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

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 Botrytis Blight Caused by Botrytis cinerea on Periwinkle (Catharanthus roseus) in Italy

Plant Disease ◽

10.1094/pdis-93-5-0554b ◽

2009 ◽

Vol 93 (5) ◽

pp. 554-554 ◽

Cited By ~ 2

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Botrytis Cinerea ◽

Catharanthus Roseus ◽

Warm Season ◽

Its Region ◽

The United States ◽

Plant Diseases ◽

Fluorescent Light ◽

Pathogenicity Test ◽

First Report ◽

Bedding Plant

Catharanthus roseus (periwinkle), a perennial plant belonging to the Apocynaceae family, is grown as a warm-season bedding plant in temperate gardens. This species is characterized by a long flowering period and prized for its white-to-dark pink flowers. In October of 2008, 15% of C. roseus plants in a public garden located in Torino (northern Italy) showed symptoms of a previously unknown blight. When the disease developed, temperatures ranged between 10 and 24°C (average 17.3°C) and plants were being watered through sprinkle irrigation. Necrosis developed on the stems first, eventually spreading to leaf stalks, and the the entire leaf. Subsequently, the pathogen developed a scant, delicate, gray mycelium on affected tissues, particularly diffused on the stems. Severely infected leaves and stems eventually became completely rotted and desiccated. Tissues were excised from diseased leaves, immersed in a solution containing 1% sodium hypochlorite for 10 s, and cultured on potato dextrose agar (PDA) medium. The fungus 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 and irregular, measuring 0.5 to 2.8 × 0.5 to 2.2 (average 1.4 × 1.1) mm. Conidia were smooth, ash colored, ovoid, measuring 8 to 16 × 6 to 10 (average 10 × 7) μm, and similar to those described for Botrytis cinerea (2). The internal transcribed spacer (ITS) region of rDNA was amplified with primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 780-bp segment showed a 100% homology with the sequence of Botryotinia fuckeliana (perfect stage of B. cinerea). The nucleotide sequence has been assigned GenBank Accession No. FJ486271. Pathogenicity tests were performed by placing numerous fragments of PDA cultures on leaves of healthy, potted, 8-month-old C. roseus plants. Plants inoculated with PDA alone served as controls. Three plants per treatment were used. Plants were covered with plastic bags for 5 days after inoculation and maintained in a greenhouse at temperatures ranging between 18 and 25°C. The first foliar lesions developed on leaves 5 days after inoculation, whereas control plants remained healthy. B. cinerea was consistently reisolated from these lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of B. cinerea on C. roseus in Italy. The same disease was previously reported in many countries including the United States (3) and Taiwan (4). References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) H. L. Barnett and B. B. Hunter. Illustrated Genera of Imperfect Fungi. Burgess Publishing Company, Minneapolis, MN, 1972. (3) M. L. Daughtrey et al. Compendium of Flowering Potted Plant Diseases. The American Phytopathological Society, St Paul, MN, 1995. (4) W. Ou-Yang and W. S. Wu. Plant Pathol. Bull. 7:147, 1998.

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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 Botrytis Blight Caused by Botrytis cinerea on Lavandula stoechas in Italy

Plant Disease ◽

10.1094/pdis-94-3-0380a ◽

2010 ◽

Vol 94 (3) ◽

pp. 380-380 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

P. Pensa ◽

M. L. Gullino

Keyword(s):

