First Report of Myrothecium roridum Causing Leaf Spot on Zantedeschia aethiopica in China

Zantedeschia aethiopica (L.) Spreng. (calla lily), belonging to family Araceae, is a popular ornamental plant in China. In the summer of 2010, leaves of calla lily with typical symptoms of necrotic lesions were observed in a commercial glasshouse in Beijing, China (116°20′ E, 39°44′ N). The initial symptoms were circular to subcircular, 1 to 3 mm, and dark brown lesions on the leaf lamina. Under high humidity, lesions expanded rapidly to 5 to 10 mm with distinct concentric zones and produced black sporodochia, especially on the backs of leaves. Later, the infected leaves were developing a combination of leaf lesions, yellowing, and falling off; as a result, the aesthetic value of the plant was significantly impacted. Leaf samples were used in pathogen isolation. Symptomatic leaf tissues were cut into small pieces and surface sterilized with 70% ethanol for 30 s and then in 0.1% mercuric chloride solution for 1 to 3 min. After being washed in sterile distilled water three times, the pieces were plated on potato dextrose agar (PDA) and incubated at 25°C in darkness for 7 days (5). Initial colonies of isolates were white, floccose mycelium and developed dark green to black concentric rings that were sporodochia bearing viscid spore masses after incubating 5 days. Conidiophores branched repeatedly. Conidiogenous cells were hyaline, clavate, and 10.0 to 16.0 × 1.4 to 2.0 μm. Conidia were hyaline, cylindrical, both rounded ends, and 6.0 to 8.2 × 1.9 to 2.4 μm. Morphological characteristics of the fungus were consistent with the description of Myrothecium roridum Tode ex Fr. (3,4). To confirm the pathogenicity, three healthy plants of calla lily were inoculated with a conidial suspension (1 × 106 conidia per ml) brushed from a 7-day-old culture of the fungus. Control plants were sprayed with sterile water. The inoculated plants were individual with clear plastic bags and placed in a glass cabinet at 25°C. After 7 days, all inoculated leaves developed symptoms similar to the original samples, but control plants remained disease free. Re-isolation and identification confirmed Koch's postulates. For molecular identification, genomic DNA of a representative isolate (MTL07081001) was extracted by modified CTAB method (1), and the rDNA-ITS region was amplified by using primers ITS1 (5-TCCGTAGGTGAACCTGCGG-3) and ITS4 (5-TCCTCCGCTTATTGATATGC-3). The 465-bp amplicon (GenBank Accession No. KF761293) was 100% identity to the sequence of M. roridum (JF724158.1) from GenBank. M. roridum has an extensive host range, covering 294 host plants (2). To our knowledge, this is the first record of leaf spot caused by M. roridum on calla lily in China. References: (1) F. M. Ausubel et al. Current Protocols in Molecular Biology. John Wiley & Sons Inc, New York, 1994. (2) D. F. Farr and A. Y. Rossman, Fungal Databases. Syst. Mycol. Microbiol. Lab., ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , October 2013. (3) M. T. Mmbaga et al. Plant Dis. 94:1266, 2010. (4) Y. X. Zhang et al. Plant Dis. 95:1030, 2011. (5) L. Zhu et al. J. Phytopathol. 161:59, 2013.

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First Report of Leaf Spot Caused by Myrothecium roridum on Coffea canephora in Brazil

Plant Disease ◽

10.1094/pdis-06-14-0643-pdn ◽

2014 ◽

Vol 98 (11) ◽

pp. 1587-1587 ◽

Cited By ~ 3

Author(s):

A. D. A. Silva ◽

D. B. Pinho ◽

H. Costa ◽

U. P. Lopes ◽

O. L. Pereira

Keyword(s):

