Plant disease最新文献

{"title":"First Report of <i>Neopestalotiopsis rosae</i> Causing Leaf Spot on <i>Stephania epigaea</i> in China.","authors":"Yimeng Li, Tong Xu, Haiqiang Zhang, Fenglian Nu, Chunju Liu, Jia Hong Dong, Pengzhang Ji, Lei Zhang","doi":"10.1094/PDIS-04-25-0719-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-04-25-0719-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Stephania epigaea Lo is an herb of significant medicinal and ornamental value in China. In May 2024, leaf spot disease was observed on S. epigaea in the medicinal plant nursery base of Yunnan University of Chinese Medicine, Kunming, Yunnan Province, China (24°33'59.21\"N, 99°55'43.71\"E), with an incidence rate of 75%. The symptomatic leaves exhibited irregular brown lesions along the margins, surrounded by a yellow halo. To determine the causal agents, symptomatic leaf tissues (5 × 5 mm) were excised, surface-sterilized in 75% ethanol for 30 s, followed by immersion in 1% sodium hypochlorite (NaClO) for 180 s, and rinsed three times with sterile distilled water. The sterilized tissues were transferred onto potato dextrose agar (PDA) and incubated at 28°C in the dark for 3 d. Pure cultures were obtained using the single-spore purification method. A total of five single-spore isolates were obtained. The isolates exhibited white, cottony aerial mycelia with undulated colony margins. Conidia were fusiform and four-septate, with three versicolor median cells and hyaline apical and basal cells (17.3-26.8 µm long × 3.7-6.2 µm wide; n = 30). The apical cells bore two to three appendages (19.6-28. 6 μm long; n = 30), while the basal cells bore a single unbranched appendage. To further identify the fungus, isolate SeF01 was randomly selected for sequencing. The nuclear ribosomal internal transcribed spacers (ITS), large subunit ribosomal RNA gene (LSU), β-tubulin gene (TUB2), and translation elongation factor-1α (TEF-1α) regions were amplified and sequenced using primer pairs ITS1/ITS4 (White et al., 1990), LR0R/LR5 (Schoch et al., 2012), T1/T2 (O'Donnell and Cigelnik, 1997), and EF1-728F/EF1-986R (Carbone and Kohn, 1999), respectively. BLASTn homology analysis revealed that the ITS (GenBank accession no. PV363391), LSU (PV363539), TUB2 (PV384116), and TEF-1α (PV384117) sequences of isolate SeF01 exhibited 99.44-100% identity with Neopestalotiopsis rosae strain CBS 101057 (KM199359, KM116245, KM199429, and KM199523). A phylogenetic tree of Neopestalotiopsis species was built based on concatenated nucleotide sequences of ITS, LSU, TUB2, and TEF-1α using the maximum likelihood method. Isolate SeF01 clustered with N. rosae on the same branch. Morphological and molecular analyses confirmed that SeF01 was identical to N. rosae. To confirm pathogenicity of the isolate, conidial suspension with 1 × 106 conidia/mL was sprayed onto S. epigaea plants until runoff, while the control plants were sprayed with sterile distilled water. Two replicates (6 plants/replicates) were performed. All plants were incubated at 28℃ and 80% relative humidity with a 12 h light/12 h dark photoperiod. After 15 d, inoculated plants developed leaf spot symptoms, whereas control plants remained symptom-free. Fungal strains re-isolated from symptomatic leaves displayed morphological characteristics identical to SeF01. N. rosae has been reported to cause leaf spot on Fragaria × ananassa","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144079326","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 graminicola</i> Causing Maize Anthracnose in Austria.","authors":"Silvia Gutiérrez-Sánchez, Lucia Rodríguez-Mónaco, Clemens Langmaier, Riccardo Baroncelli, Michael R Thon, Ivica Buhiniček, Serenella A Sukno","doi":"10.1094/PDIS-03-25-0510-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-03-25-0510-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Colletotrichum graminicola causes maize anthracnose leaf blight and stalk rot. Stalk rot causes blackening of lower stalks, dark brown pith, and often leads to sudden plant death and lodging before grain maturity. As the infection progresses, the degradation of pith tissue weakens the plant's structural integrity, leading to lodging and significant economic losses (Wise et al., 2016). On October 14, 2024, maize stem samples displaying black, irregularly shaped lesions were collected from a cultivated field in Lipsch, southern Austria. Disease incidence in this field was estimated at approximately 1%, and severity ranged from 10% to 80%. Stem sections (~50 mm²) were excised, surface-disinfected for 90 s in 20% commercial bleach (v/v), and rinsed three times with sterile distilled water. The samples were then transferred to potato dextrose agar (PDA) Petri dishes supplemented with ampicillin (100 μg/ml) and lactic acid (1.5 ml/l) and incubated at 25°C for 2 days. Subsequently, fungal colonies were subcultured onto half-strength PDA medium and incubated for an additional 2 days before being transferred to PDA and grown for 10 to 15 days (Sukno et al., 2008). Individual spores were isolated and cultured on PDA for 6 days. Morphological characterization revealed dark gray aerial mycelium with orange-colored spore masses. One hundred conidia of each isolate were examined, revealing conidia that are falcate, slightly curved, and tapered at the tips, measuring 29.85 ± 2.62 × 6.13 ± 0.66 μm. These characteristics are consistent with the description of C. graminicola. Two isolates, AU-8423-4 and AU-8423-15, were selected for molecular analysis. They were grown in PDB at 25°C under light and agitation for three days. DNA extraction was performed using a modified CTAB method (Baek & Kenerley, 1998; Irfan et al., 2013). The internal transcribed spacer (ITS) region of rDNA and the manganese-type superoxide dismutase gene (Sod2) were amplified using the primers ITS4 and ITS5 (White et al., 1990) and SOD625/SOD507 (Fang et al., 2002) and consequently sequenced. BLAST analysis showed that the sequences were 100% identical to each other and to those of C. graminicola strains in GenBank, including that of strain M1.001 which is commonly used for molecular genetic studies. Phylogenetic analysis including closely related Colletotrichum spp. confirmed the clustering of AU-8423-4, AU-8423-15, and M1.001 into a unique clade. All sequences were deposited in GenBank (accession numbers: PV200080 - PV200083). The combination of genotypic, phylogenetic, and phenotypic analyses confirmed that the isolates belonged to C. graminicola. To fulfill Koch's postulates, maize plants (Mo940) at the V3 developmental stage were placed horizontally in a tray for inoculation. Twenty droplets (7.5 μl each) of a conidial suspension (3 × 10⁵ conidia/ml) were applied to the surface of the third leaf. The trays were sealed to maintain humidity and incubated overnight at 23°C. The followi","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144079264","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":"Deciphering the magnitude and the time of action of weather factors on the allo-inoculum dynamics of <i>Pseudocercospora fijiensis</i> in Martinique.","authors":"Lucile Delatouche, Philippe Tixier, Marie-Odette Daribo, Jérôme Sainte-Rose, Luc de Lapeyre de Bellaire","doi":"10.1094/PDIS-02-25-0342-RE","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0342-RE","url":null,"abstract":"<p><p>Allo-inoculum has an important role in fungal disease epidemiology. Understanding the factors that impact the long-distance dispersal of a pathogen is crucial to improve its management. In this study, we studied Pseudocercospora fijiensis allo-inoculum dynamics in Martinique, over a period of 18 months. We used trap plants to measure (10 times) the spore abundance across six locations. Lesion densities observed on trap plants were used as a proxy of the allo-inoculum resulting from long dispersal ascospores. We analysed how the lesion densities of P. fijiensis measured with trap plants were statistically correlated with i) weather factors, and ii) the stage of evolution of disease (SED) measured in closest banana plots. The SED measured in neighbouring plots did not significantly influence the lesion densities observed on the trap plants. For each variable, we determined the period of time prior to the trap plants exposure that exhibited the strongest correlation with the lesion densities measured on these plants. Rainfall was the variable with the most influence and positively correlated with lesion densities when measured 7 to 4 days before trap plants exposure. Inversely, there was a negative correlation with UV radiation measured 2 to 1 days prior trap plants exposure. This information complements the knowledge on the biology of the fungus and holds potential for enhancing disease management, especially the importance of rainfall for the allo-inoculum dynamics. These results also showed that if commercial farms have a good management of BLSD, it does not contribute to long distance contamination.