Plant disease最新文献

{"title":"Use of commercial fertilizers in an IPDM protocol to mitigate Olive Quick Decline Syndrome caused by <i>Xylella fastidiosa</i> subsp. <i>pauca</i> in Southern Italy.","authors":"Carmine Del Grosso, Maria Saponari, Pasquale Saldarelli, Davide Palmieri, Giuseppe Altamura, Raied Abou Kubaa, Filippo De Curtis, Giuseppe Lima","doi":"10.1094/PDIS-08-24-1770-RE","DOIUrl":"https://doi.org/10.1094/PDIS-08-24-1770-RE","url":null,"abstract":"<p><p>Management of <i>Xylella fastidiosa</i> subsp. pauca (<i>Xfp</i>) presents significant challenges due to the lack of genetic resistance in major crops, pathogen variability and resistance development against the main antimicrobial compounds, and the lack of effective chemical compounds for control. Traditional bactericides in the EU are restricted, and copper-based products are increasingly limited due to environmental impacts. In this study the antibacterial side effects of some commercial fertilizers against <i>Xfp</i> were evaluated. These products, containing metal ions (mainly copper and/or zinc) complexed with phosphites and bioavailable silicon, show antimicrobial and bactericidal activities <i>in vitro</i> which suggest their possible use to control the pathogen, as well as enhanced plant resistance to biotic and abiotic stresses. Greenhouse and open field trials showed that they can significantly reduce disease severity and pathogen population, thus improving fruit yield. The integrated pest and disease management (IPDM) strategy, which combines these treatments with agronomic and phytosanitary vector-control measures, leads to a reduction of disease symptoms in treated plants compared to untreated ones. These findings highlight the potential of systemic fertilizers to mitigate <i>Xfp</i> symptoms by providing antimicrobial collateral effects and probably enhance plant defenses, since similar compounds are known to be plant defense inducers in other pathosystems. Therefore, these products offer a sustainable solution for managing plant pathogenic bacteria and improving crop health and yield. This approach is crucial for the sustainability of olive production in <i>Xf</i>-affected areas. However, further research is needed to optimize these strategies for long-term effectiveness under field conditions. Overall, the results emphasize the value of the collateral effects of some mineral fertilizers in a comprehensive strategy aimed at mitigating the symptoms of <i>Xfp</i> and safeguarding the agricultural productivity as well as the invaluable heritage of centuries-old Apulian olive trees.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143374530","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":"<i>Nigrospora aurantiaca</i> caused leaf spot disease in Bayberry in Guizhou, China.","authors":"Sha-Min Fu, Ghulam Muhae Ud Din, Yong Wang, Yan Li","doi":"10.1094/PDIS-09-24-1971-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-09-24-1971-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Bayberry (Myrica rubra) is one of the most important fruit in China. In July 2023, circular leaf spots were noted on spring bayberry (cv. Dongkui Arbutus) tree planted in Guanshanhu, Guiyang, Guizhou, China (26°37'3\"N，106°39'59\"E). The disease incidence (diseased plants/total plants × 100) varied from 55 to 60% with 15 to 20% disease severity (diseased leaf area/total leaf area × 100). Disease incidence and severity were calculated from five infected fields of bayberry using by SPSS Statistics 22.0 (IBM Corp., NY, USA). The abundance of leaf spots on the trees was predominantly observed on the young leaves. Symptoms included round or irregular spots on leaves with grayish-red during early infection and later transferred to brown dark spots on the edge of the leaves, accompanied by a pale yellow aperture on the periphery. Sixty diseased leaves (three leaves from each diseased plant) from twenty plants (four plants from each infected field) in the same growth period were collected randomly and cut into small pieces (2 mm × 2 mm), disinfected with 75% alcohol for 30 s and with 1% NaClO for 60 s and