Plant disease最新文献

{"title":"First Report of Soybean Geminivirus B Infecting <i>Salvia miltiorrhiza</i> in China.","authors":"YanHong Qin, Guohao Xu, Shuhao Lu, Suxia Gao, Yi Wen, Shaojian Li, Jin Yang, Xuemeng Li, Chuantao Lu, Shiqi Li, Xiang Li, Qi Liu, Fei Wang, Hongyan Liu","doi":"10.1094/PDIS-03-25-0585-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-03-25-0585-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Salvia miltiorrhiza Bge (Family Lamiaceae) is a traditional Chinese herbal medicine; its roots and rhizomes are used as medicines (Zhang et al. 2023). The plant has been vegetatively propagated using root tubers, and long-term asexual reproduction can lead to the accumulation of plant viruses, which may cause severe diseases. Tobacco mosaic virus and cucumber mosaic virus have been reported to infect S. miltiorrhiza (Yao et al. 2022), and their prevalence has become increasingly serious in China. From June to September 2023, 125 samples of S. miltiorrhiza symptomatic leaves were randomly collected in Henan province, China. A small portion of each leaf of above 125 collected samples was mixed into a total sample (~30 g) and sent to Berry Genomics Corporation (Beijing, China) for high-throughput sequencing (HTS) examination. Ribosomal RNA was removed by RNAprep Pure Plant Plus kit (TIANGEN Biotech, Beijing, China), and the NEBNext Ultra RNA Library Prep kit for Illumina (NEB, Ipswich, MA, USA) was used to build a cDNA library. The sequencing procedure was performed on the Illumina Nova Seq6000 sequencing system (Berry Genomics Corporation). Wuhan Biowefind Co., Ltd. (Wuhan, China) handled the subsequent processing and analysis of sequencing data. A total of 64,043,098 paired-end reads (150 nt) were obtained, and 63,559,676 clean reads were assembled by de novo (IDBA-UA, version 1.1.3) to generate 131,718 contigs (＞200 bp). There were 58,300 reads that covered 85.8% mapping to the soybean geminivirus B genome (SGVB, GenBank MH428830.1). Via BLAST analysis, 12 contigs with length from 228-882 nt were associated with CMV of a 90.4-99.7% similarity; 464 contigs with length from 202-8864 nt were associated with Betaflexiviridae of a 52.82-73.72% similarity; 2 contigs with length from 1849-6181 nt were associated with Alphaflexiviridae of a 33.4~75.3% similarity; 30 contigs with length from 205-7164 nt were associated with Fimoviridae of a 59.17~70.09% similarity. Seventeen contigs with length from 217-1046 nt were associated with SGVB of a 87.5~100% similarity. To identify the presence of the virus, the DNA of 125 samples were extracted using the EZ-10 Spin Column Plant Genomic DNA Purification Kit (Sangon Biotech, Shanghai, China). The DNA samples were subjected to PCR using the SGVB-specific primer set DSSGVBF/DSSGVBR (a 457-nt fragment), designed based on the HTS results. Results revealed 80 positive samples out of 125 (detection rate, 64%); no bands were detected in ddH2O used as a negative control. A pair of back-to-back primers (DSSGVBF1/DSSGVB1) was designed based on the sequences of the 457-nt fragments to amplify the complete sequence of SGVB. Complete sequences of seven isolates (33#, 130#, 131#, 148#, 149#, 152#, and 155#) were obtained from the positive samples with the DSSGVBF1/DSSGVB1 primer set. It was obtained by sanger sequencing (Sangon Biotech, Zhengzhou, China). The genome sequences of these isolates were 2625 nt long and were ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144026228","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>Calathea orbifolia</i> in China.","authors":"Surapong Khuna, Sinang Hongsanan, Tanapol Thitla, Ning Xie","doi":"10.1094/PDIS-03-25-0501-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-03-25-0501-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;The peacock plant (Calathea orbifolia [Linden] H. A. Kenn.) is widely grown in China as a valuable ornamental houseplant. In September 2024, anthracnose on this plant was observed in a field in Shenzhen (22°35'55\"N, 113°59'21\"E), Guangdong Province, China. The area investigated was ~900 m2, with a disease incidence of ~70% among 100 plants. Each plant had 20 to 50% leaf necrosis. This disease may become a greater problem as the plant's cultivation area expands. The initial symptoms were brown spots with a yellow halo that later enlarged and elongated, 0.5 to 8 × 0.3 to 5 cm. The spots were irregular and brown, with a yellow halo, and the affected leaves withered and dried. Ten symptomatic leaves were randomly collected and