge-Ning Song, Shuang-Ying Zhang, Jie Chen","doi":"10.1094/PDIS-11-24-2483-RE","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2483-RE","url":null,"abstract":"<p><p>Pyridaben is a novel broad-spectrum insecticide and acaricide that is effective against thrips, mites, aphids and leafhoppers. We accidentally discovered that pyridaben was able to prevent cucumber powdery mildew. In this study, we explored the inhibitory effects and underlying mechanisms of pyridaben against <i>Sphaerotheca fuliginea</i>. Pyridaben effectively inhibited the spore germination and mycelial growth of <i>S. fuliginea</i> with IC₅₀ of 10.83 mg/L and 18.28 mg/L, respectively. The spore germination, mycelial growth, and secondary spore formation of <i>S. fuliginea</i> was severely hindered on cucumber leaves treated with pyridaben at 20 mg/L. SEM revealed that the mycelia growing on pyridaben-treated cucumber leaves were much finer than that growing on untreated leaves. Transcriptomic analysis revealed that pyridaben had a significant impact on the ribosomal function and energy metabolism of the powdery mildew pathogen, restricting its normal physiological activities. In field experiments, the efficacies of pyridaben reached 76.48% in Zhejiang province and 78.40% in Shandong province at the rate of 225 g a.i./ha after two applications, which were comparable to the commercialized fungicides. These results suggest pyridaben is not only an insecticide but also an effective fungicide with the potential for further application in preventing and controlling cucumber powdery mildew.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143543080","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>Diaporthe pescicola</i> causing leaf spot on tea (<i>Camellia sinensis</i>) in China.","authors":"Yongtian Zhao, Hong Wang, Taifeng Huang, Ruixing Wang, Li Yang, Yuxin Yang, Lingyu Yang, Fen Wang, Xing'e Wang","doi":"10.1094/PDIS-01-25-0119-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-01-25-0119-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Duyun Maojian Tea mainly cultivated in Duyun City is one of the ten famous teas in China. A brown leaf spot was discovered in March 2023 in Qiannan Normal University for Nationalities' Maojian Tea experimental field (26.29°N, 107.52°E). The incidence of the disease is about 40% surveyed on about 300 m2 of tea plants. Infected leaves showed light brown, round or irregular lesions. With disease progression, they enlarged and merged, creating dark brown necrotic zones along leaf edges. To identify the responsible pathogen, three symptomatic leaves from the tea nursery base were collected. The samples were cut 3 mm x 3 mm tissues with 75% ethanol for 30 s and 5% sodium hypochlorite for 60 s, rinsing three times with sterile water. Tissues were taken to potato dextrose agar (PDA) medium and incubated dark at 28 °C for 3 days. Three isolates (TF1, TF3 and TF5) with similar morphology were obtained from three samples, respectively. The colony showed white, with short, villous hyphae expanding radially. Notably, mycelium near the disc was erect and sparse 2 cm away. After 30 days, conidia were observed. Alpha conidia (5.9 to 8.6 μm × 2.0 to 2.8 μm (n = 50)) were colorless and transparent, no septum, ellipsoid to spindle-shaped. Beta conidia (11.1 to 25.3 μm × 1.0 to 1.8 μm (n = 50)) were transparent, no septum, filiform, hooklike, tapering towards the ends. The isolates were identified as Diaporthe pescicola based on the morphology (Zhang et al. 2022). Genomic DNA was extracted, the internal transcribed spacer region (ITS), β-tubulin (tub2), and translation elongation factor 1-alpha (TEF) genes were amplified with primer pairs ITS1/ITS4 (White et al. 1990), Bt2a/Bt2b (Glass and Donaldson 1995), and EF1-728F/EF1-986R (Carbone and Kohn 1999), respectively, and sequenced. The ITS (PQ163865, PQ685064 and PQ685065), tub2 (PQ197032, PV055438 and PV055439), and TEF (PQ197029, PV055440 and PV055441) sequences of isolates (TF1, TF3 and TF5) were deposited in GenBank, respectively. BLAST searches showed &gt;97% nucleotide identity to sequences of D. pescicola MFLUCC 16-0105 (ITS, 98.40% to KU557555.1; tub2, 97.40% to KU557579.1; and TEF, 97.63% to KU557623.1). The phylogenetic tree of ITS, tub2, and TEF gene sequences was constructed using MEGA 6 software with the neighbour-joining