scholarly journals First Report of Pestalotiopsis mangiferae and P. vismiae Causing Twig Dieback of Myrica rubra in China

Plant Disease ◽  
2012 ◽  
Vol 96 (4) ◽  
pp. 588-588 ◽  
Author(s):  
F. Y. Chen ◽  
L. M. Lu ◽  
H. Z. Ni ◽  
Y. Wang ◽  
Y. G. Wang ◽  
...  
Keyword(s):  
Basal Cell ◽  
Southern China ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Fluorescent Light ◽  
Water Control ◽  
First Report ◽  
Myrica Rubra ◽  
Potted Plants ◽  
Detached Leaves

Chinese bayberry (Myrica rubra Siebold & Zucc.), an evergreen fruit tree, is widely grown in southern China. In 1999, severe twig dieback was observed on M. rubra in Taizhou and it spread to several major M. Rubra-producing areas of Zhejiang covering more than 6,000 ha by 2011. Symptoms were usually observed from June to November and first appeared as chlorosis of leaves and leaf drop, followed by the formation of dark brown lesions covered with white mycelia surrounding leaf scars. The lesions can extend to the whole twig and tree causing discoloration of the xylem. In most cases, infected trees die within 1 to 4 years. Two distinct fungi totaling 46 isolates were isolated from the surface-disinfested diseased twigs and cultured on potato dextrose agar (PDA) at 28°C. An isolate of each fungus, designated as C1 and B1, was characterized further following 10 days of growth on PDA at 28°C. C1 formed zonate, white colonies and black, acervular conidiomata with the conidia aggregated on acervuli as a creamy mass. Isolate B1 formed nonzonate, white colonies and black, acervular conidiomata with the conidia aggregated on acervuli as droplets. Conidia for each isolate were fusiform with five cells; one hyaline apical cell, one hyaline basal cell, and three, dark brown median cells. Conidia ranged from 17.8 to 25.2 × 6.7 to 9.2 μm for C1 and 21.2 to 27.8 × 4.3 to 7.5 μm for B1. There were two to three hyaline, filamentous appendages (9.8 to 23.5 μm long for C1 and 10.5 to 25.5 μm long for B1) attached to each apical cell, and one hyaline appendage (3.5 to 7.2 μm long for C1 and 3.0 to 6.8 μm long for B1) attached to each basal cell. The cultural and morphological characteristics of C1 (16 isolates) matched the description for Pestalotiopsis mangiferae while B1 (27 isolates) matched the description for P. vismiae (2). The PCR-amplified and sequenced internal transcribed spacer (ITS) region of the ribosomal DNA (ITS1-5.8S-ITS2) for isolate C1 (GenBank Accession No. JQ281542) and B1 (GenBank Accession No. JQ281543) were 99 and 100% homologous to that of the P. mangiferae isolate MM 102 (GenBank Accession No. GU722595) and P. vismiae isolate xsd08116 (GenBank Accession No. FJ481027), respectively. For pathogenicity tests, nine healthy detached leaves and 12 potted plants of M. rubra were wound inoculated with sterile water (control) or conidial suspensions (105 conidia per ml; 20 μl on each site) of C1 and B1, respectively, and maintained with relative humidity of more than 90% under fluorescent light at 28°C. Tests were performed twice. Necrotic lesions, resembling those that occurred in the field, were observed on all inoculated detached leaves and 33.3% of C1 and 25% of B1 inoculated potted plants 10 and 30 days following inoculation, respectively, while the controls remained healthy. Two fungi were reisolated from the lesions with identical morphology to the initial C1 and B1 inoculums. Therefore, P. mangiferae and P. vismiae were determined to be the causal agent for twig dieback of M. rubra in China. Pestalotiopsis spp. were previously reported as pathogens of loquat (4), mango (3), and blueberry (1) causing economic loss. To our knowledge, this is the first report of twig dieback disease of M. rubra caused by P. mangiferae and P. vismiae. References: (1) J. G. Espinoza et al. Plant Dis. 92:1407, 2008. (2) Q. X. Ge et al. Flora Fungorum Sinicorum. Vol. 38, Pestalotiopsis. Science Press, Beijing, 2009. (3). Y. Ko et al. Plant Dis. 91:1684, 2007. (4). A. E. Perelló and S. Larran. Plant Dis. 83:695, 1999.

scholarly journals First Report of Pestalotiopsis microspora Causing Leaf Blight of Reineckea carnea in Central China

Plant Disease ◽  
2009 ◽  
Vol 93 (6) ◽  
pp. 667-667 ◽  
Author(s):  
M. D. Wu ◽  
G. Q. Li ◽  
D. H. Jiang
Keyword(s):  
Basal Cell ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Leaf Blight ◽  
Causal Agent ◽  
Central China ◽  
Fluorescent Light ◽  
Leaf Margin ◽  
First Report ◽  
Pestalotiopsis Microspora