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144078912","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>Diplodia bulgarica</i> Causing Black Rot Canker on Apple in China.","authors":"Shunpei Xie, Haiyan Wu, Yanfen Wang, Chenchen Chen, Fengyue Gong, Yashuang Guo, Haiqiang Li, Meng Zhang","doi":"10.1094/PDIS-04-25-0830-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-04-25-0830-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Xinjiang, a major apple-producing region in, is renowned for its high-quality apples in China. In May 2024, symptomatic branches showing black rot canker were collected from commercial 'Golden Delicious' (Malus domestica) and Xinjiang Wild Apple (Malus. sieversii) trees in orchards located in Ili Kazakh Autonomous Prefecture (sites: 43.57°N, 81.92°E and 44.43°N, 80.78°E, respectively). The prevalence of symptomatic trees ranged from 30% to 40% (five-point sampling; n=50). External symptoms included charcoal-like cankers with bark peeling on primary and secondary branches, while internal examination revealed dark brown xylem with firm consistency. To isolate the causal pathogen, symptomatic branch samples (n = 14) were cut into 5 mm length pieces, surface-disinfected in 75% ethanol and rinsed with sterile water, and then transferred onto potato dextrose agar (PDA). Plates were incubated at 25°C for 3 days. Colonies consistent with Botryosphaeriaceae species (Phillips et al. 2013) (n = 20) were consistently obtained, and pure cultures were obtained by transferring single hyphal tips to fresh PDA. Colonies exhibited light gray coloration, irregular margins, and abundant aerial mycelium. To induce pycnidia formation, two isolates (ZM305-5 and ZM316-5) were cultured on pine needle agar (PNA) under near-ultraviolet light (340 nm) at 25°C for 20 days. Conidia (n = 50) were thick-walled, ovoid, initially hyaline, and turned dark brown at maturity, mostly aseptate, with the size of mature conidia ranging from 24.99 to 29.07 (27.14) × 13.76 to  15.78 (14.71) μm. Molecular identification was performed by sequencing the internal transcribed spacer (ITS) using primers ITS1/ITS4, results showing 100% identity with the Diplodia bulgarica holotype (CBS 124136). To further confirm the identity, the translation elongation factor 1-alpha (tef1) and the beta-tubulin (tub2) gene were sequenced using EF1-688F/EF1-1251R and Bt2a/Bt2b, respectively (Phillips et al. 2012). Sequences were deposited in GenBank (accession nos. PV362629-PV362631 for ITS, PV388909-PV388912 for tub2, and PV419584-PV419587 for tef1). A maximum likelihood (ML) multi-locus phylogenetic analysis clustered Chinese isolates with reference strains of D. bulgarica. Pathogenicity tests were conducted on 1-year-old shoots (n = 5) of 5-year-old saplings trees by wounding the bark of test shoots and inoculating mycelial plugs of these isolates. Control branches were mock-inoculated with sterile PDA plugs. After 30 days, dark-brown necrotic lesions developed in inoculated branches with length ranging from 31.5 to  45.5 mm, whereas the negative controls remained asymptomatic. The experiment was performed twice with similar results. Koch's postulates were fulfilled by re-isolating the pathogen from lesion margins and confirming its identify via morphology and ITS sequence. D. bulgarica was first described affecting M. sylvestris in Bulgaria (Phillips et al. 2012) and later associated with branch canker","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144079321","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":"QTL mapping and KASP Marker Development for Powdery Mildew Resistance in Watermelon.","authors":"Rahul C Kumar, Bidisha