First Report of Leaf Blight Caused by Pseudomonas syringae on Cornus mas

Cornellian cherry (Cornus mas) is an enduring dogwood that is primarily grown as an ornamental plant in North America, but in parts of Europe, its fruit is eaten fresh or pickled or made into soft drinks, wine, and liqueur. Cornellian cherry has demonstrated longevity and adaptability and has had no previous disease or pest problems. In Tennessee, a leaf blight was first observed during spring 1996 in nursery plants imported from Europe. The disease quickly spread to other C. mas plants within the nursery and has caused severe damage for three consecutive years. The disease affected mostly leaves and young shoots, causing dark brown necrotic lesions and some die back. In early stages, leaf infection consisted of discrete lesions, angular in shape and surrounded by a chlorotic halo. These lesions eventually coalesced to form large dark necrotic patches that covered a large portion of the leaf or the entire leaf. Disease symptoms were restricted to early spring during wet and cool weather; later in the season new growth was free of symptoms. A bacterium was isolated from infected plants and tested for pathogenicity on C. mas ‘Redstone’ and C. florida. Symptoms were reproduced on C. mas but not on C. florida. The bacterium was reisolated from inoculated plants, was characterized as gram-negative and rod-shaped, and produced fluorescent pigment on King's medium B agar. The bacterium had a positive reaction to the Levan test and negative reactions to potato rot and arginine dihydrolase tests and was identified as Pseudomonas syringae (1). Samples of the bacterium were sent to Texas A&M University, College Station, for fatty acid analysis, and the results confirmed the identity of P. syringae. P. syringae has caused severe damage in C. florida in the northwestern United States (2); however, this is the first report of P. syringae on C. mas. References: (1) N. W. Schaad, ed. 1988. Laboratory Guide for Identification of Plant Pathogenic Bacteria. The American Phytopathological Society, St. Paul, MN. (2) W. A. Sinclair et. al. 1987. Diseases of Trees and Shrubs. Cornell University Press, Ithaca, NY.

Download Full-text

First Report of Leaf Blight and Stem Canker of Pachysandra terminalis Caused by Pseudonectria pachysandricola in Korea

Plant Disease ◽

10.1094/pdis-09-11-0813 ◽

2012 ◽

Vol 96 (2) ◽

pp. 287-287

Author(s):

