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

Plant Disease ◽  
2009 ◽  
Vol 93 (4) ◽  
pp. 433-433 ◽  
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.

scholarly journals First Report of Leaf Blight on Hosta fortunei Caused by Rhizoctonia solani AG 4 in Italy

Plant Disease ◽  
2009 ◽  
Vol 93 (4) ◽  
pp. 432-432 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Rhizoctonia Solani ◽  
Aqueous Suspension ◽  
Its Region ◽  
The United States ◽  
Morphological Characters ◽  
Leaf Blight ◽  
Pathogenicity Test ◽  
First Report ◽  
Leaf Petiole

Hosta fortunei (Liliaceae) is used in semishaded areas of gardens for its lavender-colored flowers produced in midsummer. In April of 2008, in a greenhouse at the University of Torino, located in Grugliasco (northern Italy), a leaf blight was observed on 15% of potted 60-day-old plants growing at temperatures ranging between 20 and 25°C and relative humidity of 60 to 90%. Semicircular, water-soaked lesions developed on leaves just above the soil line at the leaf-petiole junction and later along leaf margins. Lesions expanded for several days along the midvein until the entire leaf was destroyed. Blighted leaves turned brown, withered, and clung to the shoots. 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 characters of Rhizoctonia solani (4) 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 of R. solani obtained from affected plants were 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, but no anastomosis was observed. The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 646-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 534556. For pathogenicity tests, the inoculum of R. solani was prepared by growing the pathogen on PDA for 10 days. Six-month-old plants of H. fortunei were grown in 1-liter pots. Inoculum, which consisted of an aqueous suspension of PDA and mycelium disks (10 g of mycelium per pot), was placed at the collar of plants. Plants inoculated with water and PDA fragments alone served as control treatments. Five plants per treatment were used. Plants were maintained in a growth chamber at 20 ± 1°C. The first symptoms, similar to those observed in the nursery, developed 15 days after 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. R. solani was reported on plants belonging to the genus Hosta in the United States (3). This is, to our knowledge, the first report of leaf blight of H. fortunei 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 Phytopathology Society, St Paul, MN, 1989. (4) B. Sneh et al. Identification of Rhizoctonia species. The American Phytopathological Society, St Paul, MN, 1991.

scholarly journals Report of Leaf Blight on Washington Lupine (Lupinus polyphyllus) Caused by Rhizoctonia solani AG 4 in Italy

Plant Disease ◽  
2009 ◽  
Vol 93 (4) ◽  
pp. 429-429
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Rhizoctonia Solani ◽  
Aqueous Suspension ◽  
Morphological Characteristics ◽  
Its Region ◽  
Leaf Blight ◽  
Herbaceous Plant ◽  
Pathogenicity Test ◽  
Lupinus Polyphyllus ◽  
Leaf Petiole ◽  
Sphagnum Peat

Lupinus polyphyllus (Leguminosae), Washington lupine, is a perennial herbaceous plant. In March 2008, in a campus greenhouse at the University of Torino, Grugliasco (northern Italy), a leaf blight was observed on 20% of potted 30-day-old plants. 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 for several days along the midvein until the entire leaf was destroyed. Blighted leaves turned brown, withered, clung to the shoots, and matted on the surrounding foliage. Severely infected plants died. Plants were grown in a sphagnum peat/perlite/clay (70:20:10) substrate at temperatures between 18 and 25°C and relative humidity of 60 to 80%. 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 of streptomycin sulfate. A fungus with the morphological characteristics of Rhizoctonia solani (4) was consistently and readily recovered, then transferred and maintained in pure culture. Ten-day-old mycelium grown on PDA at 20 ± 1°C appeared light brown, rather compact, and exhibited radial growth. The isolates of R. solani successfully anastomosed with tester isolate AG 4 (AG 4 RT 31, obtained from tobacco plants). The hyphal diameter at the point of anastomosis was reduced, the anastomosis point was obvious, and cell death of adjacent cells was observed. Results were consistent with other reports on anastomosis reactions (3). Pairings were also made with tester isolates 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 660-bp fragment showed 100% homology with the sequence of R. solani. The nucleotide sequence has been assigned GenBank Accession No. FJ486272. For pathogenicity tests, the inoculum of R. solani was prepared by growing the pathogen on PDA for 10 days. Plants of 30-day-old L. polyphyllus were grown in 10-liter containers (10 plants per container) on a steam disinfested sphagnum peat/perlite/clay (70:20:10) medium. Inoculum, consisting of an aqueous suspension of mycelium disks prepared from PDA cultures (5 g of mycelium per plant), was placed at the collar of plants. Plants inoculated with water and PDA fragments alone served as control treatments. Three replicates were used. Plants were maintained in a greenhouse at temperatures between 18 and 23°C. First symptoms, similar to those observed in the nursery, developed 10 days after the artificial inoculation. R. solani was consistently reisolated from infected leaves and stems. Control plants remained healthy. The pathogenicity test was repeated twice. The susceptibility of L. polyphyllus to R. solani was reported in Poland (2). This is, to our knowledge, the first report of leaf blight of L. polyphyllus caused by R. solani in Italy. The importance of the disease is at the moment limited. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) W. Blaszczak. Rocz. Nauk. Roln. Ser A 85:705, 1962. (3) 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. (4) B. Sneh et al. Identification of Rhizoctonia species. The American Phytopathological Society, St Paul, MN, 1991.

