scholarly journals Sclerotinia Stem and Crown Rot of Corn-Salad Caused by Sclerotinia minor in California

Plant Disease ◽  
2003 ◽  
Vol 87 (10) ◽  
pp. 1264-1264 ◽  
Author(s):  
S. T. Koike
Keyword(s):  
Soft Rot ◽  
The United States ◽  
Crown Rot ◽  
Peat Moss ◽  
Sclerotinia Minor ◽  
Rooting Medium ◽  
Initial Symptoms ◽  
Salinas Valley ◽  
White Mycelium ◽  
Made In

Corn-salad or lamb's lettuce (Valerianella locusta) is a specialty leafy green vegetable that is grown commercially in California and is harvested fresh for use in salads. In 2001, field plantings of corn-salad in coastal California showed symptoms and signs of a previously undescribed disease. Initial symptoms consisted of a light tan discoloration at the crown and lower leaf attachment areas. Once this discoloration was observed, the crown rapidly developed a soft rot, attached leaves wilted, and the entire plant collapsed. White mycelium and small (0.5 to 3.0 mm in diameter), irregularly shaped, black sclerotia formed on the crowns and lower leaves. Isolations from symptomatic crowns, mycelium, and sclerotia produced colonies of Sclerotinia minor (1). Seven-week-old corn-salad plants grown in a peat moss-based rooting medium in pots were used to test pathogenicity. Sclerotia from six corn-salad isolates from the Salinas Valley were inserted into slots made in the potting mix adjacent to the crowns of plants. Sclerotia were not placed in slots for control corn-salad. All test plants were incubated in a greenhouse at 21 to 23°C. After 4 weeks, inoculated corn-salad plants wilted and collapsed, and S. minor was reisolated from necrotic crown and stem tissues. Uninoculated plants were asymptomatic. Using the same method, sclerotia from one lettuce (Lactuca sativa) isolate were used to inoculate corn-salad plants that produced similar symptoms. All experiments were repeated and results were similar. To our knowledge, this is the first report of corn-salad as a host of S. minor in California and the United States. The susceptibility of corn-salad to S. minor from lettuce indicates that this crop might contribute to inoculum levels and lettuce drop incidence for the extensive lettuce plantings in the Salinas Valley. Reference: (1) C. L. Patterson and R. G. Grogan. Plant Dis. 72:1046, 1988.

scholarly journals Sclerotinia Petiole and Crown Rot of Celery Caused by Sclerotinia minor in California

Plant Disease ◽  
2006 ◽  
Vol 90 (6) ◽  
pp. 829-829
Author(s):  
S. T. Koike ◽  
O. Daugovish ◽  
J. A. Downer
Keyword(s):  
United States ◽  
The United States ◽  
Crown Rot ◽  
Apium Graveolens ◽  
Peat Moss ◽  
Sclerotinia Minor ◽  
San Luis ◽  
Rooting Medium ◽  
Initial Symptoms ◽  
And Control

Celery (Apium graveolens) is grown extensively in the coastal counties (Ventura, Santa Barbara, San Luis Obispo, Monterey, and Santa Cruz) of California. In 2004 and 2005, field plantings of celery in Ventura and Monterey counties showed symptoms of a petiole and crown rot. Initial symptoms consisted of a light tan discoloration at the crowns and on outer petioles that were in contact with soil. These discolored areas developed a soft, brown, watery rot. Affected petioles wilted and later collapsed. White mycelium and small (0.5 to 3.0 mm in diameter), irregularly shaped, black sclerotia formed on diseased tissues. Isolations from symptomatic petioles, crowns, mycelium, and sclerotia produced colonies of Sclerotinia minor. Eight-week-old celery transplants (cv. Conquistador) grown in a peat-moss based rooting medium in 10-cm2 pots were used to test pathogenicity. Colonized agar plugs (one plug per plant) from eight celery isolates were inserted into slots made in the potting mix adjacent to the crowns and lower petioles of the transplants. Noncolonized plugs were placed in slots for control celery plants. Twenty plants were used for each isolate and control, and all test plants were incubated in a greenhouse at 21 to 23°C. Disease development was rapid, and after 4 days, inoculated celery plants exhibited brown necrosis at inoculation points. After 9 days, celery crowns were decayed and petioles collapsed. S. minor was reisolated from necrotic crown and petiole tissues. Noninoculated plants were asymptomatic. The experiment was repeated and results were similar. To our knowledge, this is the first report of celery as a host of S. minor in California (2). In the United States, S. minor has been reported on celery in Florida (1). Celery in California is only occasionally infected by S. minor and is more often infected by S. sclerotiorum. Reference: (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) M. S. Melzer et al. Can. J. Plant Pathol. 19:272, 1997.

