First Report of Sclerotinia sclerotiorum on Campanula carpatica and Schizanthus × wisetonensis in Italy

The production of potted ornamental plants is very important in the Albenga Region of northern Italy, where plants are grown for export to central and northern Europe. During fall 2000 and spring 2001, sudden wilt of tussock bellflower (Campanula carpatica Jacq.) and butterfly flower (Schizanthus × wisetonensis Hort.) was observed on potted plants in a commercial greenhouse. Initial symptoms included stem necrosis at the soil line and yellowing and tan discoloration of the lower leaves. As stem necrosis progressed, infected plants growing in a peat, bark compost, and clay mixture (70-20-10) wilted and died. Necrotic tissues were covered with whitish mycelia that produced dark, spherical (2 to 6 mm diameter) sclerotia. Sclerotinia sclerotiorum was consistently recovered from symptomatic stem pieces of both plants disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar amended with streptomycin sulphate at 100 ppm. Pathogenicity of three isolates obtained from each crop was confirmed by inoculating 45- to 60-day-old C. carpatica and Schizanthus × wisetonensis plants grown in containers (14 cm diameter). Inoculum that consisted of wheat kernels infested with mycelia and sclerotia of each isolate was placed on the soil surface around the base of previously artificially wounded or nonwounded plants. Noninoculated plants served as controls. All plants were maintained outdoors where temperatures ranged between 8 and 15°C. Inoculated plants developed symptoms of leaf yellowing, followed by wilt, within 7 to 10 days, while control plants remained symptomless. White mycelia and sclerotia developed on infected tissues and S. sclerotiorum was reisolated from inoculated plants. To our knowledge, this is the first report of stem blight of C. carpatica and Schizanthus × wisetonensis caused by S. sclerotiorum in Italy. The disease was previously observed on C. carpatica in Great Britain (2) and on Schizanthus sp. in the United States (1). 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) J. Rees. Welsh J. Agric. 1:188, 1925.

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First Report of White Mold Caused by Sclerotinia sclerotiorum on Rosmarinus officinalis ‘Prostratus’ in Italy

Plant Disease ◽

10.1094/pd-89-1016a ◽

2005 ◽

Vol 89 (9) ◽

pp. 1016-1016

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

Sclerotinia Sclerotiorum ◽

Soil Surface ◽

The United States ◽

Rosmarinus Officinalis ◽

White Mold ◽

First Report ◽

Potted Plants ◽

Initial Symptoms ◽

Stem Necrosis ◽

Rosmarinus Officinalis L

Rosmarinus officinalis L. ‘Prostratus’ is an evergreen shrub that is native to the Mediterranean Region in southern Europe and grown as a potted plant in Italy. This cultivar is widely used in gardens and landscapes. During the winter of 2002, extensive chlorosis was observed on 8-month-old potted plants of R. officinalis L. ‘Prostratus’ grown outdoors in commercial farms near Albenga in northern Italy. Initial symptoms included stem necrosis at the soil level and darkening of leaves. As stem necrosis progressed, infected plants wilted and died. Wilt, characterized by the presence of soft and watery tissues, occurred within a few days on young plants. The disease infected 15% of the plants. Necrotic tissues became covered with a whitish mycelium that produced dark sclerotia. The diseased stem tissue was surface sterilized for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 ppm of streptomycin sulfate. Sclerotinia sclerotiorum (1) was consistently recovered from infected stem pieces. Sclerotia observed on infected plants measured 0.30 to 3.33 × 1.00 to 4.23 mm (average 1.31 × 1.88 mm). Sclerotia produced on PDA measured 0.09 to 3.08 × 0.38 to 4.05 mm (average 1.94 × 2.43 mm). Pathogenicity of three isolates obtained from infected plants and used in mixture was confirmed by inoculating 60-day-old plants grown in 14-cm-diameter pots in a glasshouse. Inoculum (wheat kernels infested with mycelium and sclerotia) for each isolate was placed on the soil surface around the base of each plant. Pathogenicity tests included three inoculated plants grown in separate pots per isolate. Three noninoculated plants grown in three pots served as controls. The inoculation trial was conducted twice. All plants were kept at temperatures ranging between 8 and 34°C (average 18°C) and watered as needed. Plants were covered with plastic for 96 h after inoculation to increase the moisture level. All inoculated plants developed symptoms of leaf yellowing within 30 days, soon followed by the appearance of white mycelium and sclerotia, and eventual wilt. Control plants remained symptomless. S. sclerotiorum was reisolated from the stems of inoculated plants. To our knowledge, this is the first report of white mold of R. officinalis L. ‘Prostratus’ in Italy and in Europe. S. sclerotiorum has been previously reported on R. officinalis in India (2) and the United States (3). The economic importance of this disease for the crop in Italy can be considered low at the moment. References: (1) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 32:75, 1949. (2) L. Mohan. Indian Phytopathol. 47:443, 1994. (3) M. L. Putnam. Plant Pathol. 53:252, 2004.