Chanda, Mihir K Mandal, Jennifer Lauren Ikerd, Sandra Branham, Patrick Wechter, Phil Wadl, Amnon Levi, Azeezahmed Shaik, Umesh Reddy, Raghupathy Karthikeyan, Chandrasekar S Kousik","doi":"10.1094/PDIS-04-25-0737-RE","DOIUrl":"https://doi.org/10.1094/PDIS-04-25-0737-RE","url":null,"abstract":"<p><p>Powdery mildew, caused by <i>Podosphaera xanthii</i>, poses a significant threat to watermelon (<i>Citrullus lanatus</i>) cultivation. Development of resistant cultivars is one of the best strategies to manage powdery mildew. To elucidate the genetic basis of resistance, bulked segregant analysis (BSA) was conducted on an F₂ population derived from a cross between resistant (USVL608-PMR) and susceptible (USVL677-PMS) genotypes. A 570-kb region on chromosome 2 was identified using QTLseq, containing 99 single nucleotide polymorphisms (SNP) and 8 putative genes. A tightly linked kompetitive allele specific PCR (KASP) marker was developed and validated across three F2 populations (USVL608-PMR × USVL677-PMS, USVL608-PMR × 'Sugar Baby', USVL608-PMR × 'Dixie Lee'), showing a 3:1 segregation ratio and very strong linkage to resistance. Marker-disease resistance linkage was further validated in the F₃ generation of all three populations. RNAseq analysis revealed the upregulation of lipoxygenase (LOX), jasmonic acid (JA), and reactive oxygen species (ROS) pathways post-inoculation, suggesting their role in powdery mildew resistance in watermelon. The development of tightly linked KASP markers in three different backgrounds for powdery mildew resistance and a molecular understanding of disease resistance will be useful for breeding and selecting new disease-resistant watermelon cultivars.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144079473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First Report of Bacterial Wilting Caused by <i>Curtobacterium flaccumfaciens</i> pv. <i>flaccumfaciens</i> on Tobacco.","authors":"Fei Dai, Yuan Xue, Quan Zhang, Shouhui Pan, Na Wang, Junxiang Zhang","doi":"10.1094/PDIS-03-25-0641-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-03-25-0641-PDN","url":null,"abstract":"<p><p>Tobacco (Nicotiana tabacum) is an economically important crop, possessing a multifaceted impact on a global scale. In July 2024, wilting symptoms resembling tobacco bacterial wilt were observed on the cultivar Yunyan87 in a tobacco field (106°05'7.1″E, 26°03'9.9″N), Anshun, Guizhou, China. The infected plants initially presented chlorotic spots on the basal part of the stem, followed by wilting of leaves or stems, vascular browning, and in some cases, even death. Disease incidence is about 40%, causing yield losses over 20%. The disease samples were subjected to a moisturizing treatment overnight at room temperature. Cultured sap obtained from excised stems was diluted with sterilized water and plated onto LB agar plates. Post-incubation at 28°C for 2 days, the buff, circular, smooth colonies were picked from the plates and amplified using colony PCR with reference primers (Gonçalves et al., 2019; Osdaghi et al., 2024; Weisburg et al., 1991). The 16S rDNA sequence data (GenBank accessions PV104305 to PV104307) of three isolates (14-28-27, 14-15-19, and 15-11-17) shared 100% similarity with that of Curtobacterium faccumfaciens type strain C-S-R1-2 (GenBank accession no. MK398100) based on BLASTn search. The phylogenetic tree constructed using MEGA-X version 10.1.6 (Kumar et al., 2018) based on the recA, gyrB, atpD, ppk, and rpoB genes demonstrated that the three isolates belong to C. flaccumfaciens pv. flaccumfaciens (Cfpf). The partial sequences of the five genes were submitted to GenBank with accession numbers PV259359 to PV259373. Pathogenicity test was conducted on 55-day-old tobacco plants grown in plastic pots (8.7 cm height, 9.7 cm upper diameter, and 6.7 cm bottom diameter). Plants were inoculated as described (Urrea, et al., 2014). The plants treated with sterilized water acted as a control. The inoculated seedlings were moved to the greenhouse at 29 ± 1°C and ≥ 60% humidity. Ten days after inoculation, wilting of lower leaves and xylem discoloration were observed in inoculated plants. No symptoms appeared in the controls. Pathogenicity tests were performed three times with consistent results. The bacteria were reisolated from the inoculated plants and identified as Cfpf through colony morphology and multilocus sequence analysis of the recA, gyrB, atpD, ppk, and rpoB genes, fulfilling Koch's postulates. Cfpf, a common plant pathogen, causes the bacterial disease in Dendrobium officinale and Phaseolus vulgaris (Wang et al., 2016; Osdaghi et al., 2020). To our knowledge, this is the first report of Cfpf causing bacterial wilt in tobacco. This report broadens the host range of Cfpf and underscores the significance of this bacterium as a plant pathogen.