scholarly journals 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 ◽  
2000 ◽  
Vol 84 (11) ◽  
pp. 1250-1250 ◽  
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.

scholarly journals First Report of White Mold Caused by Sclerotinia minor on Mexican Sunflower in California

Plant Disease ◽  
2013 ◽  
Vol 97 (9) ◽  
pp. 1250-1250 ◽  
Author(s):  
S. T. Koike
Keyword(s):  
Disease Incidence ◽  
Peat Moss ◽  
Sclerotinia Minor ◽  
First Report ◽  
Rooting Medium ◽  
Initial Symptoms ◽  
Host Status ◽  
White Mycelium ◽  
Direct Seeded ◽  
Lettuce Drop

Mexican sunflower (Tithonia rotundifolia) is a plant in the Asteraceae that is grown commercially as a cutflower commodity and also as a beneficial insectary plant. In June 2012 in coastal California (Santa Cruz County), several fields of organic lettuce (Lactuca sativa) were interplanted with direct-seeded rows of Mexican sunflower (cv. Torch) in order to attract beneficial insects. When approximately 2 to 3 weeks from harvest, lettuce plants began to wilt and collapse. Lettuce crowns were decayed and covered with white mycelium and small (0.5 to 3 mm diameter), irregularly shaped, black sclerotia. These plants were confirmed to have lettuce drop disease caused by Sclerotinia minor (2). In addition, Mexican sunflower plants began to wilt and eventually died. Initial symptoms on crowns and bases of the main stems in contact with soil consisted of a light tan discoloration. These discolored areas turned darker brown, became necrotic, and later were covered with white mycelium and sclerotia that were identical to those found on lettuce. Symptomatic sunflower stems were surface disinfested and small pieces from the margins of necrotic areas were placed into petri plates containing acidified potato dextrose agar. Resulting fungal colonies were white, produced profuse numbers (approx. 39 sclerotia/cm2) of small black sclerotia, and were identified as S. minor. Six-week-old Mexican sunflower plants grown in a peat moss-based rooting medium in 5-cm square pots were used to test the pathogenicity of four isolates. Isolates were grown on cubed and autoclaved potato pieces and resulting sclerotia were recovered and dried (1). For each isolate, 12 plants for each of three cultivars (cvs. Fiesta del Sol, Torch, and Yellow Torch) were inoculated by placing 3 to 5 sclerotia 1 cm below the soil level and adjacent to the plant crowns/stem bases. Sterile sand was placed next to crowns of the control plants. Plants were maintained in a greenhouse at 22 to 24°C. Symptom development was rapid and after 6 to 7 days, inoculated Tithonia plants exhibited brown necrosis at inoculated areas. After 10 days, Tithonia crowns were decayed and plants wilted. S. minor was reisolated from selected necrotic crown and stem tissues. Diseased plants that were not used for reisolations later supported the growth of the characteristic white mycelium and black sclerotia. There were no significant differences between the Tithonia cultivars, and overall disease incidence ranged from 74 to 100%. Non-inoculated plants were asymptomatic. The experiment was repeated and results were similar. In addition, the sclerotia of the four Tithonia isolates were similarly inoculated onto sets of 12 romaine lettuce plants (cv. Green Towers). After 5 to 6 days, all plants developed lettuce drop disease and the pathogen was reisolated. To my knowledge, this is the first report of Mexican sunflower as a host of S. minor. These findings indicate that Mexican sunflower and lettuce are susceptible to the same lettuce drop pathogen, and that this beneficial insectary plant could increase soilborne inoculum of S. minor. Growers should therefore be aware of the host status of beneficial insectary and other plants interplanted with crops. References: (1) P. Chitrampalam et al. Phytopathology 101:358, 2011. (2) K. V. Subbarao. Plant Dis. 82:1068, 1998.

