First Report of Leaf Spot of Fan Columbine (Aquilegia flabellata) Caused by Phoma aquilegiicola in Italy

Aquilegia flabellata (Ranunculaceae), fan columbine, is a perennial herbaceous plant with brilliant blue-purple flowers with white petal tips that is largely present in gardens. It can also be grown for cut flower production. In September of 2008 and 2009, in a private garden located near Biella (northern Italy), a leaf blight was observed. Leaves of infected plants showed extensive, irregular, brown, necrotic lesions, which were slightly sunken with a well-defined border and surrounded by a violet-brown halo. A hole frequently appeared in the center of dried tissues. Lesions, initially measuring 0.5 mm, later expanded up to 15 mm in diameter and eventually coalesced to cover the entire leaf, which curled without falling. At a later stage, stems were also affected, causing death of the apical part of the plant. The disease affected 90% of the plants in the garden. Dark brown, subglobose pycnidia, 116 to 145 μm, containing light gray, ellipsoid, nonseptate conidia measuring 9.0 to 16.2 × 2.6 to 4.2 (average 12.7 × 3.4) μm were observed on symptomatic tissue. On the basis of these morphological characteristics, the fungus was related to the genus Phoma (2). Diseased tissue was excised from the margin of lesions, rinsed in sterile distilled water, and then cultured on potato dextrose agar (PDA) medium at 23 ± 1°C under alternating daylight and darkness (12-h light and 12-h dark). Fungal colonies produced a pale olive green, lightly floccose mycelium, generating clusters of dark olive green swollen cells. The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 504-bp segment showed 100% homology with a sequence of Phoma aquilegiicola (GenBank Accession No. GU237735). The nucleotide sequence of our isolate was assigned GenBank Accession No. HM222537. Pathogenicity tests were performed by spraying a mycelium suspension of a homogenate of mycelium (1 × 105 mycelial fragments per ml) obtained from 15-day-old PDA cultures of the fungus on leaves of six healthy 6-month-old potted A. flabellata plants. Six plants inoculated with a homogenate of PDA served as controls. Plants were maintained in a greenhouse in a high humidity chamber for 7 days after inoculation at 23 ± 1°C and under high relative humidity conditions (70 to 90%). The first foliar lesions developed on leaves 4 days after inoculation. After 15 days, 80% of the leaves were severely infected. Control plants remained healthy. The organism reisolated on PDA from leaf lesions was identical in morphology to the isolate used for inoculation. The pathogenicity test was carried out twice. To our knowledge, this is the first report of the presence of P. aquilegiicola on A. flabellata in Italy. Ascochyta aquilegiae (synonym P. aquilegiicola) has been reported on A. vulgaris in Germany (4) and Aquilegia spp. in the United States (3). Currently, the economic importance of this disease is limited, but may become a more significant problem if the use of A. flabellata in gardens increases. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) G. H. Boerema et al. Phoma Identification Manual. Differentiation of Specific and Infra-Specific Taxa in Culture. CABI Publishing, Wallingford, UK, 2004. (3) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (4) R. Laubert. Gartenwelt 34:621, 1930.

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First Report of Leaf Spot of Milky Bellflower (Campanula lactiflora) Caused by a Phoma sp. in Italy

Plant Disease ◽

10.1094/pdis-94-5-0638a ◽

2010 ◽

Vol 94 (5) ◽

pp. 638-638

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

C. Pellegrino ◽

M. L. Gullino

Keyword(s):