Botrytis Cinerea ◽

Its Region ◽

Northern Italy ◽

Fluorescent Light ◽

Pathogenicity Test ◽

Commonwealth Mycological Institute ◽

First Report ◽

Potted Plants ◽

Lavandula Stoechas ◽

Plastic Bags

Lavandula stoechas or French lavender (Labiatae) is a perennial shrub that produces pinkish purple flowers and is endemic to the Mediterranean Region. In the Albenga area (northern Italy), this species is grown as a potted plant. In October 2008, symptoms of a previously unknown blight were observed in a commercial glasshouse in the Savona Province (northern Italy) on 10% of 3-month-old ‘Sugarberry Ruffles’ potted plants. Glasshouse temperatures ranged between 11 and 32°C (average of 21°C) and plants were overhead irrigated. Initially, leaves and stems appeared chlorotic. Subsequently, necrotic lesions developed on infected tissues. After 10 days, fluffy, gray mycelium became apparent on symptomatic tissue, especially on the basal parts of the plants. Severely infected plants eventually died. Tissues were excised from diseased leaves, immersed in an aqueous solution of 1% sodium hypochlorite for 10 s, and then cultured on potato dextrose agar (PDA). A fungus developed abundant mycelium when incubated under constant fluorescent light at 22 ± 1°C. Numerous small sclerotia developed on PDA plates incubated for 20 days at 8 ± 1°C. Sclerotia were dark and irregular and measured 2 to 5 × 1 to 2 mm. Conidia were smooth, gray, unicellular, ovoid, measured 9.4 to 13.6 × 6.2 to 7.9 (average 11.4 × 7.2) μm, and similar to those described for Botrytis cinerea (2). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 573-bp segment was 100% similar to the sequence of Botryotinia fuckeliana (perfect stage of B. cinerea). The nucleotide sequence has been assigned GenBank Accession No. GQ375747. Pathogenicity tests were performed by spraying leaves of 9-month-old healthy potted L. stoechas ‘Blue Star’, ‘Madrid Blue’, ‘Madrid Purple’, and ‘Madrid White’ plants with a 7.5 × 104 conidia/ml spore suspension obtained from 7-day-old PDA cultures. Each plant received 5 ml of inoculum. Plants sprayed with water only served as controls. Four plants per treatment and per cultivar were used. Plants were covered with plastic bags for 4 days after inoculation and maintained in a growth chamber at 20 ± 1°C. The first lesions developed on flowers 5 days after inoculation, and 2 days later, lesions developed on leaves and stems. Lesions were similar to those observed in the commercial glasshouse. Control plants remained healthy. B. cinerea was consistently reisolated from these lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of B. cinerea on L. stoechas in Italy as well as worldwide. Botrytis blight previously has been described on L. angustifolia in Japan (4) and Poland (3). In Italy, the economic importance of the disease is currently still limited. 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) L. B. Orlikowski and A. Valjiuskaite. Acta Mycol, 42:193, 2007. (4) J. Takeuch and H. Horie. Annu. Rep. Kanto-Tosan Plant Prot. Soc. 53:87, 2006.

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First Report of Botrytis Blight Caused by Botrytis cinerea on Chamelaucium uncinatum in Italy

Plant Disease ◽

10.1094/pdis-93-9-0968b ◽

2009 ◽

Vol 93 (9) ◽

pp. 968-968 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

F. Tinivella ◽

M. L. Gullino

Keyword(s):