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First Report of White Mold Caused by Sclerotinia sclerotiorum on Persian Buttercup (Ranunculus asiaticus) in Italy

Plant Disease ◽

10.1094/pdis.2003.87.9.1151a ◽

2003 ◽

Vol 87 (9) ◽

pp. 1151-1151 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

United States ◽

Sclerotinia Sclerotiorum ◽

Soil Surface ◽

The United States ◽

First Report ◽

Inoculation Trial ◽

Initial Symptoms ◽

Leaf Yellowing ◽

Ranunculus Asiaticus ◽

Stem Necrosis

Persian buttercup (Ranunculus asiaticus L.) is grown in the Albenga Region of northern Italy for cut flower production and exportation to central and northern Europe. During the winter of 2003, sudden wilt was observed in commercial plantings of R. asiaticus. Initial symptoms included stem necrosis at the soil level and yellowing and tan discoloration of leaves. As stem necrosis progressed, infected plants wilted and died. Wilt occurred within a few days on young plants and was characterized by the presence of soft and watery tissues. Necrotic tissues became covered with whitish mycelium that produced dark, spherical sclerotia (1 to 4 mm in diameter). Sclerotinia sclerotiorum (Lib.) de Bary (1) was consistently recovered from infected stem pieces of R. asiaticus that were disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 ppm of streptomycin sulfate. Pathogenicity of three isolates obtained from infected plants of persian buttercup was confirmed by inoculating 30-day-old plants grown in containers. Inoculum that consisted of wheat kernels infested with mycelium and sclerotia of each isolate was placed on the soil surface around the base of each of five plants. Noninoculated plants served as controls. The inoculation trial was repeated once. All plants were kept at temperatures ranging between 8 and 22°C and watered as needed. Inoculated plants developed symptoms of leaf yellowing followed by wilt within 15 days, while control plants remained symptomless. White mycelium and sclerotia developed on infected tissues, and S. sclerotiorum was reisolated from inoculated plants. S. sclerotiorum has been previously reported on R. asiaticus in the United States (2) and Japan (3). To our knowledge, this is the first report of wilt of R. asiaticus caused by S. sclerotiorum in Italy and Europe. References: (1) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 1949. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (3) T. Urushibara et al. Annu. Rep. Kanto-Tosan Plant Prot. Serv. 46:61, 1999.

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First Report of Sclerotinia sclerotiorum on Calendula officinalis in Italy