United States ◽

Leaf Spot ◽

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Fluorescent Light ◽

Herbaceous Plant ◽

Pathogenicity Test ◽

First Report ◽

Perennial Herbaceous Plant

Campanula lactiflora (milky bellflower), a perennial herbaceous plant in the Campanulaceae, is used in park and gardens and sometimes cultivated for cut flower production. In June 2008, a previously unknown leaf spot was observed on C. lactiflora ‘New Hybrids’ plants from an experimental nursery located near Carmagnola (Torino, northern Italy). Leaves of infected plants showed extensive and irregular, dark brown, necrotic lesions that were slightly sunken with well-defined borders. Lesions initially ranged from 0.5 to 3 mm, eventually coalesced, and covered the entire leaf. Black pycnidia (107 to 116 μm in diameter) containing hyaline, ellipsoid, nonseptate conidia measuring 3.7 to 4.7 × 1.2 to 2.0 (average 4.3 × 1.6) μm were observed. On the basis of these morphological characteristics, the fungal causal agent of the disease could be related to the genus Phoma. In some cases, the basal leaves turned completely necrotic and the plant died. The disease affected 50% of plants. Diseased tissue was excised, immersed in a solution containing 1% sodium hypochlorite for 2 to 3 s, rinsed in water, and then cultured on potato dextrose agar (PDA) medium. A fungus developed that produced a greenish gray mycelium with a white border when incubated under 12 h/day of fluorescent light at 22 to 25°C. The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 459-bp segment showed a 100% similarity with the sequence of a Didymella sp. (synonym Mycosphaerella), anamorphic stage of Phoma spp. The nucleotide sequence has been assigned GenBank Accession No. GU128503. Pathogenicity tests were performed by placing 8-mm-diameter mycelial disks removed from PDA cultures of the fungus isolated from infected plants on leaves of healthy potted 4-month-old C. lactiflora ‘New Hybrids’ plants. Eight disks were placed on each plant. Plants inoculated with PDA alone served as controls. Six plants per treatment were used. Plants were covered with plastic bags for 4 days after inoculation and maintained in a growth chamber with daily average temperatures ranging between 23 and 24°C. The first foliar lesions developed on leaves 5 days after inoculation, and after 8 days, 80% of leaves were severely infected. Control plants remained healthy. A Didymella sp. was consistently reisolated from leaf lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of a Didymella sp. on C. lactiflora in Italy. Mycosphaerella campanulae and M. minor were reported on C. americana and C. lasiocarpa in the United States (2). The economic importance of the disease currently is limited, but could become a more significant problem in the future if the cultivation of this species becomes more widespread. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989.

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First Report of Leaf Blight on Fan Columbine (Aquilegia flabellata) Caused by Rhizoctonia solani AG 4 in Italy

Plant Disease ◽

10.1094/pdis-93-4-0433a ◽

2009 ◽

Vol 93 (4) ◽

pp. 433-433 ◽

Cited By ~ 2

Author(s):

A. Garibaldi ◽

G. Gilardi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

United States ◽

Rhizoctonia Solani ◽

Aqueous Suspension ◽

Morphological Characteristics ◽

The United States ◽

Leaf Blight ◽

Herbaceous Plant ◽

Pathogenicity Test ◽

First Report ◽

Leaf Petiole

Aquilegia flabellata (Ranunculaceae), fan columbine, is a perennial herbaceous plant with brilliant blue-purple flowers with white petal tips. It can also be grown for cut flower production. In April of 2008, in several nurseries located near Biella (northern Italy), a leaf blight was observed on 10 to 15% of potted 30-day-old plants grown on a sphagnum peat substrate at 15 to 20°C and relative humidity of 80 to 90%. Semicircular, water-soaked lesions developed on leaves just above the soil line at the leaf-petiole junction and later along the leaf margins. Lesions expanded over several days along the midvein until the entire leaf was destroyed. Blighted leaves turned brown, withered, and abscised. Severely infected plants died. Diseased tissue was disinfested for 10 s in 1% NaOCl, rinsed with sterile water, and plated on potato dextrose agar (PDA) amended with 25 mg/liter streptomycin sulfate. A fungus with the morphological characteristics of Rhizoctonia solani was consistently recovered, then transferred and maintained in pure culture. Ten-day-old mycelium grown on PDA at 22 ± 1°C appeared light brown, rather compact, and had radial growth. Sclerotia were not present. Isolates obtained from affected plants successfully anastomosed with tester isolate AG 4 (AG 4 RT 31, obtained from tobacco plants). Results were consistent with other reports on anastomosis reactions (2). Pairings were also made with tester isolates of AG 1, 2.1, 2.2, 3, 6, 7, 11, and BI with no anastomoses observed between the recovered and tester isolates. The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 648-bp fragment showed a 100% homology with the sequence of R. solani AG-4 AB000018. The nucleotide sequence has been assigned GenBank Accession No. FJ 534555. For pathogenicity tests, the inoculum of R. solani was prepared by growing the pathogen on PDA for 10 days. Five plants of 30-day-old A. flabellata were grown in 3-liter pots. Inoculum consisting of an aqueous suspension of PDA and mycelium disks (5 g of mycelium + agar per plant) was placed at the collar of plants. Five plants inoculated with water and PDA fragments alone served as control treatments. Plants were maintained in a greenhouse at temperatures between 20 and 24°C. The first symptoms, similar to those observed in the nursery, developed 7 days after the artificial inoculation. R. solani was consistently reisolated from infected leaves and stems. Control plants remained healthy. The pathogenicity test was carried out twice with similar results. The presence of R. solani AG1-IB on A. flabellata has been reported in Japan (4), while in the United States, Rhizoctonia sp. is described on Aquilegia sp. (3). This is, to our knowledge, the first report of leaf blight of A. flabellata caused by R. solani in Italy as well as in Europe. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. E. Carling. Grouping in Rhizoctonia solani by hyphal anastomosis reactions. In: Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control. Kluwer Academic Publishers, The Netherlands, 1996. (3) D. F. Farr et al. Fungi on Plants and Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (4) E. Imaizumi et al. J. Gen. Plant Pathol. 66:210, 2000.