Botrytis Cinerea ◽

Its Region ◽

Northern Italy ◽

Fluorescent Light ◽

Pathogenicity Test ◽

Commonwealth Mycological Institute ◽

First Report ◽

Potted Plants ◽

Plastic Bags ◽

Chamelaucium Uncinatum

Chamelaucium uncinatum (wax flower), an evergreen shrub belonging to the Myrtaceae family, is suitable for growing in containers. In the Albenga area (northern Italy), this species is grown as a potted plant. In April 2009, symptoms of a previously unknown blight were observed in a commercial glasshouse in the Savona Province (northern Italy) on 80% of 500 potted plants of cv. Snow Flake. Glasshouse temperatures ranged between 16 and 22°C and plants were drip irrigated. Initially, leaves and calyces appeared chlorotic. Subsequently, necrotic lesions developed on flower stalks and occasionally the corollas. After 10 days, soft, gray mycelium became apparent on symptomatic tissue, especially on the foliage. Severely infected leaves and flowers eventually became completely necrotic and abscised. Tissues were excised from diseased leaves, immersed in a solution containing 1% sodium hypochlorite for 10 s, and then cultured on potato dextrose agar (PDA) medium. A fungus developed abundant mycelium when incubated under constant fluorescent light at 23 ± 1°C. Numerous, small sclerotia also developed on PDA plates incubated for 20 days at 8 ± 1°C. Sclerotia were dark, spheroid, and measured 0.5 to 1.8 × 0.5 to 1.5 (average 1.2 × 1.0) mm. Conidia were smooth, gray, unicellular, ovoid, measured 8.5 to 11.1 × 7.1 to 8.6 (average 9.7 × 7.8) μm, and similar to 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 495-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. GQ149477. Pathogenicity tests were performed by spraying leaves of healthy potted C. uncinatum with a spore suspension (2 × 104 conidia/ml) obtained from PDA cultures of the pathogen. Each plant received 30 ml of the inoculum. Plants sprayed with water only served as controls. Three plants per treatment were used. Plants were covered with plastic bags for 5 days after inoculation and maintained in a growth chamber at 20 ± 1°C. The first foliar lesions developed on leaves 7 days after inoculation and were similar to those observed in the commercial glasshouse, whereas control plants remained healthy. B. cinerea was consistently reisolated from these lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of B. cinerea on C. uncinatum in Italy as well as in Europe. The disease has been reported in California (3) and more recently in South Africa (4). In Italy, the economic importance of the disease is currently still limited. 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) A. M. French. California Plant Disease Host Index. Calif. Dep. Food Agric., Sacramento, 1989. (4) L. Swart and S. Coertze. Plant Dis. 86:440, 2002.

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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 Basal Stem Rot of Apple Cactus (Cereus peruvianus monstruosus) Caused by Fusarium oxysporum in Italy

Plant Disease ◽

10.1094/pdis-03-11-0216 ◽

2011 ◽

Vol 95 (7) ◽

pp. 877-877

Author(s):

A. Garibaldi ◽

P. Pensa ◽

D. Bertetti ◽

A. Poli ◽

M. L. Gullino

Keyword(s):

United States ◽

Fusarium Oxysporum ◽

The United States ◽

Stem Rot ◽

Fluorescent Light ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Single Spore ◽

Basal Stem Rot ◽

First Report

During the summer of 2010, 20% of 7,000 4-month-old plants of apple cactus (Cereus peruvianus monstruosus) showed symptoms of a basal stem rot in a commercial nursery located in Liguria (northern Italy). Affected plants showed yellow orange-to-pale brown color from the crown level to the stem apex and a water-soaked rot was observed on the stem starting from the base. Brown discoloration was observed in the vascular system. Eventually stems bent, plants collapsed and died, and affected tissues dried out. A Fusarium sp. was consistently and readily isolated from symptomatic tissue on Komada selective medium. Isolates were purified and subcultured on potato dextrose agar (PDA). Single-spore cultures on PDA, Spezieller Nährstoffarmer agar (SNA) (3), and carnation leaf-piece agar (CLA) (2) were incubated at 26 ± 1°C (12-h fluorescent light, 12-h dark). On PDA, cultures produced a thick growth of white-to-pink mycelium and pale pink pigments in the agar. On SNA, cultures produced short monophialides with unicellular, ovoid-elliptical microconidia measuring 4.3 to 8.2 × 2.3 to 3.8 (average 6.0 × 2.8) μm. Chlamydospores were abundant, single or paired, terminal and intercalary, rough walled, and 6 to 8 μm in diameter. On CLA, cultures produced orange sporodochia with macroconidia that were 3 to 4 septate, nearly straight with a foot-shaped basal cell and a short apical cell, and measured 31.1 to 51.5 × 4.4 to 3.5 (average 43.2 × 3.8) μm. Such characteristics are typical of Fusarium oxysporum (3). Amplification of the ITS (internal transcribed spacer) of the rDNA using primers ITS1/ITS4 (4) yielded a 498-bp band. Sequencing and BLASTn analysis of this band showed an E-value of 0.0 with F. oxysporum. The nucleotide sequence has been assigned GenBank Accession No. JF422071. To confirm pathogenicity, five 6-month-old healthy plants of C. peruvianus monstruosus were inoculated by dipping roots in a conidial suspension (2.4 × 106 CFU/ml) of F. oxysporum isolated from affected plants. Inoculum was obtained from pure cultures of three single-spore isolates grown for 10 days on casein hydrolysate liquid medium. Roots were not wounded before the inoculation. Plants were transplanted into pots filled with steam-sterilized substrate (sphagnum peat/perlite/pine bark/clay 50:20:20:10). Five noninoculated plants served as a control. Plants were placed in a climatic chamber at 25 ± 1°C (12-h fluorescent light, 12 h-dark). Basal stem rot and vascular discoloration in the crown and stem developed within 30 days on each inoculated plant. Noninoculated plants remained healthy. F. oxysporum was consistently isolated from symptomatic plants. The pathogenicity test was conducted twice. F. oxysporum has been reported on Cereus spp. in the United States (1). To our knowledge, this is the first report of F. oxysporum on C. peruvianus monstruosus in Italy as well as in Europe. Currently, this disease is present in a few nurseries in Liguria. References: (1) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (2) N. L. Fisher et al. Phytopathology 72:151, 1982. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell, Ames, IA, 2006. (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.