method (NJ), and the bootstrap method was employed for 1,000 repeated tests. Isolates TF1, TF3, TF5, and D. pescicola DT 1-1 were grouped together in a node with a bootstrap value of 99. Isolates were identified as D. pescicola. Since large quantities of conidia are difficult to produce in cultures, pathogenicity on the wounded leaves of 5-year-old tea plants of Duyun Maojian Tea local population was conducted by inoculating 6 mm mycelium discs of TF1. The control group and the treatment group were inoculated with 3 tea plants, repeated 2 times. All tea plants were incubated at 25 ± 1 °C, 70% humidity, and natural daylight. The onset of symptoms appeared 7 days later. Lesions were br","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143543048","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>Pseudomonas syringae</i> pv. <i>atrofaciens</i> Causing Leaf Spot to barley (<i>Hordeum vulgare</i>) in the Republic of Korea.","authors":"Sang-Min Kim, Young-Mi Yoon, Yang-Kil Kim, Jong-Ho Park, Su Jwa Seo, Jieun Lee","doi":"10.1094/PDIS-09-24-1987-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-09-24-1987-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Barley &lt;i&gt;(Hordeum vulgare&lt;/i&gt; L.) is one of the staple food in the Republic of Korea, with 68,000 metric tons produced on 24,000 ha in 2022 (Ministry of Agriculture, Food and Rural Affairs 2023). In April 2018, leaf spots with brownish black edges were observed on barley leaves at the early tillering stage in the field of 1,100 m&lt;sup&gt;2&lt;/sup&gt; at Iksan-si (35°56'21.4\"N 126°55'56.5\"E), with an incidence of 5%. Early symptoms on the leaf appeared as small, dark brown to black spots, then enlarged to gray lesions with brownish-black edges. Leaf cuttings (5 x 5 mm) from three symptomatic plants were surface-sterilized with 70% ethanol for 1 min, followed by 1% hypochlorite for 1 min, then macerated in sterile distilled water. The macerates were streaked on Nutrient Agar (Difco, MD, USA) media and incubated at 28 °C in the dark for 2 days. After single colony isolation, three isolates from three different plants were designated as isolates Ik 510-1, Ik511-1, and Ik513-1, then deposited in the Korean Agricultural Culture Collection (https://genebank.rda.go.kr) under the accession numbers KACC 23555, 23556, and 23557, respectively. Bacterial colonies were circular, convex, and cream-colored on NA media and produced fluorescent blue-green pigment on King Agar B media (Millipore, Merck, Darmstadt, Germany). The morphology of the three isolates was identical and showed the same characteristics as &lt;i&gt;Pseudomonas syringae&lt;/i&gt; (von Kietzell and Rudolph 1997). Biolog Identification System (Biolog Inc., Calif., USA) and BLAST similarity of the 16S rRNA gene sequence (GenBank accession no. MK140998, MK140999, and MK141000, respectively) with the primer set of F27/R1492 (Heuer et al. 1997) showed that the three isolates belonged to the &lt;i&gt;Pseudomonas syringae&lt;/i&gt; species complex, and MLSA (multi locus sequence analysis) with partial sequences of &lt;i&gt;gltA&lt;/i&gt;, &lt;i&gt;gapA&lt;/i&gt;, &lt;i&gt;gyrB&lt;/i&gt;, and &lt;i&gt;rpoD&lt;/i&gt; genes (Hwang et al. 2005) showed that the three isolates were on the same clade with &lt;i&gt;Pseudomonas syringae&lt;/i&gt; pv. &lt;i&gt;atrofaciens&lt;/i&gt; LMG5095&lt;sup&gt;PT&lt;/sup&gt;. For confirmation, PCR with the primer set of Psat-F/Psat-R (Animal and Plant Quarantine Agency 2023) amplified the 477 bp amplicons of the target region, thus identifying them as &lt;i&gt;Pseudomonas syringae&lt;/i&gt; pv. &lt;i&gt;atrofaciens&lt;/i&gt;. To determine the pathogenicity to barley, bacterial suspensions (O.D.&lt;sub&gt;600&lt;/sub&gt;=0.1 in PBS, phosphate buffered saline) of the three isolates was infiltrated at approx. 0.05 ml into leaves of three 2-week-old plants 'Keunalbori1ho' grown in pots using a needless syringe, while PBS was infiltrated as negative control, respectively. Infiltrated plants were grown in a growth chamber at 25℃ with a 16-h/8-h light/dark cycle. 