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First Report of Stem Rot on Cereus peruvianus monstruosus Caused by Bipolaris cactivora (Petr.) Alcorn in Italy

Plant Disease ◽

10.1094/pdis-06-13-0614-pdn ◽

2014 ◽

Vol 98 (1) ◽

pp. 159-159 ◽

Cited By ~ 4

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

P. Pensa ◽

A. Poli ◽

M. L. Gullino

Keyword(s):

United States ◽

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Stem Rot ◽

Pathogenicity Test ◽

First Report ◽

Plastic Bags ◽

Blastn Analysis ◽

Dark Green

Cereus peruvianus monstruosus, known as “monster cactus,” family Cactaceae, is grown as a potted plant. In the winter of 2013, a stem rot was observed on a farm located near Ventimiglia (northern Italy) on 80% of 4,000 9-month-old plants grown in trays in a peat substrate. Symptoms consisted of a rapid rot of the upper portion of the stem. Affected stems at first showed yellowish spots that became brown irregular necrotic lesions with well-defined margins. The tissues below the affected areas were blackened and dry but became soft in the presence of high relative humidity. Fungal sporulation on rotted tissues consisted of caespitose, non-branched, septate conidiophores, olivaceous to brown at the base, paler above, measuring 89.0 to 196.9 × 6.2 to 8.7 (average 124.8 × 7.0) μm. Single conidia were borne on terminal cells. At maturity, conidia with 2 to 5 (average 3) septa were brownish-olivaceous, varying in shape from obclavate, fusiform, ellipsoid or sometimes furcate, and measuring 23.4 to 48.6 × 8.0 to 12.6 (average 38.8 × 10.3) μm. Symptomatic tissues were immersed in 1% sodium hypochlorite for 2 to 3 s and rinsed in sterile distilled water, then fragments excised from the margin of internal lesions were cultured on potato dextrose agar (PDA) medium amended with 25 mg/l of streptomycin sulfate and incubated at 20 to 23°C under alternating daylight and darkness (10 h light, 14 h dark). A fungus that was consistently isolated was subcultured on PDA. At maturity, dark green floccose colonies comprised of light brown septate hyphae, 4.2 to 8.1 (average 5.6) μm in width, produced non-branched, pale to dark brown, septate conidiophores, measuring 99.6 to 176.1 × 4.5 to 6.5 (average 146.7 × 5.4) μm. The conidia produced on PDA were similar to those observed on infected tissues and measured 20.6 to 40.7 × 7.5 to 11.4 (average 32.0 × 9.7) μm, with 1 to 3 septa (average 2). On the basis of the morphological characteristics, the fungus was identified as Bipolaris cactivora (Petr.) Alcorn [Syn.: Drechslera cactivora (Petr.) M. B. Ellis] (4). The internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA) was amplified for one isolate using ITS1/ITS4 primers and sequenced (GenBank Accession No. KF041822). BLASTn analysis (1) of the 557-bp segment showed a 99% similarity with the ITS sequence of Bipolaris cactivora HM598679. For pathogenicity tests, 8 mm diameter mycelial disks removed from 15-day-old PDA cultures of the fungus were placed at the wounded stem apexes of three 7-month-old healthy plants (three disks per plant). Three plants inoculated with non-inoculated PDA disks served as controls. Plants were covered with plastic bags and maintained in a growth chamber at 23 ± 1°C with 12 h light/dark. By 8 days after inoculation, all the inoculated stems were rotted and 10 colonies of B. cactivora were re-isolated from infected tissues. Control plants remained healthy. The pathogenicity test was carried out twice with similar results. Several hosts are listed for B. cactivora including C. peruvianus, and the pathogen has been reported in the United States (2) and in South Korea (3). To our knowledge, this is the first report of B. cactivora on C. peruvianus monstruosus in Italy. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. APS Press, St Paul, MN, 1989. (3) I. H. Hyun et al. Res. Plant Dis. 7:56, 2001. (4) A. Sivanesan. Mycopathologia 111:125, 1990.