K. S. Han ◽

J. H. Park ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

United States ◽

Its Region ◽

Stem Canker ◽

The United States ◽

Culture Collection ◽

Leaf Blight ◽

First Report ◽

Cornell University ◽

Plastic Bags ◽

Young Leaves

Pachysandra terminalis Siebold & Zucc., known as Japanese pachysandra, is a creeping evergreen perennial belonging to the family Buxaceae. In April 2011, hundreds of plants showing symptoms of leaf blight and stem canker with nearly 100% incidence were found in a private garden in Suwon, Korea. Plants with the same symptoms were found in Seoul in May and Hongcheon in August. Affected leaves contained tan-to-yellow brown blotches. Stem and stolon cankers first appeared as water soaked and developed into necrotic lesions. Sporodochia were solitary, erumpent, circular, 50 to 150 μm in diameter, salmon-colored, pink-orange when wet, and with or without setae. Setae were hyaline, acicular, 60 to 100 μm long, and had a base that was 4 to 6 μm wide. Conidiophores were in a dense fascicle, not branched, hyaline, aseptate or uniseptate, and 8 to 20 × 2 to 3.5 μm. Conidia were long, ellipsoid to cylindric, fusiform, rounded at the apex, subtruncate at the base, straight to slightly bent, guttulate, hyaline, aseptate, 11 to 26 × 2.5 to 4.0 μm. A single-conidial isolate formed cream-colored colonies that turned into salmon-colored colonies on potato dextrose agar (PDA). Morphological and cultural characteristics of the fungus were consistent with previous reports of Pseudonectria pachysandricola B.O. Dodge (1,3,4). Voucher specimens were housed at Korea University (KUS). Two isolates, KACC46110 (ex KUS-F25663) and KACC46111 (ex KUS-F25683), were accessioned in the Korean Agricultural Culture Collection. Fungal DNA was extracted with DNeasy Plant Mini DNA Extraction Kits (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced using ABI Prism 337 automatic DNA sequencer (Applied Biosystems, Foster, CA). The resulting sequence of 487 bp was deposited in GenBank (Accession No. JN797821). This showed 100% similarity with a sequence of P. pachysandricola from the United States (HQ897807). Isolate KACC46110 was used in pathogenicity tests. Inoculum was prepared by harvesting conidia from 2-week-old cultures on PDA. Ten young leaves wounded with needles were sprayed with conidial suspensions (~1 × 106 conidia/ml). Ten young leaves that served as the control were treated with sterile distilled water. Plants were covered with plastic bags to maintain a relative humidity of 100% at 25 ± 2°C for 24 h. Typical symptoms of brown spots appeared on the inoculated leaves 4 days after inoculation and were identical to the ones observed in the field. P. pachysandricola was reisolated from 10 symptomatic leaf tissues, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in the United States, Britain, Japan, and the Czech Republic (2,3), but not in Korea. To our knowledge, this is the first report of P. pachysandricola on Pachysandra terminalis in Korea. Since this plant is popular and widely planted in Korea, this disease could cause significant damage to nurseries and the landscape. References: (1) B. O. Dodge. Mycologia 36:532, 1944. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , September 24, 2011. (3) I. Safrankova. Plant Prot. Sci. 43:10, 2007. (4) W. A. Sinclair and H. H. Lyon. Disease of Trees and Shrubs. 2nd ed. Cornell University Press, Ithaca, NY, 2005.

Download Full-text

First Report of Acidovorax avenae subsp. avenae Causing Bacterial Leaf Stripe of Strelitzia nicolai

Plant Disease ◽

10.1094/pdis-03-11-0160 ◽

2011 ◽

Vol 95 (11) ◽

pp. 1474-1474 ◽

Cited By ~ 2

Author(s):

T. E. Seijo ◽

N. A. Peres

Keyword(s):