used to isolate the fungal causal agents through a tissue transplanting method. Three fungal isolates (MBSZU 25-019 to MBSZU 25-021) with similar morphology were obtained with an isolation frequency of 75%. Colonies on PDA were 75 to 83 mm after 1 week at 25°C, appeared grayish-white with cottony mycelia, slightly raised with entire edges, and were gray in the center and white at the margin on the reverse side. All isolates produced asexual structures. Setae were 40 to 11 × 2.4 to 4 µm, dark brown, a cylindrical base, and an acuminate tip. Conidiophores were hyaline to pale brown, septate, and branched. Conidiogenous cells were cylindrical to ampulliform, hyaline, and 8 to 24 × 2.7 to 5.5 µm. Appressoria were oval to irregular, dark brown to black, and 8 to 16.3 × 5 to 8.8 µm. Conidia were cylindrical, one-celled, hyaline, aseptate, smooth-walled, ends rounded, guttulate, and 9 to 23 × 4 to 6.5 µm (n = 50). Morphological characteristics of all isolates resembled Colletotrichum spp. (Weir et al. 2012). The ITS, ACT, CAL, CHS-1, TUB2, GAPDH, and ApMAT genes were amplified using primer pairs ITS5/ITS4, ACT-512F/ACT-783R, CL1C/CL2C, CHS-79F/CHS-345R, T1/T22, GDF1/GDR1, and AMF1/AMR1 (Silva et al. 2012; Weir et al. 2012), respectively. The ITS (PV162976 to PV162978), ACT (PV175253 to PV175255), CAL (PV175259 to PV175261), CHS-1 (PV175262 to PV175264), TUB2 (PV175256 to PV175258), GAPDH (PV175265 to PV175267), and ApMat (PV175268 to PV175270) sequences were deposited in GenBank. In the BLAST analysis, the ITS, ACT, CAL, CHS-1, TUB2, GAPDH, and ApMAT sequences showed similarities of 99.83, 99.56, 100, 99.67, 99.85, 99.29, and 90.80%, respectively, to C. fructicola (ICMP 18581). Maximum likelihood and Bayesian inference phylogenetic analyses of the concatenated seven genes identified all isolates as C. fructicola. To test pathogenicity, the healthy leaves were wiped with 0.1% NaClO and then rinsed three times with sterile water. Conidia suspensions (15 µl of 1 × 106 conidia/ml) from each isolate cultured on PDA at 25°C for 2 weeks were placed on all samples using the attached leaf assay. Control leaves were mock-inoculated with sterile distilled water. Each treatment was replicated ten times and repeated twice. Plants were kept a","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143976149","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>Cryphonectria parasitica</i> causing dieback on Sweet Chestnut (<i>Castanea sativa</i> Mill.) in Algeria.","authors":"Souhila Aouali, Ali Guettas, Salem Boudedja, Zineb Rouabah, Sarah L Boggess, Denita Hadziabdic","doi":"10.1094/PDIS-01-25-0071-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-01-25-0071-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;In July 2023, chestnut tree mortalities were reported in the parc châtaigneraie, situated in the Akfadou mountain range, in Tizi Ouzou, Algeria. Dead sweet chestnut (Castanea sativa) trees exhibited symptoms including crown dieback, withered and dried leaves clinging to the branches, trunk and branch cracks and cankers, with a proliferation of epicormic shoots under the cankered areas (Fig 1). Examination of the cankers with a hand magnifying lens, exposed orange masses, erupting from under the bark. Cankers were found on the lower part of the trunk, with few occurrences on the branches. Flat mycelial fans were observed throughout the bark. Samples of infected wood were collected and subjected to further analysis in the laboratory. Close observation of fragments of infected wood under the stereomicroscope showed orange to dark orange fruiting structures (pycnidia), originating in the cambium, which showed a discoloration in cross section. After incubation (24 hours) in a humid chamber, twisted yellowish tendrils oozing from the pycnidia were observed (Fig 2). Pycnidia were isolated from the bark and transferred onto full strength potato dextrose agar (PDA). Fast growing whitish then turning to yellow-orange colonies developed within 5 days, with a growth rate of 7 mm/day at 30°C. Conidiospores were hyaline, aseptate, oblong to cylindrical, 2-4 x 1.5-2 µm in size. Total genomic DNA was extracted and the Elongation factor 1a (EF-1a) (Carbone & Kohn, 1999) and Beta-tubulin (βT1) (Glass & Donaldson, 1995) gene regions were amplified using the Phire Direct PCR kit (ThermoFisher) and PCR amplicons were subsequently sequenced. The EF-1a (PQ416673) and βT1 (PQ416670) sequence identity was determined using the Genbank database with 99.69% and 100% identity to