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First Report of Stem and Foliage Blight of Chrysanthemum Caused by Phytophthora drechsleri in the United States

Plant Disease ◽

10.1094/pdis-03-21-0631-pdn ◽

2021 ◽

Author(s):

Charles Krasnow ◽

Nancy Rechcigl ◽

Jennifer Olson ◽

Linus Schmitz ◽

Steven N. Jeffers

Keyword(s):

United States ◽

South Carolina ◽

Sequence Similarity ◽

Morphological Characteristics ◽

The United States ◽

Universal Primers ◽

Broad Host Range ◽

Pathogenicity Test ◽

First Report ◽

Foliage Blight

Chrysanthemum (Chrysanthemum × morifolium) plants exhibiting stem and foliage blight were observed in a commercial nursery in eastern Oklahoma in June 2019. Disease symptoms were observed on ~10% of plants during a period of frequent rain and high temperatures (26-36°C). Dark brown lesions girdled the stems of symptomatic plants and leaves were wilted and necrotic. The crown and roots were asymptomatic and not discolored. A species of Phytophthora was consistently isolated from the stems of diseased plants on selective V8 agar (Lamour and Hausbeck 2000). The Phytophthora sp. produced ellipsoid to obpyriform sporangia that were non-papillate and persistent on V8 agar plugs submerged in distilled water for 8 h. Sporangia formed on long sporangiophores and measured 50.5 (45-60) × 29.8 (25-35) µm. Oospores and chlamydospores were not formed by individual isolates. Mycelium growth was present at 35°C. Isolates were tentatively identified as P. drechsleri using morphological characteristics and growth at 35°C (Erwin and Ribeiro 1996). DNA was extracted from mycelium of four isolates, and the internal transcribed spacer (ITS) region was amplified using universal primers ITS 4 and ITS 6. The PCR product was sequenced and a BLASTn search showed 100% sequence similarity to P. drechsleri (GenBank Accession Nos. KJ755118 and GU111625), a common species of Phytophthora that has been observed on ornamental and vegetable crops in the U.S. (Erwin and Ribeiro 1996). The gene sequences for each isolate were deposited in GenBank (accession Nos. MW315961, MW315962, MW315963, and MW315964). These four isolates were paired with known A1 and A2 isolates on super clarified V8 agar (Jeffers 2015), and all four were mating type A1. They also were sensitive to the fungicide mefenoxam at 100 ppm (Olson et al. 2013). To confirm pathogenicity, 4-week-old ‘Brandi Burgundy’ chrysanthemum plants were grown in 10-cm pots containing a peat potting medium. Plants (n = 7) were atomized with 1 ml of zoospore suspension containing 5 × 103 zoospores of each isolate. Control plants received sterile water. Plants were maintained at 100% RH for 24 h and then placed in a protected shade-structure where temperatures ranged from 19-32°C. All plants displayed symptoms of stem and foliage blight in 2-3 days. Symptoms that developed on infected plants were similar to those observed in the nursery. Several inoculated plants died, but stem blight, dieback, and foliar wilt were primarily observed. Disease severity averaged 50-60% on inoculated plants 15 days after inoculation. Control plants did not develop symptoms. The pathogen was consistently isolated from stems of symptomatic plants and verified as P. drechsleri based on morphology. The pathogenicity test was repeated with similar results. P. drechsleri has a broad host range (Erwin and Ribeiro 1996; Farr et al. 2021), including green beans (Phaseolus vulgaris), which are susceptible to seedling blight and pod rot in eastern Oklahoma. Previously, P. drechsleri has been reported on chrysanthemums in Argentina (Frezzi 1950), Pennsylvania (Molnar et al. 2020), and South Carolina (Camacho 2009). Chrysanthemums are widely grown in nurseries in the Midwest and other regions of the USA for local and national markets. This is the first report of P. drechsleri causing stem and foliage blight on chrysanthemum species in the United States. Identifying sources of primary inoculum may be necessary to limit economic loss from P. drechsleri.