scholarly journals First Report of Leaf Blight on Coral Bells (Heuchera sanguinea) Caused by Rhizoctonia solani AG 1A in Italy

Plant Disease ◽  
2007 ◽  
Vol 91 (9) ◽  
pp. 1206-1206
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Rhizoctonia Solani ◽  
Aqueous Suspension ◽  
Morphological Characters ◽  
Leaf Blight ◽  
Pathogenicity Test ◽  
Uniform Size ◽  
First Report ◽  
Leaf Petiole ◽  
Pathogenicity Tests ◽  
Hyphal Diameter

Heuchera sanguinea (Saxifragaceae), coral bells or alum root, is an herbaceous perennial used in parks and gardens and sometimes grown in pots for its heart-shaped leaves and upright panicles of bright red, tiny flowers produced in late spring. At the end of fall 2006, a leaf blight was observed on 50% of a crop of potted 45-day-old plants grown in a sphagnum peat/clay/perlite (70:20:10) substrate at temperatures ranging between 20 and 25°C in a nursery. Semicircular, water-soaked lesions developed on leaves just above the soil line at the leaf-petiole junction and later along the leaf margins. For several days, lesions expanded along the midvein until the entire leaf was destroyed. Blighted leaves turned brown, withered, clung to the shoots, and matted on the surrounding foliage. Mycelia were often seen on and suspended between leaves. Blight progressed up the plant from the leaves to the shoot tip. Affected plants often died leaving wide empty areas. Diseased tissue was disinfected for 1 min in 1% NaOCl, rinsed with sterile water, and plated on potato dextrose agar (PDA) amended with 100 μg/liter of streptomycin sulfate. A fungus with the morphological characters of Rhizoctonia solani was consistently and readily recovered, then transferred and maintained in pure culture (3). The isolates of R. solani obtained from affected plants were successfully anastomosed with tester isolate AG 1 (ATCC 58946). The hyphal diameter at the point of anastomosis was reduced, the anastomosis point was obvious, and cell death of adjacent cells was observed. Results were consistent with other reports on anastomosis reactions (1). Pairings were also made with tester isolates of AG 2, 3, 4, 5, 6, 7, and 11 with no anastomoses observed between the recovered and tester isolates. Sclerotia were of uniform size with a diameter from 0.4 to 4 mm and sometimes joined laterally. The description of sclerotia was typical for subgroup 1A Type 2 (2). For pathogenicity tests, the inoculum of R. solani was prepared by growing three isolates of the pathogen on PDA for 7 days. Plants of 30-day-old H. sanguinea were grown in 10-liter containers (6 plants per container) on a steam disinfested peat/clay/perlite substrate (70:20:10)). Inoculum consisted of an aqueous suspension of PDA and mycelium disks (1 cm2 of mycelium per plant) and was placed at the base of the plant stems and on leaves. Plants inoculated with water and PDA fragments alone served as control treatments. Three replicates were used. Plants were maintained in a growth chamber at 24°C with 12 h of light/dark. The first symptoms, similar to those observed in the nursery, developed 12 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. This is, to our knowledge, the first report of leaf blight of H. sanguinea caused by R. solani in Italy and probably in the world. References: (1) 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. (2) R. T. Sherwood. Phytopathology, 59:1924, 1969. (3) B. Sneh et al. Identification of Rhizoctonia species. The American Phytopathological Society, St Paul, MN, 1991.