Plant Disease ◽

10.1094/pdis.2001.85.4.446c ◽

2001 ◽

Vol 85 (4) ◽

pp. 446-446

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

United States ◽

Sclerotinia Sclerotiorum ◽

Soil Surface ◽

The United States ◽

Calendula Officinalis ◽

First Report ◽

Initial Symptoms ◽

Leaf Yellowing ◽

Stem Necrosis ◽

Pot Marigold

Pot marigold (Calendula officinalis) has recently become popular as a potted ornamental plant in Italy. During the spring 1999, a sudden wilt of 120 day-old plants was observed in the Albenga region of Northern Italy, an area of intensive floriculture production. Initial symptoms included stem necrosis at the soil line and yellowing and tan discoloration of leaves. As stem necrosis progressed, infected plants wilted and died. Necrotic tissues resulted, covered with whitish mycelium that produced dark, spherical (2- to 6-mm diameter) sclerotia. Sclerotinia sclerotiorum was consistently recovered from symptomatic stem sections surface disinfested 1 min in 1% NaOCl and plated on potato dextrose agar (PDA), amended with 100 ppm streptomycin sulfate. Pathogenicity of three isolates was confirmed by inoculating 90-day-old pot marigold plants grown in containers. Inoculum that consisted of wheat kernels infested with mycelium and sclerotia was placed on the soil surface around the base of previously wounded or non-wounded plants. Non-inoculated plants served as controls. All plants were kept outdoors where temperatures ranged between 8 and 16°C, under 50% shade and were maintained moist. Inoculated plants developed symptoms of leaf yellowing, followed by wilt within 7 days, while control plants remained symptomless. Sclerotia developed on infected tissues and S. sclerotiorum was reisolated from inoculated plants. This is the first report of stem blight of C. officinalis caused by S. sclerotiorum in Europe. The disease was previously observed in the United States (1). 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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First Report of White Mold Caused by Sclerotinia sclerotiorum on Thymus × citriodorus in Italy

Plant Disease ◽

10.1094/pdis.2004.88.9.1044a ◽

2004 ◽

Vol 88 (9) ◽

pp. 1044-1044

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

Sclerotinia Sclerotiorum ◽

Soil Surface ◽

White Mold ◽

First Report ◽

Potted Plants ◽

Inoculation Trial ◽

Initial Symptoms ◽

Commercial Farms ◽

Stem Necrosis ◽

White Mycelium

Thymus × citriodorus is well known for the citrus aroma released by its leaves and is grown as a potted plant in northern Italy. This species is widely used in gardens and landscapes and for culinary purposes. In the Liguria Region alone, 1.5 million plants are grown. In the winter of 2002, extensive chlorosis was observed on potted plants of Thymus × citriodorus cv. Silver Queen grown outdoors on commercial farms near Albenga. Initial symptoms included stem necrosis at the soil level and darkening of leaves. As stem necrosis progressed, infected plants wilted and died. Wilt, characterized by the presence of soft and watery tissues, occurred within a few days on young plants. Necrotic tissues became covered with whitish mycelium that produced dark sclerotia. Sclerotinia sclerotiorum (Lib.) de Bary (1) was consistently recovered from infected stem pieces of Thymus × citriodorus. The diseased stem tissue was disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 ppm of streptomycin sulfate. Sclerotia produced on PDA were ellipsoid and measured 5.2 to 4.4 × 2.1 to 1.5 mm (average 3.5 × 3.0 mm). Pathogenicity of three isolates obtained from infected plants was confirmed by inoculating 30-day-old plants grown in 14-cm-diameter pots in a screenhouse. Inoculum that consisted of wheat kernels infested with mycelium and sclerotia of each isolate was placed on the soil surface around the base of each of 10 plants. Noninoculated plants served as controls. The inoculation trial was repeated once. All plants were kept at temperatures ranging between 5 and 26°C and watered as needed. Inoculated plants developed symptoms of leaf yellowing within 13 days, soon followed by the appearance of white mycelium, and eventually wilted. Control plants remained symptomless. White mycelium and sclerotia developed on infected tissues and S. sclerotiorum was reisolated from inoculated plants. To our knowledge, this is the first report of white mold of Thymus × citriodorus caused by S. sclerotiorum. The economic importance of this disease for the crop can be considered low. Reference: (1) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 1949.