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First Report of Postharvest Fruit Rot in Persimmon Caused by Phacidiopycnis washingtonensis in Italy

Plant Disease ◽

10.1094/pdis-94-6-0788b ◽

2010 ◽

Vol 94 (6) ◽

pp. 788-788 ◽

Cited By ~ 2

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. T. Amatulli ◽

M. L. Gullino

Keyword(s):

United States ◽

Its Region ◽

The United States ◽

Fruit Rot ◽

Diospyros Kaki ◽

Pathogenicity Test ◽

Conidial Suspension ◽

First Report ◽

Pathogenicity Tests ◽

Phacidiopycnis Washingtonensis

Persimmon (Diospyros kaki L.) is widely grown in Italy, the leading producer in Europe. In the fall of 2009, a previously unknown rot was observed on 3% of fruit stored at temperatures between 5 and 15°C in Torino Province (northern Italy). The decayed area was elliptical, firm, and appeared light brown to dark olive-green. It was surrounded by a soft margin. The internal decayed area appeared rotten, brown, and surrounded by bleached tissue. On the decayed tissue, black pycnidia that were partially immersed and up to 0.5 mm in diameter were observed. Light gray conidia produced in the pycnidia were unicellular, ovoid or lacriform, and measured 3.9 to 6.7 × 2.3 to 3.5 (average 5.0 × 2.9) μm. Fragments (approximately 2 mm) were taken from the margin of the internal diseased tissues, cultured on potato dextrose agar (PDA), and incubated at temperatures between 23 and 26°C under alternating light and darkness. Colonies of the fungus initially appeared ash colored and then turned to dark greenish gray. After 14 days of growth, pycnidia and conidia similar to those described on fruit were produced. The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 502-bp segment showed a 100% similarity with the sequence of Phacidiopycnis washingtonensis Xiao & J.D. Rogers (GenBank Accession No. AY608648). The nucleotide sequence has been assigned the GenBank Accession No. GU949537. Pathogenicity tests were performed by inoculating three persimmon fruits after surface disinfesting in 1% sodium hypochlorite and wounding. Mycelial disks (10 mm in diameter), obtained from PDA cultures of one strain were placed on wounds. Three control fruits were inoculated with plain PDA. Fruits were incubated at 10 ± 1°C. The first symptoms developed 6 days after the artificial inoculation. After 15 days, the rot was very evident and P. washingtonensis was consistently reisolated. Noninoculated fruit remained healthy. The pathogenicity test was performed twice. Since P. washingtonensis was first identified in the United States on decayed apples (2), ‘Fuji’, ‘Gala’, ‘Golden Delicious’, ‘Granny Smith’, ‘Red Chief’, and ‘Stark Delicious’, apple fruits also were artificially inoculated with a conidial suspension (1 × 106 CFU/ml) of the pathogen obtained from PDA cultures. For each cultivar, three surface-disinfested fruit were wounded and inoculated, while three others served as mock-inoculated (sterile water) controls. Fruits were stored at temperatures ranging from 10 to 15°C. First symptoms appeared after 7 days on all the inoculated apples. After 14 days, rot was evident on all fruit inoculated with the fungus, and P. washingtonensis was consistently reisolated. Controls remained symptomless. To our knowledge, this is the first report of the presence of P. washingtonensis on persimmon in Italy, as well as worldwide. The occurrence of postharvest fruit rot on apple caused by P. washingtonensis was recently described in the United States (3). In Italy, the economic importance of the disease on persimmon fruit is currently limited, although the pathogen could represent a risk for apple. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) Y. K. Kim and C. L. Xiao. Plant Dis. 90:1376, 2006. (3) C. L. Xiao et al. Mycologia 97:473, 2005.