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144079415","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":"Allelopathic Effects of Sorghum/Sorghum-Sudangrass Hybrids Against <i>Rotylenchulus reniformis</i>.","authors":"Roshan Paudel, Landon Balkwill, Koon-Hui Wang","doi":"10.1094/PDIS-08-24-1668-RE","DOIUrl":"10.1094/PDIS-08-24-1668-RE","url":null,"abstract":"<p><p>Reniform nematode (<i>Rotylenchulus reniformis</i>) is a damaging and difficult-to-manage pest on many agricultural crops. Sorghum and sorghum-sudangrass hybrids (SSgHs) have shown potential in managing plant-parasitic nematodes by releasing toxic hydrogen cyanide gas through the hydrolysis of dhurrin, a cyanogenic glucoside found in leaf epidermal cells. The objectives of this study were to evaluate the effect of different SSgH varieties and their age on the suppression of <i>R. reniformis</i> and to quantify their dhurrin contents. Shoot biomass of seven SSgH varieties was harvested at 1, 2, and 3 months of growth and used as a soil amendment in two greenhouse cowpea bioassay trials. Dhurrin concentration was analyzed using high-performance liquid chromatography from 2-month-old tissues. The results indicated that energy sorghum 'NX-D-61' and SSgH 'Latte' exhibited the highest dhurrin concentrations (<i>P</i> ≤ 0.05) and suppressed <i>R. reniformis</i> development in cowpea roots (<i>P</i> ≤ 0.05). In Trial I, 2-month-old amendments showed the greatest suppression, whereas in Trial II, 1-month-old amendments were more suppressive (<i>P</i> ≤ 0.05). Potential effect of environmental stress on dhurrin concentration in SSgH tissue was discussed. Nonetheless, dhurrin concentrations were negatively related to the number of <i>R. reniformis</i> infecting cowpea roots (<i>R</i>² = 0.69; <i>P</i> = 0.02). These findings suggest that high-dhurrin SSgH varieties can be integrated into reniform nematode management plans as a cover crop and terminated no more than 2 months after planting.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS08241668RE"},"PeriodicalIF":4.4,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142682531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First Report of Bacterial Leaf Spot on Sweet Potatoes Caused by <i>Acinetobacter seifertii</i> in China.","authors":"Lu Wang, Siyi Liang, Yingze Duan, Jinxin Yang, Tianhan Qin, Jing Wei, Jiahui Li, Yingzhi Zhu, Zhanbiao Li","doi":"10.1094/PDIS-03-25-0658-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-03-25-0658-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Sweet potato (Ipomoea batatas (L.) Lam), a globally essential yet underutilized staple crop, is primarily cultivated in Asia, Africa, and Latin America. In 2021, China alone accounted for 53% of global production, yielding 47 million tons and supplying essential nutrients such as proteins, minerals, and provitamin A carotenoids (Li et al. 2024). In June 2024, a new bacterial leaf spot disease was identified in a sweet potato nursery in Hengzhou City, Guangxi Province, China, with an incidence exceeding 50%. Early symptoms appeared as brownish-black necrotic spots, which progressed to widespread yellowing of stems, veins, and leaves, ultimately leading to tissue blackening and plant death. To isolate the causal agent, 12 tissue samples, including leaf blades and stalks from six symptomatic plants, were surface-sterilized (75% ethanol for 45 s, 2% NaClO for 1 min) and rinsed three times with sterilized water. A 10-fold serial dilution of homogenized tissue was prepared, and 100 μL of suspension was plated onto nutrient agar (NA) medium and incubated