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 Aspergillus niger Causing Postharvest Fruit Rot of Cherry in the Prefectures of Imathia and Pella, Northern Greece

Plant Disease ◽  
2012 ◽  
Vol 96 (3) ◽  
pp. 458-458 ◽  
Author(s):  
T. Thomidis ◽  
E. Exadaktylou
Keyword(s):  
Aspergillus Niger ◽  
Fungal Spores ◽  
Morphological Characteristics ◽  
Fruit Rot ◽  
Northern Greece ◽  
Centraalbureau Voor ◽  
Koch’S Postulates ◽  
First Report ◽  
Postharvest Rot ◽  
Koch's Postulates

In June 2011, symptoms of postharvest rot were observed on approximately 3% of all cherries collected from commercial orchards of cultivars Lapen and Ferrovia in the prefectures of Imathia and Pella (northern Greece). Fruit were harvested in a timely manner to avoid overripeness. No wounds or other predisposing injuries were observed on the infected fruits. Lesions enlarged rapidly and separated easily from healthy tissue when pressure was applied. Infected tissues were pale and water soaked and the associated fungal spores were dark and powdery and easily liberated when mature. The fungus grew rapidly and produced black colonies on acidified potato dextrose agar (2.5 ml of 85% lactic acid per liter of nutrient medium) after 5 days at 24°C. Identification of the pathogen was based on morphological characteristics (1). The conidial head was radiate, vesicles were nearly spherical and covered with metulae and phialides (biseriate). Conidia were globose (3 to 5 μm in diameter) and usually very rough with irregular ridges, bars, and verrucae. Koch's postulates were completed in the laboratory by inoculating mature cherry fruits (cv. Lapen). The fruits were surface sterilized by dipping in 10% chloride bleach solution, allowed to dry in a laminar flow hood, and wounded with a sharp glass rod that was 2 mm in diameter. A 40-μl drop of a suspension containing 20,000 conidia per ml of water was placed on each wound. There were 20 inoculated and 20 control fruits (similarly wounded and inoculated with a 40-μl drop of sterile distilled water) in a randomized design and incubated at 24 to 26°C for 6 days. Koch's postulates were satisfied after reisolating the fungus from inoculated fruit that developed symptoms similar to those observed on fruit collected from orchards. Control fruits did not show any symptom of the disease. To our knowledge, this is the first report of the occurrence of Aspergillus niger as the causal agent of postharvest rots of cherries in Greece. Postharvest fruit rots caused by A. niger have been reported in cherry orchards of other countries around the world (2). Because this disease causes postharvest rots of cherry fruits, measures may need to be implemented to manage the pathogen. References: (1) M. A. Klich. Page 12 in: Identification of Common Aspergillus Species. Centraalbureau Voor Schimmelcultures, Utrecht, the Netherlands, 2002. (2) A. Valiuskaite et al. Phytopathol. Pol. 35:197, 2005.

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 Leaf Spot Disease on Walnut Caused by Colletotrichum fioriniae in China

Plant Disease ◽  
2015 ◽  
Vol 99 (2) ◽  
pp. 289-289 ◽  
Author(s):  
Y. Z. Zhu ◽  
W. J. Liao ◽  
D. X. Zou ◽  
Y. J. Wu ◽  
Y. Zhou
Keyword(s):  
Dna Sequences ◽  
Leaf Spot ◽  
Juglans Regia ◽  
Morphological Characteristics ◽  
Leaf Spot Disease ◽  
Koch’S Postulates ◽  
First Report ◽  
Spot Disease ◽  
Leaf Spots ◽  
Koch's Postulates