5 days after inoculation, the infiltrated areas showed water-soaked symptoms, then dried to gray with characteristic brown-black edges only on leaves infiltrated with bacterial suspension and no symptoms on leaves infiltrated with PBS. The pathogenicity test was ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143543051","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>Ralstonia pseudosolanacearum</i> phylotype I sequevar 14 causing bacterial wilt on tomato (<i>Solanum lycopersicum</i>) and eggplant (<i>Solanum melongena</i>) in North Carolina, USA.","authors":"Prem Magar, Alejandra I Huerta, Gilles Cellier, Frank Louws, Tika Adhikari","doi":"10.1094/PDIS-11-24-2377-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2377-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Ralstonia solanacearum species complex (RSSC) consists of three species, including R. solanacearum, R. pseudosolanacearum, and R. syzygii. The K60-type strain of R. solanacearum was isolated from a wilted 'Marglobe' tomato in Raleigh, North Carolina (NC) in 1953 (Kelman 1954). It is classified as phylotype IIA, sequevar 7 (Prior and Fegan 2005). In July 2023, during a field visit in Eastern NC, patches of &gt;50 eggplant (Solanum melongena cv. Pingtung Oriental) and tomato (Solanum lycopersicum cv. Saybrook) plants showing wilt symptoms were observed in a 1 ha field. Two plants from each host were collected from this site and tested positive for bacterial streaming in sterile deionized water for 2 min. One plant from each host was used for bacterial isolation by plating a 10 μl aliquot of the resulting bacterial streaming suspension on triphenyl tetrazolium chloride (TZC) medium (Kelman 1954) and incubated at 28°C for 48 hr. Multiple fluidal white colonies with a pink center and irregularly round morphology reminiscent of strains in the RSSC were observed on all plates. Only one colony from each plant host, NG-RL and EP-RL from tomato and eggplant, respectively, was selected for molecular characterization. Neither strain amplified the 357 bp band and was not R. solanacearum Select Agent (Opina et al. 1997). Genomic DNA from both NG-RL and EP-RL generated the 280 bp and 144 bp bands and confirmed as R. pseudosolanacearum phylotype I using the RSSC multiplex PCR (Fegan and Prior 2005). To determine sequevar, the primers Endo-F/Endo-R (Poussier et al. 2000; Fegan and Prior 2005) were used to sequence the partial endoglucanase (egl) gene from EP-RL and NG-RL (GenBank accessions: PQ554799 and PQ554800). These sequences were compared to publicly available egl sequences from GenBank and Cellier et al. (2023). A maximum likelihood phylogenetic tree showed that both NG-RL and EP-RL clustered with reference strains PSS81, MLI71-15, and Zo4 with 100% identity, confirming NG-RL and EP-RL are R. pseudosolanacearum phylotype I sequevar 14. To fulfill Koch's postulates, NG-RL and EP-RL inoculant was prepared from 48 h cultures grown on TZC plates at 28°C. Plates were flooded with sterile deionized water and then transferred to a falcon tube, adjusting O.D. 600 to 0.2 (~1×108 CFU/ml). The roots of six-week-old eggplants (cv. Black Beauty) and tomatoes (cv. Bonny Best) were wounded by running a scalpel through the soil 2 cm from the stem. This was repeated on six plants for both NG-RL and EP-RL. Mock-inoculated plants treated with sterile deionized water (SDW) served as controls. Plants incubated at 28°C in the greenhouse showed bacterial wilt symptoms nine days post-inoculation. R. pseudosolanacearum phylotype I sequevar 14 was confirmed from all bacteria-inoculated plants using the multiplex PCR and egl sequencing methods described above. No symptoms or bacteria were isolated from SDW mock-inoculated plants. There have been no prior reports of R. pseudosolan","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143543052","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 Alternanthera mosaic virus infecting <i>Pereskia aculeata</i> in Brazil.","authors":"Marcelo Eiras, Alexandre Chaves, Fernanda Padua Del Corona, Jandson José do Vale Guimarães, Vinicius Henrique Bello, Elliot W Kitajima, Pedro Luis Ramos-González","doi":"10.1094/PDIS-01-25-0057-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-01-25-0057-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Pereskia aculeata Miller is a climbing cactus, native to native to tropical areas of the Americas, whose leaves are used in cooking and folk medicine. Known as \"Barbados gooseberry\", \"leaf cactus\" and \"ora-pro-nóbis\" (OPN), it is considered an unconventional food plant, valued for its high protein and mineral