rinsed 3 times with ddH2O. The diseased tissues were plated on PDA plate having Streptomycin and then incubated at 25 ˚C for 2 d under 16: 8 h light and dark regime. The single hypha was picked from plates and transferred to a new PDA plate having Streptomycin for purification. Sixty five pure cultures were obtained through single spore isolation and purification. After ITS-BLAST, the results indicated that among the cultures, sixty were Nigrospora sp. (92.31%), two were Flavodon sp. (3.07%) and three were Aureobasidium sp. (4.62%). Thus, the detection rate of Nigrospora sp. was the highest. From sixty obtained isolates with same morphological characters, six isolates (GUCC 23-0016, GUCC23-0017, GUCC23-0018, GUCC24-0244, GUCC24-0245 and GUCC 24-0246) were selected for pathogenicity and identification. Conidia (n = 40) were black, oval or round, smooth and size range was 11-16 × 12-14.5 µm in diameter. Based on disease symptoms and morphological characters, the pathogen was primarily recognized as a Nigrospora sp. (Wang et al. 2017). PCR was performed for each of the six isolates to amplify the internal transcribed spacer (ITS), the large subunit rDNA (LSU), β-tubulin 2 (tub2) and translation elongation factor 1-alpha (tef1) genes with primers sets of ITS4/ITS5 (Innis et al. 1990), LR0R/LR5 (Vilgalys & Hester 1990), Bt2a/Bt2b (Glass and Donaldson 1995), EF1-728F/EF-986R (Carbone and Kohn 1999), respectively and then PCR products were sequenced. GenBank accession numbers are OR647487, OR647489, OR647490, PQ803982, PQ803983 and PQ804003 for ITS, PQ351182, PQ351183, PQ351185, PQ805435, PQ804004 and PQ805436 for LSU, OR670516, OR670517 OR670518, PQ807000, PQ807001 and PQ807002 for tub2 and OR725093, OR725094 , OR725095, PQ807003, PQ807004 and PQ807005 for tef1. The BLAST results showed that DNA sequences of the present isolates were 100% identical to the","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143256282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First report of <i>Fusarium falciforme</i> and <i>Fusarium pernambucanum</i> causing root and stem rot on papaya plants in Brazil.","authors":"Jarlan Lucas Santos Silva, Elisandra Alves Bento, Ana Paula de Moura, Tatianne Raianne Costa Alves, Igor Vinícius Pereira da Silva, Juliano da Costa Fernandes, Silvan Manoel da Silva Filho, Vitória Maria Gomes Souza, Washington Luis da Silva, Márcia Michelle Queiroz Ambrosio","doi":"10.1094/PDIS-08-24-1621-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-08-24-1621-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Papaya (Carica papaya L.) is one of the major fruit crops of northeast Brazil, with an average annual production of 571,693 tons (IBGE, 2022). In August 2023, papaya plants (hybrid Tainung 01) in the production stage showed dark brown symptoms on roots and stems, wilt progression, and collapse of the plants (disease incidence of 20 - 50 % in sampled fields). Samples were collected from six production farms located in Apodi, Baraúna, and Caraúbas municipalities in Rio Grande do Norte state and Aracati in Ceará state. Small fragments of symptomatic tissues were surface sterilized sequentially in ethanol 70 % (1 sec), sodium hypochlorite 2.5 % (60 secs), and sterilized water. The fragments were placed in potato dextrose agar (PDA), supplemented with 0.05 % tetracycline, and incubated at 28° C with 12 hours of photoperiod for five days. Monosporic cultures were obtained from 10 isolates of Fusarium, characterized by morphology. The translation elongation factor 1 alpha (EF-1α) and the second largest subunit of RNA polymerase (RPB2) genes were partially amplified by PCR and sequenced from all isolates - the sequences were deposited in GenBank (PP723773.1 - PP723792.1). Maximum-parsimony tree was built in the Software MEGA (Version 11.0.10) (Tamura et al. 2021) with the concatenated partial sequences. The species were morphologically characterized in PDA (10 days), Spezieller Nährstoffarmer agar (SNA) (10 days), and carnation leaf agar (CLA) (30 days) (Leslie & Summerell, 2006). Phylogenetic analysis revealed that seven isolates are most closely