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First Report of Stem and Crown Rot of Garbanzo Caused by Sclerotinia minor in the United States and by Sclerotinia sclerotiorum in Arizona

Plant Disease ◽

10.1094/pdis.2000.84.11.1250a ◽

2000 ◽

Vol 84 (11) ◽

pp. 1250-1250 ◽

Cited By ~ 4

Author(s):

M. E. Matheron ◽

M. Porchas

Keyword(s):

United States ◽

Cicer Arietinum ◽

Soil Surface ◽

The United States ◽

Crown Rot ◽

Sclerotinia Minor ◽

First Report ◽

Initial Symptoms ◽

Stem Necrosis ◽

White Mycelium

In March 2000, plants began to die within two garbanzo (Cicer arietinum L.) fields about 48 km apart in southwestern Arizona. Initial symptoms included wilting of leaves and stem necrosis on individual branches, followed by entire plant necrosis and death. White mycelium was present on plant stems near the soil surface. In one field, small black irregularly shaped sclerotia (1 mm in diameter) were present on the infected stem surface along with the white mycelia, whereas in the other field the associated sclerotia were of similar shape but larger (5 to 6 mm in diameter). Isolation from diseased garbanzo stem tissue from the respective fields yielded Sclerotinia minor, which produced small sclerotia when cultured on potato-dextrose agar and S. sclerotiorum, which produced the typical larger sclerotia of this species. To fulfill Koch's postulates, healthy plants and associated soil from a garbanzo field with no evidence of infection by Sclerotinia were removed with a shovel and transferred into a series of 8-liter plastic pots. After transporting back to the laboratory, some of the plants were inoculated by wounding stems with a 5-mm-diameter cork borer, placing an agar disk containing either S. minor or S. sclerotiorum onto each wound, securing the agar disk to the stem with plastic tape, then incubating the plants at 25°C for 7 days. Control plants were treated similarly except that agar disks did not contain Sclerotinia. Stems inoculated with S. minor or S. sclerotiorum developed symptoms of wilt and necrosis, including the appearance of white mycelium and sclerotia on the stem surface, whereas control plants remained healthy. S. minor or S. sclerotiorum were recovered from garbanzo stems inoculated with the respective species of the pathogen. Sclerotinia leaf drop, which can be caused by S. minor or S. sclerotiorum on lettuce in Arizona, had been observed in both fields previously. Garbanzo fields in Arizona usually are watered by furrow irrigation. Disease was most severe in areas of the garbanzo fields that were heavily irrigated with resultant wetting of tops of plant beds. Proper management of irrigation water and avoidance of establishing a garbanzo planting in fields following lettuce could help reduce future losses from these pathogens. S. minor previously had been reported as a pathogen on Cicer arietinum from the island of Sardinia (2); however, this is apparently the first report of the pathogen on garbanzo other than in Sardinia. S. sclerotiorum has been reported as a pathogen on this host in several countries including the United States (California) (1) but not previously in the state of Arizona. References: (1) I. W. Buddenhagen, F. Workneh, and N. A. Bosque-Perez. Int. Chickpea Newsl. 19:9–10, 1988. (2) F. Marras. Rev. Appl. Mycol. 43:112, 1964.

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First Report of Sclerotinia sclerotiorum on Gazania sp. Hybrid in Italy

Plant Disease ◽

10.1094/pdis.2001.85.11.1207d ◽

2001 ◽

Vol 85 (11) ◽

pp. 1207-1207

Author(s):

A. Garibaldi ◽

A. Minuto ◽

G. Gilardi ◽

M. L. Gullino

Keyword(s):