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

Plant Disease ◽

10.1094/pdis-05-10-0391 ◽

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.

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First Report of Collar and Stem Rot Caused by Pythium aphanidermatum on Figmarigold (Lampranthus sp.) in Italy

Plant Disease ◽

10.1094/pdis-93-6-0672a ◽

2009 ◽

Vol 93 (6) ◽

pp. 672-672 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

P. Pensa ◽

M. L. Gullino

Keyword(s):

United States ◽

Its Region ◽

The United States ◽

Pythium Aphanidermatum ◽

Peat Moss ◽

Fluorescent Light ◽

Rooted Cuttings ◽

First Report ◽

Light Yellow ◽

Pathogenicity Tests

Lampranthus sp. N.B. Brown (figmarigold) of the Aizoaceae family is used as groundcover in gardens. In October of 2008, severe outbreaks of a previously unknown rot were observed in a nursery located in Liguria, near Savona (northern Italy), on 35-day-old rooted cuttings grown in a peat substrate. Approximately 50% of rooted cuttings of red-flowered cultivars were affected. Lesions on collars and young stems were brown, water soaked, and soft. Plants eventually collapsed as roots rotted. Thin, aerial hyphae were visible on the surface of the stems and substrate. Later, a thick, light yellow, mycelial mat surrounded infected plants. Tissue fragments were excised from the margins of the lesions, dipped in a solution containing 1% sodium hypochlorite, and plated on potato dextrose agar and a medium selective for Oomycetes (4). Plates were incubated under constant fluorescent light at 23 ± 1°C for 4 to 5 days. Hyphae of five isolates grown on V8 medium were aseptate and 4.2 to 7.9 (average 6.2) μm wide. Sporangia consisted of complexes of swollen hyphal branches. Oogonia were globose, smooth, and 23.5 to 28.0 (average 25.9) μm in diameter. Antheridia were barrel shaped, intercalary, and diclinous. Oospores were globose and 19.4 to 23.6 (average 21.4) μm in diameter. The internal transcribed spacer (ITS) region of rDNA of a single isolate (DB24112008) was amplified with primers ITS4/ITS6 and sequenced. A BLAST analysis (1) in GenBank of the 1,074-bp segment showed a 100% homology with the sequence of Pythium aphanidermatum (Accession No. EU245039). The nucleotide sequence has been assigned the GenBank Accession No. FJ492745. Pathogenicity tests were performed twice on a red-flower cultivar of a Lampranthus sp. grown in 1-liter pots containing a peat moss substrate infested with wheat and hemp kernels colonized with one isolate of P. aphanidermatum at a rate of 20 g/liter. Ten plants were grown in infested media and 10 plants were grown in noninfested media. Greenhouse temperatures were 18 to 24°C. The first symptoms of stem and root rot developed 15 days later, while control plants remained healthy. P. aphanidermatum was consistently reisolated from the lesions. To our knowledge, this is the first report of P. aphanidermatum on a Lampranthus sp. in Italy. The disease has been reported in Japan (3) in 2008, while in the United States, a Pythium sp. was reported on L. aureus and L. glomeratus (2). Currently, the economic importance of Pythium rot on figmarigold in Italy is still limited. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. F. Farr et al. Fungi on Plants and Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) H. Kawarazachi et al. J. Gen. Plant Pathol. 74:94, 2008. (4) H. Masago et al. Phytopathology, 67, 425, 1977.

