scholarly journals First report of Fusarium concentricum causing wilt on Podocarpus macrophyllus in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Dong Qin ◽  
Yanyan Jiang ◽  
Rui Zhang ◽  
Emran Ali ◽  
Junwei Huo ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Vascular Tissue ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Distilled Water ◽  
Conidial Suspension ◽  
First Report ◽  
Shoot Blight ◽  
Podocarpus Macrophyllus ◽  
Dark Blue

Podocarpus macrophyllus (Thunb.) D. Don is used in many fields, including landscape, medicine, and forest interplanting. In July 2019, shoot blight was observed on P. macrophyllus at three nurseries in Harbin, China. Approximately 15% of plants had symptoms of the disease, which included rapid, synchronized death of leaves on individual branches. Eventually the whole plant wilted. Leaves and stems turned dark blue to brown. Ten infected vascular tissue samples from 10 individual plants were surface-disinfested in 0.5% NaOCl for 5 min, rinsed 3 times in sterile distilled water, and cultured on potato dextrose agar (PDA) amended with 50 µg/ml streptomycin at 26°C. Six similar fungal isolates from ten samples were isolated and subcultured. Single-conidium isolates were generated with methods reported previously (Leslie and Summerell 2006). Colonies on PDA consisted of densely floccose aerial hyphae with light yellow and pinkish pigments. Microconidia were oval to obovoid or allantoid, 3.8 to 11.8 μm in length and 2.8 to 4.6 μm in width, mostly non-septate on carnation leaf agar (CLA). Macroconidia were naviculate-to-fusiform slender, 24.9 to 57.2 μm in length and 2.8 to 4.5 μm in width with 3- to 5- septate, with a beaked apical cell and a foot-shaped basal cell. According to these morphological characteristics, all isolates were identified as Fusarium spp. (Aoki et al. 2001 ). Genomic DNA was extracted from a representative isolate LHS1. The internal transcribed spacer regions (ITS), translation elongation factor 1-alpha gene (TEF-1ɑ) and β-tubulin (TUB2) gene were amplified using the primers ITS1 and ITS4 (Yin et al. 2012)，EF1-728F/EF1-986R (Carbone and Kohn 1999) and T1/Bt2b (Glass and Donaldson 1995), respectively. DNA sequences of LHS1 were deposited in GenBank (accession nos. MT914496 for ITS, MT920920 for TEF-1ɑ and MT920921 for TUB2, respectively). MegaBLAST analysis of the ITS, TEF-1a, and TUB2 sequences indicated 100%, 97.7% and 100% similarity with Fusarium concentricum isolate CBS 450.97 (accession no. MH862659.1 for ITS, MT010992.1 for TEF-1a, and MT011040.1 for TUB2, respectively). To determine pathogenicity, P. macrophyllus plants were grown in 10-cm pots containing a commercial potting mix (five plants/pot). At the 10 to 12 leaf stage, 10 healthy plants (2 pots) were inoculated by spraying 5 ml of a conidial suspension (4×106 spores/ml) onto every plant. Ten plants treated with sterile distilled water served as a control. The test was repeated twice. All plants were placed in a humidity chamber (>95% RH, 26℃) for 48 h after inoculation and then transferred to a greenhouse at 22/28°C (night/day). All inoculated wilted with leaves and stems turning dark blue to brown 15 days after inoculation. No symptoms were observed on the control plants. The fungus was re-isolated and confirmed to be F. concentricum according to morphological characteristics and molecular identification. To our knowledge, this is the first report of F. concentricum on P. macrophyllus in world. The disease caused a large number of plants to wilt and die, seriously impacting the ability of the horticulture industry to produce P. macrophyllus. Although this pathogen causes leaf and shoot blight symptoms, it is not clear if the pathogen is also a vascular wilt disease. The occurrence of the new disease caused by F. concentricum highlights the importance of developing management strategies to protect P. macrophyllus. 

scholarly journals First Report of Leaf Blight of Japanese Yew Caused by Pestalotiopsis microspora in Korea

Plant Disease ◽  
2014 ◽  
Vol 98 (5) ◽  
pp. 691-691 ◽  
Author(s):  
Y. H. Jeon ◽  
W. Cheon
Keyword(s):  
Dna Sequences ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Leaf Blight ◽  
Economic Damage ◽  
Leaf Margin ◽  
Conidial Suspension ◽  
First Report ◽  
Pestalotiopsis Microspora ◽  
Large Trees

