First Report of White Mold Caused by Sclerotinia sclerotiorum on Blue Marguerite (Felicia amelloides) in Italy

Felicia amelloides (Asteraceae family), also known as blue marguerite, is cultivated as a potted plant in Italy and increasingly used for ornamental purposes. In winter 2002, plants grown outdoors in 14-cm-diameter pots (2 liters) in commercial farms near Albenga (northern Italy) showed leaf yellowing. At the soil level, soft and watery tissues covered with whitish mycelium were evident. Later, dark brown sclerotia differentiated from the mycelium. As necrosis progressed, infected plants wilted and died. Sclerotinia sclerotiorum (1) was consistently recovered from infected stem pieces of F. amelloides that were 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 1.3 to 6.1 × 1.1 to 3.3 mm (average 2.9 × 2.3 mm) (2). Pathogenicity of three isolates (used as a mixture and obtained from infected plants from the same farm) was confirmed by inoculating 90-day-old plants grown in 14-cm-diameter pots. 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 20 plants. Ten noninoculated plants served as controls. The inoculation trial was repeated. All plants were kept outdoors at temperatures ranging between 5 and 26°C and watered as needed. All inoculated plants developed symptoms of leaf yellowing, followed by the appearance of white mycelium within 15 days, and then 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 F. amelloides caused by S. sclerotiorum in Italy as well as elsewhere in the world. References: (1) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 32:75, 1949. (2) C. M. Messiaen et al. Les Maladies des Plantes Maraichères. INRA, Paris, 1991.

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First Report of White Mold Caused by Sclerotinia sclerotiorum on Hutchinsia alpina in Italy

Plant Disease ◽

10.1094/pdis.2004.88.9.1045a ◽

2004 ◽

Vol 88 (9) ◽

pp. 1045-1045

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

Sclerotinia Sclerotiorum ◽

Soil Surface ◽

Planting Density ◽

White Mold ◽

First Report ◽

Inoculation Trial ◽

Leaf Yellowing ◽

Commercial Farms ◽

White Mycelium ◽

Wheat Kernels

Hutchinsia alpina (Chamois cress), a plant belonging to the Brassicaceae family, is cultivated as a potted ornamental plant in Italy. In the winter of 2002, leaves and stems of plants grown in pots (14-cm diameter) in commercial farms near Albenga (northern Italy) developed soft and watery tissues covered with whitish mycelium at the soil line. As necrosis progressed, infected plants wilted and died. Dark sclerotia developed on infected tissues. Because of high planting density, the infection spread very rapidly. Sclerotinia sclerotiorum was consistently recovered from infected stem pieces of H. alpina disinfested 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 1.3 to 9.3 × 1.3 to 4.5 mm (average 3.9 × 2.8 mm) (1). Pathogenicity of three isolates obtained from infected plants grown in a single greenhouse was confirmed by inoculating 90-day-old plants grown in pots (14 cm). Inoculum that consisted of wheat kernels infested with mycelium and sclerotia of each isolate were placed on the soil surface around the base of each of 10 plants. Plants treated with plain wheat kernels 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, followed by the appearance of white mycelium within 15 days, and eventually wilted while control plants remained symptomless. White mycelium and sclerotia developed on infected tissues, and S. sclerotiorum was reisolated only from inoculated plants. To our knowledge, this is the first report of white mold on Hutchinsia alpina caused by S. sclerotiorum. Reference: (1) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 1949.

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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 Southern blight Incited by Sclerotium rolfsii on Dichondra repens in Italy