at 30°C for 48 h in the dark. A predominant colony type was found on purified NA, and a representative isolate, designated J-5, was selected for further study. The colonies were small, round, smooth, and white. Biochemical tests identified the isolate as gram-negative, methyl red positive, catalase positive, Voges-Proskauer negative, nonmotile, and highly salt-tolerant. The 16S rRNA gene was amplified and sequenced using primers 27F and 1492R (Lane 1991). BLAST analysis of the sequence against the NCBI database showed a 99.79% identity with Acinetobacter seifertii (GenBank accession no. OK178959.1). Additionally, partial sequences of four housekeeping genes (dnaK, fyuA, gyrB, and rpoD) were amplified and sequenced (Young et al. 2008), with sequences deposited in GenBank (16S rRNA: PQ638888; dnaK: PQ757048; fyuA: PQ757047; gyrB: PQ757043; rpoD: PQ757045). BLAST analysis confirmed a 99.15%-99.93% identity and 98%-100% coverage with A. seifertii. Pathogenicity was assessed by spraying a bacterial suspension (10⁸ CFU/mL) onto slightly scratched stems of 10 healthy sweet potato seedlings. A control group of 10 healthy sweet potato seedlings was treated with sterile nutrient broth. Seedlings were maintained in a greenhouse at 25°C with 70% relative humidity for 7 days. At seven days post-inoculation, inoculated plants developed symptoms identical to those observed in the nursery, while control plants remained asymptomatic. The pathogen was successfully reisolated from necrotic tissues and confirmed as A. seifertii through amplification in the polymerase chain reaction assay and sequencing of the 16S rRNA gene. A. seifertii, a species within the genus of the bacterium known for its ecological versatility in soil and water, plays a significant role in biodegradation (Budkum et al. 2022; Yang et al. 2016). To the best of our knowledge, this is the first report of A. seifertii that causes bacterial leaf spo","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144079398","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 Wilt Caused by <i>Fusarium nirenbergiae</i> on tomato (<i>Solanum lycopersicum</i>) in China.","authors":"Sheng-Li Zhang, Bingbing Fan, Bowen Jiang, Bingqian Guo, Qingyu Yin, Abdullah Gera, Jing-Jing Wang, Yanping Xu","doi":"10.1094/PDIS-02-25-0304-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0304-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;In May 2024, Fusarium wilt was observed in a tomato field in Weifang City, Shandong Province (36°54'6.876\" N, 118°51'17.003\" E) with an incidence of approximately 32%. The typical symptoms of the disease included leaf wilting and light brown or dirty white elongated lesions on one side of the stem. Three diseased plants were collected and labeled as FQKW24-1-FQKW24-3. Stem tissues with lesions were cut into 5 mm pieces and then surface sterilized with 75% ethanol for 45 s and 3% NaClO for 1 min. After triple rinsing with sterile distilled water, the tissue were transferred on potato dextrose agar (PDA) and incubated in darkness at 25°C for 5 days. After purification using hyphal-tip method (Leslie and Summerell. 2006), 9 isolates with consistent colony morphology were obtained. The representative strains FQKW24-1A and FQKW24-2A were selected for morphological identification. The colonies exhibited white or pale vinaceous center, with a floccose texture and abundant aerial mycelium. Reverse white or pale vinaceous in the center, lacking diffusible pigment. Microconidia on synthetic nutrient poor agar (SNA) were ellipsoidal to falcate, measuring 7.3 - 13.7 (x̄=10.1) × 2.7 - 4.7 (x̄=3.7) μm and 8.9 - 18.7(x̄=13.0) ×3.3 - 5.9 (x̄=4.6) μm for FQKW24-1A and FQKW24-2A, respectively. On carnation leaf agar (CLA), macroconidia were falcate, 3-5 septate, 33.9-50.4 (x̄=41.6) × 5.6 - 3.2 μm (x̄=4. 