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First Report of Botrytis Blight Caused by Botrytis cinerea on Platycodon grandiflorum in Italy

Plant Disease ◽

10.1094/pdis-93-9-0969b ◽

2009 ◽

Vol 93 (9) ◽

pp. 969-969

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

United States ◽

Botrytis Cinerea ◽

Its Region ◽

The United States ◽

Fluorescent Light ◽

Pathogenicity Test ◽

Commonwealth Mycological Institute ◽

Platycodon Grandiflorum ◽

First Report ◽

Bedding Plant

Platycodon grandiflorum (balloon flower), a perennial plant belonging to the Campanulaceae family, is widely grown as a bedding plant in temperate gardens. This species is characterized by the ability to bloom profusely throughout the summer into early fall and for its white to blue and pink flowers. In September 2008, symptoms of a previously unknown blight were observed in six gardens located in the Biella Province of northern Italy. When the disease developed, temperatures ranged between 15 and 22°C with frequent rains (149.8 mm of rainfall registered in September 2008 by the meteorological station of Oropa, located in the same area in which the disease appeared). Initially, leaves and petioles appeared chlorotic. Subsequently, lesions developed on the stems and flowers were sometimes affected. In each garden examined, approximately 50% of the plants were affected by the disease. A soft, gray mycelium was observed on symptomatic tissues, especially the stems. Severely infected leaves and stems eventually became completely rotted and later desiccated. Diseased tissue was excised from affected leaves, immersed in a solution containing 1% sodium hypochlorite for 10 s, and then cultured on potato dextrose agar (PDA) medium. A fungus developed that produced abundant mycelium on PDA medium when incubated under constant fluorescent light at 22 ± 1°C. Numerous sclerotia were produced on PDA plates incubated for 20 days at 8 ± 1°C. Sclerotia were dark, irregular, and measured 1 to 3.5 × 0.9 to 2.5 (average 2.1 × 1.5) mm. Conidia were smooth, ash colored, unicellular, ovoid, and measured 11 to 19 × 7 to 13 (average 15 × 11) μm. These morphological features were typical of those described for Botrytis cinerea (2). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 539-bp segment showed 100% similarity with the sequence of Botryotinia fuckeliana (perfect stage of B. cinerea). The nucleotide sequence has been assigned the GenBank Accession No. GQ149480. Pathogenicity tests were performed by placing 1-cm2 fragments removed from PDA cultures of B. cinerea isolated from balloon flower on leaves of healthy potted P. grandiflorum plants (4-month-old). Five fragments were placed on each plant. Plants inoculated with PDA alone served as controls. Ten plants per treatment were used. Plants were covered with plastic bags for 5 days after inoculation and maintained in a greenhouse at temperatures between 18 and 23°C. The first foliar lesions developed on leaves 3 days after inoculation, and after 5 days, 80% of the leaves were severely infected. As the infection progressed after the inoculation, the stems also became infected. Control plants remained healthy. B. cinerea was consistently reisolated from leaf and stem lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of B. cinerea on P. grandiflorum in Italy, as well as in Europe. Blight on balloon flower attributed to Botrytis spp. was previously reported in the United States (3). References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, England, 1971. (3) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989.

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First Report of Damping-Off of Rhodiola sachalinensis Caused by Rhizoctonia solani AG-4 HG-II in China

Plant Disease ◽

10.1094/pdis-07-11-0559 ◽

2012 ◽

Vol 96 (1) ◽

pp. 142-142 ◽

Cited By ~ 1

Author(s):

Q. Bai ◽

Y. Xie ◽

X. Wang ◽

Y. Li ◽

J. Gao ◽

...

Keyword(s):