related to F. falciforme (99 % bootstrap), and three isolates are most closely related to F. pernambucanum (99 % bootstrap). The morphological characters of the isolates correlated with the original descriptions of each species (Leslie & Summerell, 2006). Pathogenicity tests were performed on 45-day-old papaya seedlings (hybrid Tainung 01) using the infested soil method (Lefèvre & Souza, 1993). Autoclaved substrate was infested with fragments of PDA from each isolate colony and incubated for seven days to create the inoculum. Then, 36 g L-1 of inoculum was added to each pot, in which a papaya seedling was planted, and grown for 60 days under greenhouse conditions (33°C ± 5°). The experiment was conducted twice, each time five plants were inoculated with each isolate, and five plants were left uninoculated (mock). Symptoms on stems appeared 30 days after inoculation, while on roots it took 60 days. F. falciforme and F. pernambucanum caused identical symptoms in the field and in our pathogenicity test. No symptoms were observed on plants from the mock treatment. The pathogens were re-isolated from the necrotic tissue and re-identified, morphologically and through Sanger sequencing as described above, to fulfill Koch's postulates. Correia et al. (2013) reported the Fusarium solani species complex (FSSC) as the etiologic agent of stem rot in C. papaya in Brazil; however, they weren't able to identify the isol","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143256324","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 genotypes of citrus tristeza virus breaking resistance in sweet orange and clementine in Spain.","authors":"Ana Belén Ruiz-García, Antonio Olmos","doi":"10.1094/PDIS-11-24-2496-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2496-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Citrus tristeza virus (CTV) classified as Closterovirus tristezae within the genus Closterovirus, family Closteroviridae is broadly distributed in the major citrus-growing regions. CTV has eight main strains (genotypes or phylogenetic groups): T36, T30, T3, T68, VT, RB, HA16-5, and S1, that can induce different symptoms (Sun et al., 2024) with RB isolates being the only variants able to infect and spread within Poncirus trifoliata (Yokomi et al., 2017). In Spain, most isolates belong to the biologically mild T30 strain. Citriculture relies on CTV-resistant P. trifoliata rootstock and its hybrids to prevent virus-induced graft incompatibility. Only rarely, severe VT isolates inducing stem pitting on sweet orange have been reported (Moreno et al., 2008). From February to June 2023, citrus orchards in 4 areas in the Valencian Community were surveyed for monitoring circulanting strains. Five plants (3 sweet orange and 2 clementine trees) showing symptoms of tristeza disease and decline, grafted onto the resistant rootstock Carrizo citrange (Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.) were individually analyzed by high-throughput sequencing (HTS): sweet orange trees 137.4 in Moncada, 141.4 and 141.5 in Sagunto and clementine trees 142.13 in Nules and 152.7 in Burriana. Five leaves showing vein chlorosis and leaf cupping were pooled and analyzed per tree. Total RNA purified from leaf tissue was sequenced in a Novaseq 6000 platform using TrueSeq Illumina methodology with ribo-depletion. Bioinformatic analysis by CLC Genomics Workbench 10.1.1, according to Ruiz-García et al. (2019), allowed the recovery of 13 near full-length CTV genomes from different strains. Interestingly, 3 isolates belonged to the RB strain, 5 to the VT strain and 5 to the T30 strain. Sweet orange trees exhibited co-infections with CTV isolates from different strains: VT and T30 (OQ714508 and PQ576736) in 137.4; RB, VT and T30 (PQ538530, PQ576743 and PQ576742) in 141.4; and RB, VT and T30 (OQ848758, PQ576738 and PQ576737) in 141.5. In clementine trees CTV co-infections were also observed: RB, VT and T30 (PQ538529, PQ576740 and PQ576739) in 142.13; and VT and T30 (PQ576741 and PQ576744) in 152.7. BLASTn analysis showed that the RB isolates PQ538530 and OQ848758 belong to RB2 group, with