content, offering sustainable healthy food options. In 2024, three OPN plants displaying ringspots, mosaic and leaf distortion were collected in a vegetable garden at the Instituto Biológico, São Paulo, Brazil. Elongated and flexuous particles were observed in negatively stained extracts from OPN symptomatic leaves under a transmission electron microscope (TEM). Ultrathin sections of these tissues revealed the presence of aggregates of elongated particles, presumably viral, and unknown crystalline structures in epidermal and mesophyll cells. RNA extracts were isolated using TRIzol® (ThermoFisher Scientific) and analyzed by high-throughput sequencing (HiSeq 2500 Technology, 2x150 nt paired-end reads, Illumina, San Diego, CA, USA). Bioinformatic analyses of the generated library (15.9 million row reads) revealed the complete genome (6,652 nucleotides, GenBank accession PQ650655) of an isolate of Alternanthera mosaic virus (AltMV, Potexvirus alternantherae) with a mean coverage of 14.000x. This Brazilian isolate, named AltMV_BR1, shared 94.7% nucleotide sequence identity with the genome of AltMV isolates detected in a phlox (Phlox stolonifera) plant identified in the state of Pennsylvania, USA (RefSeq NC_007731). For validation, RNA extracts from the original samples were tested by RT-PCR using primers (Potex5: 5'-CAYCARCARGCMAARTGAYGA-3'/ Potex1RC: 5'-TCAGTRTTDGCRTCRAARGT-3') designed to anneal in the RdRp gene of potexviruses (Van der Vlugt and Berendsen 2002). Amplified fragments (expected size of 735 bp) were sequenced (GenBank accession PQ811939) and the presence of the AltMV was confirmed. The host range of this isolate was evaluated by mechanical inoculation on several cactus species, including OPN, as well as indicator plant species previously described as hosts of AltMV. OPN plants showed mosaic and leaf distortion, whereas Pereskia grandifolia plants expressed local necrotic rings and systemic chlorotic rings. Dragon fruit (Hylocereus undatus) and orchid cactus (Epiphyllum sp.) plants were infected but remained asymptomatic. Necrotic local lesions were observed on Gomphrena globosa. Local chlorotic lesions were detected on Chenopodium amaranticolor and C. quinoa, which developed into systemic infections on plants of both species. Amaranthus viridis and Portulaca oleracea plants also developed infections, resulting in systemic chlorosis and leaf crinkling, respectively. The presence of the virus in these hosts, as well as in the original host, was confirmed with a specific polyclonal antiserum (kindly provided by Dr. J.E. Thomas, Queensland Horticulture Institute, Australia) against AltMV by PTA-ELISA and TEM through detection of","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143543074","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>Alternaria alternata</i> Causing Brown Leaf Spot of Potato in South India.","authors":"Shajith Basha Jaffer, Parthiban V Kumaresan, Iruthayasamy Johnson, Sambasivam Periyannan, Muthusamy Karthikeyan","doi":"10.1094/PDIS-10-24-2065-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-10-24-2065-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Potato (Solanum tuberosum L.), as one of the major food crops, is cultivated in both temperate and subtropical climatic regions worldwide. During the field survey conducted in December 2023, black to brown colored spots with dark brown to black margins were observed in the leaves of the potato cultivar Kufri Jyothi, grown annually to monitor pest and disease incidence at the Indian Council of Agricultural Research (ICAR) - Central Potato Research Institute (CPRI) Research Station, Ooty, Tamil Nadu, India (Latitude - 11.370796 N, Longitude - 76.664094 E, Elevation - 2110 m above mean sea level. As the disease progressed, the spots were scattered throughout the leaves and coalesced to form necrotic lesions. The disease incidence reached 40 - 45%, attributed by airborne inoculum spread. Tissues collected from the margin of the infected leaf (5 × 5 mm) were surface disinfected with 1% NaOCl for 1 min, 70% ethanol for 30 sec and rinsed with sterilized water for three consecutive times before incubation at 25 ± 1°C on the potato dextrose agar (PDA) medium for pathogen culturing. Five cultures were obtained through single spore isolation and denoted as PTAA-01 to PTAA-05. The colony