Rhizoctonia Solani ◽

Morphological Characteristics ◽

Its Region ◽

Herbaceous Plant ◽

Protective Effects ◽

Damping Off ◽

First Report ◽

Rhodiola Sachalinensis ◽

Perennial Herbaceous Plant ◽

Safranin O

Rhodiola sachalinensis A. Bor (family Crassulaceae), a perennial herbaceous plant, is distributed mainly in the mountainous areas of China, Japan, Korea, and Russia. It is widely used as a traditional Chinese medicine with adaptogenic properties, cardiopulmonary protective effects, and central nervous system activities (3). Currently, it is extensively cultivated in northeastern China. In August 2010, widespread (>60% of plants were symptomatic) damping-off was observed in a seedling field in Linjiang, China. Leaves and stems near the ground were affected first, with dark lesions forming on the stem and the lowest leaves exhibiting wilt. The wilt spread rapidly over the entire plant with leaves becoming grayish brown and water soaked and then turned black and died. Root rot, defoliation, and damping-off were also observed. Six isolates with morphological characteristics of Rhizoctonia solani Kühn were isolated from symptomatic stems when plated on potato dextrose agar (PDA). Mycelium was branched at right angles with a septum near the branch and a slight constriction at the branch base. Fungal colonies were initially white, turned brown with age, and produced irregularly shaped, brown sclerotia after 8 days on PDA. 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 magnification. The internal transcribed spacer (ITS) region of the nuclear rDNA was amplified by using the primers ITS4/ITS5 (2). The ITS sequences (715 bp) were identical in these six isolates (GenBank Accession No. FR878087) and had 100% sequence identity with R. solani AG-4 HG-II (GenBank Accession No. HQ629873) along with numerous other accessions from this AG subgroup. Pathogenicity tests were performed on healthy, potted seedlings of R. sachalinensis. Twenty plants were inoculated near the base of the stem with a 0.6-cm-diameter mycelial plug from 3-day-old PDA cultures for each isolate. Twenty plants inoculated with only PDA plugs served as controls. The plants were covered with plastic bags and kept in a greenhouse at 20 to 25°C for 72 h. All inoculated plants showed characteristic symptoms as previously observed in the seedling field 13 days after inoculation, while control plants remained healthy. R. solani AG-4 HG-II was reisolated from symptomatic tissues on inoculated plants. To our knowledge, this is the first report of R. solani AG-4 HG-II causing damping-off on R. sachalinensis in China. References: (1) R. J. Bandoni. Mycologia 71:873, 1979. (2) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (3) T. F. Yan et al. Conserv. Genet. 4:213, 2003.

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First Report of Leaf Spot Disease Caused by Glomerella magna on Lobelia chinensis in China

Plant Disease ◽

10.1094/pdis-03-13-0346-pdn ◽

2013 ◽

Vol 97 (10) ◽

pp. 1383-1383 ◽

Cited By ~ 4

Author(s):

Q. L. Li ◽

J. Y. Mo ◽

S. P. Huang ◽

T. X. Guo ◽

Z. B. Pan ◽

...

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

Its Region ◽

Tween 20 ◽

Leaf Spot Disease ◽

Herbaceous Plant ◽

Single Spore ◽

First Report ◽

Small Water ◽

Perennial Herbaceous Plant

Lobelia chinensis is a perennial herbaceous plant in the family Campanulaceae that is native to China, where it grows well in moist to wet soils. It is commonly used as a Chinese herbal medicine. In May 2012, symptoms of leaf spot were observed on leaves of L. chinensis in Nanning, Guangxi Zhuang Autonomous Region, China. The leaf lesions began as small, water-soaked, pale greenish to grayish spots, which enlarged to gray to pale yellowish spots, 4 to 6 mm in diameter. At later stages, numerous acervuli appeared on the lesions. Acervuli were mostly epiphyllous, and 40 to 196 μm in diameter. On potato dextrose agar (PDA), a fungus was consistently recovered from symptomatic leaf samples, with a 93% isolation rate from 60 leaf pieces that were surface sterilized in 75% ethanol for 30 s and then in 0.1% mercuric chloride for 45 s. Three single-spore isolates were used to evaluate cultural and morphological characteristics of the pathogen. Setae were two to three septate, dark brown at the base, acicular, and up to 90 μm long. Conidia were long oblong-elliptical, guttulate, hyaline, and 11 to 20 × 4.1 to 6.3 μm (mean 15.2 × 5.1 μm). These morphological characteristics of the fungus were consistent with the description of Colletotrichum magna (teleomorph Glomerella magna Jenkins & Winstead) (1). The rDNA internal transcribed spacer (ITS) region of one isolate, LC-1, was sequenced (GenBank Accession No. KC815123), and it showed 100% identity to G. magna, GenBank HM163187.1, an isolate from Brazil cultured from papaya (2). Although KC815123 was identified as G. magna, it shows 99% identity to GenBank sequences from isolates of C. magna, and more research is needed to elucidate the relationships between these taxa, especially with consideration to host specificity. Pathogenicity tests were performed with each of the three isolates by spraying conidial suspensions (1 × 106 conidia/ml) containing 0.1% Tween 20 onto the surfaces of leaves of 30-day-old and 6- to 8-cm-high plants. For each isolate, 30 leaves from five replicate plants were treated. Control plants were treated with sterilized water containing 0.1% Tween 20. All plants were incubated for 36 h at 25°C and 90% relative humidity in an artificial climate chamber, and then moved into a greenhouse. Seven days after inoculation, gray spots typical of field symptoms were observed on all inoculated leaves, but no symptoms were seen on water-treated control plants. Koch's postulates were fulfilled by reisolation of G. magna from diseased leaves. To our knowledge, this is the first report of G. magna infecting L. chinensis worldwide. References: (1) M. Z. Du et al. Mycologia 97:641, 2005. (2) R. J. Nascimento et al. Plant Dis. 94:1506, 2010.