6) and 35.5 - 57.7 (x̄=44.7) × 3.6 - 5.8 (x̄=4.8) μm for FQKW24-1A and FQKW24-2A, respectively. The translation elongation factor 1-alpha gene (tef1), calmodulin (cmdA), and RNA polymerase II second largest subunit (rpb2) were amplified according to Wang et al. (2019). Sequences of tef1, cmdA, and rpb2 (PV018785-PV018793) of the isolates FQKW24-1A, FQKW24-2A and FQKW24-3A were submitted to GenBank. Alignment analysis of these sequences revealed similarities of 99.8% (614/615), 99.4% (871/876) and 99.8% (601/602) with the ex-type culture of F. nirenbergiae CBS 840.88 for tef1, rpb2 and cmdA, respectively. Phylogeny inferred based on the combined cmdA, tef1 and rpb2 sequences using PhyloSuite software, showed the three isolates and F. nirenbergiae were clustered into one branch. Based on morphology and phylogenetic analyses, the isolates were identified as F. nirenbergiae. Pathogenicity tests were conducted twice in an artificial climate box (12-h photoperiod at 25 °C, RH 80%) on 15-20 cm tomatoes seedlings with the pot culture. Plants were grown in sterilized soil and separately inoculated in pots with 20 ml of F. nirenbergiae spore suspension (106 conidia/ml). Control plants were mock-inoculated with water. Each treatment contained 10 plants. The first symptoms appeared 20 days after inoculation, which were a characteristic yellowing and wilting of foliage, falling off from bottom to upward. Within 3 months, stem tissues of the inoculated plants exhibited typical symptoms similar to those observed in the field. The controls remained healthy. To fulfill Koch's","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144079424","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":"Susceptibility of Pruning Wounds of Apple Trees to <i>Diplodia mutila</i>, <i>D. seriata</i>, <i>Lasiodiplodia theobromae</i>, <i>and Neofusicoccum arbuti</i> Infections and Conidial Release of Botryosphaeriaceae spp. in the Maule Region, Chile.","authors":"Adrián Valdez-Tenezaca, Bernardo A Latorre, Gonzalo A Díaz","doi":"10.1094/PDIS-07-24-1498-RE","DOIUrl":"10.1094/PDIS-07-24-1498-RE","url":null,"abstract":"<p><p>Studies on the susceptibility of pruning wounds of different ages and the effect of pruning time on infection by Botryosphaeriaceae species in apple trees are scarce. This work aimed to determine the susceptibility of pruning wounds of different ages (1, 15, 30, or 45 days after pruning) and the effect of pruning time during early (June) and late pruning (August) in apple cultivars Fuji and Gala on the infection of <i>Diplodia mutila</i>, <i>D. seriata</i>, <i>Neofusicoccum arbuti</i>, and <i>Lasiodiplodia theobromae</i>. Additionally, seasonal conidial release of Botryosphaeriaceae spp. was monitored using Vaseline-coated glass slides in two orchards, cultivars Fuji and Gala, during two consecutive growing seasons (2020 and 2021) in the Maule Region, Central Chile. The analysis of the variance of each pruning wound age showed significant interaction between the factors, <i>Botryosphaeria</i> isolate × apple cultivar (<i>P</i> = 0.0001). The isolates of <i>N. arbuti</i> and <i>D. seriata</i> were significantly more aggressive than the other isolates of <i>Botryosphaeria</i>, with mean values of 45.2 mm (1 day of age) to 7.9 mm (45 days of age) and 31.0 mm (1 day of age) to 6.6 mm (45 days of age), respectively. Independent of the Botryosphaeriaceae species, the pruning wound susceptibility considerably decreased as the age of the pruning wound increased, where fresh pruning wounds (1 and 15 days) are more susceptible than older pruning wounds (30 and 45 days). Our results indicated significant (<i>P</i> < 0.0001) interaction between <i>Botryosphaeria</i> isolates and pruning time for both cultivars. Necrotic lesions varied among the Botryosphaeriaceae species, where lesion length was significantly greater in the isolates of <i>N. arbuti</i>, <i>D. mutila</i>, and <i>D. seriata</i> inoculated in early pruning than in inoculations conducted in late pruning. This study demonstrated a strong relationship between conidial release and rainfall, where 70.3 and 86.3% of the total conidia of Botryosphaeriaceae spp. were released during rainfall periods between June and August (winter). This work suggests that a delay in pruning times may be justified to reduce the risk of Botryosphaeria canker and dieback in apple trees in the Maule Region, Chile, considering rain-free days.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS07241498RE"},"PeriodicalIF":4.4,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142682149","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}