Pink reineckia (Reineckea carnea (Andrews) Kunth) is an evergreen herbaceous perennial plant widely grown as groundcover or for medical purposes in southern China. In 2006 and 2007, severe leaf blight was observed on pink reineckia in Wuhan, China. On newly formed pink reineckia leaves, symptoms were first noted in early May as grayish to dark brown, oval or irregular-shaped lesions, 1.5 to 0.2 × 0.5 to 0.1 cm (n = 50), on the leaf margin or leaf tip. A yellowish halo surrounded each lesion. Lesions enlarged and coalesced and diseased leaves became blighted during the fall and winter. In severely infected plots, most plants became straw-colored and had to be replaced with healthy seedlings. A fungus was isolated from surface-disinfested lesions on potato dextrose agar (PDA) at a frequency of 85.7%. One of 30 isolates, designated C2, was characterized further. The fungus growing on PDA at 20°C for 14 days formed zonate white colonies and black acervular conidiomata. Conidia of the fungus aggregated on acervuli as droplets. Conidia were fusiform and 20.7 to 32.2 × 5.8 to 9.8 μm (n = 50). Each conidium had one hyaline apical cell, one hyaline basal cell, and three dark brown median cells. There were two to four hyaline filamentous appendages 8.1 to 20.4 μm long attached to each apical cell and one hyaline appendage 2.4 to 7.1 μm long attached to each basal cell. The cultural and morphological characteristics of isolate C2 matched the description for Pestalotiopsis microspora (Speg.) Batista & Peres (1,2). The internal transcribed spacer (ITS) region of the ribosomal DNA (ITS1-5.8S-ITS2) was PCR-amplified and sequenced. The ITS sequence (606 bp) for isolate C2 (GenBank Accession No. EU935587) was 100% similar to P. microspora isolates TA-57 (GenBank Accession No. AY924267) and LK32 (GenBank Accession No. DQ001002). Pathogenicity of isolate C2 was tested with the method described by Keith et al. (2). Four detached leaves were wound inoculated or inoculated without wounding with mycelia on agar plugs (4 mm in diameter; three plugs per leaf) or conidial suspensions (107 conidia per ml; 20 μl on each of three sites per leaf). Control leaves were wound inoculated with PDA or sterile water. All inoculated leaves were maintained in a moist enamel tray under fluorescent light for 7 days at 20°C. The test was performed twice. After 4 days of incubation, necrotic leaf lesions resembling symptoms that occurred in the field were observed on the wound-inoculated leaves, whereas the control leaves and C2-inoculated leaves without wounding remained healthy. Therefore, wounding was necessary for symptom development (2). A fungus was reisolated from the C2-induced leaf lesions and the morphology of colonies and conidia were identical to that for isolate C2 of P. microspora. On the basis of the results of isolations, inoculations, and fungal identification, P. microspora was determined to be the causal agent for leaf blight of pink reineckia occurring in Wuhan, China. This fungus previously has been reported as the causal agent of scab disease of Psidium guajava in Hawaii (2), decline of Torreya taxifolia in Florida (3), and leaf blight of Lindera obtusiloba in Korea (1). To our knowledge, this is the first report of the occurrence of P. microspora on R. carnea. References: (1) Y. H. Jeon et al. Plant Pathol. 56:349, 2007. (2) L. M. Keith et al. Plant Dis. 90:16, 2006. (3) M. W. Schwartz et al. Plant Dis. 80:600, 1996.

scholarly journals First Report of Fusarium Root Rot of Stored Carrot Caused by Fusarium avenaceum in Serbia

Plant Disease ◽  
2015 ◽  
Vol 99 (2) ◽  
pp. 286-286
Author(s):  
I. Stanković ◽  
K. Milojević ◽  
A. Vučurović ◽  
D. Nikolić ◽  
B. Krstić ◽  
...  
Keyword(s):  
Root Rot ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Fusarium Avenaceum ◽  
Control Treatment ◽  
Fluorescent Light ◽  
Fungal Mycelium ◽  
Vegetable Crops ◽  
Orange Pigment ◽  
First Report