Sclerotinia Sclerotiorum ◽

Soil Surface ◽

Soft Rot ◽

The United States ◽

Crown Rot ◽

First Report ◽

Initial Symptoms ◽

Leaf Yellowing ◽

Stem Necrosis ◽

Wheat Kernels

Gazania sp. hybrid is produced in pots in the Albenga Region of northern Italy for export to central and northern Europe. During fall 2000 to spring 2001, sudden wilt was observed in commercial plantings of this ornamental. Initial symptoms included stem necrosis at the soil level and yellowing and tan discoloration of leaves. As stem necrosis progressed, infected plants wilted and died. Wilt followed by soft rot occurred within a few days on young plants after the first leaf symptoms. Necrotic tissues became covered with white mycelia that produced dark, spherical (2 to 6 mm diameter) sclerotia. Sclerotinia sclerotiorum was consistently recovered from infected stem pieces of Gazania disinfested for 1 min in 1% NaOCl, plated on potato dextrose agar amended with streptomycin sulfate at 100 mg/liter. Pathogenicity of three fungal isolates was confirmed by inoculating 45- to 60-day-old plants grown in containers (14 cm diameter). Inoculum that consisted of wheat kernels infested with mycelium and sclerotia of each isolate was placed on the soil surface around the base of each plant. Noninoculated plants served as controls. All plants were maintained outdoors where temperatures ranged between 8 and 15°C. Inoculated plants developed symptoms of leaf yellowing, followed by wilt, within 7 to 10 days, while control plants remained symptomless. White mycelia and sclerotia developed on infected tissues, and S. sclerotiorum was reisolated from inoculated plants. To our knowledge, this is the first report of wilt of Gazania sp. hybrid caused by S. sclerotiorum in Italy. A crown rot of Gazania caused by S. sclerotiorum has been reported from California in the United States(1). Reference: (1) V. M. Muir and A. H. McCain. Calif. Plant Pathol. 16:1, 1973.

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First Report of Sclerotium rolfsii on Jerusalem Cherry (Solanum pseudocapsicum) in Europe

Plant Disease ◽

10.1094/pdis.2000.84.9.1048b ◽

2000 ◽

Vol 84 (9) ◽

pp. 1048-1048

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

United States ◽

Sclerotium Rolfsii ◽

Soil Surface ◽

The United States ◽

Northern Italy ◽

Ornamental Plant ◽

Potato Dextrose Agar ◽

First Report ◽

Initial Symptoms ◽

Stem Necrosis

Jerusalem cherry (Solanum pseudocapsicum) has recently become popular as a potted ornamental plant in Italy. During the summer of 1999, a sudden wilt of 60-day-old plants was observed in the Albenga region (Northern Italy), an area of intensive floriculture. Initial symptoms included stem necrosis at the soil line and yellowing and tan discoloration of leaves. As stem necrosis progressed, infected plants wilted and died. Necrotic tissues were covered with whitish mycelium that differentiated into reddish brown, spherical (1 to 2 mm diameter) sclerotia. Sclerotium rolfsii was consistently recovered from the surface of symptomatic stem sections that were disinfected for 1 min in 1% NaOCl and then plated on potato-dextrose agar (PDA) amended with 100 ppm streptomycin sulfate. Pathogenicity of three S. rolfsii isolates was confirmed by inoculating 90-day-old S. pseudocapsicum plants grown in pots. Inoculum consisted of mycelium and sclerotia of the pathogen placed on the soil surface around the base of each plant. Noninoculated plants served as controls. All plants were kept in a growth chamber at 18 to 28°C and RH > 85%. Inoculated plants developed symptoms within 7 days, while control plants remained symptomless. Sclerotia developed on infected tissues and S. rolfsii was reisolated from symptomatic tissues. The disease has been observed in the United States (1), but this is the first report of stem blight of S. pseudocapsicum caused by S. rolfsii in Europe. Reference: (1) S. A. Alfieri, Jr., K. R. Langdon, C. Wehlburg, and J. W. Kimbrough, J. W. Index Plant Dis. Florida Bull. 11:215, 1984.

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First Report of Sclerotinia sclerotiorum on Calceolaria integrifolia in Italy