morphology of all five isolates was identical, with a greyish-brown and black appearance on the upper and undersides of the Petri dishes. The mycelia were septate, light grey and had a geniculate brown conidiophore with a short conidial chain. Conidia were brown, short-beaked, obclavate to obpyriform in shape, one to six and zero to two transverse and oblique septa. The dimensions of the conidia (n = 50) are 18 - 53 x 9 - 14 (length × width) µm. Morphological characters of the pathogen were consistent with Alternaria alternata (Fr.) Keissl, described earlier by Simmons (2007). Genomic DNA was extracted from the representative isolate PTAA-01 using CTAB method (Murray and Thompson 1980). PCR was performed with primers ITS1 / ITS4 targeting internal transcribed spacer (ITS) sequence (White et al. 1990), gpd1/gpd2 for glyceraldehyde-3-phosphate dehydrogenase (GAPDH), PG3/PG2b for endopolygalacturonase (EndoPG), Alt a1F/Alt a1R for Alternaria major allergen gene and EF1-728F/EF1-986R for translation elongation factor (TEF) 1-α (Woudenberg et al. 2015). Amplified products were sequenced and deposited in NCBI GenBank with accession numbers; PP864706 (ITS), PP943430 (GAPDH), PP968830 (EndoPG), PQ031066 (Alt a1) and PQ031067 (TEF1-α) and all shared &gt; 99% identity with A. alternata (GenBank accession numbers: MN919390, KX226447, KP123997, OK040811, and MZ648042), respectively. A neighbour-joining phylogenetic tree was constructed based on concatenated sequences of ITS, GAPDH, EndoPG, Alt a1, and TEF1-α using MEGA 11, where PTAA-01 isolates formed a clade with the strain of CBS 916.96 of A. alternata. For pathogenicity test, the conidial suspension (106 spores/ml) prepared from 15 days old culture was spray inoculated on one-month-old potato cultivar Kufri Jyothi in triplicates ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143543047","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":"Vascular Streak Dieback: A Novel Threat to Redbud and Other Woody Ornamental Production in the United States.","authors":"Prabha Liyanapathiranage, Farhat A Avin, John Bonkowski, Janna L Beckerman, Michael Munster, Denita Hadziabdic, Robert N Trigiano, Fulya Baysal-Gurel","doi":"10.1094/PDIS-04-24-0905-FE","DOIUrl":"10.1094/PDIS-04-24-0905-FE","url":null,"abstract":"<p><p>Eastern redbud (<i>Cercis canadensis</i> L.) is a popular and high-value woody ornamental plant native to the Eastern and South Central United States. In recent years, redbud production in the Southeastern United States has been greatly affected by a novel threat: vascular streak dieback (VSD). Infected plants exhibit a common set of symptoms, including leaf scorch, tip dieback, and vascular streaking that creates a marbled pattern in stem cross-section. Based on both conventional diagnosis and molecular identification, it has been found that the fungus <i>Ceratobasidium</i> sp. D.P. Rogers (<i>Csp</i>) is consistently associated with VSD-symptomatic eastern redbuds. However, the causal agent(s) of VSD has not yet been conclusively confirmed. Although eastern redbud has been the most frequently identified host tree, more than 25 other native plant genera have been confirmed to have VSD associated with <i>Csp</i>. The near-obligate nature of this fungus has made it challenging to culture, extract DNA, and conduct further studies to confirm its pathogenicity. This article highlights the emerging challenges of VSD, focusing on the following: (i) the recent history of VSD; (ii) the increasing importance of VSD to woody ornamental nursery production in the United States; (iii) the currently available protocols for isolating, culturing, storing, and maintaining the putative causal agent; (iv) the rapid molecular detection of <i>Csp</i>; (v) phylogenetic findings on the origin and relatedness of <i>Csp</i> to previously recorded diseases, especially VSD in cacao (<i>Theobroma cacao</i> L.); and (vi) preliminary results and observations from fungicide trials and cultivar screening in Tennessee. The article also outlines research needed to comprehensively understand VSD and accelerate the development of effective management strategies.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS04240905FE"},"PeriodicalIF":4.4,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141907401","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}