Worldwide, Japanese yew (Taxus cuspidata Sieb. & Zucc.) is a popular garden tree, with large trees also being used for timber. In July 2012, leaf blight was observed on 10% of Japanese yew seedling leaves planted in a 500-m2 field in Andong, Gyeongsangbuk-do Province, South Korea. Typical symptoms included small, brown lesions that were first visible on the leaf margin, which enlarged and coalesced into the leaf becoming brown and blighted. To isolate potential pathogens from infected leaves, small sections of leaf tissue (5 to 10 mm2) were excised from lesion margins. Eight fungi were isolated from eight symptomatic trees, respectively. These fungi were hyphal tipped twice and transferred to potato dextrose agar (PDA) plates for incubation at 25°C. After 7 days, the fungi produced circular mats of white aerial mycelia. After 12 days, black acervuli containing slimy spore masses formed over the mycelial mats. Two representative isolates were further characterized. Their conidia were straight or slightly curved, fusiform to clavate, five-celled with constrictions at the septa, and 17.4 to 28.5 × 5.8 to 7.1 μm. Two to four 19.8- to 30.7-μm-long hyaline filamentous appendages (mostly three appendages) were attached to each apical cell, whereas one 3.7- to 7.1-μm-long hyaline appendage was attached to each basal cell, matching the description for Pestalotiopsis microspora (2). The pathogenicity of the two isolates was tested using 2-year-old plants (T. cuspidata var. nana Rehder; three plants per isolate) in 30-cm-diameter pots filled with soil under greenhouse conditions. The plants were inoculated by spraying the leaves with an atomizer with a conidial suspension (105 conidia/ml; ~50 ml on each plant) cultured for 10 days on PDA. As a control, three plants were inoculated with sterilized water. The plants were covered with plastic bags for 72 h to maintain high relative humidity (24 to 28°C). At 20 days after inoculation, small dark lesions enlarged into brown blight similar to that observed on naturally infected leaves. P. microspora was isolated from all inoculated plants, but not the controls. The fungus was confirmed by molecular analysis of the 5.8S subunit and flanking internal transcribed spaces (ITS1 and ITS2) of rDNA amplified from DNA extracted from single-spore cultures, and amplified with the ITS1/ITS4 primers and sequenced as previously described (4). Sequences were compared with other DNA sequences in GenBank using a BLASTN search. The P. microspora isolates were 99% homologous to other P. microspora (DQ456865, EU279435, FJ459951, and FJ459950). The morphological characteristics, pathogenicity, and molecular data assimilated in this study corresponded with the fungus P. microspora (2). This fungus has been previously reported as the causal agent of scab disease of Psidium guajava in Hawaii, the decline of Torreya taxifolia in Florida, and the leaf blight of Reineckea carnea in China (1,3). Therefore, this study presents the first report of P. microspora as a pathogen on T. cuspidata in Korea. The degree of pathogenicity of P. microspora to the Korean garden evergreen T. cuspidata requires quantification to determine its potential economic damage and to establish effective management practices. References: (1) D. F. Farr and A. Y. Rossman, Fungal Databases, Syst. Mycol. Microbiol. Lab. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ (2) L. M. Keith et al. Plant Dis. 90:16, 2006. (3) S. S. N. Maharachchikumbura. Fungal Diversity 50:167, 2011. (4) T. J. White et al. PCR Protocols. Academic Press, San Diego, CA, 1990.

scholarly journals First Report of Fusarium Wilt Caused by Fusarium equiseti on Cabbage (Brassica oleracea var. capitate L.) in Korea

Plant Disease ◽  
2020 ◽  
Author(s):  
Tania Afroz ◽  
Samnyu JEE ◽  
Hyo-Won Choi ◽  
Ji Hyeon Kim ◽  
Awraris Derbie Assefa ◽  
...  
Keyword(s):  
Brassica Oleracea ◽  
Fusarium Wilt ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Mlst Database ◽  
Fusarium Equiseti ◽  
First Report ◽  
Representative Isolate

Cabbage (Brassica oleracea var. capitate L.) is an important vegetable crop that is widely cultivated throughout the world. In August 2019, wilting symptoms on cabbage (stunted growth, withered leaves, and wilted plants) were observed in a cabbage field of Pyeongchang, Gangwon Province, with an incidence of 5 to 10%. To identify the cause, symptomatic root tissue was excised, surface-sterilized with 70% ethanol, and rinsed thrice with sterile distilled water. The samples were dried on blotter paper, placed onto potato dextrose agar (PDA), and incubated at 25°C for 1 week. Five morphologically similar fungal isolates were sub-cultured and purified using the single spore isolation method (Choi et al. 1999). The fungus produced colonies with abundant, loosely floccose, whitish-brown aerial mycelia and pale-orange pigmentation on PDA. Macroconidia had four 4 to six 6 septa, a foot-shaped basal cell, an elongated apical cell, and a size of 20.2 to 31.8 × 2.2 to 4.1 μm (n = 30). No microconidia were observed. Chlamydospores were produced from hyphae and were most often intercalary, in pairs or solitary, globose, and frequently formed chains (6.2? to 11.7 μm, n = 10). Based on these morphological characteristics, the fungus was identified as Fusarium equiseti (Leslie and Summerell 2006). A representative isolate was deposited in the Korean Agricultural Culture Collection (KACC48935). For molecular characterization, portions of the translation elongation factor 1-alpha (TEF-1α) and second largest subunit of RNA polymerase II (RPB2) genes were amplified from the representative isolate using the primers pair of TEF-1α (O’Donnell et al. 2000) and GQ505815 (Fusarium MLST database), and sequenced. Searched BLASTn of the RPB2 sequence (MT576587) to the Fusarium MLST database showed 99.94% similarity to the F. incarnatum-equiseti species complex (GQ505850) and 98.85 % identity to both F. equiseti (GQ505599) and F. equiseti (GQ505772). Further, the TEF-1α sequence (MT084815) showed 100% identity to F. equiseti (KT224215) and 99.85% identity to F. equiseti (GQ505599), respectively. Therefore, the fungus was identified as F. equiseti based on morphological and molecular identification. For pathogenicity testing, a conidial suspension (1 × 106 conidia/ml) was prepared by harvesting macroconidia from 2-week-old cultures on PDA. Fifteen 4-week-old cabbage seedlings (cv. 12-Aadrika) were inoculated by dipping roots into the conidial suspension for 30 min. The inoculated plants were transplanted into a 50-hole plastic tray containing sterilized soil and maintained in a growth chamber at 25°C, with a relative humidity of >80%, and a 12-h/12-h light/dark cycle. After 4 days, the first wilt symptoms were observed on inoculated seedlings, and the infected plants eventually died within 1 to 2 weeks after inoculation. No symptoms were observed in plants inoculated with sterilized distilled water. The fungus was re-isolated from symptomatic tissues of inoculated plants and its colony and spore morphology were identical to those of the original isolate, thus confirming Koch's postulates. Fusarium wilt caused by F. equiseti has been reported in various crops, such as cauliflower in China, cumin in India, and Vitis vinifera in Spain (Farr and Rossman 2020). To our knowledge, this is the first report of F. equiseti causing Fusarium wilt on cabbage in Korea. It This disease poses a threat to cabbage production in Korea, and effective disease management strategies need to be developed.