Carrot (Daucus carota L. subsp. sativus (Hoffm.) Thell., Apiaceae), a widely consumed antioxidant-rich plant, is among the major vegetable crops grown in Serbia, with average annual production of 65,400 tons on approximately 7,000 ha (4). In May 2013, a severe root rot was observed on approximately 20% of cold-stored carrot roots originating from Gospođinci, South Bačka District, Serbia. Symptoms included dry rot of the collar and crown as well as large, brown to dark brown, circular, sunken lesions on the stored roots. Frequently, abundant whitish mycelium was observed covering the surface of the colonized roots. To determine the causal agent, small pieces of infected tissue were surface-disinfested with 2% NaOCl without rinsing, air-dried, and placed on potato dextrose agar. Five single-spore isolates obtained from collar and crown tissue sections, as well as nine isolates from root sections, all formed abundant, cottony white to pale salmon fungal colonies with reddish orange pigment on the reverse surface of the agar medium when grown at 25°C under 12 h of fluorescent light per day. All recovered isolates formed numerous, three- to six-septate, hyaline, needle-like, straight to slightly curved, fusoid macroconidia (30 to 80 × 4 to 5.5 μm, average 58.3 × 4.9 μm, n = 100 spores) each with a tapering apical cell. Microconidia of all isolates were generally scarce, two- to four-septate, spindle-shaped, and 15 to 35 × 3 to 5 μm (average 21.3 × 4.2 μm). Chlamydospores were not observed. Based on these morphological characteristics, the pathogen was identified as Fusarium avenaceum (Fries) Saccardo (1). The pathogenicity on carrot was tested for isolate 19-14 by inoculating each of five carrot roots surface-disinfected with 2% NaOCl, by placing a mycelial plug into the surface of a wound created with a cork borer. Carrot roots inoculated with sterilized PDA plugs served as a negative control treatment. After 5 days of incubating the roots at 25°C, root rot symptoms identical to those observed on the source carrot plants developed on all inoculated roots, and the pathogen was re-isolated from each of these roots using the same procedure descibed above. There were no symptoms on the control roots. Morphological species identification was confirmed by sequencing the translation elongation factor (EF-1α) gene (2). Total DNA was extracted directly from fungal mycelium of isolate 19-14 with a DNeasy Plant Mini Kit (Qiagen, Hilden, Germany), and PCR amplification was performed with primer pair EF-1/EF-2 (2). Sequence analysis of the EF-1α gene revealed 100% nucleotide identity of isolate 19-14 (GenBank Accession No. KM102536) with the EF-1α sequences of two F. avenaceum isolates from Canada (KC999504 from rye and JX397864 from Triticum durum). To our knowledge, this is the first report of F. avenaceum causing collar, crown, and root rots of stored carrot in Serbia. Since F. avenaceum can produce several mycotoxins, including moniliformin, acuminatopyrone, and chrysogine (3), the presence of this pathogen on stored carrots could represent a significant constraint for carrot production in Serbia, for both direct yield losses and potential mycotoxin contamination. References: (1) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual, Blackwell Publishing, London, UK, 2006. (2) K. O'Donnell et al. Proc. Natl. Acad. Sci. U.S.A. 95:2044, 1998. (3) J. L. Sorenson. J. Agric. Food Chem. 57:1632, 2009. (4) Statistical Office, Republic of Serbia. Retrieved from http://webrzs.stat.gov.rs in May 2014.

scholarly journals First Report of Brown Leaf Spot of Juglans hybrid Caused by Ophiognomonia leptostyla in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Chunlin Yang ◽  
Feng Liu ◽  
Qian Zeng ◽  
Xiulan Xu ◽  
Yicong Lv ◽  
...  
Keyword(s):  
Basal Cell ◽  
Leaf Spot ◽  
Juglans Regia ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Control Measures ◽  
Effective Control ◽  
First Report ◽  
Brown Leaf Spot ◽  
Brown Leaf