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First Report of Gray Mold Caused by Botrytis cinerea on Stevia rebaudiana in Italy

Plant Disease ◽

10.1094/pdis-93-3-0318a ◽

2009 ◽

Vol 93 (3) ◽

pp. 318-318

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

P. Pensa ◽

M. L. Gullino

Keyword(s):

Botrytis Cinerea ◽

Stevia Rebaudiana ◽

Its Region ◽

Morphological Characters ◽

Gray Mold ◽

Fluorescent Light ◽

Pathogenicity Test ◽

Leaf Extracts ◽

First Report ◽

Potted Plants

Stevia rebaudiana (sweetleaf) is a perennial shrub belonging to the Asteraceae family and is widely grown for its sweet leaves. With its extracts having as much as 300 times the sweetness of sugar, this species is used in many countries for the production of sugar substitutes. However, in Italy, as well as in other countries, this species cannot be grown for the use of its leaf extracts. This plant is grown in a few nurseries in the Albenga Region (northern Italy) as potted plants. In February of 2008, 3-month-old plants grown in plastic pots (14-cm diameter) under glasshouse on heated benches started showing symptoms of a previously unknown blight. The temperature in the glasshouse ranged between 16 and 20°C and plants were watered by sprinkle irrigation. Leaves, starting from the basal ones, showed small, brown spots that spread across the entire leaf surface. Subsequently, the crown and stem were infected, and the pathogen developed abundant, soft, gray mycelium on leaves and stems and in the middle of the heads of S. rebaudiana. Flowers were not present when the symptoms appeared. Severely infected leaves dried out and became necrotic. The disease was observed in one nursery in which 5% of the plants were affected. The margins of the lesions were excised from leaves, immersed in a solution containing 1% sodium hypochlorite, and then cultured on potato dextrose agar (PDA) medium. A fungus produced abundant mycelium when incubated under constant fluorescent light at 22 ± 1°C after 10 days. The conidia were smooth, hyaline, ovoid, measuring 15.5 to 8.3 × 11.1 to 7.3 (average 11.6 × 8.6) μm, and were similar to those described for Botrytis cinerea. Conidiophores were slender and branched with enlarged apical cells bearing conidia on short sterigmata. The identity of the fungus was also confirmed by the production of numerous, small, black sclerotia on PDA plates incubated for 20 days at 8 ± 1°C. Sclerotia were dark and irregular with a diameter ranging from 1 to 2 mm. These morphological characters identified the fungus as B. cinerea (2). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 780-bp segment showed a 100% homology with the sequence of Botryotinia fuckeliana (perfect stage of B. cinerea). The nucleotide sequence has been assigned GenBank Accession No. FJ486270. Pathogenicity tests were performed by spraying leaves of six healthy 6-month-old potted S. rebaudiana plants with a 105 conidia/ml suspension. Six plants sprayed with water only served as controls. Plants were covered with plastic bags for 3 days after inoculation to maintain high relative humidity and were placed in a growth chamber at 20 ± 1°C. The first foliar lesions developed on leaves 4 days after inoculation, whereas control plants remained healthy. B. cinerea was consistently reisolated from these lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of B. cinerea on S. rebaudiana in Italy. The disease has been reported in Ukraine (3) and more recently in Japan (4). The economic importance of this disease is at the moment limited. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) H. L. Barnett and B. B. Hunter. Illustrated Genera of Imperfect Fungi. Burgess Publishing Company, Minneapolis, MN, 1972. (3) J. Takeuch and H. Horie. Annu. Rep. Kanto-Tosan Plant Prot. Soc. 53:87, 2006. (4) V. F. Zubenko et al. Zash. Rast. 18, 1991.