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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 Black Rot of Carrots Caused by Alternaria radicina in Michigan

Plant Disease ◽

10.1094/pd-90-0684b ◽

2006 ◽

Vol 90 (5) ◽

pp. 684-684

Author(s):

C. Saude ◽

M. K. Hausbeck

Keyword(s):

United States ◽

New York ◽

Sequence Similarity ◽

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Distilled Water ◽

First Report ◽

Plastic Bags ◽

Alternaria Sp

In April 2005, an Alternaria sp. was isolated from carrot (Daucus carota) roots harvested in the fall of 2004 and held at 1 to 3°C in a storage facility in Newaygo County, MI. The pathogen was readily isolated on water agar from root tissue exhibiting grayish black, sunken lesions. Morphological characteristics were noted 5 to 7 days after single-conidium cultures were established on potato dextrose agar (3). Sixteen Alternaria sp. isolates were recovered. Cultures were dark olive brown, and conidia were pigmented, ellipsoidal, and produced singly or in chains of two. Conidia were 35 to 45 μm long and 15 to18 μm in diameter, usually with three to eight transverse and one to four longitudinal septa. Pathogenicity of isolates was tested on carrot roots in the laboratory and carrot seedlings (cv. Goliath) in the greenhouse. In the laboratory, four surface-sterilized, whole carrot roots were sprayed until runoff with 2 × 106 conidia/ml of each isolate and incubated at 23 to 25°C in a moist chamber for 10 days. Controls were sprayed with sterile distilled water. Ten to fifteen days after inoculation, inoculated carrots exhibited grayish black, sunken lesions, and an Alternaria sp. was reisolated from the margin of the lesions. Controls remained healthy. In the greenhouse, seven pots containing one 2-week-old carrot seedling were watered to saturation and plants were sprayed until runoff with 2 × 106 conidia/ml for each isolate. Control plants were sprayed with sterile distilled water. After inoculation, plants were enclosed in clear plastic bags, placed under 63% woven shade cloth and watered regularly. Black lesions were observed on the foliage 7 days after inoculation, and wilt and death of plants were observed 15 to 30 days after inoculation. Alternaria sp. was reisolated from the foliage of symptomatic plants. Control plants remained healthy. DNA was extracted from all isolates, and the nuclear ribosomal internal transcribed spacer (ITS) region amplified with primers ITS4 and ITS5 and sequenced. A portion of the ITS sequence has been deposited in the NCBI database (GenBank Accession No. DQ394073). A BLAST search of the NCBI database with the ITS sequences revealed A. radicina, Accession No AY154704, as the closest match with 100% sequence similarity. In September 2005, an Alternaria sp. was isolated from black lesions on carrot roots, crowns, and foliage that were collected from fields in Newaygo and Oceana counties, MI. The recovered isolates were morphologically similar to A. radicina isolates obtained from stored carrots in April 2005. First isolated and identified on stored carrots in New York (3), A. radicina is also present in other carrot-producing areas of the United States (1) and was isolated not only from stored carrots but also from carrots in the field (2) and carrot seeds (4). To our knowledge, this is the first report of A. radicina on stored and field carrots in Michigan, which signifies a serious risk to a carrot industry that ranks among the top five in the United States. References: (1) D. F. Farr et al. Fungi on Plants and Plant Produce in the United States.The American Phytopathological Society, St. Paul, MN, 1989. (2) R. G. Grogan and W. C. Snyder. Phytopathology 42:215, 1952. (3) F. C. Meier and E. D. Eddy. Phytopathology 12:157, 1922. (4) B. M. Pryor and R. L. Gilbertson. Plant Dis. 85:18, 2001.

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