“Chuanzao 2” is a walnut variety derived from the hybridization of Juglans regia L. and J. sigillata Dode distributed in southwest China, where it is an economically important tree species in rural regions (Xiao et al. 2012). In April 2020, the variety in a walnut garden showed symptoms of brown leaf spot in Beishan Town (107°21′43.93″E, 31°28′12.34″N), Dazhou City in Sichuan, China, with 5% to 10% of leaves per plant affected (5 plants). Symptomatic leaves showed brown to dark brown spots (2 to 5 mm) with a dark brown to black halo and grayish-tan center. The spots were subcircular to irregular in shape, and gradually expanded and formed necrotic spots. A single conidium isolation was performed (Senanayake et al. 2020) and transferred to Potato Dextrose Agar (PDA). Five isolates were obtained from five different infected leaves. Colonies of five isolates were subcircular, erose or dentate, flat or effuse, white initially, gradually becoming yellowish with white margins, developed and fluffy aerial mycelia, and conidiogenensis was produced underneath mycelia after 25-days-incubation. Conidiogenous cells were subcylindrical to cylindrical, or irregular in shape, and hyaline. Macroconidia were lunate, reniform, hyaline, basal cell bluntly rounded, apical cell with acute end, 1-septate, rarely aseptate, sometimes slightly constricted at septum, basal cell equal or larger than apical cell, and measured 16.5 to 30.5 × 5 to 8.5 μm (mean = 23.2 × 6.3 μm, n = 50). Microconidia were not observed. These morphological characteristics resembled those of Ophiognomonia leptostyla (Fr.) Sogonov (Walker et al. 2012a). For molecular identification, genomic DNA (isolates SICAUCC 21-0008 and SICAUCC 21-0010) was extracted, and the internal transcribed spacers (ITS) region, guanine nucleotide-binding protein subunit beta (MS204) gene, and translation elongation factor 1-alpha (tef1-α) were amplified and sequenced by using the primers ITS5/ITS4 (White et al. 1990), E1F1/E5R1a (Walker et al. 2012a), and EF1-728F/EF1-1567R (Walker et al. 2012b), respectively. Phylogenetic analyses (maximum likelihood) based on a combined dataset showed 100% bootstrap support values in a clade with O. leptostyla. The sequences of ITS, MS204, and tef1-α genes were deposited in GenBank with accession numbers MW493111/MZ026300, MW495270/MZ031975, and MW495271/MZ031974, respectively. To fulfill Koch’s postulates, five healthy hybrid plants (2 to 3 years old) with 5 to 8 leaves per plant were spray inoculated with conidium suspensions (104 conidia/mL; isolate SICAUCC 21-0008) prepared from 40-days-old cultures onto the wounded sites via pin-prick inoculation. Similarly, five noninoculated plants sprayed with sterile water served as controls. Plants were placed in a growth chamber at 25℃ on a 12-h fluorescent light/dark regime and daily sprayed with sterile distilled water. After two weeks, observed symptoms were similar to those from natural infections. No disease symptoms were found on control plants. The fungus O. leptostyla was reisolated from the diseased leaves and characterized morphologically. O. leptostyla is a global pathogen and has been reported to cause the leaf spot in many walnut trees, viz. J. ailantifolia, J. californica, J. cinerea, and J. major, etc. To our knowledge, this is the first report of O. leptostyla causing brown leaf spot on Juglans hybrid (J. regia × J. sigillata) in China. The increasing risk of this pathogen in the walnut-growing areas of Sichuan Province of China needs a further exploration and outreach effort to develop effective control measures. Chunlin Yang, Feng Liu, and Qian Zeng contributed equally to this paper.

scholarly journals First Report of Pestalotiopsis sydowiana Causing Leaf Necrosis of Myrica rubra in China

Plant Disease ◽  
2012 ◽  
Vol 96 (5) ◽  
pp. 764-764
Author(s):  
X. R. Chen ◽  
Y. P. Xing ◽  
T. X. Zhang ◽  
J. T. Zheng ◽  
J. Y. Xu ◽  
...  
Keyword(s):  
Southern China ◽  
Morphological Characteristics ◽  
Internal Transcribed Spacers ◽  
Effective Control ◽  
Morphological Identification ◽  
Basal Cells ◽  
Sterile Water ◽  
First Report ◽  
Myrica Rubra ◽  
Leaf Necrosis

Red bayberry (Myrica rubra Seib. & Zucc.) has great economic importance in eastern and southern China. However, increasing cultivation of red bayberry has resulted in an increase in diseases such as leaf necrosis. In April 2011, a survey was conducted to identify the causal agents of leaf necrosis of red bayberry (cv. Biqi) in Cixi City, Zhejiang Province. Symptoms began with oval and pale brown lesions (2 mm in diameter) that developed into a round to irregular shape (4 to 12 mm in diameter) with pale brown centers and dark brown borders. After approximately 4 months, necrotic lesions expanded to the leaf tips or margins. Black acervuli developed on lesions at later stages. Leaf tissues were surface sterilized with 0.5% sodium hypochlorite for 3 min and rinsed in sterile water before plating onto potato dextrose agar (PDA). Seven isolates were obtained from four samples from four fields on PDA at 25°C. The colonies were cottony white with filiform edges and produced a honey yellow color into the agar at 7 days. Conidia were produced in ink-like fruiting bodies at 4 days at 25°C on PDA. Conidia were straight or slightly curved, fusiform, and five celled with constrictions at the septa. Conidia ranged from 18.7 to 25.8 × 6.2 to 7.7 μm with hyaline apical and basal cells. Thirteen percent of the apical cells had two and the rest had three hyaline appendages ranging from 11.2 to 26.0 μm long. Basal appendages were hyaline, straight, and varied from 3.6 to 5.8 μm long. The color of three median cells was light to dark brown and demonstrated versicolorous. These morphological characteristics matched those of Pestalotiopsis sydowiana (Bresadola) Sutton (1). The morphological identification of the fungus was confirmed by nucleotide blast analysis of the 5.8S subunit and flanking internal transcribed spacers (ITS1 and ITS2) of rDNA regions (GenBank Accession No. JQ322999), which revealed 100% with those of other P. sydowiana isolates (e.g., GenBank Accession No. FJ478105). Koch's postulates were confirmed with 20 healthy leaves of the same size on three branches of three plants in the field. Leaves were wounded by pressing slightly with sterile needles. Mycelial plugs (5 mm in diameter) obtained from the periphery of 7-day-old cultures were placed onto the wounds and covered with sterile-water-saturated cotton. Wounded leaves treated with sterile agar plugs served as controls. The inoculated leaves were sealed in moist plastic bags for 24 h to establish high humid conditions at 21 to 30°C. After 23 days, symptoms on all inoculated leaves were identical to those described above, whereas noninoculated control leaves did not show any symptoms. The fungus was consistently reisolated from the lesions. To our knowledge, this is the first report of P. sydowiana causing leaf necrosis of M. rubra in China. Results can help to better understand the diseases threatening red bayberry trees and develop effective control strategies for better fruit production. Reference: (1) E. F. Guba. Monograph of Monochaetia and Pestalotia. Harvard University Press, Cambridge, MA, 1961.