Leaf Spot ◽

Its Region ◽

Coffea Canephora ◽

Leaf Spot Disease ◽

Isolation And Identification ◽

Espírito Santo ◽

First Report ◽

Initial Symptoms ◽

Myrothecium Roridum ◽

Espirito Santo

Coffea canephora (conilon coffee) represents approximately 30% of the coffee marketed worldwide. The state of Espírito Santo is the largest conilon coffee-producing state in Brazil. In 2013 and 2014, leaves with a leaf spot were observed on most of the conilon coffee seedlings in a commercial nursery in Laranja da Terra, Espírito Santo, Brazil. The infected leaves were deposited in the VIC Herbarium (VIC 42482) and a pure single-spore culture of the pathogen was deposited in the culture collection of the Universidade Federal de Viçosa (Accession No. COAD 1729). The initial symptoms were circular, brown to dark brown lesions with yellow margins occurring on both leaf surfaces. In high humidity, concentric rings formed and the lesions expanded rapidly to reach up to 30 mm in diameter, and later became dark brown with a grayish center. Black sporodochia with white, and marginal mycelial tuffs bearing black spore masses were observed in the older lesions. These symptoms were consistent with those of Myrothecium leaf spot reported on Coffea spp. (3). Microscopic observation revealed aseptate, hyaline, and cylindrical conidia, rounded at both ends, greenish to black in mass, and 5 to 6 μm long and 1 to 2 μm wide. The symptoms and morphological characteristics described above matched the description of Myrothecium roridum Tode (4). To confirm this identification, DNA was extracted using a Wizard Genomic DNA Purification Kit and the sequence of an internal transcribed spacer (ITS) region was obtained and deposited in GenBank (Accession No. KJ815095). The sequence of the ITS region exhibited 100% identity over 561 bp with another M. roridum sequence in GenBank (JF343832). To verify the pathogenicity of the fungus, healthy leaves of the C. canephora clones 12v and 14 (four seedlings each) were wounded superficially with a sterilized needle and inoculated by spraying them with a suspension of M. roridum conidia (106 conidia ml−1). The seedlings were covered with plastic bags and incubated in a growth chamber at 25°C under a photoperiod of 12 h light/12 h dark for 5 days. The control seedlings were sprayed with distilled water and incubated similarly. Fifteen days after inoculation, symptoms in all inoculated seedlings were consistent with those initially observed on the naturally infected seedlings, whereas the controls remained healthy. Re-isolation and identification confirmed Koch's postulates. M. roridum has a wide host range, and symptoms were similar to those reported in other hosts of the pathogen in Brazil (2,3). There is only one report of M. roridum on C. canephora in Colombia (1); however, this pathogen was previously reported on C. arabica in Brazil, Colombia, Costa Rica, Guatemala, India, Indonesia, Puerto Rico, and the Virgin Islands (1,3). To our knowledge, this is the first report of a leaf spot caused by M. roridum on conilon coffee in Brazil. The cultivation of conilon coffee is increasing and the reported leaf spot disease affects the quality of the seedlings in nurseries. It is therefore important to conduct a thorough study of management strategies for this disease. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab. ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases , 27 May 2014. (2) A. M. Quezado Duval et al. Braz. J. Microbiol. 41:246, 2010. (3) S. F. Silveira et al. Fitopatol. Bras. 32:440, 2007. (4) M. Tulloch. Mycol. Pap. No. 130. CMI, Wallingford, UK, 1972.

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First Report of Septoria Leaf Spot of Lavandin Caused by Septoria lavandulae in Croatia

Plant Disease ◽

10.1094/pdis-07-13-0735-pdn ◽

2014 ◽

Vol 98 (2) ◽

pp. 282-282

Author(s):

K. Vrandečić ◽

J. Ćosić ◽

D. Jurković ◽

I. Stanković ◽

A. Vučurović ◽

...

Keyword(s):

Leaf Spot ◽

Antibacterial Properties ◽

Morphological Characteristics ◽

Its Region ◽

Morphological Identification ◽

Conidial Suspension ◽

Necrotic Tissue ◽

First Report ◽

Initial Symptoms ◽

Septoria Leaf Spot

Lavandula × intermedia Emeric ex Loiseleur, commonly known as lavandin, is an aromatic and medicinal perennial shrub widely and traditionally grown in Croatia. The lavandin essential oil is primarily used in perfumery and cosmetic industries, but also possesses anti-inflammatory, sedative, and antibacterial properties. In June 2012, severe foliar and stem symptoms were observed on approximately 40% of plants growing in a commercial lavandin crop in the locality of Banovo Brdo, Republic of Croatia. Initial symptoms on lower leaves included numerous, small, oval to irregular, grayish brown lesions with a slightly darker brown margin of necrotic tissue. Further development of the disease resulted in yellowing and necrosis of the infected leaves followed by premature defoliation. Similar necrotic oval-shaped lesions were observed on stems as well. The lesions contained numerous, dark, sub-globose pycnidia that were immersed in the necrotic tissue or partly erumpent. Small pieces of infected internal tissues were superficially disinfected with 50% commercial bleach (4% NaOCl) and placed on potato dextrose agar (PDA). A total of 10 isolates from leaves and five from stems of lavandin formed a slow-growing, dark, circular colonies with raised center that produced pycnidia at 23°C, under 12 h of fluorescent light per day. All 15 recovered isolates formed uniform hyaline, elongate, straight or slightly curved conidia with 3 to 4 septa, with average dimensions of 17.5 to 35 × 1.5 to 2.5 μm. Based on the morphological characteristics, the pathogen was identified as Septoria lavandulae Desm., the causal agent of lavender leaf spot (1,2). Pathogenicity of one selected isolate (428-12) was tested by spraying 10 lavandin seedlings (8 weeks old) with a conidial suspension (106 conidia/ml) harvested from a 4-week-old monoconidial culture on PDA. Five lavandin seedlings, sprayed with sterile distilled water, were used as negative control. After 5 to 7 days, leaf spot symptoms identical to those observed on the source plants developed on all inoculated seedlings and the pathogen was successfully re-isolated. No symptoms were observed on any of the control plants. Morphological identification was confirmed by amplification and sequencing of the internal transcribed spacer (ITS) region of rDNA (3). Total DNA was extracted directly from fungal mycelium with a DNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and PCR amplification performed with primers ITS1F/ITS4. Sequence analysis of ITS region revealed at least 99% identity between the isolate 428-12 (GenBank Accession No. KF373078) and isolates of many Septoria species; however, no information was available for S. lavandulae. To our knowledge, this is the first report of Septoria leaf spot of lavandin caused by S. lavandulae in Croatia. Since the cultivation area of lavandin plants has been increasing in many continental parts of Croatia, especially in Slavonia and Baranja counties, the presence of a new and potentially harmful disease may represent a serious constraint for lavandin production and further monitoring is needed. References: (1) T. V. Andrianova and D. W. Minter. IMI Descriptions of Fungi and Bacteria, 142, Sheet 1416, 1999. (2) R. Bounaurio et al. Petria 6:183, 1996. (3) G. J. M. Verkley et al. Mycologia 96:558, 2004.