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

Plant Disease ◽  
2011 ◽  
Vol 95 (7) ◽  
pp. 880-880
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. T. Amatulli ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Morphological Characteristics ◽  
Its Region ◽  
Apical Part ◽  
The United States ◽  
Herbaceous Plant ◽  
Pathogenicity Test ◽  
First Report ◽  
Perennial Herbaceous Plant ◽  
Olive Green

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.

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

Plant Disease ◽  
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.

scholarly journals First Report of Leaf Blight Caused by Rhizoctonia solani AG 1B on Madagascar Periwinkle (Catharanthus roseus) in Italy

Plant Disease ◽  
2006 ◽  
Vol 90 (10) ◽  
pp. 1361-1361 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Rhizoctonia Solani ◽  
Catharanthus Roseus ◽  
The United States ◽  
Morphological Characters ◽  
Leaf Blight ◽  
Pathogenicity Test ◽  
Madagascar Periwinkle ◽  
Public Park ◽  
First Report ◽  
Leaf Petiole

Madagascar periwinkle (Catharanthus roseus), a plant belonging to the Apocynaceae family, is used for parks and gardens and sometimes grown in pots. At the end of the summer of 2005, a leaf blight was observed on plants in a public park of Torino. 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 for several days along the midvein until the entire leaf was destroyed. Blighted leaves turned brown, withered, clung to the shoots, and matted on the surrounding foliage. Although lesions were not seen on the stem, affected plants often died leaving wide empty areas. Mycelia of the pathogen were often seen on and suspended between the leaves. Blight progressed from the leaves to the shoot tip. The diseased tissue was disinfected for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 μg/l streptomycin sulphate. A fungus with the morphological characters of Rhizoctonia solani was consistently and readily isolated and maintained in pure culture after single-hyphal tipping (4). The isolates of R. solani obtained from affected plants were successfully anastomosed with tester isolate AG 1 (ATCC 58946). The hyphal diameter at the point of anastomosis was reduced, the anastomosis point was obvious, and cell death of adjacent cells was observed. These results are consistent with other reports on anastomosis reactions (2). Pairing was also made with AG 2, 3, 4, 5, 7, and 11, with no anastomoses observed between the isolates and testers. Sclerotia were subspheroid in shape and had a size of 1 mm, which indicated that this pathogen was in subgroup 1B (4). For pathogenicity tests, the inoculum of R. solani was prepared by growing the pathogen on PDA for 7 days. Plants of C. roseus were grown in 3-liter containers (2 plants per pot) on a steam disinfested substrate (peat/ pomix/pine bark/clay). Artificial inoculation was carried out on 7-day-old plants by placing numerous fragments of PDA cultures on the leaves of the plants. Plants inoculated with PDA alone served as control treatments. Three replicates were used. Plants were maintained in a glasshouse at 20 to 25°C. The first symptoms, similar to those observed in the public park, developed 5 days after inoculation, and R. solani was consistently reisolated from infected plants. Control plants remained healthy. The pathogenicity test was carried out twice with similar results. This is, to our knowledge, the first report of R. solani on periwinkle in Italy. The same disease was reported in India (1) and the United States (3). References: (1) R. Balasubramanian and K. S. Bhama. Indian Phytopathol. 30:556, 1977. (2) D. E. Carling. Grouping in Rhizoctonia solani by hyphal anastomosis reactions. Pages 37–47 in: Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control. B. Sneh et al., eds. Kluwer Academic Publishers, the Netherlands, 1996. (3) A. K. Hagan and J. M. Mullen Plant Dis. 77:1169, 1993. (4) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St Paul, MN, 1991.