scholarly journals First report of root rot of Schisandra chinensis caused by Fusarium acuminatum in Northeast China

Plant Disease ◽  
2021 ◽  
Author(s):  
Baoyu Shen ◽  
Wensong Sun ◽  
Kun Liu ◽  
Jing Tian Zhang
Keyword(s):  
Root Rot ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Liaoning Province ◽  
Effective Control ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Schisandra Chinensis ◽  
First Report ◽  
Fusarium Acuminatum

Wuweizi [Schisandra chinensis（Turcz.）Baill.] is used for traditional medicine in northeastern China. In August of 2019, root rot of S. chinensis with an incidence of 30%-50% was observed in a commercial field located in Liaozhong city (41º29’57” N, 122º52’33” E) in the Liaoning province of China. The diseased plants were less vigorous, stunted, and had leaves that turned yellow to brown. Eventually, the whole plant wilted and died. The diseased roots were poorly developed with brown lesion and eventually they would rot. To determine the causal agent, symptomatic roots were collected, small pieces of root with typical lesions were surface sterilized in 2% NaOCl for 3 min, rinsed three times in distilled water, and then plated onto PDA medium. After incubation at 26°C for 5 days, whitish-pink or carmine to rose red colonies on PDA were transferred to carnation leaf agar (CLA). Single spores were isolated with an inoculation needle using a stereomicroscope. Five single conidia isolates obtained from the colonies were incubated at 26°C for 7 days, abundant macroconidia were formed in sporodochia. Macroconidia were falcate, slender, with a distinct curve to the latter half of the apical cell, mostly 3 to 5 septate, measuring 31.3 to 47.8 × 4.8 to 7.5µm (n=50). Microconidia were oval and irregular ovals, 0-1 septate, measuring 5.0 to 17.5 × 2.5 to 17.5µm (n=50). Chlamydospores formed in chains on within or on top of the mycelium. Morphological characteristics of the isolates were in agreement with Fusarium acuminatum (Leslie and Summerell, 2006). To confirm the identity, the partial sequence of the translation elongation factor 1 alpha (TEF1-á) gene of five isolates was amplified using the primers EF-1(ATGGGTAAGGARGACAAG) and EF-2 (GGARGTACCAGTSATCATGTT) (O’Donnell et al. 2015 ) and sequenced. The rDNA internal transcribed spacer (ITS) region for the five isolates was also amplified using the primers ITS1 (TCCGTAGGTGAACCTGCGG) and ITS4 (TCCTCCGCTATTGATATGC) (White et al.1990) and sequenced. The identical sequences were obtained, and one representative sequence of isolate WW31-5 was submitted to GenBank. BLASTn analysis of the TEF-á sequence (MW423624) and ITS sequence (MZ145386), revealed 100%（708/685bp, 563/563bp）sequence identity to F. acuminatum MH595498 and MW560481, respectively. Pathogenicity tests were conducted in greenhouse. Inoculums of F. acuminatum was prepared from the culture of WW31-5 incubated in 2% mung beans juice on a shaker (140 rpm) at 26°C for 5 days. Ten roots of 2-years old plants of S. chinensis were immersed in the conidial suspension (2 × 105 conidia/ml) for 6 hours, and another ten roots immersed in sterilized distilled water in plastic bucket for 6 hours. All these plants were planted into pots with sterilized field soil (two plants per pot). Five pots planted with inoculated plants and another five pots planted with uninoculated plants served as controls. All ten pots were maintained in a greenhouse at 22-26°C for 21 days and irrigated with sterilized water. The leaves of the inoculated plants became yellow，gradually dried up, eventually finally all the aboveground parts died. The roots of the inoculated plants were rotted. Non-inoculated control plants had no symptoms. F. acuminatum was reisolated from the roots of inoculated plants and had morphology identical to the original isolate. The experiment was repeated twice with similar results. F. acuminatum has been reported as a pathogen caused root rot of ginseng (Wang et al. 2016) and not reported on Wuweizi in China. To our knowledge, this is the first report of root rot of S. chinensis caused by F. acuminatum. We have also observed the disease at Benxi city of Liaoning Province in 2020 and it has become an important disease in production of S. chinensis and the effective control method should be adopted to reduce losses.