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First Report of Leaf Spot Caused by Ascochyta marginata on Aralia elata in Korea

Plant Disease ◽

10.1094/pdis-08-11-0658 ◽

2012 ◽

Vol 96 (1) ◽

pp. 147-147

Author(s):

S. H. Lee ◽

C. K. Lee ◽

M. J. Park ◽

H. D. Shin

Keyword(s):

East Asia ◽

Leaf Spot ◽

Morphological Characteristics ◽

Culture Collection ◽

Research Report ◽

Conidial Suspension ◽

First Report ◽

Commercial Cultivation ◽

Aralia Elata ◽

Initial Symptoms

Aralia elata (Miq.) Seem., known as Japanese angelica tree, is a deciduous shrub belonging to the Araliaceae, which is native to East Asia. The young shoots have long been used in various dishes in East Asia. Commercial cultivation of this shrub, especially in polytunnels, is expanding in Korea. Several diseases including Sclerotinia rot have been known to be present on this plant (1,2). In early September 2007, leaf spot symptoms were first observed on several trees in Hongcheon, Korea. Microscopic observations revealed that the leaf spots were associated with an Ascochyta sp. Further surveys of the Ascochyta leaf spot showed the occurrence of the disease in approximately 5 to 10% of the trees in the 3 ha of commercial fields surveyed in Chuncheon, Gapyeong, Inje, and Jinju, Korea. Initial symptoms on leaves were circular to irregular, brown to dark brown, becoming zonate, and finally fading to grayish brown in the center with a yellow halo. Representative samples were deposited in the herbarium of Korea University. Conidiomata on leaf lesions were pycnidial, amphigenous, but mostly epiphyllous, immersed or semi-immersed in host tissue, light brown to olive brown, and 60 to 200 μm in diameter. Ostioles were papillate, 20 to 35 μm wide, and surrounded by a ring of darker cells. Conidia were hyaline, smooth, cylindrical to clavate, straight to mildly curved, slightly constricted at the septa, medianly one-septate, sometimes aseptate, 8 to 16 × 2.5 to 3.5 μm, and contained small oil drops. These morphological characteristics were consistent with the previous reports of Ascochyta marginata J.J. Davis (3,4). A monoconidial isolate was cultured on potato dextrose agar (PDA) plates and accessioned in the Korea Agricultural Culture Collection (Accession KACC43082). The conidia were readily formed on PDA. Inoculum for the pathogenicity tests was prepared by harvesting conidia from 30-day-old cultures of KACC43082 and a conidial suspension (approximately 2 × 106 conidia/ml) was sprayed onto leaves of three healthy seedlings. Three noninoculated seedlings served as controls. Inoculated and noninoculated plants were covered with plastic bags for 48 h in a glasshouse. After 7 days, typical leaf spot symptoms started to develop on the leaves of the inoculated plants. The fungus, A. marginata, was reisolated from those lesions, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in Japan (4) and China (3). To our knowledge, this is the first report of A. marginata on Japanese angelica trees in Korea. According to our field observations in Korea, the Ascochyta leaf spot mostly occurred on plants growing in a humid environment, especially during the rainy season. The seedlings as well as the trees growing in sunny, well-ventilated plots were nearly free from this disease. Therefore, the growing conditions seemed to be the most important factor for the development and severity of the disease. References: (1) C. K. Lee et al. Plant Pathol. J. 26:426, 2010. (2) S. H. Lee et al. Diseases of Japanese Angelica Tree and Their Control. Research Report 08-10. Korea Forest Research Institute. Seoul, Korea, 2008. (3) J. Sun et al. Acta Mycol. Sin. 14:107, 1995. (4) M. Yoshikawa and T. Yokoyama. Mycoscience 36:67, 1995.