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

Plant Disease ◽  
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.

scholarly journals Southern Blight of Areca Palm (Chrysalidocarpus lutescens) Caused by Sclerotium rolfsii in California

Plant Disease ◽  
2005 ◽  
Vol 89 (9) ◽  
pp. 1012-1012
Author(s):  
S. T. Koike
Keyword(s):  
Sclerotium Rolfsii ◽  
Plant Diseases ◽  
Crown Rot ◽  
Peat Moss ◽  
Southern Blight ◽  
Foliage Plants ◽  
Rooting Medium ◽  
Brown Discoloration ◽  
Initial Symptoms ◽  
Rot Disease

Areca palm (Chrysalidocarpus lutescens) is a popular ornamental palm that can be grown outdoors in mild climates and is commonly used as an indoor ornamental plant. During 2005, commercial palm producers lost significant numbers of areca palm seedlings grown in transplant trays to a crown rot disease. Initial symptoms consisted of a light brown discoloration of stems near the soil line. As disease progressed, the brown discoloration extended up the stem and down into the crown, foliage became gray green, and the entire plant then dried up and died. Extensive, white, cottony mycelium and numerous sclerotia developed externally on the lower stem, crown, attached palm seed, and surrounding peat moss medium. Mycelial growth was so extensive that the fungus often grew from one transplant tray cell, bridged across the plastic cell border, and into an adjacent transplant cell. Tan, spherical sclerotia measured approximately 1 mm in diameter. Isolations from diseased plants resulted in the recovery of the same white fungus that produced sclerotia. On the basis of sclerotia morphology and the presence of clamp connections at hyphal septa, the fungus was identified as Sclerotium rolfsii. Pathogenicity was tested by growing isolates on potato dextrose agar, drying the resulting sclerotia for 48 h, and then depositing 8 to 10 sclerotia at the base of healthy areca palm seedlings. Five isolates were tested using 40 plants per isolate. Non-inoculated controls were also included. All plants were incubated in a greenhouse at 22 to 25°C. After 2 weeks, inoculated plants began to show brown necrosis at the base of the stems; by the third week, plants began to dry up, and mycelium and sclerotia developed on the crowns. S. rolfsii was reisolated from all necrotic crown and stem tissues. Noninoculated controls did not develop any disease symptoms. To my knowledge, this is the first report of southern blight of C. lutescens in California. This disease has been reported on areca palms and other foliage plants in the southern United States and Central and South America (1). Circumstantial evidence (the disease occurred on palm seedlings that were planted in previously unused transplant trays and new peat moss rooting medium) suggests that the pathogen may have been brought in on palm seed. In the nursery, other foliage plants that are susceptible to S. rolfsii were planted in the same rooting medium but were unaffected by southern blight. Reference: (1) A. R. Chase. Compendium of Ornamental Foliage Plant Diseases. The American Phytopathological Society. St. Paul, MN, 1987.

scholarly journals First Report of Sclerotinia Stem Rot and Watery Soft Rot Caused by Sclerotinia sclerotiorum on Sand Rocket (Diplotaxis tenuifolia) in Italy

Plant Disease ◽  
2005 ◽  
Vol 89 (11) ◽  
pp. 1241-1241 ◽  
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.

scholarly journals Southern Blight of Jerusalem Artichoke Caused by Sclerotium rolfsii in California

Plant Disease ◽  
2004 ◽  
Vol 88 (7) ◽  
pp. 769-769 ◽  
Author(s):  
S. T. Koike
Keyword(s):  
Sclerotium Rolfsii ◽  
Jerusalem Artichoke ◽  
The United States ◽  
Peat Moss ◽  
Stem Tissue ◽  
Disease Symptoms ◽  
Southern Blight ◽  
Potted Plants ◽  
Initial Symptoms ◽  
Advanced Stages