Cryphonectria parasitica (OM112254.1 and MK578073.1) respectively. Based on disease symptoms, cultural and morphological characters, and DNA sequence similarity, the fungal pathogen was identified as Cryphonectria parasitica. Koch's postulates were performed to confirm the pathogenicity of C. parasitica by using chestnut tree detached twigs as described in Hunter et al. (2013). Twelve Chestnut twigs (20 cm long and 2 cm in diameter) were surface sterilized then put to dry in a laminar hood under a constant air flow for 10 minutes. Seven day old mycelial plugs from cultures of C. parasitica were used to inoculate two branches with three replicates. The six controls were inoculated with PDA plugs. After 5 weeks incubation at 20°;C (9/15 hours light/dark regime, respectively), canker zones developed around the inoculation point, from which the pathogen was reisolated. The recovered C. parasitica isolate was confirmed using methods described above. The resulting consensus sequences of the recovered pathogen matched C. parasitica with EF-1a 99.71-100% identity (PQ416674, PQ416675) and βT1 100% identity (PQ416671, PQ416672). This represents the first report of C. parasitica in Algeria, and the second","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144037769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A bacterial gall disease of <i>Myrica rubra</i> caused by <i>Pseudomonas amygdali</i> pv. <i>myricae</i> in Taiwan.","authors":"Huang-Hsi Chu, Wen-Chien Tang, Kachonsak Iamnok, Reun-Ping Goh, Chia-Ching Chu, Jenn-Wen Huang, Chih-Li Wang","doi":"10.1094/PDIS-02-25-0365-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0365-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Chinese bayberry (&lt;i&gt;Myrica rubra&lt;/i&gt;), or yamamomo, is cultivated for fruit production and ornamental purposes. In 2023, an unknown disease affecting &lt;i&gt;M. rubra&lt;/i&gt; was reported in the Huisun Experimental Forest, National Chung Hsing University, Renai, Nantou County, Taiwan. The disease is expressed as galls on petioles, young shoots, twigs, and trunks, particularly on twig branches. These galls appeared cracked, dark brown, irregular, and rough on surfaces. The disease incidence was 100% among approximately 80 trees. Samples collected in March 2023 exhibited internal vascular discoloration and bacterial streaming was observed. Diseased tissues were immersed in sterile water, and the bacterial suspensions were streaked on nutrient agar for isolation. Purified strains underwent hypersensitive response (HR) assays on Nicotiana benthamiana leaves, identifying six bacterial strains (MrBG-1 to MrBG-6) that triggered a HR reaction. Pathogenicity assays were performed on lower woody stems and upper non-woody stems of six 15-month-old &lt;i&gt;M. rubra&lt;/i&gt; seedlings in a greenhouse (22 to 25℃) under natural daylight. The six bacterial strains were inoculated on three seedlings while the other three seedlings were treated with sterile water. A suspension of each strain (20 ul; 108 CFU / mL) was dropped on an inoculation site which was wounded with needles in an area of 5 mm2. Inoculation sites swelled with cracked surfaces at one month post-inoculation (mpi) and formed galls on woody tissue and cankers on non-woody tissue at three mpi, while wounds in the controls healed. The pathogens were re-isolated and confirmed identical to the original inoculated bacteria via 16S rDNA sequencing (PV082408 to PV0824013). Since isolates MrBG-1 to MrBG-6 produced fluorescent pigment on King's B medium, LOPAT tests were performed (Schaad et al. 2001). Results indicated that these isolates produced levan, induced HR in tobacco, lacked oxidase and arginine dihydrolase activity, and failed to cause soft rot in potato tuber slices. These characteristics were consistent with those of &lt;i&gt;P. amygdali&lt;/i&gt; pv. &lt;i&gt;myricae&lt;/i&gt; (formerly &lt;i&gt;P. syringae&lt;/i&gt; pv. &lt;i&gt;myricae&lt;/i&gt;) strains causing gall symptoms on &lt;i&gt;M. rubra&lt;/i&gt; in Japan (Ogimi and Higuchi 1981). Phylogenetic identification utilized concatenated gene sequences of DNA gyrase subunit B (&lt;i&gt;gyrB&lt;/i&gt;, PV089501 to PV089506), RNA polymerase beta subunit (&lt;i&gt;rpoB&lt;/i&gt;, PV089507 to PV089512), and RNA polymerase sigma factor (&lt;i&gt;rpoD&lt;/i&gt;, PV089513 to PV089518) by using the maximum likelihood method. The primers used for amplifying the three genes and the reference strains included in the phylogenetic analysis were referred from a