Pathogenic Bacteria ◽

Fatty Acid Analysis ◽

South Florida ◽

Metabolic Phenotype ◽

Bacterial Suspension ◽

Rrna Gene ◽

First Report ◽

Plastic Bags ◽

Young Leaves ◽

Symptomatic Tissue

White bird of paradise (Strelitzia nicolai Regel & K. Koch) is a commonly grown ornamental in central and south Florida. Each summer of 2004 to 2007, a reoccurring disease was observed at a commercial nursery in central Florida. Diseased plants had brown, necrotic stripes between the lateral leaf veins, which usually appeared along the midvein and spread toward the leaf edge. Lesions developed on the youngest leaves as they emerged from the central whorl. During 2004 and 2005, 20 symptomatic leaves were sampled. A white, nonfluorescent bacterium was consistently isolated from symptomatic tissue. It induced a hypersensitive response (HR) on tomato, grew at 41°C, and was identified as a Acidovorax sp. based on fatty acid analysis and as Acidovorax avenae subsp. avenae by Biolog metabolic phenotype analysis (similarity 0.76 to 0.86). A partial 16S rRNA gene sequence (1,455 bp) (Accession No. EF418616) was identical to four sequences in the NCBI (National Center for Biotechnology Information) database: one from A. avenae subsp. avenae and three from A. avenae of undetermined subspecies. To confirm pathogenicity, a bacterial suspension (O.D590 = 0.1) was applied to fill the central whorl (~0.5 to 1 ml) of potted S. nicolai. Plants were incubated for 7 to 10 days inside plastic bags at ambient temperature. Plants were inoculated individually with five strains of A. avenae subsp. avenae, four from S. nicolai, and one from corn (ATCC19860). Two to nine plants per strain were inoculated in each experiment. All strains were tested at least twice and noninoculated control plants were included. Symptoms were reproduced on the emerging leaf of 50 to 100% of inoculated plants with all five A. avenae subsp. avenae strains. No symptoms were observed on the controls. The bacteria recovered from symptomatic tissue were confirmed to be A. avenae subsp. avenae. Corn seedlings were inoculated as described above, except that entire seedlings were sprayed. Water-soaked lesions along the length of older leaf blades developed in 4 to 7 days. Only the corn strain was pathogenic (>80% of seedlings symptomatic), indicating host specificity. To our knowledge, this is the first report of A. avenae subsp. avenae infecting S. nicolai. In 1971, Wehlburg (2) described the same symptoms on orange bird of paradise (S. reginae) as being caused by a nonfluorescent Pseudomonas sp. This report likely describes the same disease since the published description is consistent with symptoms caused by A. avenae subsp. avenae. The pathogen reported by Wehlburg (2) had one polar flagellum, reduced nitrate, produced oxidase and a HR, and utilized arabinose, but not sucrose or arginine, characteristics consistent with those of A. avenae subsp. avenae (1). The only difference was A. avenae subsp. avenae has a delayed positive starch hydrolysis (1), whereas Welhburg's strain was negative. This disease occurs mainly on young leaves when plants receive daily overhead irrigation. Incidence can be as high as 40%, occasionally causing mortality, but even mild symptoms affect appearance and reduce marketability as an ornamental. References: (1) N. W. Schaad et al. Laboratory Guide for Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2001. (2) C. Wehlburg. Plant Dis. Rep. 55:447, 1971.

Download Full-text

First Report of Bacterial Canker of Kiwifruit Caused by Pseudomonas syringae pv. actinidiae in Spain

Plant Disease ◽

10.1094/pdis-06-11-0537 ◽

2011 ◽

Vol 95 (12) ◽

pp. 1583-1583 ◽

Cited By ~ 35

Author(s):

A. Abelleira ◽

M. M. López ◽

J. Peñalver ◽

O. Aguín ◽

J. P. Mansilla ◽

...

Keyword(s):