Jerusalem artichoke or sunchoke (Helianthus tuberosus) is a specialty vegetable that is grown commercially in California. The fleshy tubers are harvested and used as a fresh salad ingredient or cooked vegetable. During 2003, field plantings of Jerusalem artichoke in coastal California (Santa Cruz County) showed symptoms of an unfamiliar disease. Initial symptoms consisted of wilting of new shoots and leaves followed by browning and collapse of all foliage. Crown and lower stem tissues turned tan to brown. In advanced stages of the disease, crown and stem tissues were colonized internally and externally by white, cottony mycelium. Tan, spherical sclerotia that measured approximately 1 mm in diameter formed on the surfaces of the affected crowns and stems. Mycelia and sclerotia also grew on the soil adjacent to infected plants. Isolations from symptomatic crowns, mycelia, and sclerotia produced colonies that were identified as Sclerotium rolfsii. Pathogenicity was tested using two methods that included sclerotial inocula collected from five isolates grown on potato dextrose agar plates. With the first method, sclerotia of each isolate were applied to sets of tubers (10 tubers per isolate) prior to planting tubers into a soilless, peat moss-based medium in pots. With the second method, 3-week-old potted plants were inoculated by placing sclerotia of each isolate adjacent to stem tissue that was 3 cm below the surface of the soilless medium. Noninoculated controls were included for both methods. All plants were incubated in a greenhouse at 21 to 24°C. For the first method, by the third week after planting, 10 to 40% of plants did not emerge because the tubers were rotted and decayed. For the plants that did emerge, wilting of foliage and browning of crown and stem tissue occurred approximately 6 weeks after planting and by 10 weeks, all plants were diseased. S. rolfsii was reisolated from all necrotic tuber, crown, and stem tissues. For the second method, disease symptoms and signs of the pathogen occurred 5 weeks after inoculation and by week 10, 75% of test plants were symptomatic. S. rolfsii was again reisolated from all necrotic tuber, crown, and stem tissues. Symptoms were not observed on any of the noninoculated plants. To my knowledge, this is the first report of southern blight of Jerusalem artichoke in California. This disease has been reported on Jerusalem artichoke in several southern U.S. states (1,2). The two inoculation methods demonstrated that the pathogen could infect propagation organs (tubers) and also emergent stems of this host. 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) S. M. McCarter and S. J. Kays. Plant Dis. 68:299, 1984.

scholarly journals Pseudomonas Blight Caused by Pseudomonas syringae on Raspberry in California

Plant Disease ◽  
2014 ◽  
Vol 98 (8) ◽  
pp. 1151-1151 ◽  
Author(s):  
S. T. Koike ◽  
M. P. Bolda ◽  
C. T. Bull
Keyword(s):  
Pacific Northwest ◽  
Pseudomonas Syringae ◽  
Soft Rot ◽  
The United States ◽  
Rubus Idaeus ◽  
Plastic Bags ◽  
Nicotiana Tabacum L ◽  
The Pacific ◽  
Initial Symptoms ◽  
Northwest Region

In February 2013 in coastal California (Santa Cruz County), plantings of red raspberry (Rubus idaeus var. strigosus) exhibited symptoms of a previously undocumented disease. Initial symptoms were small (less than 5 mm wide), angular, water-soaked lesions on leaf and petiole tissues of recently emerged foliage. Lesions were observable from both adaxial and abaxial leaf surfaces. As disease progressed, lesions enlarged and coalesced, resulting in significant dark brown to black blighting of the foliage. The foliage of severely affected plants was stunted and wilted. The disease affected 5 ha and incidence was approximately 30%. Cream-colored bacterial colonies were isolated from surface disinfested symptomatic tissue that was macerated and streaked onto King's medium B (KMB) and sucrose peptone agar (SPA). Fungi were not recovered from any tissue that was surface disinfested and placed into acidified potato dextrose agar. Four representative strains were fluorescent on KMB and gram-negative based on lysis by KOH. Strains were positive for levan formation, negative for oxidase and arginine dihydrolase, and did not cause soft rot on potato slices but induced a hypersensitive response in tobacco (Nicotiana tabacum L. cv. Samsun); strains thus belonged to Lelliot's LOPAT group 1, P. syringae (3). All four strains had identical DNA fragment-banding patterns generated by repetitive extragenic palindromic sequence (rep)-PCR using the BOXA1R primer (4). The pattern generated was different than all P. syringae pathovars in genomospecies 1 including P. syringae pv. syringae. According to multilocus sequence analysis conducted by previously described methods, the strains are most closely related to P. syringae pv. aceris and P. syringae pv. solidagae in genomospecies 1 (1). Potted raspberry plants were used to test four strains for pathogenicity. Inoculum was prepared by growing the bacteria on SPA for 48 h and suspending the bacteria in sterile distilled water (SDW) for a final concentration of approximately 107 CFU/ml. Suspensions were sprayed until runoff onto three replicate plants per strain. Control plants were sprayed with SDW until runoff. Plants were enclosed in plastic bags for 24 h and then maintained in a greenhouse (23 to 25°C). After 7 to 8 days, water soaked lesions developed on all inoculated plants; lesions later turned dark brown and appeared similar to symptoms observed in the field. Plants treated with water developed no symptoms. Bacteria re-isolated onto KMB from symptomatic tissues were fluorescent and appeared identical to the bacteria used to inoculate the plants; two selected re-isolated strains were identical to the original strains according to rep-PCR, fluorescence, and LOPAT reactions. The experiment was repeated and disease development and recovery of fluorescent strains on KMB was identical to the first experiment. To our knowledge, this is the first report of Pseudomonas blight of raspberry, caused by P. syringae, in California. Affected plants initially were stunted in growth but later in the summer exhibited no lasting effects from the disease. Pseudomonas blight has been reported in the Pacific Northwest region of the United States, the British Columbia region of Canada, and Serbia (2). References: (1) C. T. Bull et al. Phytopathology 101:847, 2011. (2) Z. Ivanovic et al. Eur. J. Plant Pathol. 134:191, 2012. (3) R. A. Lelliott. J. Appl. Bacteriol. 29:470, 1966. (4) A. S. A. Marques, et al. Genet. Mol. Biol. 31:106. 2008.