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 Damping-Off Caused by Rhizoctonia solani AG-4 on Mediterranean Fan Palm in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 125-125 ◽  
Author(s):  
G. Polizzi ◽  
D. Aiello ◽  
I. Castello ◽  
V. Guarnaccia ◽  
A. Vitale
Keyword(s):  
Rhizoctonia Solani ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Mediterranean Area ◽  
Western Mediterranean ◽  
Fluorescent Light ◽  
Damping Off ◽  
Centraalbureau Voor ◽  
First Report ◽  
Stem Lesions

Mediterranean fan palm (Chamaerops humilis L.), one of just two autochthonous European palms, is native to the western Mediterranean Region in southwestern Europe and northwestern Africa. It can be found growing wild in the Mediterranean area. In Europe, this species is very popular as an ornamental plant. In March 2009, a widespread damping-off was observed in a stock of approximately 30,000 potted 1-month-old plants of C. humilis cv. Vulcano in a nursery in eastern Sicily. Disease incidence was approximately 20%. Disease symptoms consisted of lesions at the seedling shoot (plumule). Stem lesions were initially orange, turned brown, and followed by death of the entire plumule or eophyll. A fungus with mycelial and morphological characteristics of Rhizoctonia solani Kühn was consistently isolated from lesions when plated on potato dextrose agar (PDA) amended with streptomycin sulfate at 100 μg/ml. Fungal colonies were initially white, turned brown with age, and produced irregularly shaped, brown sclerotia. Mycelium was branched at right angles with a septum near the branch and a slight constriction at the branch base. Hyphal cells removed from cultures grown at 25°C on 2% water agar were determined to be multinucleate when stained with 1% safranin O and 3% KOH solution (1) and examined at ×400. Anastomosis groups were determined by pairing isolates with tester strains AG-1 IA, AG-2-2-1, AG-2-2IIIB, AG-2-2IV, AG-3, AG-4, AG-5, AG-6, and AG-11 on 2% water agar in petri plates (3). Anastomosis was observed only with tester isolates of AG-4, giving both C2 and C3 reactions (2). One representative isolate obtained from symptomatic tissues was deposited at the Fungal Biodiversity Centre, Centraalbureau voor Schimmelcultures (CBS No. 125095). Pathogenicity tests were performed on container-grown, healthy, 1-month-old seedlings. Twenty plants of C. humilis cv. Vulcano were inoculated near the base of the stem with two 1-cm2 PDA plugs from 5-day-old mycelial cultures. The same number of plants served as uninoculated controls. Plants were incubated in a growth chamber and maintained at 25°C and 95% relative humidity on a 12-h fluorescent light/dark regimen. Symptoms identical to those observed in the nursery appeared 5 days after inoculation and all plants died within 20 days. No disease was observed on control plants. A fungus identical in culture morphology to R. solani AG-4 was consistently reisolated from symptomatic tissues, confirming its pathogenicity. To our knowledge, this is the first report in the world of R. solani causing damping-off on Mediterranean fan palm. References: (1) R. J. Bandoni. Mycologia 71:873, 1979. (2) D. E. Carling. Page 37 in: Grouping in Rhizoctonia solani by Hyphal Anastomosis Reactions. Kluwer Academic Publishers, the Netherlands, 1996. (3) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.

scholarly journals First Report of Stemphylium botryosum Causing Leaf Blight of Kiwi in the Province Imathia, Northern Greece

Plant Disease ◽  
2008 ◽  
Vol 92 (4) ◽  
pp. 650-650 ◽  
Author(s):  
T. Thomidis ◽  
T. J. Michailides
Keyword(s):  
Apical Cell ◽  
Morphological Characteristics ◽  
Leaf Blight ◽  
Width Ratio ◽  
Northern Greece ◽  
Cell Width ◽  
Koch’S Postulates ◽  
First Report ◽  
Stemphylium Botryosum ◽  
Koch's Postulates