Plant Disease ◽

10.1094/pd-89-0203b ◽

2005 ◽

Vol 89 (2) ◽

pp. 203-203 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

Sclerotium Rolfsii ◽

Soil Surface ◽

The United States ◽

First Report ◽

Southern Blight ◽

Inoculation Trial ◽

Leaf Yellowing ◽

White Mycelium ◽

Wheat Kernels ◽

Reddish Brown Color

Kidney weed (Dichondra repens) is increasingly used for low maintenance turf in Italy, particularly for gardens and parks in areas characterized by mild climate. During September 2003, on the D. repens turf of a private garden located near Imperia (northern Italy), yellow, circular areas as much as 60 cm in diameter appeared with the grass becoming chlorotic and thin. A ring of the patch at its periphery exhibited a reddish brown color and eventually died. An area of green grass remained in the center of the patch. Rings of dead grass enlarged rapidly during hot, humid weather. In the presence of abundant moisture, a white mycelium occurred on the dying grass at the periphery of the ring. White or light-to-dark brown sclerotia (1 to 3 mm in diameter) developed from mycelium on the dead grass. The diseased tissue was disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar amended with 100 mg/l of streptomycin sulphate. Sclerotium rolfsii was consistently isolated from infected plants. Pathogenicity of three isolates obtained from infected plants was confirmed by inoculating healthy D. repens turf (1 m2 plots and three replicates). Inoculum that consisted of wheat kernels infested with mycelium and sclerotia of each isolate was placed on the soil surface. Noninoculated plots served as controls. The inoculation trial was repeated once. Turf was covered with a plastic film for 7 days, kept at temperatures ranging between 22 and 25°C, and watered as needed. Inoculated plants developed symptoms of leaf yellowing within 11 days, soon followed by the appearance of white mycelium and sclerotia, and then eventually wilted. Control plants remained symptomless. Sclerotium rolfsii was re-isolated from inoculated plants. To our knowledge, this is the first report of S. rolfsii on D. repens in Italy. This disease has been reported on kidney weed in several countries such as the United States (3), Brazil (1), and India (2). References: (1) M. Menezes and J. A. A. Lima. Fitossanidade 1:18, 1974. (2) K. Ranganathan and N. Shanmugam. Indian Phytopathol, 27:113, 1974. (3) J. D. Smith et al. Fungal Diseases of Amenity Turf Grasses. E & F.N. Spon, London, 1989.

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First Report of White Mold Caused by Sclerotinia sclerotiorum on Oreganum vulgare and Taraxacum officinale in Italy

Plant Disease ◽

10.1094/pdis-91-10-1360c ◽

2007 ◽

Vol 91 (10) ◽

pp. 1360-1360

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

Sclerotinia Sclerotiorum ◽

Soil Surface ◽

Taraxacum Officinale ◽

White Mold ◽

Economic Losses ◽

Medicinal Uses ◽

First Report ◽

Potted Plants ◽

Mycelial Plug ◽

Commercial Farms

Oreganum vulgare (wild marjoram) and Taraxacum officinale (dandelion) plants with culinary and medicinal uses are grown in the field and as potted plants in Liguria in northern Italy. In the spring of 2006, extensive chlorosis was observed on both crops on commercial farms. Economic losses were low. Symptoms included foliar necrosis and a watery decay of the stem at the soil level. Necrotic tissues became covered with a whitish mycelium that produced dark sclerotia. Eventually, affected plants wilted and died. Samples of diseased stem tissue were 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 (1) was consistently recovered from diseased stem pieces. Sclerotia from infected O. vulgare plants measured 1.8 to 3.4 × 1.8 to 6.1 (average 2.5 to 3.6) mm. Sclerotia from these isolates measured 1.3 to 4.7 × 1.6 to 6.1 (average 2.7 to 3.4) mm on PDA. Sclerotia from infected T. officinale plants measured 1.8 to 3.4 × 1.8 to 6.1 (average 2.5 to 3.6) mm. Sclerotia from these isolates measured 1.7 to 5.2 × 2.0 to 5.7 (average 3.3 to 3.8) mm on PDA. Pathogenicity of three isolates obtained from O. vulgare and three isolates from T. officinale was confirmed on each host. 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. Plants were incubated at 10 to 27°C (average 18°C) and watered as needed. Pathogenicity tests were repeated once. All inoculated plants developed chlorosis within 12 to 18 days, followed by the appearance of white mycelium and sclerotia, and eventually wilt. Control plants remained symptomless. S. sclerotiorum was reisolated from inoculated plants of both hosts. To our knowledge, this is the first report of white mold on O. vulgare in Italy as well as worldwide and the first report of white mold on T. officinale in Italy. S. sclerotiorum is a well known pathogen of T. officinale (2) and its use as a mycoherbicide has been proposed (3). References: (1) N. F. Buchwald. Page 75. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 1949. (2) D. M. McLean. Plant Dis. Rep. 35:162, 1951 (3) G. E. Riddle et al. Weed Sci. 39:109, 1991.

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First Report of White Mold Caused by Sclerotinia sclerotiorum on Common Sage (Salvia officinalis) in Italy