scholarly journals First Report of Fusarium oxysporum f. sp. lycopersici Race 3 Causing Fusarium Wilt on Tomato in Korea

Plant Disease ◽  
2013 ◽  
Vol 97 (10) ◽  
pp. 1377-1377 ◽  
Author(s):  
H.-W. Choi ◽  
S. K. Hong ◽  
Y. K. Lee ◽  
H. S. Shim
Keyword(s):  
Fusarium Wilt ◽  
Dna Sequences ◽  
Vascular Tissue ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Spore Suspension ◽  
Vascular Bundles ◽  
Laboratory Manual ◽  
First Report ◽  
Blastn Analysis

In July 2010, fusarium wilt symptoms of tomato (Lycopersicon esculentum Mill.) plants were found in two commercial greenhouses in the Damyang area of Korea. Approximately 1% of 7,000 to 8,000 tomato plants were wilted and chlorotic in each greenhouse. The vascular tissue was usually dark brown and the discoloration extended to the apex. Fragments (each 5 × 5 mm) of the symptomatic tissue were surface-sterilized with 1% NaOCl for 1 min, then rinsed twice in sterilized distilled water (SDW). The tissue pieces were placed on water agar and incubated at 25°C for 4 to 6 days. Nine Fusarium isolates were obtained from four diseased plants, of which three isolates were identified as F. oxysporum based on morphological characteristics on carnation leaf agar medium and DNA sequences of the translation elongation factor 1-alpha (EF-1α) gene (2). Macroconidia were mostly 3- to 5-septate, slightly curved, and 28 to 53 × 2.8 to 5.2 μm. Microconidia were abundant, borne in false heads or short monophialides, generally single-celled, oval to kidney shaped, and 5 to 23 × 3 to 5 μm. Chlamydospores were single or in short chains. The EF-1α gene was amplified from three isolates by PCR assay using ef1 and ef2 primers (3), and the amplification products were sequenced. The nucleotide sequences obtained were deposited in GenBank (Accession Nos. KC491844, KC491845, and KC491846). BLASTn analysis showed 99% homology with the EF-1α sequence of F. oxysporum f. sp. lycopersici MN-24 (HM057331). Pathogenicity tests and race determination were conducted using root-dip inoculation (4) on seedlings of tomato differential cultivars: Ponderosa (susceptible to all races), Momotaro (resistant to race 1), Walter (resistant to races 1 and 2), and I3R-1 (resistant to all races). A spore suspension was prepared by flooding 5-day-old cultures on potato dextrose agar with SDW. Plants at the first true-leaf stage were inoculated by dipping the roots in the spore suspension (1 × 106 conidia/ml) for 10 min. Inoculated plants were transplanted into pots containing sterilized soil, and maintained in the greenhouse at 25/20°C (12/12 h). Twenty-four seedlings of each cultivar were arranged into three replications. An equal number of plants of each cultivar dipped in water were used as control treatments. Disease reaction was evaluated 3 weeks after inoculation, using a disease index on a scale of 0 to 4 (0 = no symptoms, 1 = slightly swollen and/or bent hypocotyl, 2 = one or two brown vascular bundles in the hypocotyl, 3 = at least two brown vascular bundles and growth distortion, 4 = all vascular bundles brown and the plant either dead or very small and wilted). All isolates caused symptoms of fusarium wilt on all cultivars except I3R-1, indicating that the isolates were race 3. The pathogen was reisolated from the discolored vascular tissue of symptomatic plants. Control plants remained asymptomatic, and the pathogen was not reisolated from the vascular tissue. Fusarium wilt of tomato caused by isolates of F. oxysporum f. sp. lycopersici races 1 and 2 has been reported previously; however, race 3 has not been reported in Korea (1). To our knowledge, this is the first report of isolates of F. oxysporum f. sp. lycopersici race 3 on tomato in Korea. References: (1) O. S. Hur et al. Res. Plant Dis. 18:304, 2012 (in Korean). (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (3) K. O'Donnell et al. Proc. Nat. Acad. Sci. 95:2044, 1998. (4) M. Rep et al. Mol. Microbiol. 53:1373, 2004.

scholarly journals First Report of Tuber Rot Disease of Kala Zeera Caused by a Member of the Fusarium solani Species Complex in India

Plant Disease ◽  
2012 ◽  
Vol 96 (7) ◽  
pp. 1067-1067 ◽  
Author(s):  
V. Gupta ◽  
D. John ◽  
V. K. Razdan ◽  
S. K. Gupta
Keyword(s):  
Fusarium Solani ◽  
Species Complex ◽  
Morphological Characteristics ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Potato Dextrose Broth ◽  
First Report ◽  
Fusarium Solani Species Complex ◽  
Rot Disease ◽  
Tuber Rot