the highest nucleotide identity of 99.63% (19198/19269 nt) and 99.62% (19197/19270 nt), respectively, to the isolate B390-5 (KU883265); whereas RB isolate PQ538529 belongs to RB1 group, with the highest nucleotide identity of 99.1% (19082/19255 nt) to the isolate B301 (JF957196). Supplementary Table 1 shows data from the HTS analysis, including additional viruses and viroids detected for which no association with the symptoms was established. The presence of the RB isolates found by HTS was confirmed by RT-PCR analysis and Sanger sequencing, using CTV-RB specific primers previously reported (Cook et al., 2016). In a survey of 147 citrus trees with tristeza symptoms across 7 orchar","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143256333","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":"<i>Septoria lamiicola</i> Causing Leaf Spot on <i>Lamium purpureum</i> in Korea.","authors":"Joon-Ho Choi, Bora Nam, Seong-Jin Lee, Young-Joon Choi, Hyeon-Dong Shin","doi":"10.1094/PDIS-12-24-2711-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-12-24-2711-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Lamium purpureum L. (purple dead-nettle), an annual herbaceous plant in the family Lamiaceae, is native to Europe and western Asia. It has become invasive in eastern Asia, including Korea and North America. Due to its rapid growth and tolerance of disturbed soils, it invades croplands and natural ecosystems, reducing crop yields (Mock et al. 2009). It also serves as an overwintering host for cucumber mosaic virus (Tomlinson et al. 1970). Leaf spots on purple dead-nettle were first observed in April 2022 in Gimje (35°43'10\"N, 127°00'42\"E) and in April 2023 in Jangsu (35°36'16\"N, 127°22'43\"E), Korea, with a disease incidence of 20-30% among surveyed plants. Symptoms were distinct, angular, pale brown to brown, and bordered by leaf veins. Numerous blackish conidiomata with cirriform conidial horns were visible on the spots. Conidiomata were numerous, scattered, pycnidial, amphigenous but abundantly epigenous, scattered, dark brown to rusty brown, globose, embedded in host tissue or partly erumpent, 60 to 110 µm in diameter, with ostioles measuring 28 to 56 µm in diameter. Conidiogenous cells lining the inner wall layer were hyaline and ampulliform. Conidia were filiform, straight or slightly curved, 32 to 48 × 2 to 3 µm, hyaline, 2 to 5-septate, but often 3-septate. Morphological descriptions were consistent with Septoria lamiicola Sacc. (Verkley et al. 2013). For monoconidial isolation, a conidial horn was collected, placed in a 1.5 ml tube containing sterile water, and streaked onto the surface of 2% water agar (WA). After four days, a hyphal tip was transferred to fresh potato dextrose agar (PDA). Colonies incubated for two weeks at 25°C on PDA were measured 10 to 15 mm in diameter, with a white to greyish at the center and a dark grey to black at the margin. Voucher specimens were deposited at the Korea University Herbarium (KUS-F32758 and F33612), and a representative culture was deposited at the Korea Agricultural Culture Collection (Acc. No. KACC 410468). Nucleotide sequences of the internal transcribed spacer (ITS), 28S rDNA (LSU), β-tubulin (TUB2), translation elongation factor 1-α (EF), actin (ACT), and RNA polymerase II second largest subunit (RPB2) genes were determined (Verkley et al. 2013) and deposited in GenBank (Accession Nos: PQ061283, PQ106849, PQ120989, PQ120981, PQ120994, and PQ120985). BLASTn search of the sequences showed 100% identity with the reference sequences of Septoria lamiicola CBS 102328 for ITS (KF251441.1), LSU (KF251945.1), ACT (KF253745.1), and RPB2 (KF252438.1). The TUB2 sequences showed 99.7% similarity (1/311 nucleotides different) with KF252913.1, and the EF sequences showed 96.0% similarity (13/368 different) with KF253389.1. In a phylogenetic tree reconstructed using the multi-loci sequences, the Korean isolate formed a well-supported group with reference isolates of S. lamiicola (Verkley et al. 2013). Pathogenicity was tested twice by spraying a conidial suspension (1×104 conidia/mL) harvested from a ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143256285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First Report of <i>Lasiodiplodia theobromae</i> Causing Wilt and Fruit Rot of Pepper in Hainan Province, China.","authors":"Lizhu Tang, Wentao Huang, Jiaqi Wang, Shaopeng Huang, Yu Liu, Maofu Li, Shun Feng","doi":"10.1094/PDIS-10-24-2161-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-10-24-2161-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Ornamental pepper (Capsicum annuum L.) is an economically important plant with extensive genetic diversity (Zhang et al. 2020). In September 2022, symptoms of wilt and fruit rot were identified in approximately 0.02 hectares of an ornamental pepper plantation in Haikou, Hainan Province, China (110°32' E, 20°06' N). Disease severity reached 85%, with an incidence rate of 90%. Symptoms started as black foliar spots that expanded into large lesions, spreading to fruits and stems, causing wilting (Fig. S1). Samples from symptomatic leaves, fruits, and stems of 27 plants were surface-sterilized with 75% ethanol for 30 s, rinsed five times with sterile water, air-dried, plated on potato dextrose agar (PDA), and incubated at 28°C for 5 to 6 days. To obtain pure fungal cultures, initial isolates were subcultured onto fresh PDA. Among the 27 fungal cultures, 11 isolates from leaves and fruits consistently formed gray to olivaceous colonies. Isolate LJY224 initially produced grayish-white, fluffy mycelia with radiating aerial hyphae. Over time, the colony became grayish-black and produced black, nearly spherical pycnidia. The conidia were oval, initially transparent, and single-celled. Mature conidia were dark brown, septate, with longitudinal striations, averaging 11.55 ± 0.75 µm in width and 24.93 ± 1.50 µm in length (n=35) (Fig. S2), indicating Lasiodiplodia spp. Genomic DNA was extracted using a fungal DNA extraction kit (OMEGA BIO-TEK, GZ Feiyang Biotech Co., Ltd., Guangzhou, China). Molecular identification involved sequencing the rRNA internal transcribed spacer (ITS) region and genes encoding β-tubulin (TUB) and translation elongation factor 1-α (TEF1) with primers ITS1/ITS4, Bt2a/Bt2b, and EF1-983F/EF1-2218R, respectively (White et al. 1990; Rosado et al. 2016; Rehner and Buckley 2005). BLASTn searches with the obtained ITS, TUB, and TEF1 sequences (GenBank accessions OQ612711, OR039814, OR039813) revealed 98% to 100% identity with Lasiodiplodia theobromae reference sequences from the NCBI database (OR018404, KR260830, MN461169), matching 541/548, 446/446, and 947/955 base pairs, respectively. A phylogenetic tree was constructed using concatenated multi-locus sequence analysis (MLSA) of ITS, TUB, and TEF1 (Fig. S3). To fulfill Koch's postulates, healthy 3-month-old ornamental pepper plants were inoculated by spraying the entire plant with a conidial suspension (50 ml, 107 conidia/L) of LJY224, using sterile water as a negative control. Each treatment included three replicates. Plants were maintained at 25°C, 75% humidity, under a 12-h light/dark cycle, and monitored daily. After 14 days, inoculated plants developed black foliar spots that expanded into large lesions, spreading to fruits and stems, and causing wilting, consistent with initial symptoms, while control plants remained healthy (Fig. S4). The re-isolated pathogen showed identical morphology to the original strain. In contrast, no fungi were isolated or recovered from the plants in","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143256331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First report of <i>Fusarium proliferatum</i> causing rhizome rot on <i>Polygonatum cyrtonema</i> in China.","authors":"Shan Zhong, Jian-Jun Qi, Rong Wang, Bin Wang, Jian-He Wei, Wan-Long Ding, Jing Yu, Yong Li","doi":"10.1094/PDIS-11-24-2310-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2310-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Polygonatum cyrtonema Hua (Asparagaceae) is a perennial herb widely distributed in China (Chen et al. 2021). The rhizome has antioxidant, anti-inflammatory, and immunomodulatory properties and is traditionally