Plant Disease ◽

10.1094/pdis.2004.88.9.1044b ◽

2004 ◽

Vol 88 (9) ◽

pp. 1044-1044

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

Sclerotinia Sclerotiorum ◽

Plant Density ◽

Soil Surface ◽

Salvia Officinalis ◽

White Mold ◽

Rooted Cuttings ◽

First Report ◽

Streptomycin Sulfate ◽

High Plant Density ◽

White Mycelium

Salvia officinalis L. is cultivated as an aromatic ornamental plant in Italy. In the spring of 2003, rooted cuttings grown in containers in commercial farms near Albenga (northern Italy) had soft and watery stem tissue covered with whitish mycelium at the soil level. Leaves and stems showed necrotic areas of irregular shape and size. As necrosis progressed, infected plants wilted and died. Wilt occurred within a few days on young plants. Because of high plant density, the pathogen spread rapidly within and across containers to infect many rooted cuttings. Sclerotinia sclerotiorum (Lib.) de Bary (2) was consistently recovered from infected stem pieces of Salvia officinalis that were 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 1.4 to 4.2 × 1.1 to 2.1 (average 2.1 × 1.5) mm. Pathogenicity of three isolates obtained from infected plants was confirmed by inoculating 30-day-old plants grown in pots (14-cm diameter). Inoculum of each isolate was 14-day-old cultures of mycelium and sclerotia grown on sterile wheat kernels (300 g) and deionized water (320 ml) in a 1-liter flask at 20 to 25°C. Inoculum (10 g) of each isolate was placed on the soil surface around the base of 10 plants. Ten noninoculated plants served as controls. The inoculation trial was repeated once. All plants were kept in a screenhouse at temperatures ranging between 8 and 31°C and watered as needed. Inoculated plants developed symptoms of leaf yellowing, followed by the appearance of white mycelium within 7 days, and eventually wilted within 12 to 15 days. Control plants remained symptomless. White mycelium and sclerotia developed on infected tissues, and S. sclerotiorum was reisolated from inoculated plants on PDA amended with 100 ppm of streptomycin sulfate. To our knowledge, this is the first report of white mold of Salvia officinalis caused by S. sclerotiorum in Italy. The disease has been observed in Canada (1) as well as Tasmania and New Zealand. References: (1) G. J. Bolland and R. Hall. Can. J. Plant Pathol. 16:93, 1994. (2) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 1949.

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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 Southern Blight Caused by Sclerotium rolfsii on Lily in China

Plant Disease ◽

10.1094/pd-91-0109c ◽

2007 ◽

Vol 91 (1) ◽

pp. 109-109 ◽

Cited By ~ 3

Author(s):

X. M. Yang ◽

J. H. Wang ◽

S. P. Qu ◽

L. H. Wang

Keyword(s):

Disease Incidence ◽

Sclerotium Rolfsii ◽

First Report ◽

Southern Blight ◽

Inoculation Trial ◽

Leaf Yellowing ◽

White Mycelium ◽

Bulb Rot ◽

Oriental Lily ◽

Wheat Kernels

Lily (Lilium spp.) is an economically important cut flower cultivated in China. The soilborne fungus, Sclerotium rolfsii, is a major pathogen on many plants. During July 2005, severe basal stem rot and bulb rot symptoms were observed on an oriental lily cultivar (Sorbonne) in some commercial fields in northern Kunming (China). Disease incidence ranged from 20 to 30% across fields. Leaves of infected plants were chlorotic initially. As the disease progressed, stems and bulbs rotted and plants wilted. In the presence of abundant moisture, a white mycelium occurred on infected tissues. White or light-to-dark brown sclerotia (1 to 3 mm in diameter) developed from mycelium. Fungal isolates from infected bulbs grown on potato dextrose agar (PDA) produced white mycelia and 1- to 2-mm diameter dark brown sclerotia. Sclerotia were nearly round with smooth surfaces and distributed over the entire colony. Isolates were identified as S. rolfsii on the basis of mycelial characteristics and color, size, and distribution of sclerotia. Pathogenicity was tested in the greenhouse on oriental lily cv. Sorbonne grown in pots (1 plant per pot, five replicates). Inoculum that consisted of 1 g per pot of wheat kernels infested with mycelium and sclerotia was placed at the base of each inoculated plant. Five noninoculated plants served as controls. The inoculation trial was repeated once. After inoculation, all plants were covered with a polyethylene bag for 72 h and kept at temperatures ranging between 25 and 27°C. Inoculated plants developed symptoms of leaf yellowing within 12 days, soon followed by the appearance of white mycelium and sclerotia, and then eventually wilted. Control plants remained symptomless. S. rolfsii was reisolated from inoculated plants. To our knowledge, this is the first report of southern blight caused by S. rolfsii on lily in China. Infection of lily bulbs by S. rolfsii may cause losses in production fields in China, and the presence of infected bulbs may also interfere with bulb shipment.