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

Plant Disease ◽

10.1094/pdis-05-14-0545-pdn ◽

2015 ◽

Vol 99 (3) ◽

pp. 417-417 ◽

Cited By ~ 11

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.

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First report of Cercospora cf. citrulina causing leaf spot of Ipomoea pes-caprae in China

Plant Disease ◽

10.1094/pdis-05-20-1081-pdn ◽

2020 ◽

Author(s):

Min Li ◽

Meijiao Hu ◽

Zhaoyin Gao ◽

Xiaoyu Hong ◽

Chao Zhao ◽

...

Keyword(s):

Molecular Identification ◽

Leaf Spot ◽

Plant Protection ◽

Morphological Characteristics ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Xisha Islands ◽

First Report ◽

Initial Symptoms ◽

Leaf Surfaces

Ipomoea pes-caprae plays an important role in protecting the tropical and subtropical coastal beach of the world. In 2018, a leaf spot was observed on I. pes-caprae in Xisha islands of China, 13.2–25.8% of leaves were infected. The initial symptoms were small (1–3 mm diameter), single, circular, dark gray spots with a light-yellow center on the leaves. The lesions enlarged and were scattered or confluent, distinct and circular, subcircular or irregular, occasionally vein-limited, pale to dark gray-brown, with a narrow dark brown border surrounded by a diffuse yellow margin. Microscopic observations of the spots revealed that caespituli were dark brown and amphigenous, but abundant on the underside of the leaves. Mycelia were internal. Conidiophores were fasciculate, occasionally solitary, pale olivaceous-brown throughout, 0- to 3-septate, 27.9–115.8 (63.4±22.5) µm × 3.2–5.3 (4.3±0.87) µm (n=100). Conidial scars were conspicuously thickened. Conidia were solitary, hyaline, filiform, acicular to obclavate, straight to slightly curved, subacute to obtuse at the apex, truncate at the base, multi-septate, 21.0–125.5 (60.2±20.1) µm × 2.0–5.0 (3.8±0.83) µm (n=100). Single-conidium isolates were obtained from representative colonies grown on potato dextrose agar (PDA) incubated at 25℃ in the dark. The colonies grew slowly and were dense, white to gray and flat with aerial mycelium. Mycelia were initially white, and then became gray. Conidia were borne on the conidiophores directly. The pure isolate HTW-1 was selected for molecular identification and pathogenicity test, which were deposited in Microbiological Culture Collection Center of Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences. The internal transcribed spacer (ITS) region of rDNA, translation elongation factor 1-alpha (tef1) and histone H3 (his3) genes were amplified with ITS1/ITS4, EF-1 / EF-2, and CYLH3F / CYLH3R primers, respectively (Groenewald et al. 2013). The obtained sequences of HTW-1 were all deposited in GenBank with accession numbers MT410467 for ITS, MT418903 for tef1 and MT418904 for his3. The ITS, tef1 and his3 genes all showed 100% similarity for ITS (JX143582), tef1 (JX143340) and his3 (JX142602) with C. cf. citrulina (MUCC 588; MAFF 239409) from I. pes-caprae in Japan. Based on the morphological characteristics and molecular identification, the pathogen was identified as Cercospora cf. citrulina (Groenewald et al. 2013). The pathogenicity test was conducted by spraying conidial suspension (1×104 conidia/mL) on wounded and unwounded leaves for seedling of I. pes-caprae in greenhouse and in sterile vitro condition. The conidial suspension was prepared using conidia from 30-day-old culture grown on PDA at 25℃ in the dark. Leaf surfaces of seedling in greenhouse were wounded by lightly rubbing with a steel sponge and detached leaf surfaces were wounded by sterile needles. the treatments were sprayed with conidial suspensions on wounded and unwounded leaf surfaces. The control was sprayed with sterile water. After eight days, the typical symptoms of spots which were small, single, circular and dark gray appeared on the inoculated wounded leaves, while the inoculated unwounded leaves and the control leaves were symptomless. The pathogen was only re-isolated from the inoculated wounded leaves. The pathogen may be infected by wound. A total of 20 Cercospora and related species was found on Ipomoea spp. (García et al. 1996). Cercospora cf. citrulina has been reported on I. pes-caprae in Japan, although it was unclear if it was a pathogen or saprophyte (Groenewald et al. 2013). To our knowledge, this is the first report of C. cf. citrulina causing leaf spot of I. pes-caprae in China. This disease could threat the cultivation of I. pes-caprae in China.