used to treat dizziness, diabetes, and asthma (Lu et al. 2023; Pang et al. 2022). About 3000 P. cyrtonema plants were planted in five fields at the Institute of Medicinal Plant Development (40.04°N, 116.28°E), Beijing, China, where rhizome rot was observed from June to October 2023, with an incidence rate of about 10%. Most cases occurred in low-lying, waterlogged fields. Initially, infected plants had no obvious aboveground symptoms but had brown spots on their rhizomes. In severe cases, plants exhibited aboveground withering and brown rot in rhizomes. A fungus was isolated from symptomatic plants (isolation rate 73%), and single spores were used to grow pure colonies on potato-dextrose-agar (PDA) and incubated for 5 d at 25°C in the dark. Eleven isolates with the same morphology were obtained. The upper surface of the colonies was white, with cottony mycelium and a light purple center. The lower surface of the colonies was hazel in the center. Two representative isolates, C76 and C78, were cultivated on carnation leaf agar medium. Microconidia of the isolates were aseptate, oval, elliptic or clavate, and their dimensions were 4.9 to 12.1 × 1.5 to 4.5 μm (n = 50). Macroconidia were long, slender and thin, rod-shaped or slightly curved, with one to five septa, and their dimensions were 15.3 to 44.9 × 2.7 to 4.5 μm (n = 50). The isolates were classified as Fusarium based on morphology (Leslie and Summerell 2006). To determine the species identity, we sequenced the translation elongation factor (TEF-1α) and partial RNA polymerase second largest subunit (RPB2) of two isolates (i.e., C76 and C78, GenBank access numbers: TEF-1α, PQ550044, PQ285402; RBP2, PQ550045, PQ285403, respectively) (Crous et al 2009) and compared them to other Fusarium species found at Fusarium-ID and GenBank databases. Both isolates exhibited 99.84% (TEF-1α, MT305203) and 100% (RBP2, LT841252) similarity with Fusarium proliferatum. The phylogenetic tree was constructed by combining TEF-1α, and RBP2 using MEGA6, and the two isolates clustered with F. proliferatum. To demonstrate pathogenicity, 2 mL of conidial suspension (1 × 106 conidia/mL) of the isolate of F. proliferatum designed C76 were dropped on the surface of four rhizomes without wounding. For the control, sterile water was applied on two control rhizomes. All treatments were repeated three times. Seedlings were grown at 25°C in moist soil. After 7 d, inoculated roots exhibited similar symptoms to those in the field, while control roots showed no symptoms. The same isolate was reisolated from diseased roots and was identified based on morphological characteristics, fulfilling Koch's postulates. Based on morphology and molecular biology, the isolates were identified as F. proliferatum, a ubiquitous pathogen ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143256325","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":"Host range and molecular characterization of the four races of <i>Fusarium oxysporum</i> f. sp. <i>lactucae</i>.","authors":"Muhammad Waqas, Giovanna Gilardi, Vladimiro Guarnaccia, Davide Spadaro","doi":"10.1094/PDIS-07-24-1505-RE","DOIUrl":"https://doi.org/10.1094/PDIS-07-24-1505-RE","url":null,"abstract":"<p><p>Vascular wilt of lettuce is caused by strains of the Fusarium oxysporum species complex. According to their biological activity, these strains are members of the forma specialis lactucae (FOL). The aim of this study was to characterize strains of Fusarium oxysporum isolated from lettuce in Italy and other countries, belonging to the four currently known races. Strains were analyzed based on pathogenicity on different hosts and a combined phylogenetic analysis of rpb2, tef-1α, cmdA and tub2 genes. For uncharacterized strains, the race was determined through pathogenicity test with a set of differential lettuce cultivars for races 1 and 4. To assess the host range, pathogenicity tests were performed on five species: lettuce (Lactuca sativa), lamb's lettuce (Valerianella locusta), spinach (Spinacia oleracea), wild rocket (Diplotaxis tenuifolia) and cultivated rocket (Eruca sativa). Most FOL strains