scholarly journals First Report of Sclerotinia sclerotiorum on Calceolaria integrifolia in Italy

Plant Disease ◽  
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.

scholarly journals First Report of Verticillium Wilt Caused by Verticillium dahliae on Coleus verschaffeltii in Italy

Plant Disease ◽  
2011 ◽  
Vol 95 (7) ◽  
pp. 878-878 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
A. Poli ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
The United States ◽  
Peat Moss ◽  
Conidial Suspension ◽  
First Report ◽  
Vascular Tissues ◽  
Initial Symptoms ◽  
Bedding Plant

Coleus verschaffeltii Lem. (synonym C. blumei Benth., Plectranthus scutellaroides (L.) R. Br., and Solenostemon scutellarioides (L.) Codd), a perennial plant belonging to the Lamiaceae family, is used as a bedding plant for public gardens. The most popular cultivars produce speckled leaves of various colors. In October 2010, severe outbreaks of a previously unknown wilt were observed in a public garden at Torino (northern Italy) on 50 8-month-old plants. Plants were sprinkle irrigated. Initial symptoms were withering of leaves starting from the collar and brown streaks in the vascular tissue of roots, crown, and stem. Subsequently, infected tissues wilted and plants became stunted. Early leaf drop was observed and plants appeared bare, keeping few leaves only at the end of stems. Infected plants did not die but they lost the original ornamental aspect. Seventy percent of the plants were affected. Stems of 10 plants were disinfected with 1% sodium hypochlorite. Cross-sections through symptomatic vascular tissues were plated on potato dextrose agar amended with 25 ppm of streptomycin sulfate. After 10 days at 20 to 23°C, a fungus was consistently recovered from 90% of stems. Irregular, black microsclerotia, 29 to 76 × 14 to 52 (average 49 × 28) μm, developed in hyaline hyphae after 15 days of growth. Hyaline, elliptical, single-celled conidia, 3.9 to 7.2 × 1.7 to 2.8 (average 5.1 × 2.2) μm, developed on verticillate conidiophores with three phialides at each node. On the basis of these morphological characteristics, the fungus was identified as Verticillium dahliae (3). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 (4) and sequenced. BLASTn analysis (1) of the 491-bp segment showed a 99% homology with the sequence of V. dahliae (Accession No. GU461634). The ITS nucleotide sequence of our isolate has been assigned the GenBank Accession No. JF704205. Pathogenicity tests were performed twice using 45-day-old plants obtained from seeds of C. verschaffeltii grown in 1-liter pots containing a 50:20:20:10 steamed mix of peat moss/pumice/pine bark/clay. Roots of 10 healthy plants were immersed in a conidial suspension (1.7 × 107 ml–1) of one culture of V. dahliae isolated from infected plants. Ten plants immersed in sterile water served as controls. Plants were maintained in a glasshouse at daily average temperatures between 20 and 28°C and relative humidity between 50 and 80%. First wilt symptoms and vascular discoloration in the roots, crown, and stems developed 20 days after inoculation. V. dahliae was consistently reisolated from infected vascular tissues of crown and stems of symptomatic plants. Noninoculated plants remained healthy. To our knowledge, this is the first report of Verticillium wilt on C. verschaffeltii in Italy. Verticillium wilt had been previously reported on S. scutellaroides in the United States (2). At this time, the economic importance of Verticillium wilt on C. verschaffeltii in Italy is limited. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society. St Paul, MN, 1989. (3) G. F. Pegg and B. L. Brady. Verticillium Wilts. CABI Publishing, Wallingford, UK, 2002. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

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