Bunium persicum (Kala zeera, also black cumin) is an economically important culinary crop that is cultivated for its seed pods and its tuberlike roots. In India, high-altitude regions of Himachal Pradesh, including the Padder valley and the Gurez area of Jammu and Kashmir, are areas of kalazeera production (3). In 2008 to 2009, tuber rot disease of kala zeera was observed during the late spring season in the Padder valley. Symptomatic plants were distributed in localized areas in the field and the symptoms included drying of foliage and rotting of tubers. White mycelia were found on the tubers at the late stages of disease development. Incidence of infection in the surveyed area was 80 to 90%. Yield losses were 50 to 60%. To isolate the causal pathogen, we cultured tissues from symptomatic tubers. Small bits of the infected tissue were surface disinfested in 0.1% mercuric chloride, followed by rinsing three times in sterile distilled water. The surface disinfested tissues were plated on potato dextrose agar (PDA) and incubated at 27°C for 4 days. Pure cultures of the mycelium from the diseased tissues were transferred to a second set of PDA for species identification. The fungus produced three types of spores: small, one-celled, oval microconidia; large, slightly curved, septate macroconidia; and rounded, thick-walled chlamydospores. Microconidia were mostly non-septate and 8.91 to 15.73 × 2.3 to 3.5 μm, whereas macroconidia were three- to five-septate and were 35.55 to 54.74 × 3.91 to 6.5 μm. On the basis of morphological characteristics (1), the fungus was identified and deposited as a member of the Fusarium solani species complex in the Indian Type Culture Collection, New Delhi (ID No. 8422.11). To confirm pathogenicity, healthy tubers were submerged for 20 min in a conidial suspension of the isolated fungus (1 × 105 cfu/ml), which was prepared in potato dextrose broth, incubated for 10 days at 27°C, and centrifuged at 140 rpm. Noninoculated controls were submerged in distilled water. Inoculated and control tubers were then planted in separate pots filled with sterilized soil and kept in a shade house. Symptoms appeared on inoculated tubers 9 to 10 days after planting. Signs of the pathogen in the form of mycelia were present. The tubers rotted and died 12 to 15 days after inoculation. Control tubers did not display any symptoms. F. solani species complex was reisolated from inoculated tubers, fulfilling Koch's postulates. F. solani has been reported to cause corm rot on gladiolus and saffron (2). To our knowledge, this is the first report of the F. solani species complex as pathogenic to tubers of kalazeera in India. References: (1) C. Booth. The Genus Fusarium. 47, 1971. (2) L. Z. Chen et al. J. Shanghai Agric. College 12:240, 1994. (3) K. S. Panwar et al. Agriculture Situation in India. 48:151, 1993.

scholarly journals First Report of Fusarium solani on Utah Sweetvetch in the United States

Plant Disease ◽  
2013 ◽  
Vol 97 (3) ◽  
pp. 423-423 ◽  
Author(s):  
S. Uppala ◽  
B. M. Wu ◽  
T. N. Temple
Keyword(s):  
Native American ◽  
Fusarium Solani ◽  
Vascular Tissue ◽  
Agricultural Research ◽  
Apical Cell ◽  
The United States ◽  
Conidial Suspension ◽  
Soil Dna ◽  
First Report ◽  
Fungal Isolates

Utah sweetvetch (Hedysarum boreale Nutt.) is a native American perennial nitrogen fixing legume used mainly in rangeland reclamation, soil rejuvenation, and erosion control. In June 2011, a field of Utah sweetvetch grown for seeds in central Oregon had approximately 15% of the plants exhibiting chlorosis, defoliation, stunting, wilting, and/or death. Dissection of the crown of symptomatic plants revealed discolored pinkish brown vascular tissue. Symptomatic tissues from six random plants were surface sterilized, placed on acidified potato dextrose agar (PDA) medium, and cultured for 7 days at room temperature, which allowed six fungal isolates (SS1 through SS6) to be collected. On PDA, all six isolates had rapid, creamy white colored growth. Based on observations of 1-week-old isolates, microconidia were oval to kidney shaped, single celled, 8 to 10 × 2.5 to 4 μm, and formed at the tips of long unbranched monophialides. Macroconidia were three to four septate, cylindrical to slightly curved, with characteristic foot shaped basal cell and blunt apical cell, 37 to 49 × 4.4 to 5.3 μm. Chlaymydospores observed were 8.5 to 11 × 7.6 to 9 μm. Based on fungal references (1,2,3), the isolates were identified as Fusarium solani (Mart.) Sacc. Identification of the isolates at the molecular level was determined by amplification of the internal transcribed spacer (ITS) region using PCR and amplicon sequencing. Botrytis cinerea and F. graminearum cultures were used as controls for the extraction, amplification, and sequencing steps. Genomic DNA was extracted from mycelia using protocols of the MOBIO Ultraclean Soil DNA Isolation Kit (MO-BIO Laboratories Inc, Carlsbad, CA, USA). PCR was performed using ITS1/ITS4 primers and resulted in 563- to 573-bp amplicons, which were sequenced. Analysis of the ITS sequences (GenBank Accession Nos. JX524018 to JX524023) for the six fungal isolates using BLASTn revealed a 99% sequence identity with F. solani strains (AB470903, AB513851, AJ608989, EF152426, EU029589, and HM214456). Pathogenicity was confirmed on Utah sweetvetch plants in the greenhouse. Seeds of Utah sweetvetch were first plated on acidified PDA for germination; healthy seedlings were then selected and transplanted into pots with sterilized soil after 2 weeks of growth. The plants were kept in a greenhouse at Central Oregon Agricultural Research Center, Madras, Oregon. Ten 40-day-old healthy vetch plants were inoculated by drenching with a mixed conidial suspension (107 conidia/ml) of the six F. solani isolates. Ten plants drenched with sterile distilled water were included as controls. Symptoms of chlorosis and stunting similar to those in the commercial field were observed within 30 days of inoculation on 8 of 10 inoculated plants, while control plants were symptomless. Fungal isolates identical to F. solani were reisolated from the symptomatic plants. To our knowledge, this is the first report of F. solani on Utah sweetvetch plants. References: (1) C. Booth. The Genus Fusarium. CMI, Kew, Surrey, UK, 1971. (2) P. E. Nelson et al. Fusarium species: An illustrated manual for identification. The Pennsylvania State University Press, USA, 1983. (3) H. I. Nirenberg. A simplified method for identifying Fusarium spp. occurring on wheat. Can. J. Bot. 59:1599, 1980.