previous study (Maleki-Zadeh et al. 2022). The phylogenetic results clustered MrBG-1 to MrBG-6 in the clade of &lt;i&gt;Pseudomonas amygdali&lt;/i&gt; pv. &lt;i&gt;myricae&lt;/i&gt; Ogimi and Higuchi with a 86% bootstrap value. Based on the pathogenicity assay, phenotypic tests, and phylogenetic analysis, we concluded that th","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144017453","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 description of <i>Diplodia mutila</i> causing Botryosphaeria stem blight of highbush blueberry cv. Brigitta in the Maule Region, Central Chile.","authors":"Fernanda B Núñez, Yadira Hernández, Enrique Ferrada, Mauricio Gutierrez, Mauricio A Lolas, Claudia Moggia, Gustavo Lobos, Gonzalo A Díaz","doi":"10.1094/PDIS-02-25-0338-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0338-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Highbush blueberry (Vaccinium corymbosum L.) is an important economic fruit crop in Chile, with an approximate total area of 17,000 ha, i.e., 5,626 ha in the Maule region (35°26'S, 71°40'W), Central Chile (www.odepa.cl, 2025). Botryosphaeria stem blight is a threat to blueberry production in Chile, with incidence between 15 and 45%, attributed to Botryosphaeriaceae spp., including Neofusicoccum arbuti, N. australe, N. nonquaesitum, and N. parvum (Espinosa et al. 2009; Perez et al. 2014; Millas et al. 2023). In January 2023, five bushes of 12-year-old blueberry cv. Brigitta, from a commercial plantation, with and incidence of 8% was assessed across the 5 ha, in Longaví, Maule region, were submitted to the Fruit Pathology Lab at the University of Talca. Symptoms included decline, basal canker, stem and cane blight (red flagging) (Polashok et al. 2017). In cross-section, lignified stems have brown U or V-shaped necrotic or discolored hard tissues. Diseased stems were disinfected according to Díaz and Latorre (2014), and internal tissues were cut into small pieces (3 x 3 mm) and placed on potato dextrose agar (PDA) and 0.1% Igepal CO-630. After 5 days incubation at 20°C in darkness, 10 pure cultures were transferred to PDA. Four isolates developed white to white-grey fast-growing colonies with abundant aerial mycelium, and abundant aggregated black pycnidia after 28 days at 20°C. Conidia were one-cell, hyaline, thick-walled, ellipsoidal to cylindrical with a size of (27.7-) 25.1 ±1.5 (-22.4) x (14.7-) 13.2 ± 1.3 (-11.4) µm with a ratio 1.9 length/width. To determine the species level, three isolates were amplified and sequenced using ITS1/ITS4, Bt2a/Bt2b and EF1-728F/EF1-986R pair-primers of the internal transcribed spacer (ITS1-5.8S-ITS2) region, a beta-tubulin (tub), and the translation elongation factor 1-α (TEF) DNA regions, respectively (Alves et al., 2004; Dissanayake et al. 2015). The sequences showed a 99% similarity with sequences of D. mutila CBS 112553 ex-type. The sequences of D. mutila isolates Bot-ara-1 to Bot-ara 3 were deposited in GenBank (ITS: PV032958 to PV032960; BT: PV037028 to PV037030; TEF: PV037031 to PV037033). A phylogenetic tree, constructed using the maximum parsimony method using the concatenated sequences of the three regions, grouped the three isolates in the same clade with CBS 112553 ex-type. Pathogenicity tests were conducted in the field (Longaví, Maule region) using D. mutila isolates (Bot-ara-1 to Bot-ara-3) on blueberry of five-year-old cv. Brigitta in July. Twenty dormant stems (five per bush) were pruned (tip) with shears, and 80 µL of conidial suspension (105 conidia/mL) was placed on each fresh pruning using a micropipette. Additionally, 20 dormant stems (40 cm long) were wounded with a sterile cork borer and inoculated with mycelial plugs of D. mutila (5 days old). An equal number of stems inoculated with sterile water or sterile PDA media were used as controls. Necrotic lesions of 61 to 90 mm in lengt","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144009536","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":"Establishing the pathogenicity of four <i>Cercospora</i> species associated with Cercospora leaf blight of soybean.","authors":"Ernesto Da Silva, Jacob Searight, Paul Price, Vinson P Doyle","doi":"10.1094/PDIS-02-25-0407-RE","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0407-RE","url":null,"abstract":"<p><p>Cercospora leaf blight (CLB) of soybean is caused by multiple Cercospora species globally, presenting significant challenges to disease management. The lack of standardized methods for inoculating and inducing