Pseudomonas Syringae ◽

Online Publication ◽

Untreated Control ◽

Early Spring ◽

Bacterial Suspension ◽

Bacterial Canker ◽

Biochemical Tests ◽

Woody Vines ◽

First Report ◽

Sterile Needle

Bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae was first described in Japan and Korea and is currently an emerging disease that causes major losses in China, Italy, New Zealand, France, Portugal, and Chile. Gold kiwifruit (Actinidia chinensis), especially cvs. Jin Tao and Hort 16A, seem to be more susceptible than green kiwifruit (Actinidia deliciosa) cvs. Hayward and Summer. The bacterium affects male and female woody vines equally, with young vines being more susceptible. The most characteristic symptoms that appear in early spring are reddish orange or white exudates associated with cankers and wounds in branches and/or trunk, as well as brown leaf spots. Buds and fruits were also affected (1). In Spain, 1,132 ha of kiwifruit orchards yielded 25,285 t of fruit in 2009 (2). Most Spanish kiwifruit is cultivated in Galicia (northwest Spain), where the main cultivar is Hayward. In 2010, the first plantation of cv. Jin Tao and one plantation of cv. Summer were established in this area close to Hayward woody vine. In early spring 2011, 80% of the vines in one orchard had twigs with reddish exudates and branches and trunks as well as leaves with angular spots surrounded by yellow haloes. Isolations from both Actinidia spp. were conducted on nutrient agar with sucrose. One hundred and twelve isolates were obtained and seventy-seven were aerobic, gram negative and nonfluorescent on King's B medium. Biochemical tests performed were levan, oxidase, potato rot, arginine didhydrolase, hypersensitivity in tobacco, and utilization of 49 carbohydrates by the API 50 CH system (BioMérieux, Marcy l'Etoile, France). Three PCR protocols were used: two with pathovar-specific primers (PSAF1/PSAR2 and PSAF3/PSAR4) and one with nonspecific primers (PsITSF1/PsITSR2) (3). The results of all biochemical and molecular tests were in agreement with those expected for P. syringae pv. actinidiae. The 16S-23S region of strain EFA 37 isolated from A. deliciosa cv. Summer was sequenced (GenBank Accession No. JF815537) and had 100% sequence identity with P. syringae pv. actinidiae (GenBank Accession Nos. AY342165 and D86357). Pathogenicity tests were performed on 15 plants of A. deliciosa cv. Hayward (five plants per isolate) with the Spanish representative strain EFA 37 and compared with two reference strains isolated from both Actinidia species in Italy and five plants of an untreated control. Three buds per healthy vine were wounded with a sterile needle, inoculated with 30 to 50 μl of each bacterial suspension (108 CFU/ml), sealed, and then covered with plastic. Five leaves per healthy vine were also pierced with a sterile needle and then atomized with the same suspension. Symptoms began to appear after 5 days on inoculated vines, but not on untreated control vines. The bacterium, P. syringae pv. actinidiae, was reisolated from symptomatic plants. The kiwifruit orchard with affected plants was eradicated (25 ha). To our knowledge, this is the first report of P. syringae pv. actinidiae in Spain. References: (1) EPPO Alert List. Online publication. Retrieved from http://www.eppo.org/QUARATINE/Alert_List , June, 2011. (2) Ministerio de Medio Ambiente y Medio Rural y Marino (MARM). Anuario de Estadística, Online Publication. Retrieved from http://www.marm.es/estadistica/pags/anuario/2010 , June 2011. (3) J. Rees-George et al. Plant Pathol. 59:453, 2010.

Download Full-text

Isolation of copper and streptomycin resistant phytopathogenic Pseudomonas syringae from lakes and rivers in the central North Island of New Zealand

New Zealand Plant Protection ◽

10.30843/nzpp.2008.61.6822 ◽

2008 ◽

Vol 61 ◽

pp. 80-85 ◽

Cited By ~ 2

Author(s):

J.L. Vanneste ◽

D.A. Cornish ◽

J. Yu ◽

R.J. Boyd ◽

C.E. Morris

Keyword(s):

New Zealand ◽

Cytochrome C Oxidase ◽

Pseudomonas Syringae ◽

Pathogenic Bacteria ◽

Tobacco Plant ◽

Hypersensitive Reaction ◽

Streptomycin Resistance ◽

Copper Resistance ◽

Plant Pathogenic Bacteria ◽

Fluorescent Pigment

Plant pathogenic strains of Pseudomonas syringae were isolated from lakes and rivers in the central North Island of New Zealand These strains were identified by their ability to produce a fluorescent pigment on a modified Kings B medium by their ability to cause a hypersensitive reaction when infiltrated into tobacco plant and by the absence of a cytochrome c oxidase Different aspects of the protocol used to isolate these strains have been assessed Some of the strains isolated and in some cases the majority of them were resistant to copper and/or streptomycin Significantly these plant pathogenic bacteria were isolated from waterways in areas where no agriculture or horticulture is present and waterways used for crop irrigation These results suggest that natural waterways could be a source of inoculum of plant pathogenic bacteria and a source of genes that confer streptomycin resistance and/or copper resistance to these bacteria

Download Full-text

First Report of Bacterial Blight Caused by Pseudomonas viridiflava on Pea in Spain

Plant Disease ◽

10.1094/pdis-94-1-0128a ◽

2010 ◽

Vol 94 (1) ◽

pp. 128-128 ◽

Cited By ~ 4

Author(s):

A. Martín-Sanz ◽

J. L. Palomo ◽

M. Pérez de la Vega ◽

C. Caminero

Keyword(s):