scholarly journals First Report of Nigrospora Leaf Blight on Tea Caused by Nigrospora sphaerica in India

Plant Disease ◽  
2015 ◽  
Vol 99 (3) ◽  
pp. 417-417 ◽  
Author(s):  
J. Dutta ◽  
S. Gupta ◽  
D. Thakur ◽  
P. J. Handique
Keyword(s):  
Camellia Sinensis ◽  
West Bengal ◽  
Morphological Characteristics ◽  
Its Region ◽  
Causative Organism ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Tea Leaves ◽  
First Report ◽  
Initial Symptoms

Tea [Camellia sinensis (L.) O. Kuntze] is an economically important non-alcoholic caffeine-containing beverage crop widely cultivated for leaves in India, especially in the Darjeeling district of West Bengal. In May 2012, distinct blight symptoms were observed on leaves of popular tea cultivars AV-2, Tukdah 78, Rungli Rungliot 17/144, and Bannockburn 157 in commercial tea estates of the Darjeeling district. This disease reduces yield and quality of the leaves. The initial symptoms were frequently observed on the young leaf margins and apices. Foliar symptoms are characterized by grayish to brown, semicircular or irregular shaped lesions, often surrounded by pale yellow zones up to 9 mm in diameter. The lesions later expand and the affected leaves turn grayish to dark brown and eventually the dried tissue falls, leading to complete defoliation of the plant. The disease causes damage to leaves of all ages and is severe in young leaves. A portion of the symptomatic leaf tissues were surface sterilized in 70% ethanol for 30 s, then in 2% NaClO for 3 min, rinsed three times in sterile distilled water, and plated onto potato dextrose agar (PDA). The fungal colonies were initially white and then became grayish to brown with sporulation. Conidia were spherical to sub spherical, single-celled, black, 19 to 21 μm in diameter, and were borne on a hyaline vesicle at the tip of each conidiophore. Morphological characteristics of the isolates were concurring to those of Nigrospora sphaerica (1). Moreover, the internal transcribed spacer (ITS) region of the ribosomal RNA was amplified by using primers ITS1 and ITS4 and sequenced (GenBank Accession No. KJ767520). The sequence was compared to the GenBank database through nucleotide BLAST search and the isolate showed 100% similarity to N. sphaerica (KC519729.1). On the basis of morphological characteristics and nucleotide homology, the isolate was identified as N. sphaerica. Koch's postulates were fulfilled in the laboratory on tea leaves inoculated with N. sphaerica conidial suspension (106 conidia ml−1) collected from a 7-day-old culture on PDA. Six inoculated 8-month-old seedlings of tea cultivars AV-2 and S.3/3 were incubated in a controlled environment chamber at 25°C and 80 to 85% humidity with a 12-h photoperiod. In addition, three plants of each cultivar were sprayed with sterile distilled water to serve as controls. Twelve to 14 days after inoculation, inoculated leaves developed blight symptoms similar to those observed on naturally infected tea leaves in the field. No symptoms were observed on the control leaves. The pathogen was re-isolated from lesions and its identity was confirmed by morphological characteristics. It was reported that N. sphaerica is frequently encountered as a secondary invader or as a saprophyte on many plant species and also as a causative organism of foliar disease on several hosts worldwide (2,3). To our knowledge, this is first report of N. sphaerica as a foliar pathogen of Camellia sinensis in Darjeeling, West Bengal, India, or worldwide. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (2) D. F. Farr and A. Y. Rossman. Fungal Databases, Syst. Mycol. Microbiol. Lab., ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ July 01, 2013. (3) E. R. Wright et al. Plant Dis. 92:171, 2008.

scholarly journals First report of fruit blight caused by Alternaria alternata on sesame in Northeast China

Plant Disease ◽  
2021 ◽  
Author(s):  
Hongsen Cheng ◽  
De Xue Gao ◽  
Huijie Sun ◽  
Yanbin Na ◽  
Jing Xu
Keyword(s):  
Alternaria Alternata ◽  
Morphological Characteristics ◽  
Its Region ◽  
Liaoning Province ◽  
Oilseed Crop ◽  
Distilled Water ◽  
Conidial Suspension ◽  
First Report ◽  
Health Products ◽  
Blight Disease