In May 2014, a severe leaf spot disease was observed on walnut tree (Juglans regia L.) in Hechi, Guangxi, China. Leaf spots were circular to semicircular in shape, water-soaked, later becoming grayish white in the center with a dark brown margin and bordered by a tan halo. Necrotic lesions were approximately 3 to 4 mm in diameter. Diseased leaves were collected from 10 trees in each of five commercial orchards. The diseased leaves were cut into 5 × 5 mm slices, dipped in 75% ethanol for 30 s, washed three times in sterilized water, sterilized with 0.1% (w/v) HgCl2 for 3 min, and then rinsed five times with sterile distilled water. These slices were placed on potato dextrose agar (PDA), followed by incubating at 28°C for about 3 to 4 days. Fungal isolates were obtained from these diseased tissues, transferred onto PDA plates, and incubated at 28°C. These isolates produced gray aerial mycelium and then became pinkish gray with age. Moreover, the reverse of the colony was pink. The growth rate was 8.21 to 8.41 mm per day (average = 8.29 ± 0.11, n = 3) at 28°C. The colonies produced pale orange conidial masses and were fusiform with acute ends, hyaline, sometimes guttulate, 4.02 to 5.25 × 13.71 to 15.72 μm (average = 4.56 ± 0.31 × 14.87 ± 1.14 μm, n = 25). The morphological characteristics and measurements of this fungal isolate matched the previous descriptions of Colletotrichum fioriniae (Marcelino & Gouli) R.G. Shivas & Y.P. Tan (2). Meanwhile, these characterizations were further confirmed by analysis of the partial sequence of five genes: the internal transcribed spacer (ITS) of the ribosomal DNA, beta-tubulin (β-tub) gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene, chitin synthase 3(CHS-1) gene, and actin (ACT) gene, with universal primers ITS4/ITS5, T1/βt2b, GDF1/GDR1, CHS1-79F/CHS1-354R, and ACT-512F/ACT-783R, respectively (1). BLAST of these DNA sequences using the nucleotide database of GenBank showed a high identify (ITS, 99%; β-tub, 99%; GAPDH, 99%; CHS-1, 99%; and ACT, 100%) with the previously deposited sequences of C. fioriniae (ITS, KF278459.1, NR111747.1; β-tub, AB744079.1, AB690809.1; GAPDH, KF944355.1, KF944354.1; CHS-1, JQ948987.1, JQ949005.1; and ACT, JQ949625.1, JQ949626.1). Koch's postulates were fulfilled by inoculating six healthy 1-year-old walnut trees in July 2014 with maximum and minimum temperatures of 33 and 26°C. The 6-mm mycelial plug, which was cut from the margin of a 5-day-old colony of the fungus on PDA, was placed onto each pin-wounded leaf, ensuring good contact between the mycelium and the wound. Non-colonized PDA plugs were placed onto pin-wounds as negative controls. Following inoculation, both inoculated and control plants were covered with plastic bags. Leaf spots, similar to those on naturally infected plants, were observed on the leaves inoculated with C. fioriniae within 5 days. No symptoms were observed on the negative control leaves. Finally, C. fioriniae was re-isolated from symptomatic leaves; in contrast, no fungus was isolated from the control, which confirmed Koch's postulates. To our knowledge, this is the first report of leaf disease on walnut caused by C. fioriniae. References: (1) L. Cai et al. Fungal Divers. 39:183, 2009. (2) R. G. Shivas and Y. P. Tan. Fungal Divers. 39:111, 2009.

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 Botryosphaeria dothidea Causing Shoot Blight of Kiwifruit (Actinidia deliciosa) in Greece

Plant Disease ◽  
2010 ◽  
Vol 94 (12) ◽  
pp. 1503-1503 ◽  
Author(s):  
T. Thomidis ◽  
E. Exadaktylou
Keyword(s):  
Random Amplified Polymorphic Dna ◽  
Morphological Characteristics ◽  
Fungal Mycelium ◽  
Adhesive Tape ◽  
Petroleum Jelly ◽  
Koch’S Postulates ◽  
First Report ◽  
Agar Plug ◽  
Dna Primers ◽  
Koch's Postulates