Plant Disease ◽

10.1094/pdis-92-7-1133c ◽

2008 ◽

Vol 92 (7) ◽

pp. 1133-1133

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

Sclerotinia Sclerotiorum ◽

Soil Surface ◽

Its Region ◽

The United States ◽

First Report ◽

Potted Plants ◽

Initial Symptoms ◽

Mycelial Plug ◽

Blastn Analysis ◽

White Mycelium

Calceolaria integrifolia L. is an ornamental species grown as a potted plant in Liguria, northern Italy. In the winter of 2006, extensive chlorosis was observed on approximately 10% of the 10-month-old potted plants in a commercial greenhouse. Initial symptoms included stem necrosis and darkening of leaves. As stem and foliar necrosis progressed, infected plants wilted and died. Wilt occurred on young plants within a few days after the initial appearance of symptoms. Infected plants were characterized by the presence of soft, watery tissues that became covered with white mycelium and dark sclerotia. The diseased stem tissue was surface sterilized for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 mg/liter of streptomycin sulfate. Sclerotinia sclerotiorum (Lib.) de Bary (3) was consistently recovered from infected stem pieces. Sclerotia observed on infected plants measured 0.7 to 1.0 × 2.8 to 4.4 mm (average 1.6 to 2.1 mm). Sclerotia produced on PDA measured 1.0 to 1.1 × 3.0 to 4.2 mm (average 1.7 to 2.3 mm). The internal transcribed spacer (ITS) region of rDNA was amplified with primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 522-bp amplicon resulted in 100% homology with the sequence of S. sclerotiorum. The nucleotide sequence has been assigned GenBank Accession No. EU 627004. Pathogenicity of two isolates obtained from infected plants was confirmed by inoculating 10 120-day-old plants grown in individual 14-cm-diameter pots maintained in a greenhouse under partial shade. Inoculum consisted of 1 cm2 of mycelial plugs excised from a 10-day-old PDA culture of each isolate. Plants were inoculated by placing a mycelial plug on the soil surface around the base of each plant. Ten plants were inoculated per isolate and an equal number of noninoculated plants served as controls. The trial was repeated once. All plants were kept at temperatures ranging between 8 and 17°C (average 12.5°C) and watered as needed. All inoculated plants developed leaf yellowing within 8 days after inoculation, soon followed by the appearance of white mycelium and sclerotia, and then by wilt. Control plants remained symptomless. S. sclerotiorum was reisolated from the stems of inoculated plants. S. sclerotiorum was reported previously on a Calceolaria sp. in the United States (2). To our knowledge, this is the first report of white mold on C. integrifolia in Italy. The economic importance of this disease is currently limited. References (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) Anonymous. USDA Agric. Handb. 165:441, 1960. (3) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift 75, 1949.

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First Report of Sclerotinia Blight Caused by Sclerotinia sclerotiorum on Petunia × hybrida in Italy

Plant Disease ◽

10.1094/pdis-93-12-1353a ◽

2009 ◽

Vol 93 (12) ◽

pp. 1353-1353 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

P. Pensa ◽

M. L. Gullino

Keyword(s):

United States ◽

Relative Humidity ◽

Sclerotinia Sclerotiorum ◽

Petunia Hybrida ◽

Ornamental Plants ◽

Its Region ◽

The United States ◽

First Report ◽

Potted Plants ◽

Sclerotinia Blight

Petunia × hybrida (Solanaceae) includes several hybrids that are grown as ornamental plants and are very much appreciated for their long-lasting flowering period. During the spring of 2009, extensive wilting was observed on 2-month-old potted plants of Petunia × hybrida cv. Sanguna Lilac Vein grown in a commercial glasshouse near Albenga (northern Italy). First symptoms included stem necrosis and darkening and withering of leaves. Wilt occurred a few days after the appearance of the first symptoms. Infected plants were characterized by the presence of soft, watery tissues. In the presence of high relative humidity, lesions became covered with a whitish mycelium and irregular, dark gray sclerotia (3.0 to 6.5 × 2.0 to 5.0 mm, average 4.8 × 3.3 mm) were produced on the mycelium. Diseased tissue was surface sterilized for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 mg/l of streptomycin sulfate. Sclerotinia sclerotiorum (Lib.) de Bary (3) was consistently recovered from infected stem pieces. Sclerotia produced on PDA measured 2.0 to 6.0 × 1.5 to 5.0 mm (average 3.9 × 3.1) mm. The internal transcribed spacer (ITS) region of rDNA was amplified with primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 548-bp segment showed a 100% homology with the sequence of S. sclerotiorum. The nucleotide sequence has been assigned GenBank Accession No. GQ375746. Pathogenicity of one isolate obtained from sclerotia of infected plants was confirmed by inoculating three 90-day-old plants belonging to cv. Sanguna Lilac Vein transplanted in 22-cm-diameter pots in a glasshouse in a sphagnum peat/pomix/pine bark/clay (50:20:20:10) mix. Inoculum that consisted of 2 g/liter of substrate of wheat kernels infested with mycelium and sclerotia was placed in the soil and around the base of each plant. Three noninoculated plants served as controls. Plants were maintained in greenhouse at temperatures ranging between 22 and 26°C and relative humidity >90%. The inoculation trial was carried out twice. All inoculated plants developed leaf yellowing by 20 days after soil infestation. White, cottony mycelium and dark sclerotia developed on stems and at the base of all inoculated plants. Eventually, infected plants wilted. Control plants remained symptomless. S. sclerotiorum was reisolated from the stems of inoculated plants. To our knowledge, this is the first report of S. sclerotiorum on Petunia × hybrida in Italy. The disease has been previously reported on Petunia × hybrida in Bermuda (2) and the United States (4). References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) R. M. Brien. N.Z. J. Sci. Tech., A, 24, 62, 1942. (3) N. F. Buchwald. Kongl. Veterisk Landb. Aarssk. 75, 1949. (4) 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 Sclerotinia Stem Rot and Watery Soft Rot Caused by Sclerotinia sclerotiorum on Sand Rocket (Diplotaxis tenuifolia) in Italy