Sesame (Sesamum indicum L.) is an important oilseed crop in China and it is also used in food and health products. In August of 2019, a blight sesame fruit was observed in a field of Liaoyang city, Liaoning province of China. Initial disease symptoms consisted of brown or dark brown spots on fruit. With time, lesions coalesced and the whole fruit turned dark brown or black. Most of the diseased fruit had thin and small, deformed, necrotic, hardened cracked epidermal lesions. Lesions were also produced on stem and petioles leading to leaf abscission. The disease results in premature fruit death, and in turn, considerable yield losses. To determine the causal agent, symptomatic fruit with developing lesions were collected, and surface sterilized in 2% NaClO for 3 min, rinsed three times in distilled water, and plated onto PDA medium. After incubation at 25°C for 5 days, a dark olivaceous fungus with abundant, branched, brown to black, and septate hyphae was consistently isolated. Twenty single spores were separated with an inoculation needle under stereomicroscope. The conidia were in chains, brown, obclavate, ovoid or ellipsoid, with 1-6 transverse septa and 0-4 longitudinal or oblique septa 12.5 to 45 × 6.5 to 14.5 μm in size. Conidiophores were septate, light brown to olive brown, measuring 22-60 μm × 2-4 μm. The morphological characteristics of the 20 isolates all matched the description of Alternaria alternata (Simmons, 2007). The internal transcribed spacer (ITS) region of rDNA of 15 isolates was amplified using primers ITS1/ITS4 (White et al. 1990) and EF1-728F/EF1-986R (Carbone et al. 1999) and sequenced. Identical sequences were obtained and the sequence of the isolate ZMHG12 was submitted to GenBank (Accession no. MW418181 and MW700316). BLAST analysis of the sequences of the isolates of ZMHG12 showed 100% to A. alternata (KP739875 and LC132712). In pathogenicity tests, a conidial suspension (2.5 × 105 conidia per ml) was prepared from 7 days-old cultures of isolate ZMHG12 grown on PDA at 25°C. Fruit of 10 two-month-old potted sesame plants (Variety “Liaozhi 8”) were sprayed with the conidia suspension until runoff. Another 10 plants sprayed with distilled water to served as non-inoculated controls. All plants were maintained for 48 h in a humid chamber with a temperature of 25°C to 26°C, and then moved to a greenhouse. Ten days after inoculation, all fruit of inoculated plants exhibited symptoms similar to those observed in the field and non-inoculated control plants remained symptomless. The experiment was repeated twice with similar results. A. alternata has been reported as a pathogen caused leaf blight disease of sesame in Pakistan (Nayyar et al. 2017). To our knowledge, this is the first report of A.alternata causing fruit blight of sesame in China. To date, we have observed the disease on sesames in fields of Fuxin, Chaoyang and Tieling city in Liaoning Province, and Tongliao city in Inner Mongolia of China, and it has become an important disease in sesame production of China. References : Simmons E. G. 2007. Alternaria: An identification manual. CBS Fungal Biodiversity Center, Utrecht, Netherlands. White T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego. Carbone I., et al. 1999. Mycologia, 91: 553-556. Nayyar, B. G., et al. 2017. Plant Pathology Journal, 33 (6): 543-553.

scholarly journals First Report of Fusarium ipomoeae Causing Peanut leaf Spot in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Manlin Xu ◽  
Xia Zhang ◽  
Jing Yu ◽  
zhiqing Guo ◽  
Ying Li ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Genomic Dna ◽  
Block Design ◽  
Management Strategies ◽  
Morphological Characteristics ◽  
Ethanol Solution ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Internal Transcribed Spacer Region ◽  
First Report

Peanut (Arachis hypogaea L.) is one of the most economically important crops as an important source of edible oil and protein. In August 2020, circular to oval-shaped brown leaf spots (2-6 mm in diameter) with well-defined borders surrounded by a yellow margin were observed on peanut plant leaves in Laixi City, Shandong Province, China. Symptomatic plants randomly distributed in the field, the incidence was approximately 5%. Leave samples were collected consisted of diseased tissue and the adjacent healthy tissue. The samples were dipped in a 70% (v/v) ethanol solution for 30 s and then soaked in a 0.1% (w/v) mercuric chloride solution for 60 s. The surface-sterilized tissues were then rinsed three times with sterile distilled water, dried and placed on Czapek Dox agar supplemented with 100 μg/ml of chloramphenicol. The cultures were incubated in darkness at 25 °C for 3–5 days. Fungal colonies were initially white and radial, turning to orange-brown in color, with abundant aerial mycelia. Macroconidia were abundant, 4 to 7 septate, with a dorsiventral curvature, and were 3.3–4.5 × 18.5–38.1 μm (n=100) in size; microconidia were absent; chlamydospores were produced in chains or clumps, ellipsoidal to subglobose, and thick walled. The morphological characteristics of the conidia were consistent with those of Fusarium spp. To identify the fungus, an EasyPure Genomic DNA Kit (TransGEN, Beijing, China) was used to extract the total genomic DNA from mycelia. The internal transcribed spacer region (ITS rDNA) and the translation elongation factor 1-α gene (TEF1) were amplified with primers ITS1/ITS4 (White et al. 1990) and EF1/EF2 (O’Donnell et al. 1998), respectively. Based on BLAST analysis, sequences of ITS (MT928727) and TEF1 (MT952337) showed 99.64% and 100% similarity to the ITS (MT939248.1), TEF1 (GQ505636.1) of F. ipomoeae isolates. Sequence analysis confirmed that the fungus isolated from the infected peanut was F. ipomoeae (Xia et al. 2019). The pathogenicity of the fungus was tested in the greenhouse. Twenty two-week-old peanut seedlings (cv. Huayu20) grown in 20-cm pots (containing autoclaved soil) were sprayed with a conidial suspension (105 ml−1) from a 15-day-old culture. Control plants were sprayed with distilled water. The experiment was conducted as a randomized complete block design, and placed at 25 °C under a 12-h photoperiod with 90% humidity. Symptoms similar to those in the field were observed on leaves treated with the conidial suspension ten days after inoculation, but not on control plants. F. ipomoeae was re-isolated from symptomatic leaves but not from the control plants. Reisolation of F. ipomoeae from inoculated plants fulfilled Koch's postulates. To our knowledge, this is the first report of F. ipomoeae causing peanut leaf spot in China. Our report indicates the potential spread of this pathogen in China and a systematic survey is required to develop effective disease management strategies.