scholarly journals First Report of Leaf Blight on Woodland Sage Caused by Rhizoctonia solani AG 1 in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 1071-1071 ◽  
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
Rhizoctonia Solani ◽  
Aqueous Suspension ◽  
Its Region ◽  
Morphological Characters ◽  
Leaf Blight ◽  
Pathogenicity Test ◽  
First Report ◽  
Leaf Petiole ◽  
Perennial Plant ◽  
Potted Plants

Woodland sage (Salvia nemorosa L.; Lamiaceae) is a hardy herbaceous perennial plant that is easy to grow and propagate and is used in parks and grown as potted plants. During the summer of 2009 in a nursery near Torino in northern Italy, a leaf blight was observed on 30-day-old plants of cv. Blau Koenigin grown in pots under shade. Semicircular, water-soaked lesions developed on leaves just above the soil line at the leaf-petiole junction and later along leaf margins. Lesions expanded along the midvein until the entire leaf was destroyed. Blighted leaves turned brown, withered, and clung to the shoots. No symptoms were observed on the roots. 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 of streptomycin sulfate. A fungus with morphological characters of Rhizoctonia solani (3) was consistently recovered. Ten-day-old mycelium grown on PDA at 22 ± 1°C appeared light brown, rather compact, and with radial growth. Sclerotia were irregular and measured between 0.5 and 2 mm. Pairings were made with tester isolates of AG 1, 2, 3, 4, 5, 6, 7, 11, and AG B1. The only successful anastomosis was with tester isolate AG 1 (ATCC 58946). The hyphal diameter at the point of anastomosis was reduced, the anastomosis point was obvious, and cell death of adjacent cells was observed. Results were consistent with other reports on anastomosis reactions (2). The description of sclerotia of the isolate AG1 was typical for subgroup 1A Type 2 (3). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 688 bp showed a 100% homology with the sequence of R. solani AG-1A and the nucleotide sequence has been assigned (GenBank Accession No. HM044764). For pathogenicity tests, the inoculum of one isolate of R. solani from the nursery was prepared by growing the pathogen on PDA for 7 days. The foliage of 30-day-old potted plants of S. nemorosa cv. Blau Koenigin was artificially inoculated with an aqueous suspension of PDA and mycelium fragments (1 g per mycelium per plant) prepared from cultures with a blender. Plants were covered with plastic bags for 3 days. Plants inoculated with water and PDA fragments alone served as control treatments. Plants were maintained in a glasshouse at 20 to 25°C. The first symptoms, similar to those observed in the nursery, developed 7 days after foliar inoculation. R. solani was consistently reisolated from infected leaves. Control plants remained healthy. The pathogenicity test was carried out twice with similar results. To our knowledge, this is the first report of leaf blight of S. nemorosa caused by R. solani in Italy as well as worldwide. The importance of the disease is still unknown. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. E. Carling. Page 35 in: Rhizoctonia Species: Taxonomy, Molecular Biology, Ecology, Pathology and Disease Control. Kluwer Academic Publishers, the Netherlands, 1996. (3) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St Paul, MN, 1991.

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

Plant Disease ◽  
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.

scholarly journals First Report of Rust Caused by Pucciniastrum circaeae on Fuchsia × hybrida in Italy

Plant Disease ◽  
2012 ◽  
Vol 96 (4) ◽  
pp. 588-588 ◽  
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
G. Ortu ◽  
M. L. Gullino
Keyword(s):  
Phylogenetic Trees ◽  
Aqueous Suspension ◽  
Morphological Characteristics ◽  
Pcr Amplification ◽  
Signs And Symptoms ◽  
The United States ◽  
Pathogenicity Test ◽  
First Report ◽  
Potted Plants ◽  
Plastic Bags