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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 Argyranthemum frutescens in Italy

Plant Disease ◽

10.1094/pdis-92-8-1250c ◽

2008 ◽

Vol 92 (8) ◽

pp. 1250-1250 ◽

Cited By ~ 3

Author(s):

A. Garibaldi ◽

P. Pensa ◽

M. L. Gullino

Keyword(s):

Sclerotinia Sclerotiorum ◽

Soil Surface ◽

Its Region ◽

Northern Italy ◽

First Report ◽

Potted Plants ◽

Inoculation Trial ◽

Leaf Yellowing ◽

Stem Necrosis ◽

The Moment

Paris daisy (Argyranthemum frutescens (L.) Sch. Bip.) is an economically important crop on the Riviera Ligure (northern Italy), where approximately 10 million plants per year are produced for export. In the winter of 2007, extensive wilting was observed on 5-month-old potted plants of A. frutescens grown in a commercial greenhouse near Albenga. First symptoms included stem necrosis, darkening and withering of leaves, and wilting of young buds. As stem and foliar necrosis progressed, infected plants wilted and died. Wilt occurred a few days after the appearance of the first symptoms. Infected plants were characterized by the presence of soft, watery tissues. Lesions became covered with a whitish mycelium and dark sclerotia were produced on the mycelium. Diseased stem tissue was surface sterilized for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 mg/l streptomycin sulfate. Sclerotinia sclerotiorum (Lib.) de Bary (2) was consistently recovered from infected stem pieces. Sclerotia produced on PDA measured 1.4 to 5.2 × 2.3 to 6.7 (average 3.3 to 4.2) mm. The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and then sequenced. BLAST analysis (1) of the 531-bp segment showed a 100% homology with the sequence of S. sclerotiorum. The nucleotide sequence has been assigned GenBank Accession No. EU 556701. Pathogenicity of two isolates obtained from infected plants was confirmed by inoculating 10 90-day-old plants for each isolate. Plants were grown singly in 18-cm-diameter pots maintained in a greenhouse under shade and were regularly irrigated and fertilized. Mycelium plugs 1 cm2 were excised from a 10-day-old PDA culture of both isolates and placed on the soil surface around the base of each plant. Ten noninoculated plants served as controls. Plants were maintained in a greenhouse under shade at temperatures ranging between 6 and 22°C (average 18°C) and relative humidity at >90%. The inoculation trial was carried out twice. All inoculated plants developed leaf yellowing by 22 days after inoculation. White, cottony mycelium and black 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 causing white mold on A. frutescens in Italy as well as worldwide. The economic importance of this disease can be considered limited at the moment. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) N. F. Buchwald. Kongl. Veterisk Landb. Aarssk. 75, 1949.

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First Report of White Mold Caused by Sclerotinia sclerotiorum on Iberis sempervirens in Italy

Plant Disease ◽

10.1094/pdis-91-4-0464c ◽

2007 ◽

Vol 91 (4) ◽

pp. 464-464

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

Sclerotinia Sclerotiorum ◽

Disease Incidence ◽

Soil Surface ◽

Northern Italy ◽

White Mold ◽

First Report ◽

Potted Plants ◽

Inoculation Trial ◽

Initial Symptoms ◽

The Moment

Iberis sempervirens (candytuft) is an ornamental plant that thrives in cool conditions, and its growth as a potted plant has been increasing in Liguria (northern Italy). In the spring of 2004, extensive chlorosis was observed on 10-month-old potted plants of I. sempervirens grown in a plastichouse on a commercial farm near Albenga in northern Italy. Initial symptoms included stem necrosis at the soil level and darkening of leaves. As stem and foliar necrosis progressed, infected plants wilted and died. Wilt occurred within a few days on young plants, characterized by the presence of soft, watery tissues, particularly on affected leaves. Symptomatic plants were found on many farms, with an average disease incidence of 5 to 10%. 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 (Lib.) de Bary (1) was consistently recovered from infected stem pieces. Sclerotia observed on infected plants measured 1.4 to 3.2 × 2.1 to 4.1 mm (average 2.1 to 2.7 mm). Sclerotia produced on PDA measured 1.2 to 4.2 × 1.4 to 6.1 mm (average 2.5 to 3.1 mm). Pathogenicity of three isolates obtained from infected plants and used in a mixture was confirmed by inoculating 10 single-potted 120-day-old plants grown in 18-cm diameter pots maintained outside under shade. Inoculum that consisted of 1 cm2 of mycelium excised from a 10-day-old PDA culture plate of each isolate was placed on the soil surface around the base of each plant. Ten noninoculated plants served as control. The inoculation 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 symptoms of leaf yellowing within 18 days, soon followed by the appearance of white mycelium and sclerotia, and then eventual wilt. Control plants remained symptomless. S. sclerotiorum was reisolated from the stems of inoculated plants. S. sclerotiorum has been previously reported only on I. umbellata (2). To our knowledge, this is the first report of white mold on I. sempervirens in Italy as well as worldwide. The economic importance of this disease can be considered low at the moment in the case of field-grown plants. References: (1) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift 75, 1949. (2) J. M. Waterston. Report of the Plant Pathologist, 1946. Dep. Agric. Bermuda, 1947.

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