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First Report of Verticillium Wilt Caused by Verticillium dahliae on Figmarigold in Italy

Plant Disease ◽

10.1094/pdis-94-1-0129b ◽

2010 ◽

Vol 94 (1) ◽

pp. 129-129

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

P. Pensa ◽

M. L. Gullino

Keyword(s):

Verticillium Wilt ◽

Cross Sections ◽

Vascular Tissue ◽

Morphological Characteristics ◽

Ground Cover ◽

Its Region ◽

Peat Moss ◽

Conidial Suspension ◽

First Report ◽

Initial Symptoms

Lampranthus spp. N.B. Brown (figmarigold) belongs to the Aizoaceae family and is grown as a ground cover in gardens or as a potted plant. In January 2009, severe outbreaks of a previously unknown wilt were observed at a commercial farm in Liguria (northern Italy) where 7-month-old potted plants were grown outdoors in a mix of peat/clay/pumice at pH 6.5. In cultivars with pink flowers, 12% of plants were affected, while only a few cultivars with red flowers were diseased. Initial symptoms were yellowing of external leaves and brown or black streaks in the vascular tissue of roots, crown, and leaves. Subsequently, infected tissues wilted and stopped growing, stems and leaves appeared desiccated, and infected plants died. Stems of 10 pink-flowered plants were severed with a knife, cut ends sealed with wax, and surfaces disinfected with 1% sodium hypochlorite. Cross-sections (1 mm long) through symptomatic vascular tissue were plated onto potato dextrose agar. After 10 days at 22°C, 90% of the stems tested positive for Verticillium. Irregular, dark microsclerotia, 22 to 128 × 13 to 66 (average 51 × 29) μm, developed in hyaline hyphae after 10 days of growth at 22 ± 1°C (12-h photoperiod). Hyaline, elliptical, single-celled conidia, 2.9 to 4.8 × 1.3 to 2.4 (average 4.1 × 1.7) μm, developed on verticillate conidiophores. On the basis of these morphological characteristics, the fungus was identified as V. dahliae (3). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 (2) and sequenced. BLASTn analysis (1) of the 476-bp segment showed a 100% homology with the sequence of V. dahliae. The nucleotide sequence has been assigned GenBank Accession No. GQ 149479. Pathogenicity tests were performed twice using five 40-day-old plants of a pink-flower cultivar of a Lampranthus sp. grown in 1-liter pots containing a 50:20:20:10 mix of peat moss/pumice/pine bark cortex/clay. The substrate was infested with a conidial suspension (1.0 × 107/ml) of one isolate of V. dahliae recovered from infected plants. Inoculum (50 ml) were added to each pot, drenching the top of the soil. Noninoculated plants served as controls. Plants (five per treatment) were maintained in a glasshouse at daily average temperatures between 20 and 26°C and at 50 to 70% relative humidity. The first wilt symptoms and a vascular discoloration in the roots, crown, and veins developed 30 days after inoculation. V. dahliae was consistently reisolated. Noninoculated plants remained healthy. In a second test, the susceptibility of purple-, white-, yellow-, red-, and orange-flowered cultivars was tested. Ten rooted cuttings of each cultivar were inoculated as described above. The severity of Verticillium wilt was evaluated and each cultivar was classified as resistant, partially resistant, average susceptible, susceptible, or highly susceptible. All tested cultivars were susceptible or highly susceptible to Verticillium. Only the purple cultivar showed an average susceptibility. To our knowledge, this is the first report of Verticillium wilt on Lampranthus spp. in Italy as well as worldwide. Today, the economic importance of Verticillium wilt on figmarigold in Italy is still limited. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) M. A. Innis et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990. (3) G. F. Pegg and B. L. Brady. Verticillium Wilts. CABI Publishing, Wallingford, UK, 2002.