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First Report of Botrytis Blight Caused by Botrytis cinerea on Flowering Dogwood (Cornus florida) in Italy

Plant Disease ◽

10.1094/pdis-93-5-0549c ◽

2009 ◽

Vol 93 (5) ◽

pp. 549-549 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Botrytis Cinerea ◽

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Deciduous Tree ◽

Fluorescent Light ◽

Cornus Florida ◽

First Report ◽

Flowering Dogwood ◽

Botryotinia Fuckeliana

Flowering dogwood (Cornus florida L., Cornaceae), is a small deciduous tree whose showy inflorescences, clusters of bright red fruits and red and purple leaves in autumn, make it a much appreciated ornamental. In June of 2008, severe outbreaks of a previously unknown blight were observed in several private gardens near Biella (northern Italy) after a rainy spring with temperatures that ranged from 7 to 25°C. Dogwoods in the gardens were 10 to 15 years old, and the disease was observed on 20 to 30% of 30 trees. First symptoms consisted of blighted leaves and then shoot dieback. As the disease progressed, entire leaves became necrotic and were covered by an abundant, soft, gray, sporulating mycelium. Tissue fragments of 1 mm2 were excised from the margins of the lesions, immersed in a solution containing 1% sodium hypochlorite, plated on potato dextrose agar (PDA) medium, and incubated under constant fluorescent light at 22 ± 1°C for 10 days. Conidiophores were slender and branched with enlarged apical cells bearing smooth, ash-colored conidia 6 to 10 × 6 to 8 (average 9 × 7) μm on short sterigmata. A few, black, irregularly shaped sclerotia (3 to 5 × 1 to 2 mm) were produced on PDA plates incubated for 20 days at 8 ± 1°C. These morphological characteristics identified the fungus as Botrytis cinerea (2). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 491-bp segment showed a 100% homology with the sequence of Botryotinia fuckeliana (perfect stage of B. cinerea). The nucleotide sequence has been assigned GenBank Accession No. FJ 572049. Pathogenicity tests were performed twice by placing mycelium fragments (1 cm2) of PDA cultures on 30 leaves of 6 healthy 3-year-old potted C. florida plants. Six plants inoculated with PDA alone served as controls. Plants were maintained outdoors at temperatures ranging between 15 and 22°C, spraying leaves with water three times a day. The first foliar lesions similar to those observed in the gardens developed 10 days after inoculation on 23 inoculated leaves, whereas control plants remained healthy. B. cinerea was consistently reisolated from these lesions. To our knowledge, this is the first report of the presence of B. cinerea on C. florida in Italy. The disease has been reported in the United States (4) as well as in Japan (3). At this time, the economic importance of Botrytis blight to flowering dogwoods in Italy is undetermined. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) H. L. Barnett and B. B. Hunter. Illustrated Genera of Imperfect Fungi. Burgess Publishing Company, Minneapolis, MN, 1972. (3) T. Kobayashi. Ann. Phytopathol. Soc. Jpn. 50:528, 1984. (4) C. Westcott. Plants Gard. 7:136, 1951.

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