Plant Disease ◽

10.1094/pd-89-1241c ◽

2005 ◽

Vol 89 (11) ◽

pp. 1241-1241 ◽

Cited By ~ 4

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

Relative Humidity ◽

Sclerotinia Sclerotiorum ◽

Severe Disease ◽

Soil Surface ◽

Soft Rot ◽

Sclerotinia Stem Rot ◽

First Report ◽

Initial Symptoms ◽

Stem Necrosis ◽

White Mycelium

Several species of Diplotaxis (D. tenuifolia, D. erucoides, and D. muralis), known as wild or sand rocket, are widely cultivated in Italy. Rocket is used in Mediterranean cuisine as salad, a component of packaged salad products, and as a garnish for food. In winter 2003, a severe disease was observed on D. tenuifolia grown in unheated glasshouses on commercial farms near Albenga in northern Italy. Initial symptoms included stem necrosis at the soil level and darkening of leaves. As stem necrosis progressed, infected plants wilted and died. Wilt, characterized by the presence of soft and watery tissues, occurred within a few days on young plants. The disease was extremely severe in the presence of high relative humidity and mild temperature (15°C). Necrotic tissues became covered with white mycelium that produced dark sclerotia. Diseased stem tissue was disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 ppm streptomycin sulfate. Sclerotinia sclerotiorum (1) was consistently recovered from infected stem pieces. Sclerotia observed on infected plants measured 1.23 to 3.00 × 1.40 to 5.38 mm (average 2.10 × 2.85 mm). Sclerotia produced on PDA measured 1.00 to 4.28 × 1.00 to 6.01 mm (average 2.38 × 3.23 mm). Pathogenicity of three isolates obtained from infected plants was confirmed by inoculating 30-day-old plants of D. tenuifolia grown in 18-cm-diameter pots in a glasshouse. Inoculum, 2 g per pot of wheat kernels infested with mycelium and sclerotia of each isolate, was placed on the soil surface around the base of each plant. Three replicates of five pots each were used per isolate. Noninoculated plants served as controls. The inoculation trial was repeated once. All plants were kept at temperatures ranging between 10 and 26°C (average 15°C) with an average relative humidity of 80% and were watered as needed. Inoculated plants developed symptoms of leaf yellowing within 12 days, soon followed by the appearance of white mycelium and sclerotia, and eventually wilted. Control plants remained symptomless. S. sclerotiorum was reisolated from inoculated plants. To our knowledge, this is the first report of infection of D. tenuifolia by S. sclerotiorum in Italy as well as worldwide. The disease currently has been observed in the Liguria Region but not yet in other areas where sand rocket is cultivated. The economic importance of this disease for the crop can be considered medium at the moment, but is expected to increase in the future. Reference: (1) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 75, 1949.

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