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First Report of Verticillium Wilt Caused by Verticillium dahliae on Rudbeckia fulgida (Orange Coneflower) in Italy

Plant Disease ◽

10.1094/pdis-92-9-1367c ◽

2008 ◽

Vol 92 (9) ◽

pp. 1367-1367 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

United States ◽

Verticillium Wilt ◽

Verticillium Dahliae ◽

Vascular Tissue ◽

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Conidial Suspension ◽

First Report ◽

Initial Symptoms

Rudbeckia fulgida (common name orange coneflower) is an herbaceous perennial (Asteraceae) grown in full sun in perennial borders in gardens. At the end of the summer of 2007, in a public garden located in Turin (northern Italy), symptoms of vascular wilt and stunting were observed on approximately 80% of the plants grown in a mixed border. Initial symptoms were yellowing of external leaves and brown or black streaks in the vascular tissue of roots, crown, and leaves. A fungus was consistently and readily isolated on potato dextrose agar from symptomatic vascular tissue previously disinfested in 1% sodium hypochloride. Ovoid, dark microsclerotia, 41 to 108 μm, developed in hyaline hyphae after 10 days of growth at 23°C (12 h of light and 12 h of dark). Hyaline, elliptical, single-celled conidia, 3.2 to 7.3 × 2.1 to 3.7 (average 4.7 × 2.8) μm, developed on verticillate conidiophores. On the basis of these morphological characteristics, the fungus was identified as Verticillium dahliae (4). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 530 bp showed a 100% homology with the sequence of V. dahliae. The nucleotide sequence has been assigned GenBank Accession No. EU 627007. Healthy, 30-day-old R. fulgida plants were grown in a steam-disinfested mix of sphagnum peat:pomix:pine bark:clay (50:20:20:10) infested with a conidial suspension (1.5 × 106/ml) of three isolates of V. dahliae isolated from infected plants. Noninoculated plants served as controls. Plants (16 per treatment) were grown in pots (3 liter vol) and maintained in a glasshouse at temperatures between 22 and 25°C and relative humidity between 50 and 70%. First wilt symptoms and vascular discoloration in the roots, crown, and veins developed 17 days after inoculation. Noninoculated plants remained healthy. The pathogenicity tests were carried out twice. To our knowledge, this is the first report in Italy of Verticillium wilt on R. fulgida. Wilts caused by V. dahliae on R. laciniata in Poland (3) and V. albo-atrum on R. hirta in the United States (2) were previously reported. The importance and economic impact of this disease is currently limited but may increase because of the popularity of Rudbeckia spp. in private and public parks. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. F. Farr et al. Fungi on Plants and Their Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) B. Leski. Rocz. Nauk Roln. 253, 1974. (4) G. F. Pegg and B. L. Brady. Verticillium Wilts. CABI Publishing, Wallingford, UK, 2002.

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First Report of Leaf Spot Caused by Septoria erigerontis on Erigeron strigosus in Korea

Plant Disease ◽

10.1094/pdis-08-12-0755-pdn ◽

2012 ◽

Vol 96 (12) ◽

pp. 1827-1827

Author(s):

J. H. Park ◽

K. S. Han ◽

S. H. Hong ◽

H. D. Shin

Keyword(s):

North America ◽

Leaf Spot ◽

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Culture Collection ◽

Leaf Spot Disease ◽

Conidial Suspension ◽

Voucher Specimen ◽

First Report

Erigeron strigosus Muhl. ex Willd., known as daisy fleabane, is native to North America and was accidently introduced to Korea in the 1990s (2). It is increasingly invasive in natural and managed ecosystems throughout Korea. In June 2011, a leaf spot was first observed on daisy fleabanes growing wild in Hongcheon County of Korea. A voucher specimen was deposited in the Korea University Herbarium (KUS-F25759). Symptoms developed on lower leaves as small, distinct, reddish brown lesions, which enlarged progressively and turned into pale, dull brown spots surrounded by dark purplish-brown margins. Black pycnidia became visible in the lesions. Pycnidia were epigenous, occasionally hypogenous, scattered, dark brown to rusty brown, globose, embedded in host tissue or partly erumpent, 60 to 160 μm in diameter, with ostioles measuring 10 to 30 μm in diameter. Conidia were straight to mildly curved or even flexuous, guttulate, hyaline, 30 to 75 × 1.5 to 2 μm, and one- to seven-septate. Based on the morphological characteristics, the fungus was consistent with Septoria erigerontis Peck (3,4). Conidia were harvested from cirrhi of pycnidia on leaf lesions with a drop of sterile water and then directly streaked onto water agar media using a bacterial loop. Isolates were incubated at 24°C for 48 h. Germinating conidia were individually transferred to potato dextrose agar (PDA) plates. An isolate was deposited in the Korean Agricultural Culture Collection (Accession No. KACC46120). Genomic DNA was extracted using the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1/ITS4 primers and sequenced. The resulting sequence of 505 bp was deposited in GenBank (Accession No. JX480493). A GenBank BLAST search was conducted with the 505-bp sequence showing 100% identity with the sequences of S. erigerontis ex Erigeron annuus (EF535638, GU269862). Pathogenicity was tested by spraying leaves of three potted plants with a conidial suspension (2 × 105 conidia/ml) harvested from a 4-week-old PDA culture. Control leaves were sprayed with sterile distilled water. The plants were placed in a dew chamber at 26°C in darkness and continuous dew for the first 24 h and then moved to a greenhouse bench. After 7 days, leaf spot symptoms identical to those observed in the field developed on the leaves inoculated with the fungus. No symptoms were observed on control plants. S. erigerontis was reisolated from the lesions of inoculated plants, fulfilling Koch's postulates. A leaf spot disease of E. strigosus associated with S. erigerontis has been reported in the United States and Canada (1). To our knowledge, this is the first report of leaf spot on E. strigosus caused by S. erigerontis outside of North America as well as in Korea. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication. ARS, USDA, Retrieved June 2, 2012. (2) S. H. Park. Colored Illustrations of Naturalized Plants of Korea. Ilchokak Publishers, Seoul, Korea, 1995. (3) M. J. Priest. Fungi of Australia: Septoria. ABRS/CSIRO Publishing, Melbourne, Australia, 1997. (4) E. Radulescu et al. Septoriozele din Romania. Ed. Acad. Rep. Soc. Romania, Bucuresti, Romania, 1973.