In Greece, kiwi (Actinidia deliciosa) is mostly found in the northern part of the country where approximately 440,000 ha are grown. In the summer of 2006, a Stemphylium sp. was frequently isolated from leaves of kiwi (cv. Hayward) grown in the province of Imathia. Symptomatic leaves were covered with irregular, necrotic, brown areas. Lesions had a distinct margin that, in some cases, covered a wide part of the diseased leaves. Intense symptoms were frequently observed and associated with defoliation. This Stemphylium sp. was consistently isolated from diseased leaves onto potato dextrose agar (PDA) after surface sterilization with 0.1% chlorine solution. On the basis of morphological characteristics of mycelia, dimensions (length 20 to 29 μm and width 14 to 21 μm) and mean length/width ratio (1.42 μm) of conidia, and width and apical cell width of condiophores, the fungus was identified as Stemphylium botryosum (Wallr.) (2,3) Koch's postulates were completed in the laboratory by inoculating leaves of kiwi (cv. Hayward) with an isolate of S. botryosum originated from a symptomatic leaf of a Hayward kiwi. Twenty leaves were surface sterilized by dipping them into 0.1% chlorine solution for 2 to 3 min, washing in sterile distilled water, and allowing them to dry in a laminar flow hood. A leaf was then placed into a petri plate containing a wet, sterilized paper towel. Inoculation was made by transferring a 5-mm-diameter mycelial disc from the margins of a 7-day-old culture onto the center of each leaf surface. Petri plates were closed and incubated at 25°C with 12 h of light for 6 days. Koch's postulates were satisfied when the same S. botryosum was reisolated from 100% of inoculated leaves that developed symptoms similar to those observed in the vineyards. Leaves inoculated with a PDA plug alone (with no S. botryosum) did not develop any symptoms. Previously, Alternaria alternata was reported as the causal agent of a leaf spot pathogen of kiwi (1,4). To our knowledge, this is the first report of the occurrence of S. botryosum causing leaf blight of kiwi in Greece and worldwide. This pathogen can cause a high level of defoliation in diseased plants. References: (1) L. Corazza et al. Plant Dis. 83:487, 1999. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Mycology Institute. London, England, 1971. (3) E. G. Simmons. Mycologia 61:1, 1969. (4) C. Tsahouridou and C. C. Thanassoulopoulos. Plant Dis. 84:371, 2000

scholarly journals First report of Leptosphaeria biglobosa ‘canadensis’ causing blackleg on oilseed rape (Brassica napus) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Tao Luo ◽  
Guoqing Li ◽  
Long Yang
Keyword(s):  
Brassica Napus ◽  
Oilseed Rape ◽  
Southern China ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Gansu Province ◽  
Bootstrap Support ◽  
First Report ◽  
Fungal Isolates ◽  
Leptosphaeria Biglobosa