In the spring of 2010, in commercial orchards located in the Prefecture of Pieria in northern Greece, wilted shoots of kiwifruit cv. Hayward were observed. Blighted shoots took on a distinct dark color. Isolations from the lower margins of the cankers were made by plating sodium-hypochlorite-treated shoot tissue sections of approximately 3 mm on acidified (2.5 ml of 85% lactic acid per liter of nutrient medium to create a pH = 3.5 after autoclaving) potato dextrose agar. Plates were incubated at 23°C for 5 days, and a fast-growing, mouse-gray colored fungus was consistently isolated from diseased stems. Identification of the pathogen was based on morphological characteristics and confirmed by using the four random amplified polymorphic DNA primers (K19 [CAC AGG CGG A], K20 [GTG TCG CGA G], R13 [GGA CGA CAA G], and R15 [GGA CAA CGA G], suggested by Ma et al. (2). This fungus formed darkly pigmented pycnidia (170 × 155 μm), while the conidia observed in these bodies were one-celled, hyaline, ellipsoidal to fusoid with distinctly truncate bases, and measured 10.9 to 21.55 × 3.25 to 10.10 μm. The pycnidia exuded conidia in white tendrils. Koch's postulates were completed in the laboratory by inoculating 20 segments (6 cm long and 1.5 to 2 cm in diameter) of 1-year-old woody shoots of kiwifruit cv. Hayward. Using a cork borer, a 7-mm-diameter wound was created in the middle of each shoot segment by removing the bark and a 6-mm-diameter agar plug bearing mycelia from a 15-day-old culture of B. dothidea was inserted into the wound. The wound was covered with petroleum jelly and wrapped with adhesive tape to prevent desiccation. Ten control segments were similarly wounded and inoculated with an agar disk without fungal mycelium. All inoculated and noninoculated shoot segments were incubated at 25°C in moist chambers, after which the resulting necrosis was recorded. Koch's postulates were satisfied after reisolating the fungus from inoculated shoots that developed symptoms similar to those observed on shoots collected from orchards. Although B. dothidea has been previously reported to cause dieback on kiwifruit in Japan (1), to our knowledge, this is the first report of the occurrence of B. dothidea on kiwifruit in Greece. This pathogen can cause a high level of shoot blights in diseased plants and presents a significant threat to the commercial kiwifruit production in Greece. References: (1) M. Kinugawa and T. Sato. Ann. Phytopathol. Soc. Jpn. 69:373, 2003. (2) Z. Ma et al. Phytopathology 91:665, 2001.

scholarly journals First Report of Phomopsis amygdali Causing Fruit Rot on Peaches in Greece

Plant Disease ◽  
2006 ◽  
Vol 90 (12) ◽  
pp. 1551-1551 ◽  
Author(s):  
T. J. Michailides ◽  
T. Thomidis
Keyword(s):  
Prunus Persica ◽  
Morphological Characteristics ◽  
Fruit Rot ◽  
Peach Fruit ◽  
Koch’S Postulates ◽  
Canker Disease ◽  
First Report ◽  
Immature Fruit ◽  
Diseased Fruit ◽  
Koch's Postulates

In the summer of 2005, the fungus Phomopsis amygdali (Del.) Tuset & Portilla was frequently isolated from decayed peaches (Prunus persica cv. Andross) grown in the province of Imathia, Greece. Fruit infected by P. amygdali developed gray-to-brown decay lesions with white mycelium forming on the surface of lesions. Identification of the pathogen was based on morphological characteristics. Dark-pigmented pycnidia (flask-shaped, conidia-bearing fruiting bodies) were produced over the surface of potato dextrose agar. The pycnidia exuded conidia in white tendrils 7 days later. Koch's postulates were completed in the laboratory by inoculating mature and immature cv. Andross peach fruits with an isolate of P. amygdali isolated from decayed cv. Andross peaches. Thirty peach fruit were surface sterilized by dipping them into 0.1% chlorine solution and allowing them to dry in a laminar flow hood. The peach fruit were wounded with a 2-mm diameter glass rod and a 40-μl drop of 5 × 105 conidia of P. amygdali per milliliter suspension was applied to the wound. Thirty control fruits were similarly wounded and inoculated with a 40-μl drop of sterile water. All inoculated and noninoculated fruit were incubated at 24 to 26°C for 7 days. Koch's postulates were satisfied when the same fungus was reisolated from 100% of inoculated mature and immature fruit that developed symptoms similar to diseased fruit collected from orchards. Although P. amygdali has been previously reported as a causal agent of canker disease (2) and fruit rots of peaches (1) in other countries, to our knowledge, this is the first report of the occurrence of P. amygdali causing a fruit rot of peaches in Greece. References: (1) Y. Ko and S. Sun. Plant Pathol. Bull. 12:212, 2003. (2) E. I. Zehr, Constriction canker. Page 31 in: Compendium of Stone Fruit Diseases. J. M. Ogawa et al., eds. The American Phytopathological Society, St. Paul, MN, 1995.

scholarly journals First Report of Magnaporthe poae, Cause of Summer Patch Disease on Annual Bluegrass, in Canada