CLB symptoms in controlled environments inhibits experiments on pathogen biology and host resistance. Consequently, limited understanding of the biology and epidemiology of these pathogens prohibits the development of tailored management strategies. Inducing sporulation of <i>Cercospora</i> species associated with CLB on amended media has been challenging, and the recommendations in the literature are inconsistent. To address these issues, standardized protocols were developed for inducing sporulation and reproducing CLB symptoms in controlled environments. Eleven culture media were tested for <i>Cercospora</i> cf. <i>flagellaris</i> conidia production, with V8A being the most effective. Five V8A concentrations were tested, and the conidia were harvested between 3 to 7 days with the highest conidial production (4.3 x 105 per ml) occurring on day 4 with 30% V8A. Peak sporulation varied, with <i>C.</i> cf. <i>flagellaris</i> peaking on day 4 and <i>Cercospora</i> cf. <i>sigesbeckiae</i>, <i>Cercospora kikuchii</i>, and <i>Cercospora iranica</i> peaking on day 3. Pathogenicity tests under controlled conditions fulfilled Koch's postulates by reproducing symptoms for all species tested, confirming their role in CLB development. These protocols provide the first standardized, efficient, and reproducible methods for <i>Cercospora</i> sporulation and inoculation. These methods offer insights for fundamental research into <i>Cercospora</i> biology and their interactions with soybeans, ultimately improving CLB management.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143974959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of <i>Ramulariopsis pseudoglycines</i> causing areolate mildew of cotton in Georgia and first detection of QoI resistant isolates in the United States.","authors":"Alejandra M Jimenez Madrid, Gabriel Munoz, Tessie Wilkerson, Peng W Chee, Robert Kemerait","doi":"10.1094/PDIS-02-25-0414-SC","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0414-SC","url":null,"abstract":"<p><p>Areolate mildew, caused by two Ramulariopsis species (R. gossypii and pseudoglycines), is an important re-emergent cotton disease in the Southeastern United States. This disease has been considered of secondary importance, but the recent prevalence and high incidence observed in cotton regions have raised concern about its importance. Timely applications of quinone outside inhibitor (QoI) fungicides have been suggested to manage this disease, but QoI resistance development is frequently detected for many fungal pathogens. In 2023, Ramulariopsis spp. isolates collected from Georgia were tested for species identification and for QoI resistance using molecular assays. Sequencing results revealed that all 6 isolates tested belong to R. pseudoglycines, confirming the presence of this species for the first time in Georgia. The partial amplification of the cytB gene showed that 83.3% of isolates had the G143A mutation, and no other amino acid substitution was observed. This also represents the first report of QoI-resistant isolates showing the presence of this amino acid substitution in R. pseudoglycines in the United States.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144006327","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":"Development of a quantitative SYBR Green real-time PCR for <i>Trichoderma afroharzianum</i>, causal agent of ear rot of maize.","authors":"Martina Sanna, Simone Bosco, Monica Mezzalama, Davide Spadaro, Vladimiro Guarnaccia","doi":"10.1094/PDIS-11-24-2339-SR","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2339-SR","url":null,"abstract":"<p><p><i>Trichoderma afroharzianum</i>, the causal agent of Trichoderma ear rot, is an emerging pathogen of maize (<i>Zea mays</i> L.). It was recently reported as a maize pathogen in Germany, France and in Italy. In 2023, nine seed lots from three farms in Northern Italy were tested for their phytosanitary conditions, revealing infection rates of up to 71% with <i>Trichoderma</i> spp. All seed lots showed symptoms of Trichoderma ear rot infection, and 26 out of 50 isolates were identified as <i>T. afroharzianum</i>. The study confirmed that <i>T. afroharzianum</i> infect maize seeds causing severe disease. Thirteen isolates from infected seeds were used to design species-specific primers on the translation elongation factor 1α as gene, and to develop a SYBR Green quantitative PCR to detect and quantify <i>T. afroharzianum</i> in maize seeds. The assay was validated following EPPO