were pathogenic on lettuce with different levels of disease severity; in particular, FOL races 3 and 4 showed the highest level of virulence on lettuce. FOL races 3 and 4 were pathogenic both on lettuce and lamb's lettuce, whereas races 1 and 2 only on lettuce. Furthermore, this study identified the first occurrence of FOL race 4 in Italy to 2016, as the strain FOL 1/16 was assigned to race 4. Results of multigene phylogenetic analysis showed that FOL races 1 and 4 cluster with the species F. curvatum, strains of race 2 with F. curvatum and F. odoratissimum and strains of race 3 with F. cugenangense. Phylogenetically, race 4 is very close to race 1, but it showed more similarities to race 3 for host range and virulence. This study shows for the first time a broader host range for the races 3 and 4 of FOL. The results demonstrate that phylogenetic analysis permits the separation of some races of FOL, but phylogenetic classification alone is insufficient for conclusive separation of races, therefore it should be accompanied by biological assays based on pathogenicity.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143190175","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 Needle Cast of <i>Cathaya argyrophylla</i> caused by <i>Neofusicoccum parvum</i> in China.","authors":"Hongjin Wei, JiaoJiao Lei, Cun Yu, Xuewen Wang, Run Luo, Mingyue Ou, Xiao-Li Wei","doi":"10.1094/PDIS-04-24-0920-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-04-24-0920-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Cathaya argyrophylla Chun et Kuang is a first-grade protected tree in China with significant conservation value. In June 2022, needle cast was observed in approximately 27 to 34% of C. argyrophylla (n=200, covering about 1 ha) at Dashahe National Nature Reserve (28.89° N, 107.6° E) in Daozhen County, Guizhou, China. Initial symptoms were small red lesions (3 to 5 mm in diameter) on needles. Over time, these lesions expanded, turned necrotic, and led to needle cast. In addition, the diseased needles exhibit brown spots surrounded by a yellowish discoloured area measuring 0.5 mm2. The disease is most severe in young trees, with over 60% of the needles displaying discoloration in 15% of young trees (n=100). Forty infected conifer tissues were randomly selected, surface sterilized, and incubated on PDA in the dark at 26°C for 5d. Among the 40 samples, 39 exhibited fungi with similar morphology. Single-spore isolation method was used to obtain pure cultures for 9 isolates. The isolates were morphologically identical. On PDA medium, colonies were white with abundant aerial mycelium. After 14 days of growth under light, the colonies became greyish black with septate mycelium. Conidia were hyaline, thin-walled, smooth-surfaced, and ranged from ellipsoid to ovoid in shape, measuring 6.5 to 15.2 ×2.0 to 3.1 μm (n=50). Based on these morphological characteristics, the isolates were identified as belonging to Neofusicoccum spp. (Pavlic et al., 2009). For molecular identification, genomic DNA was extracted from 3 selected isolates. The internal transcribed spacer (ITS) region was amplified using primers ITS1/ITS4 (White et al., 1990). In addition, chitin synthase 1 (CS1) was amplified using primers CT-WK3-S/CT-WK3-A (Zimoch et al., 2003). The ITS (OR710949) and CS1 (OR714767) sequences of isolate JY1-1 were deposited in GenBank, exhibiting a homology of 99% to 100% (537/538, 191/192) with N. parvum MUCC211 (accession numbers EU301017 and EU339495). The reconstructed phylogenetic tree further substantiated the genetic relationship between isolate JY1-1 and N. parvum. Consequently, the isolate associated with needle cast on C. argyrophylla was identified as N. parvum. Isolates JY1-1, JY1-2, and JY1-3 were used to confirm Koch's postulates. The needles of 15 healthy 2-year-old C. argyrophylla saplings were inoculated with a conidial suspension of N. parvum (2.0 × 105 conidia/mL). As a control, the needles of C. argyrophylla saplings were treated with sterile water (n=10). The needles were covered with Ziplock bags, and maintained at humidity levels exceeding 90%. All