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First Report of Anthracnose on Rubus rosaefolius Smith Caused by Colletotrichum boninense in China

Plant Disease ◽

10.1094/pdis-06-20-1309-pdn ◽

2021 ◽

Author(s):

Xiao Zheng ◽

Li-tao Tan ◽

Sheng Cheng ◽

Pengyu Liang ◽

Lan Fang ◽

...

Keyword(s):

Leaf Spot ◽

Management Strategies ◽

Morphological Characteristics ◽

Its Region ◽

Essential Amino Acids ◽

Leaf Spot Disease ◽

Control Group ◽

Conidial Suspension ◽

First Report ◽

Vegetable Juice

Raspberry (Rubus rosaefolius Smith), also called march bubble or milk bubble, is widely distributed and economically important in China. Raspberries are rich in nutrients such as essential amino acids, vitamin C, dietary fiber, superoxide dismutase (SOD) and minerals (Yang et al. 2019). In May 2019, a leaf spot disease was observed on raspberry in Enshi (N29°07'10', E108°23'12'), Hubei province of China. The symptoms were small dark-brown spots (Fig.1) on over 90% of observed plants. To isolate the pathogen, leaf sections (5 mm × 3 mm) from the border of the symptomatic tissue were cut and sterilized with 75% ethanol for 30 s, followed by 2% sodium hypochlorite (NaClO) for 2 min, and then rinsed three times with sterile water. Leaf sections were placed on potato dextrose agar (PDA) medium amended with 25 μg / ml ampicillin and incubated at 25 °C in the dark for 3 days. Isolated colonies were sub-cultured on PDA by hyphal tip transfer. Eight fungal isolates with similar morphology, abundant white aerial hyphae, were collected. Colonies on PDA grew up to 80 mm in diameter by 7 days at 25 °C. The center of each colony became black (Fig.2). Conidia were unicellular, oval and hyaline. Conidia ranged in size from 14.5 to 19.75 µm × 5.80 to 10.20 µm (n=50) in 20% (v/v) V8 vegetable juice medium. No appressoria were observed. Morphological characteristics are similar to those of Colletotrichum spp. (Moriwaki et al. 2003). Total genomic DNA of a representative isolate S1 was extracted with a CTAB method (Stenglein et al. 2006). Internal transcribed spacer (ITS) region of rDNA, actin (ACT) , beta-tubulin (TUB2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were amplified and sequenced with the primer pairs of ITS4 / ITS5, ACT512F / ACT783R, Bt-2a / Bt-2b and GDF1 / GDR1, respectively (Weir et al. 2012). BLAST results showed that ITS, ACT, TUB2 and GAPDH gene sequences (GenBank accession nos. MN498030, MT780498, MT780496 and MT780497, respectively) were 99% identical to those of Colletotrichum boninense Moriwaki, Sato & Tsukiboshi (GenBank accession nos. MF076598, JX009583, JQ005588 and JX009905, respectively). Concatenated sequences of the four genes were used to conduct a phylogenetic analysis using neighbor-joining method in MEGA7 (Toussaint et al. 2016). The isolate S1 clustered with above C. boninense strains retrieved from NCBI database. Therefore, the present isolate S1 was identified as C. boninense. Pathogenicity tests were performed using one-month-old raspberry plants, 24 controls and 30 inoculated. The plants were sprayed with conidial suspension ( 106 conidia / mL) cultured on 20% (v/v) V8 vegetable juice medium for 15 days. The control plants were sprayed with sterile distilled water. All plants were covered with plastic bags 24h to maintain the relative humidity in the field. Fifteen days after inoculation, typical symptoms of brown spots were observed on leaves similar to the disease on field plants, while the leaves from the control group remained asymptomatic. C. boninense was reisolated and identified from inoculated symptomatic leaves. Anthracnose on raspberry caused by Colletotrichum gloeosporioides (Dai et al. 2013) and C. fioriniae (Schoeneberg et al. 2020) has previously been reported. However, to the best of our knowledge, this is the first report of Colletotrichum boninense causing leaf spot on Raspberry in China. If more reports of this pathogen are found on raspberries, then it may be necessary to develop effective management strategies for controlling this disease.