standard PM 7/98 guidelines, assessing analytical sensitivity, specificity, selectivity, repeatability, and reproducibility. The specificity of the method was validated using 19 <i>T. afroharzianum</i> strains and 16 non-target species, including <i>Trichoderma</i> species belonging to <i>T. harzianum</i> species complex. Only target DNA produced positive amplifications. Analytical sensitivity was tested using serial dilutions of <i>T. afroharzianum</i> DNA revealed a detection limit of 50 fg, even in the presence of maize seed DNA. The assay enables specific and sensitive detection of target DNA in asymptomatic samples, providing a valuable tool for early target detection and quantification during seed certification.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144040225","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":"Experimental reproduction of field symptoms in 'Shatangju' mandarin (<i>Citrus reticulata</i> Blanco) confirms citrus yellow vein clearing virus as causal agent of spring shoot leaf curl disease.","authors":"Zheng Liu, Jiaxing Wu, Chenyu Liu, Shan Nie, Le Xue, Song Zhang, Cuiyun Lei, Xuedong Liu, Binghai Lou, Mengji Cao","doi":"10.1094/PDIS-12-24-2700-SC","DOIUrl":"https://doi.org/10.1094/PDIS-12-24-2700-SC","url":null,"abstract":"<p><p>Citrus yellow vein clearing virus (CYVCV), the causal agent of citrus yellow vein clearing disease, has been posing an emerging threat to citrus production in China. In this study, we confirm that CYVCV is the causal agent of spring shoot leaf curl disease in 'Shatangju' mandarin (Citrus reticulata Blanco), a major commercial citrus cultivar in Guangxi Province, Field surveys revealed high incidence of typical viral symptoms, including leaf curling and vein clearing, with a CYVCV detection rate of 95.65% in the symptomatic samples. To verify the association between CYVCV and field symptoms, we inoculated Shatangju plants using a previously constructed full-length infectious cDNA clone of CYVCV derived from the CYVCV-FL-16 isolate. Graft-inoculated plants developed symptoms resembling those observed in the field, including vein clearing, leaf rolling, chlorosis, stunting, and internode shortening. RT-PCR and Western blot assays confirmed the viral systemic infection. Chlorophyll content was significantly reduced in infected leaves, and virus accumulation showed tissue- and season-specific distribution. These results fulfill Koch's postulates for CYVCV in Shatangju and provide experimental evidence linking CYVCV infection to field symptoms, laying the foundation for disease management and virus-free seedling certification.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144000039","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":"Molecular Characterization of <i>Botrytis</i> Isolates from Blueberry and Red Raspberry in the Pacific Northwest with Resistance to SDHI Fungicides.","authors":"Roshani Baral, Jeffery A DeLong, Gayle C McGhee, Virginia Stockwell, Chakradhar Mattupalli","doi":"10.1094/PDIS-12-24-2576-SC","DOIUrl":"https://doi.org/10.1094/PDIS-12-24-2576-SC","url":null,"abstract":"<p><p><i>Botrytis cinerea</i>, a high-risk pathogen for fungicide resistance development, poses a significant threat to yield and fruit quality of blueberry and red raspberry in the Pacific Northwest. Succinate dehydrogenase inhibitor (SDHI) fungicides are effective botryticides that are considered medium to high risk for resistance development. Analysis of <i>sdhB</i> sequences from <i>Botrytis</i> isolates (n = 278) exhibiting different levels of sensitivity to any of four SDHIs (boscalid, fluxapyroxad, fluopyram, and isofetamid) revealed six previously characterized mutations in 244 isolates: N230I, P225F, H272R, H272V, H272Y, and I274V, at frequencies of 40, 22, 22, 10, 5, and 1%, respectively. Different mutations in the <i>sdhB</i> gene resulted in twelve phenotypic profiles exhibiting in vitro resistance to the four SDHIs. In contrast, <i>sdhC</i> and <i>sdhD</i> sequences revealed no consistent mutations linked to a specific fungicide resistance profile. Importantly, among the mutations in <i>sdhB</i>, 72% were P225F, H272V, or N230I, which confer cross-resistance to multiple SDHI fungicides. These findings emphasize the need for balanced use and rotation of fungicides to manage <i>Botrytis</i> effectively in blueberry and red raspberry fields in the Pacific Northwest.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143977442","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}