Pseudomonas Syringae ◽

Pathogenic Bacteria ◽

Carbon Sources ◽

Preliminary Test ◽

Soft Rot ◽

First Report ◽

Leaf Spots ◽

Pea Seedlings ◽

Disease Surveys ◽

Plant Pathol

Because production of dry peas (Pisum sativum L.) is increasing in Spain, disease surveys were carried out from 2004 to 2006 in Castilla y Leon, the largest pea-producing region. In May of 2004, a leaf and stem blight caused an estimated 25% loss in yield in pea (cv. Messire) fields in El Cerrato (Palencia). Bacteria were isolated on King's B medium from 10 symptomatic plants from different fields (3). Thirty gram-negative isolates produced fluorescent, yellowish mucoid colonies. All isolates showed oxidative glucose metabolism on Hugh-Leifson medium and were levan and oxidase negative, potato soft rot positive, arginine dihydrolase negative, and tobacco hypersensitive positive. They also hydrolyzed esculine and gelatine. These results were different than those expected by Pseudomonas syringae pv. pisi and P. syringae pv. syringae (3). API 50 CH tests (bioMerieux, Marcy l'Etoile, France) revealed that all the isolates used the following carbon sources: glycerol, erythritol, l-arabinose, ribose, d-xylose, galactose, d-glucose, d-fructose, d-manose, inositol, manitol, sorbitol, d-raffinose, d-fucose, and d-arabitol. This nutritional profile is identical with that of P. viridiflava strain CFBP 6730, originally from pea plants in France. Therefore, these isolates were tentatively identified as P. viridiflava (2). Since a preliminary test demonstrated that 9 of the 30 isolates were pathogenic on pea plants, pathogenic isolates P44, P45, and P46 were selected arbitrarily for further tests. These three isolates plus strains HRI-W 1704 (P. syringae pv. pisi type race 6) and CFBP 1769 (P. syringae pv. syringae) were inoculated onto 10 pea seedlings (cv. Messire) each in two identical trials, following a described protocol (1). Seedlings inoculated with sterile distilled water were used as controls. After 10 days of incubation in a growth chamber at 22°C and 80% relative humidity, severe rotting and collapse similar to symptoms observed in fields appeared on pea seedlings inoculated with isolates P44, P45, and P46, while water-soaked leaf spots and necrotic symptoms were caused by P. syringae pv. pisi and P. pv. syringae. No symptoms were observed on plants inoculated with sterile water. Isolates recovered from symptomatic stems showed the same morphological and biochemical features of the original isolates. Sequences of 1,399 bp long from the three isolates (GenBank Accession Nos. GQ398128, GQ398129, and GQ398130) were 100% identical to P. viridiflava 16S rDNA database reference sequences. To our knowledge, this is the first report of P. viridiflava causing a disease of pea in Spain. The disease has been reported in New Zealand (4) and France (2). References: (1) E. M. Elvira-Recuenco et al. Eur. J. Plant Pathol. 109:555, 2003. (2) C. Grondeau et al. Plant Pathol. 41:495, 1992 (3) N. W. Schaad et al., eds. Laboratory Guide for the Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2001. (4) J. D. Taylor et al. N. Z. J. Agric. Res. 5:432, 1972.

Download Full-text

Biology and Control of Bacterial Leaf Blight of Cornus mas

HortScience ◽

10.21273/hortsci.41.3.721 ◽

2006 ◽

Vol 41 (3) ◽

pp. 721-724 ◽

Cited By ~ 2

Author(s):

M.T. Mmbaga ◽

E.C. Nnodu

Keyword(s):