Plant Disease ◽  
2012 ◽  
Vol 96 (11) ◽  
pp. 1698-1698 ◽  
Author(s):  
M. M. I. Bassoriello ◽  
K. S. Jordan
Keyword(s):  
Morphological Characteristics ◽  
Root Tissue ◽  
Golf Course ◽  
Koch’S Postulates ◽  
First Report ◽  
Annual Bluegrass ◽  
Streptomycin Sulfate ◽  
Magnaporthe Poae ◽  
Patch Disease ◽  
Koch's Postulates

The ectotrophic, root-infecting fungus Magnaporthe poae Landschoot & Jackson, the causal agent of summer patch disease in the U.S. (2), is implicated in the damage and loss of annual bluegrass (Poa annua L.) on golf course greens. This pathogenic fungus, one of the important root pathogens of turfgrass, attacks and colonizes susceptible turfgrass roots suffering from environmental or cultural stresses. Over 100 turf samples that exhibited symptoms (chlorotic circular or irregular patches of ≥15 cm in diameter with necrotic crowns and discolored roots) reminiscent of summer patch were collected from 77 southwestern Ontario golf courses from July to August of 2009 and 2010. Roots and crowns were often covered with dark, ectotrophic runner hyphae, lobed hyphopodia, and growth cessation structures, characteristic of M. poae. Sections of root tissue were surface sterilized in 0.6% sodium hypochlorite (NaOCl) for 5 min. Sterilized root tissue was plated on potato dextrose agar (PDA) containing 50 mg L–1 streptomycin sulfate and incubated at 28°C for 7 to 10 days. A fungus with morphological characteristics (hyaline mycelium that appears gray or olive-brown when mature) similar to those of M. poae (1) was consistently isolated (≥100 isolates were obtained) and used to identify M. poae through molecular techniques and Koch's postulates. DNA was extracted from the fungal mycelium of the collected isolates using the PowerPlant DNA isolation kit (MO BIO Laboratories, Inc., Carlsbad, CA). The rDNA internal transcribed spacer (ITS) regions of the isolates (≥100 isolates) were amplified by PCR using universal fungal rDNA primers ITS 4 (5′-TCCTCCGCTTATTGATATGC-3′) and ITS 5 (5′- GGAAGTAAAAGTCGTAACAAGG-3′) (3). The purified PCR products were sequenced (GenBank Accession No. JX134588 through JX134601) and a BLAST search exhibited seven isolates with 99% (MAG3, MAG6, MAG13, MAG16, and MAG17) and 100% (MAG1 and MAG14) similarity to M. poae in the GenBank database. Pathogenicity of four isolates (MAG1, MAG3, MAG6, and MAG14) was confirmed with Koch's postulates. Sixteen healthy P. annua core samples (four replicates of each treatment/isolate) collected from an Ontario golf course were inoculated with 25 mg M. poae-infested Kentucky bluegrass seed (Poa pratensis L.; 12.5 mg inoculum applied at the surface of the potting medium and 12.5 mg inoculum applied on the foliar surface) and were placed in a growth chamber with 12-h day/night cycles at 30/25°C and approximate relative humidity. After 2 to 3 weeks, inoculated plants exhibited chlorotic foliage and necrotic roots covered with dark ectotrophic runner hyphae and lobed hyphopodia. Infected root sections from each replication were surface sterilized and placed on PDA containing 50 mg L–1 streptomycin sulfate. The fungal cultures exhibited morphological characteristics consistent with M. poae (1). To our knowledge, this is the first report of summer patch caused by M. poae in Canada. References: (1) B. B. Clarke and A. B. Gould, eds. Turfgrass Patch Diseases Caused by Ectotrophic Root-Infecting Fungi. The American Phytopathological Society, St. Paul, MN, 1993. (2) P. J. Landschoot and N. Jackson. Mycol. Res. 93:59, 1989. (3) T. J. White et al. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. Pages 315-322 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al. eds. Academic Press, San Diego, CA, 1990.

scholarly journals Occurrence of a Fruit Spot Disease of Pear Caused by Septoria pyricola in Tyrnavos Larissa, Northern Greece

Plant Disease ◽  
2014 ◽  
Vol 98 (6) ◽  
pp. 845-845
Author(s):  
T. Thomidis ◽  
S. Katerinis
Keyword(s):  
South Africa ◽  
Leaf Spot ◽  
Morphological Characteristics ◽  
Northern Greece ◽  
Koch’S Postulates ◽  
Randomized Design ◽  
Fruit Spot ◽  
Koch's Postulates ◽  
Wounded Area ◽  
Septoria Leaf Spot