treatments were placed in a greenhouse at 26℃. After 7 days of inoculation, the needles exhibited a change in color, with reddish-brown symptoms observed on day 30 (disease rate=100%). Furthermore, the lesion expanded, and needles were shed after 4 months. No symptoms were observed in the control group. Pathogens reisolated from all diseased plants exhibited morphological and ITS sequence iden","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143190170","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>Curtobacterium flaccumfaciens</i> pv. <i>flaccumfaciens</i> the causal agent of bacterial wilt disease in bean plants (<i>Phaseolus vulgaris</i>) in The Netherlands.","authors":"Rita Volkers, Bo van Doorn, Jeroen van de Bilt, Peggy Gorkink-Smits, Manon Teunissen, Nathalie Blom, Marco Landman, Aron A L A M van Duijnhoven, Tijs van den Bosch, Michiel Pel, Robert Vreeburg, Tom Raaymakers, Maria Bergsma-Vlami","doi":"10.1094/PDIS-01-25-0172-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-01-25-0172-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff), a European quarantine organism, is the causal agent of bacterial wilt in several members of the Fabaceae family (Osdaghi et al., 2020). Recently, several Cff findings have been reported on the European continent (Tarakanov et al., 2022; EPPO 2022; EPPO 2024). In August 2024, following the Cff finding in an imported common bean seed lot, asymptomatic common bean plants were sampled from three fields in the Netherlands, ranging from approximately 0.5 to 4.8 ha in size, where the crop was cultivated for human consumption. Each sample consisted of 200 pieces of stem of 2-4 cm long. After short surface sterilization in 70% EtOH the pieces were crushed in a Stomacher bag and incubated in 50 mL 0.05 M phosphate buffer with 0.02% Tween 20 at 100 rpm at room temperature for 30 minutes. For bacteria isolation, 20 µL of the plant extract was plated onto YPG medium (5 g/L yeast extract, 10 g/L peptone, 5.5 g/L glucose, 15 g/L agar) and modified King's B medium (38 g/L Pseudomonas agar F, 10 g/L sucrose, 100 mg/L cycloheximide) by dilution plating. After incubation at 28 °C for 4 days, one typical colony (shiny, slimy, cream-colored) per sample was selected from the modified King's B medium for purification. For preliminary identification MALDI-TOF MS analysis was performed (Bruker, Germany) comparing the spectra of the three purified isolates with in-house made reference spectra of several C. flaccumfaciens (Cf) strains. The DNA of isolates that were identified as Cf was isolated by thermal lysis and used for identification at the pathovar level using the conventional PCR by Tegli et al. (2002). The genomes of these isolates, generated using Illumina sequencing (accession numbers JBKYKM000000000, JBKYKN000000000 and JBKYKO000000000) share between 96.0-97.3% average nucleotide identity (ANI) with the Cf type strain CFBP 3418 confirming they fall within the species boundary. Recently, yellow-pigmented Cf strains showed higher than 94 % ANI among themselves and with CFBP 3418 but below 94% ANI with members of the pink-/orange-/red-pigmented strains (Osdaghi et al., 2024). A pathogenicity test on Phaseolus vulgaris var. Ferrari plants, performed according to EPPO (2011), confirmed the virulence of these isolates. Per isolate, 7-8 out of 10 plants showed typical Cff symptoms at 7 dpi, including wilting and interveinal chlorotic areas in the leaves, similar to the positive control plants. Negative control plants remained asymptomatic. The isolates were successfully re-isolated from the inoculated plants and identified as Cff using the above mentioned methods. The diagnostic procedure followed justifies the classification of the three Cf isolates as Cff. This is the first confirmed report of Cff on common bean in the Netherlands. Eradication measures have been imposed on the fields from which plants tested positive, including destruction of the crop and crop remains, hygiene measures, and prohibition to ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143190095","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}