Disease Management ◽

Pseudomonas Syringae ◽

Bordeaux Mixture ◽

Management Strategies ◽

Leaf Blight ◽

Bacterial Leaf Blight ◽

Cupric Sulfate ◽

Mature Leaves ◽

Cornus Mas ◽

Young Leaves

Cornelian cherry (Cornus mas L.) has been free of disease and pest problems until recently when a bacterial leaf blight caused by Pseudomonas syringae was reported. Since its first observation in middle Tennessee in 1999, the disease has become endemic in the nursery where it was first discovered. The objective of this study was to assess the disease, evaluate factors that favor disease development, and develop disease management strategies. Cool temperatures of 20 to 24 °C (day) and 10 to 15 °C (night) were most favorable to the disease and young leaves were highly susceptible while mature leaves were resistant to infection. Leaf wounding increased the susceptibility of leaves and mature leaves developed infection at 28 °C, temperature at which nonwounded leaves were completely resistant to infection. Results from this study also showed that plant propagation from seemingly healthy branches of infected plants may have perpetuated the disease at the nursery. Six chemicals—Phyton-27 (copper sulfate), Camelot (copper salt of fatty acids), Agri-Mycin 17 (streptomycin), Kocide 101 (copper hydroxide), Basicop (elemental copper 53%), and, Bordeaux mixture (cupric sulfate + lime) were evaluated for disease control. Phyton-27, and Agri-Mycin—were most effective and reduced disease severity to 10% of foliage showing disease symptoms. Information from this study will be useful in designing effective disease management strategies.

Download Full-text

Pseudomonas capsici sp. nov., a plant-pathogenic bacterium isolated from pepper leaf in Georgia, USA

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY ◽

10.1099/ijsem.0.004971 ◽

2021 ◽

Vol 71 (8) ◽

Cited By ~ 6

Author(s):

Mei Zhao ◽

Santosh Koirala ◽

Hsiao-Chun Chen ◽

Ronald Gitaitis ◽

Brian Kvitko ◽

...

Keyword(s):

Pseudomonas Syringae ◽

Type Species ◽

Fatty Acid Analysis ◽

Rrna Gene ◽

Bacterial Strains ◽

Pseudomonas Cichorii ◽

Content Type ◽

Link Type ◽

Fluorescent Pigment ◽

Phylogenomic Analyses

Three phytopathogenic bacterial strains (Pc19-1T, Pc19-2 and Pc19-3) were isolated from seedlings displaying water-soaked, dark brown-to-black, necrotic lesions on pepper (Capsicum annuum) leaves in Georgia, USA. Upon isolation on King’s medium B, light cream-coloured colonies were observed and a diffusible fluorescent pigment was visible under ultraviolet light. Analysis of their 16S rRNA gene sequences showed that they belonged to the genus Pseudomonas , with the highest similarity to Pseudomonas cichorii ATCC 10857T (99.7 %). The fatty acid analysis revealed that the majority of the fatty acids were summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c), C16 : 0 and summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c). Phylogenomic analyses based on whole genome sequences demonstrated that the pepper strains belonged to the Pseudomonas syringae complex with P. cichorii as their closest neighbour, and formed a separate monophyletic clade from other species. Between the pepper strains and P. cichorii , the average nucleotide identity values were 91.3 %. Furthermore, the digital DNA–DNA hybridization values of the pepper strains when compared to their closest relatives, including P. cichorii , were 45.2 % or less. In addition, biochemical and physiological features were examined in this study and the results indicate that the pepper strains represent a novel Pseudomonas species. Therefore, we propose a new species Pseudomonas capsici sp. nov., with Pc19-1T (=CFBP 8884T=LMG 32209T) as the type strain. The DNA G+C content of the strain Pc19-1T is 58.4 mol%.