Pear tree (Pyrus communis) is an important crop in Greece. In 2012, fruits of the pear cv. Kontoula were observed in commercial fields located in Tirnavos, Prefecture of Larrisa, Greece, with symptoms of well-defined brown angular margins and their grayish white centers in which a few pycnidia (about 180 × 150 μm) were produced within the spots. Pycnidia were dark, separate, and globe-shaped with an ostiole (opening at the apex) from which conidia (about 40 to 60 × 3 μm) were extruded, and erupted through the surface of the infected tissue. Conidia were produced on short conidiophores. They were clear, narrowly elongated to filiform, and several-celled. The pathogen was isolated on acidified-PDA (2.5 ml 85% lactic acid per liter of nutrient medium) and incubated at 23°C for 7 days. The pathogen was identified as Septoria pyricola Desm. based on morphological characteristics. Koch's postulates were completed in the laboratory by placing a 40-μl drop of suspension (4 × 105 conidia ml−1 of water) on a wounded area of healthy fruits of cv. Kontoula. Fruits were surface sterilized with dipping in 0.1% chlorine solution, allowed to dry in a laminar flow hood. There were 15 inoculated and 15 control fruits (similarly inoculated with sterile distilled water) in a randomized design. Fruits were covered with perforated polythene bags to maintain a high humidity necessary for infection and these bags were removed 48 h after inoculation and maintained at room temperature (23 ± 2°C). Lesion development was recorded daily for each fruit. Koch's postulates were satisfied after re-isolating the fungus from inoculated fruit that developed symptoms similar to those observed on fruits collected from fields. Symptoms of this disease were found in all pear orchards cultivating the cv. Kontoula located in Tyrnavos (a municipality in the Prefecture of Larissa). Symptoms of septoria leaf spot were also observed in the above pear orchards. In contrast, no symptom of septoria fruit spot and septoria leaf spot was observed in apple orchards of the above regions. To our knowledge, this is the first report of the occurrence of S. pyricola as causal agent of fruit spot of pears in Greece. Fruit spotting is relatively uncommon; nevertheless, Sivanesan (3) gives two reports of conidia infecting pear fruits from Italy and South Africa (1,2). References: (1) G. Florenzano. Int. Bull. Plant Prot. 20:17, 1946. (2) A. J. Louw. Farming in South Africa 23:737, 1948. (3) A. Sivanesan. IMI Descriptions of Fungi and Bacteria, vol. 99, sheet 989. CABI, Wallingford, UK, 1990.

scholarly journals First Report of Azalea Petal Blight Caused by Pestalotiopsis guepini in Argentina

Plant Disease ◽  
2000 ◽  
Vol 84 (1) ◽  
pp. 100-100 ◽  
Author(s):  
M. C. Rivera ◽  
E. R. Wright
Keyword(s):  
Buenos Aires ◽  
Morphological Characteristics ◽  
Potato Dextrose Agar ◽  
Commonwealth Mycological Institute ◽  
Conidial Suspension ◽  
Koch’S Postulates ◽  
First Report ◽  
Pure Cultures ◽  
Pathogenicity Testing ◽  
Koch's Postulates

The most important azalea (Rhododendron spp.) growing area in Argentina is located in the outskirts of Buenos Aires. A disease of the azalea flower was detected during surveys conducted during September 1998. Irregular brown spots were uniformly distributed on petals and resulted in a flower blight that did not lead to abscission of petals. Pieces of infected petals were surface-sterilized for 1 min in 2% NaOCl, plated on potato dextrose agar, and incubated at 24 ± 2°C. Pure cultures were identified as Pestalotiopsis guepini (Desmaz.) Steyaert (synamorph P. guepini Desmaz.) based on morphological characteristics (1,2). Inoculation for pathogenicity testing was carried out by spraying a conidial suspension (1 × 106 conidia per ml) on plants with previously punctured petals. Inoculated plants with unwounded flowers, as well as noninoculated controls, were included. Plants were incubated in moist chambers at 24°C. Symptoms appeared on all punctured flowers within 4 to 5 days. Petals were blighted by 9 days after inoculation and were covered with black acervuli by 12 days after inoculation. Unwounded and noninoculated controls remained symptomless. The pathogen was reisolated from inoculated flowers, completing Koch's postulates. Pathogenicity of P. guepini on azalea leaves in Argentina was reported in 1991. This is the first report of P. guepini causing disease on azalea flowers in Argentina. References: (1) J. E. M. Mordue. CMI Descr. Pathog. Fungi Bact. No. 320, 1971. (2) B. C. Sutton. 1980. The Coelomycetes. Commonwealth Mycological Institute, Kew, England.