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Veronica sibirica Leaf Spots Caused by Phacellium veronicae, a New Disease in China

Plant Disease ◽

10.1094/pdis-11-12-1052-pdn ◽

2013 ◽

Vol 97 (12) ◽

pp. 1662-1662 ◽

Cited By ~ 1

Author(s):

Q. R. Bai ◽

S. Han ◽

Y. Y. Xie ◽

J. Gao ◽

Y. Li

Keyword(s):

Morphological Characteristics ◽

Its Region ◽

Control Treatment ◽

Perennial Herb ◽

Conidial Suspension ◽

New Disease ◽

Medical College ◽

Leaf Spots ◽

Plastic Bags ◽

Insect Bites

Veronica sibirica (Veronicastrum sibiricum) is an erect perennial herb, an ornamental, and a traditional Chinese medicine plant distributed mostly in northeastern, northern, and northwestern China. It has dehumidifying and detoxifying properties, and is mainly used for the treatment of cold, sore throat, mumps, rheumatism, and insect bites (4). In June 2008 through 2012, leaf spots of V. sibirica were observed in the Medicinal Herb Garden of Jilin Agricultural University (43°48′N, 125°23′E) and the medicinal plantations of Antu County (43°6′N, 128°53′E), Jilin Province. Leaf spots were amphigenous, subcircular, angular-irregular, brown, and 1 to 10 mm in diameter; they occasionally merged into a larger spot with an indefinite margin or with a pale center and dark border. Pale conidiomata were hypophyllous and scattered on the spots. The conidiophores were 100 to 400 μm high and clustered together to form synnemata 20 to 50 μm in diameter, which splayed out apically and formed loose to dense capitula. Conidiophores occasionally emerged through the stomata individually and produced conidia on the surface of the infected leaves. The conidiogenous cell terminal was geniculate-sinuous with somewhat thickened and darkened conidial scars. Conidia were solitary or catenulate, ellipsoid-ovoid or subcylindric-fusiform, hyaline and spinulose, 4.01 to 7.18 × 11.16 to 20.62 μm with obtuse to somewhat attenuated ends, and slightly thickened, darkened hila. Six isolates were obtained from necrotic tissue of leaf spots and cultured on potato dextrose agar at 25°C. After incubation for 14 days, colony surfaces were white to pinkish. The colony diameter increased by 12 mm after 21 days' incubation. Hyphae were hyaline, septate, and branched. Conidiophores grew individually or fascicularly. The symptoms and morphological characteristics were consistent with previous descriptions (1,2), and the fungus was identified as Phacellium veronicae (Pass.) (U. Braun 1990). The internal transcribed spacer (ITS) region of the nuclear rDNA was amplified using primers ITS4/ITS5 (3). The ITS was identical among all six isolates (HE995799) and 98% identical to that of P. veronicae (JQ920427, HQ690097). Pathogenicity was confirmed by spraying five 1-year-old V. sibirica seedlings with a conidial suspension (106 conidia/ml) of each isolate and five seedlings with sterile water as a control treatment. Plants were grown in the greenhouse at 20 to 25°C and were covered with plastic bags to maintain humidity on the foliage for 72 h. After 15 days, the same symptoms appeared on the leaves as described earlier for the field-grown plants; the control plants remained healthy. The same fungus was reisolated from the leaf spots of inoculated plants. Currently, the economic importance of this disease is limited, but it may become a more significant problem, as the cultivated area of V. sibirica is increasing. To our knowledge, although P. veronicae was recorded on the other species of Veronica (V. austriaca, V. chamaedrys, V. grandis, V. longifolia, V. paniculata, and V. spicata ssp. incana) in Europe (Germany, Denmark, Ireland, Romania) and V. wormskjoldii in North America (Canada) (1), this is the first report of V. sibirica leaf spots caused by P. veronicae in the world, and it is a new disease in China. References: (1) U. Braun. A monograph of Cercosporella, Ramularia and allied genera (phytopathogenic Hyphomycetes) 2, IHW-Verlag, Germany, 1998. (2) U. Braun. Nova Hedwigia 50:499, 1990. (3) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (4) Jiangsu New Medical College. Dictionary of Chinese Materia Medica. Shanghai: Shanghai Scientific and Technical Publishers, China, 1977.

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