Download Full-text

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

Plant Disease ◽

10.1094/pdis.2000.84.12.1344d ◽

2000 ◽

Vol 84 (12) ◽

pp. 1344-1344

Author(s):

G. E. Holcomb ◽

D. E. Carling

Keyword(s):

United States ◽

Rhizoctonia Solani ◽

Gulf Coast ◽

The United States ◽

Anastomosis Group ◽

Early Spring ◽

Leaf Blight ◽

Infected Leaf ◽

First Report ◽

Bedding Plant

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

Download Full-text

First Report of Bacterial Blight Caused by Pseudomonas syringae pv. syringae on Common Vetch in Spain

Plant Disease ◽

10.1094/pdis-93-12-1348b ◽

2009 ◽

Vol 93 (12) ◽

pp. 1348-1348 ◽

Cited By ~ 4

Author(s):

A. Martín-Sanz ◽

J. L. Palomo ◽

C. Caminero

Keyword(s):

Pseudomonas Syringae ◽

Bacterial Blight ◽

Pathogenic Bacteria ◽

The United States ◽

Bacterial Suspension ◽

Citrus Limon ◽

Sterile Water ◽

Common Vetch ◽

First Report ◽

Castilla Y Leon

Common vetch (Vicia sativa L.) is an important legume crop used for livestock feed in the Mediterranean Area. This crop has an important role for sustainable agriculture in dryland rotations in Spain, where the Castilla y León Region is the major production area. During the springs of 2007 and 2008, necrotic lesions on stems, leaves, and flowers were observed in five different common vetch plots around Medina de Rioseco (Castilla y León). Four of the plots were sown with cv. Buza. No information was available about the cultivar in the fifth plot. In many cases, lesions had expanded into the stems causing complete wilting. Disease incidence was estimated at approximately 20%. Two symptomatic plants per plot were sampled. One section per plant was individually surface disinfested in 0.5% NaOCl for 1 min, followed by three washes in sterile water. Macerates were plated in King's B medium (KB) agar (24°C for 48 h) (2). Colonies from all isolations on KB agar were pale yellow and blue-green fluorescent under UV light, as typical of fluorescent Pseudomonas spp. (2). Ten isolates (one per section) were characterized. These were identified as Pseudomonas syringae by the LOPAT scheme (2) and Hugh-Leifson reaction and all utilized erythritol, l-lactate, and dl-homoserine, but not l(+)-tartrate, as carbon sources. They were positive for aesculin and gelatine hydrolysis. The 10 isolates caused severe necrotic lesions when they were puncture inoculated (108 CFU/ml suspension, 50 μl per wound, and two replicates) on immature lemon fruits (Citrus × limon, cv. Primofioro), bean pods (Phaseolus vulgaris L., cv. Ancha Lisa), and pea pods (Pisum sativum L., cv. Ucero). PCR amplification of a 752-bp syrB fragment (3) was positive for all isolates. On the basis of these tests, the 10 isolates were identified as P. syringae pv. syringae (2). Subsequently, each isolate was inoculated into two sets of 10 plants of V. sativa cv. Buza by injecting 200 μl of a bacterial suspension (108 CFU/ml) into the stem (2); 10 plants were injected with sterile water as controls. Ten days after inoculation, necrotic symptoms were observed on all plants, and 1 week later, all plants were completely wilted and dead. These symptoms were similar to those observed in the field. Control plants remained symptomless. Isolations were made from two inoculated plants per each original isolate, and all reisolates were identical to the original isolates in the above biochemical tests and PCR of the syrB gene. P. syringae pv. syringae reference strains, CFBP1768 and CFBP1769 (Collection Française de Bactéries Phytopathogènes), gave the same results in all biochemical, pathogenicity, and PCR tests. To our knowledge, this is the first report of bacterial blight caused by this pathogen on vetch in Spain. This pathogen had been previously identified in this crop in France (4) and in V. villosa (a closely related species) in the United States (1). Therefore, to prevent the spread of this pathogen, research on efficient preventive and control measures is needed. References: (1) G. L. Ercolani et al. Phytopathology 64:1330, 1974. (2) N. W. Schaad et al., eds. Laboratory Guide for the Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2001. (3) K. N. Sorensen et al. Appl. Environ. Microbiol. 64:226, 1998. (4) C. Tourte and C. Manceau. Eur. J. Plant Pathol. 101:483, 1995.

Download Full-text