scholarly journals First Report of Verticillium Wilt caused by Verticillium dahliae Kleb. on New Zealand Spinach (Tetragonia tetragonioides) in Italy

Plant Disease ◽  
2013 ◽  
Vol 97 (1) ◽  
pp. 145-145
Author(s):  
A. Garibaldi ◽  
S. Rapetti ◽  
P. Martini ◽  
L. Repetto ◽  
D. Bertetti ◽  
...  
Keyword(s):  
New Zealand ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Vascular Tissue ◽  
Spinacia Oleracea ◽  
Morphological Characteristics ◽  
Conidial Suspension ◽  
Potato Dextrose Broth ◽  
First Report ◽  
Tetragonia Tetragonioides

Tetragonia tetragonioides (New Zealand spinach, Aizoaceae) is an Australasian annual species that occurs naturally in Italy, where it is cultivated for the edible young shoots and succulent leaves. In September 2011, a previously unknown wilt was observed in 10 private gardens, each 0.1 to 0.5 ha, near Castellaro, Northern Italy, on 7-month-old New Zealand spinach plants. Leaves wilted, starting from the collar and moving up the plant, and vascular tissues showed brown streaks in the roots, crowns, and stems. Diseased plants were stunted with small, chlorotic leaves. Infected stems and leaves then wilted, and plants often died. Of about 500 plants, 30% were affected. Stems of 10 diseased plants were disinfected with 1% NaOCl for 1 min. Sections of symptomatic vascular tissue were plated on potato dextrose agar. After 3 days at 23 ± 1°C, colonies developed that were white and turned a grey to dark green color. Irregular, black microsclerotia (32.0) 63.1 ± 16.8 μm (106.1) × (18.7) 39.1 ± 12.3 μm (65.8) developed in hyaline hyphae after 8 days. Hyaline, elliptical, single-celled conidia (2.7) 3.8 ± 0.6 μm (4.8) × (1.9) 2.6 ± 0.5 μm (3.5) developed on verticillate conidiophores with three phialides at each node. Based on these morphological characteristics, the fungus was identified as Verticillium dahliae (1). The internal transcribed spacer (ITS) region of rDNA was amplified for one isolate using the primers ITS1/ITS4 (3) and sequenced (GenBank Accession No. JX308315). BLASTn analysis of the 479-bp segment showed 100% homology with the ITS sequence of a V. dahliae isolate (AB551206). Pathogenicity tests were performed twice using 60-day-old plants of T. tetragonioides. Unwounded roots of eight plants were dipped for 1 min in a conidial suspension (5 × 107 conidia/ml) of one isolate of V. dahliae obtained from the original infected New Zealand spinach plants, and grown in potato dextrose broth. The inoculated plants were transplanted into 2-liter pots (1 plant/pot) containing steamed potting mix (sphagnum peat-perlite-pine bark-clay; 50:20:20:10) and maintained in a growth chamber at 20 to 24°C and 50 to 80% RH. Eight plants immersed in sterile water served as a control treatment. Wilt symptoms were observed 30 days after inoculation, with vascular discoloration in the roots, crowns and stems. V. dahliae was reisolated consistently from infected tissues, but not from the control plants that remained healthy. Pathogenicity was also tested using the same method on plants of four cultivars (five plants/cultivar) of Spinacia oleracea (Matador, Asti, Merlo Nero, and America). Wilt symptoms developed on all cultivars and V. dahliae was reisolated from each inoculated plant. No fungal colonies were reisolated from control plants, which remained healthy. To our knowledge, this is the first report of Verticillium wilt caused by V. dahliae on T. tetragonioides in Italy, as well in Europe. V. dahliae was reported on T. tetragonioides in Canada (2). At this time, the economic impact of Verticillium wilt on New Zealand Spinach in Italy is limited, although the use of this vegetable in Italy is increasing. References: (1) G. F. Pegg and B. L. Brady. Verticillium Wilts. CABI Publishing, Wallingford, UK, 2002. (2) M. J. Richardson. Page 387 in: An Annotated List of Seed-Borne Diseases, Fourth Edition. International Seed Testing Association, Zurich, Switzerland, 1990. (3) T. J. White et al. Page 315 in: PCR Protocols. A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

Sign in / Sign up

Export Citation Format

Share Document