Oilseed rape (Brassica napus L.) is one of the most important oilseed crops in China. It is widely cultivated in China, with winter oilseed rape in Yangtze River basin and in southern China, and spring oilseed rape in northern China. In August 2017, a survey for Leptosphaeria spp. on spring oilseed rape was conducted in Minle county, Zhangye city, Gansu Province, China. The symptoms typical of blackleg on basal stems of oilseed rape were observed in the field. A large number of black fruiting bodies (pycnidia) were present on the lesions (Fig. 1A). The disease incidence of basal stem infection in the surveyed field was 19%. A total of 19 diseased stems were collected to isolate the pathogen. After surface sterilizing (75% ethanol for 30 s, 5% NaOCl for 60 s, followed by rinsing in sterilized water three times), diseased tissues were cultured on acidified potato dextrose agar (PDA) plates at 20°C for 7 days. Twelve fungal isolates were obtained. All fungal isolates produced typical tan pigment on PDA medium, and produced pycnidia after two weeks (Fig. 1B). Colony morphological characteristics indicated that these isolates might belong to Leptosphaeria biglobosa. To confirm identification, multiple PCR was conducted using the species-specific primers LmacF, LbigF, LmacR (Liu et al. 2006). Genomic DNA of each isolate was extracted using the cetyltrimethylammonium bromide (CTAB) method. DNA samples of L. maculans isolate UK-1 and L. biglobosa isolate W10 (Cai et al. 2015) were used as references. Only a 444-bp DNA band was detected in all 12 isolates and W10, whereas a 333-bp DNA band was detected only in the UK-1 isolate (Fig. 1C). PCR results suggested that these 12 isolates all belong to L. biglobosa. In addition, the internal transcribed spacer (ITS) region of these 12 isolates was analyzed for subspecies identification (Vincenot et al. 2008). Phylogenetic analysis based on ITS sequence showed that five isolates (Lb1134, Lb1136, Lb1138, Lb1139 and Lb1143) belonged to L. biglobosa ‘brassicae’ (Lbb) with 78% bootstrap support, and the other seven isolates (Lb1135, Lb1137, Lb1140, Lb1141, Lb1142, Lb1144 and Lb1145) belonged to L. biglobosa ‘canadensis’ (Lbc) with 95% bootstrap support (Fig. 1D). Two Lbb isolates (Lb1134 and Lb1136) and two Lbc isolates (Lb1142 and Lb1144) were randomly selected for pathogenicity testing on B. napus cultivar Zhongshuang No. 9 (Wang et al. 2002). Conidial suspensions (10 μL, 1 × 107 conidia mL-1) of these four isolates were inoculated on needle-wounded cotyledons (14-day-old seedling), with 10 cotyledons (20 wounded sites) per isolate. A further 10 wounded cotyledons were inoculated with water and served as controls. Seedlings were maintained in a growth chamber at 20°C with 100% relative humidity and a 12-h photoperiod. After 7 days, cotyledons inoculated with the four isolates showed necrotic lesions in the inoculated wounds. Control cotyledons had no symptoms (Fig. 2). Fungi re-isolated from the infected cotyledons showed similar colony morphology as the original isolates. Therefore, L. biglobosa ‘brassicae’ and L. biglobosa ‘canadensis’ appear to be the pathogens causing the observed blackleg symptoms on spring oilseed rape in Gansu, China. In previous studies, L. biglobosa ‘brassicae’ has been found in many crops in China, including oilseed rape (Liu et al. 2014; Cai et al. 2015), Chinese radish (Raphanus sativus) (Cai et al. 2014a), B. campestris ssp. chinensis var. purpurea (Cai et al. 2014b), broccoli (B. oleracea var. italica) (Luo et al. 2018), ornamental kale (B. oleracea var. acephala) (Zhou et al. 2019a), B. juncea var. multiceps (Zhou et al. 2019b), B. juncea var. tumida (Deng et al. 2020) and Chinese cabbage (B. rapa subsp. pekinensis) (Yu et al. 2021 accepted). To the best of our knowledge, this is the first report of L. biglobosa ‘canadensis’ causing blackleg on B. napus in China.

scholarly journals First Report of Fusarium pernambucanum Causing Fruit Rot of Muskmelon in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Xianping Zhang ◽  
Jiwen Xia ◽  
Jiakui Liu ◽  
Dan Zhao ◽  
Lingguang Kong ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Fruit Rot ◽  
Likelihood Method ◽  
Correct Identification ◽  
Pathogenicity Test ◽  
First Report ◽  
The Core ◽  
Representative Isolate

Muskmelon (Cucumis melo L.) is one of the most widely cultivated and economically important fruit crops in the world. However, many pathogens can cause decay of muskmelons; among them, Fusarium spp. is the most important pathogen, affecting fruit yield and quality (Wang et al. 2011). In May 2017, fruit rot symptoms were observed on ripening muskmelons (cv. Jipin Zaoxue) in several fields in Liaocheng of Shandong Province, China. Symptoms appeared as brown, water-soaked lesions, irregularly circular in shape, with the lesion size ranging from a small spot (1 to 2 cm) to the decay of the entire fruit. The core and the surface of the infected fruit were covered with white to rose-reddish mycelium. Two infected muskmelons were collected from each of two fields, 10 km apart. Tissues from the inside of the infected fruit were surface disinfected with 75% ethanol for 30 s, and cultured on potato dextrose agar (PDA) at 25 °C in the dark for 5 days. Four purified cultures were obtained using the single spore method. On carnation leaf agar (CLA), macroconidia had a pronounced dorsiventral curvature, falcate, 3 to 5 septa, with tapered apical cell, and foot-shaped basal cell, measuring 19 to 36 × 4 to 6 μm. Chlamydospores were abundant, 5.5–7.5 μm wide, and 5.5–10.5 μm long, ellipsoidal or subglobose. No microconidia were observed. These morphological characteristics were consistent with the descriptions of F. pernambucanum (Santos et al. 2019). Because these isolates had similar morphology, one representative isolate was selected for multilocus phylogenetic analyses. DNA was extracted from the representative isolate using the CTAB method. The nucleotide sequences of the internal transcribed spacers (ITS) (White et al. 1990), translation elongation factor 1-α gene (TEF1), RNA polymerase II second largest subunit gene (RPB2), calmodulin (CAM) (Xia et al. 2019) were amplified using specific primers, sequenced, and deposited in GenBank (MN822926, MN856619, MN856620, and MN865126). Based on the combined dataset of ITS, TEF1, RPB2, CAM, alignments were made using MAFFT v. 7, and phylogenetic analyses were processed in MEGA v. 7.0 using the maximum likelihood method. The studied isolate (XP1) clustered together with F. pernambucanum reference strain URM 7559 (99% bootstrap). To perform pathogenicity test, 10 μl of spore suspensions (1 × 106 conidia/ml) were injected into each muskmelon fruit using a syringe, and the control fruit was inoculated with 10 μl of sterile distilled water. There were ten replicated fruits for each treatment. The test was repeated three times. After 7 days at 25 °C, the interior of the inoculated muskmelons begun to rot, and the rot lesion was expanded from the core towards the surface of the fruit, then white mycelium produced on the surface. The same fungus was re-isolated from the infected tissues and confirmed to fulfill the Koch’s postulates. No symptoms were observed on the control muskmelons. To our knowledge, this is the first report of F. pernambucanum causing of fruit rot of muskmelon in China. Considering the economic value of the muskmelon crop, correct identification can help farmers select appropriate field management measures for control of this disease.