Fuchsia is a genus of flowering plants that is native to South America and New Zealand and belongs to the family Onagraceae. In September 2011, 2-year-old potted plants of Fuchsia × hybrida, cv. Citation, in a garden located near Biella (northern Italy) showed signs and symptoms of a previously unknown disease. Typically, infected plants showed leaf chlorosis followed by the appearance of necrosis on the adaxial leaf surfaces, while the abaxial surfaces showed orange uredinia irregularly distributed. As the disease progressed, infected leaves turned yellow and wilted. Affected plants showed a progressive phylloptosis and also flowering was negatively affected. Urediniospores were globose, yellow to orange, and measured 14.6 to 25.9 (average 19.6) μm. Teliospores were not observed. Morphological characteristics of the fungus corresponded to those of the genus Pucciniastrum. DNA extraction and PCR amplification were carried out with Terra PCR Direct Polymerase Mix (Clontech, Saint Germain-en-Laye, France) and primers ITS1/ITS4 (4). A 700-bp PCR product was sequenced and a BLASTn search (1) confirmed that the sequence corresponded with a 96% identity to Pucciniastrum circaeae. The nucleotide sequence has been assigned the GenBank Accession No. JQ029688. Pathogenicity tests were performed by spraying leaves of healthy 1-year-old potted Fuchsia × hybrida plants with an aqueous suspension of 1 × 103 urediniospores ml–1. The inoculum was obtained from infected leaves. Plants sprayed only with water served as controls. Three plants were used for each treatment. Plants were covered with plastic bags for 4 days after inoculation and maintained outdoors at temperatures ranging between 18 and 25°C. Lesions developed on leaves 20 days after inoculation with the urediniospore suspension, showing the same symptoms as the original plants, whereas control plants remained healthy. The organism that was recovered from the lesions after inoculation was the same as the one obtained from the diseased plants. The pathogenicity test was carried out twice with similar results. The presence of P. fuchsiae, later identified as P. epilobii, was repeatedly reported in the United States (3). P. epilobii and P. circaeae have closely related hosts and morphologically similar urediniospores. These species were reported to form a single group in molecular phylogenetic trees (2). This is, to our knowledge, the first report of P. circaeae on Fuchsia × hybrida in Italy. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) Y. M. Liang et al. Mycoscience 47:137, 2006. (3) L. B. Loring and L. F. Roth. Plant Dis. Rep. 48:99, 1964. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

scholarly journals First Report of Leaf Blight of Dianthus chinensis Caused by Rhizoctonia solani

Plant Disease ◽  
2000 ◽  
Vol 84 (12) ◽  
pp. 1344-1344
Author(s):  
G. E. Holcomb ◽  
D. E. Carling
Keyword(s):  
United States ◽  
Rhizoctonia Solani ◽  
Gulf Coast ◽  
The United States ◽  
Anastomosis Group ◽  
Early Spring ◽  
Leaf Blight ◽  
Infected Leaf ◽  
First Report ◽  
Bedding Plant

Dianthus chinensis (rainbow pink) is a popular seasonal bedding plant for the Gulf Coast of the United States and is primarily grown during the fall, winter, and early spring months. In August 1999, diseased plants were observed in a Baton Rouge, LA, propagation nursery with irregularly oval, tan leaf spots 3 to 10 mm in diameter. Heavily infected leaves became blighted and were killed, but plants survived and roots, crowns, and flowers were not affected. Infected leaf samples were surface-disinfected for 1 to 3 min in 70% ethyl alcohol, blotted dry, and sections were placed on 2% acidified water agar. A fungus that was identified as Rhizoctonia solani, and belonging to anastomosis group (AG)-1 IB, was consistently isolated from infected leaves. Inoculum was prepared by blending one 7-day-old plate culture, grown on acidified potato-dextrose agar, in 100 ml distilled deionized water. Pathogenicity tests were performed by dripping inoculum from a 10-ml pipette on leaf surfaces of healthy rainbow pink plants. Inoculated and noninoculated plants were held in a dew chamber at 26°C for 2 to 3 days and then removed to a greenhouse where temperatures ranged from 25 to 32°C. Inoculated plants developed water-soaked spots after 2 to 3 days that turned tan and became necrotic 5 to 10 days later. These symptoms were like those observed on the original diseased plants. R. solani was reisolated from inoculated plants, and noninoculated plants remained healthy. Although R. solani has been reported previously as a root and stem pathogen of D. chinensis (1), this is the first report of leaf blight disease caused by this fungus. Reference: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN.

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