scholarly journals First Report of Garlic Leaf Blight Caused by Botrytis porri in China

Plant Disease ◽  
2009 ◽  
Vol 93 (11) ◽  
pp. 1216-1216 ◽  
Author(s):  
J. Zhang ◽  
G. Q. Li ◽  
D. H. Jiang
Keyword(s):  
Average Length ◽  
Morphological Characteristics ◽  
Its Region ◽  
Gray Mold ◽  
Leaf Blight ◽  
Lesion Length ◽  
Width Ratio ◽  
Its Sequence ◽  
First Report ◽  
5.8S Rdna

In the spring of each year from 2007 to 2009, a leaf blight of garlic (Allium sativum L.) was observed in more than 50 fields in Zhushan County of Hubei Province, China. Gray mold was observed on many of the blighted garlic leaves. The percentage of garlic plants with blight and gray mold symptoms ranged from 10 to 50% with one to three blighted leaves on each plant, which severely reduced the yield of young garlic plants (produced as a green vegetable). Ten strains of a Botrytis sp. were isolated from symptomatic garlic leaves collected from 10 different fields. These strains were inoculated onto potato dextrose agar (PDA) in petri dishes and incubated at 20°C for 3 to 15 days for observation of colony characteristics and morphology of sclerotia and conidia. All 10 Botrytis strains formed flat and “ropy” mycelia (mycelial strands) on PDA. Abundant sporulation with a gray powdery appearance was observed on the colonies after 6 days. Conidiophores were erect with alternate branches at the top and ranged from 907 to 1,256 μm high. Conidia were borne in botryose clusters on conidiophores, obovate, and 10.4 to 17.6 × 7.6 to 13.1 μm with an average length/width ratio of 1.36. Discrete sclerotia were produced on each colony after 15 days. Mature sclerotia were black, cerebriform and convoluted, and 1.9 to 9.1 × 1.6 to 6.5 mm. Morphological characteristics of the colonies, conidia, and sclerotia of these Botrytis strains were similar to Botrytis porri Buchwald (1,2). Strain GarlicBC-16 was selected as a representative for molecular identification. Genomic DNA was extracted from mycelia of this strain and used as a template for amplification of the internal transcribed spacer (ITS) region of rDNA using primer pair ITS1/ITS4. A 539-bp amplicon was obtained and sequenced (GenBank Accession No. EU519206). Excluding the flanking regions, the amplicon contained a 453-bp ITS sequence (ITS1 + 5.8S rDNA + ITS2) 100% identical to the ITS sequence of strain MUCL3234 of B. porri (GenBank Accession No. AJ716292). Pathogenicity of strain GarlicBC-16 was tested by inoculation of 10 young and fully expanded garlic leaves taken from 100-day-old garlic plants with mycelial agar plugs (three plugs per leaf and spaced by 5 cm). Ten garlic leaves inoculated with agar plugs of PDA alone served as controls. Inoculated garlic leaves were covered with a plastic film (0.1 mm thick; Gold Mine Plastic Industrial Ltd. Jiangmen, China) and incubated at 20°C with 12-h light/12-h dark. Control leaves remained healthy after 48 to 120 h, but gray, water-soaked lesions appeared on leaves inoculated with strain GarlicBC-16 after 48 h. The average lesion length reached 27.3 mm after 90 h and abundant sporulation was produced on necrotic leaf lesions after 120 h. Microscopic examination showed the shape and size of conidia that formed on garlic leaf lesions were similar to those formed by strain GarlicBC-16 on PDA. On the basis of the isolation, identification, and pathogenicity tests, B. porri was determined to be the causal agent of garlic leaf blight in Zhushan County. B. porri has been reported to cause neck rot of leek (A. porrum) (1) and clove rot of garlic (2), and has been isolated from asymptomatic foliage and seeds of A. cepa (3). To our knowledge, this is the first report of garlic leaf blight caused by B. porri in China. References: (1) S. K. Asiedu et al. Plant Dis. 70:259, 1986. (2) F. M. Dugan et al. J. Phytopathol. 155:437. 2007. (3) L. J. du Toit et al. Plant Dis. 86:1178, 2002.

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