scholarly journals First Report of Fusarium Wilt on Eremophila spp. Caused by Fusarium oxysporum in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (12) ◽  
pp. 1509-1509 ◽  
Author(s):  
G. Polizzi ◽  
D. Aiello ◽  
V. Guarnaccia ◽  
A. Vitale ◽  
G. Perrone ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Morphological Characteristics ◽  
Gene Sequences ◽  
Single Spore ◽  
First Report ◽  
Potted Plants ◽  
Plastic Bags ◽  
Gene Coding ◽  
Affected Plant ◽  
Tubulin Protein

Eremophila spp. (Myoporaceae family), endemic to Australia, are evergreen shrubs or small trees occurring in arid, semi-arid, tropical, or temperate regions. In Europe, Eremophila spp. are grown for their horticultural appeal. During 2009 and 2010, extensive wilting was observed on 2-month to 1-year-old potted plants of Eremophila laanii F. Muell., E. glabra subsp. carnosa Chinnock, and E. maculata (Ker Gawl.) F. Muell. grown in a commercial nursery near Catania (southern Italy). Internally, symptomatic plants had conspicuous vascular discoloration from the crown to the canopy. Diseased crown and stem tissues were surface disinfested for 30 s in 1% NaOCl, rinsed in sterile water, plated on potato dextrose agar (PDA) amended with 100 mg/liter of streptomycin sulfate, and incubated at 25°C. A Fusarium sp. was consistently isolated from affected plant tissues. Colonies with purple mycelia and violet reverse colors developed after 9 days. On carnation leaf agar, single-spore isolates produced microconidia on short monophialides, macroconidia that were three to five septate with a pedicellate base, and solitary and double-celled or aggregated chlamydospores. A PCR assay was conducted on two representative isolates (ITEM 12591 and ITEM 12592) by analyzing sequences of the partial CaM gene (coding calmodulin protein) and benA (coding beta-tubulin protein) using the primers as reported by O'Donnell et al. (1). Calmodulin sequences of ITEM 12951 and ITEM 12952 isolates (GenBank Nos. FR671157 and FR671158) exhibited 99.8 and 99.5% identity with Fusarium oxysporum strain ITEM 2367 (GenBank No. AJ560774), respectively, and had 99.5% homology between them. BenA gene sequences of ITEM 12951 (GenBank No. FR671426) exhibited an identity of 100% to F. oxysporum f. sp. vasinfectum strain CC-612-3 (GenBank No. AY714092.1), and benA gene sequences of ITEM 12952 (GenBank No. FR671427) exhibited an identity of 100% to F. oxysporum f. sp. vasinfectum strain LA 140 (GenBank No. FJ466740.1), whereas the homology between the two strains is 99.5%. Morphological characteristics, as well as CaM and benA sequences, identified the isolates as F. oxysporum Schlechtend:Fr. Pathogenicity tests were performed by placing 1-cm2 plugs of PDA from 9-day-old mycelial cultures near the crown on potted, healthy, 3-month-old cuttings of E. laanii, E. glabra subsp. carnosa, and E. maculata. Twenty plants for each species were inoculated with each isolate. The same number of plants served as noninoculated controls. All plants were enclosed for 4 days in plastic bags and placed in a growth chamber at 24 ± 1°C. Plants were then moved to a greenhouse where temperatures ranged from 23 to 27°C. Symptoms identical to those observed in the nursery developed 20 days after inoculation with both strains. Crown and stem discoloration was detected in all inoculated plants after 45 days. Wilting was detected on 15% of plants. Control plants remained symptomless. F. oxysporum was consistently reisolated from symptomatic tissues and identified as previously above. To our knowledge, this is the first report of F. oxysporum causing disease of Eremophila spp. worldwide. Reference: (1) K. O'Donnell et al. Mycoscience 41:61, 2000.

Sign in / Sign up

Export Citation Format

Share Document