First Report of Leaf Spot Caused by Pseudomonas cichorii on Coreopsis lanceolata in Italy

Coreopsis lanceolata L. (Compositae), an ornamental species grown in parks and gardens, is very much appreciated for its long-lasting flowering period. In August of 2008, pot-grown plants with necrotic leaf lesions were observed in a commercial nursery located near Biella (northern Italy). Lesions were present, especially along the margin of basal leaves, and sometimes had a chlorotic halo. On infected leaves, dark brown necrosis developed. Leaf stalks were sometimes affected. In many cases, the leaves, especially those at collar level, were withered. Of 1,500 plants, 15% were infected by the disease. Microscopic examination did not reveal any fungal structures within the lesions. Small fragments of tissue from 30 affected leaves were macerated for 15 min in casein hydrolysate and 0.1-ml aliquots of the resulting suspension were spread onto Luria Bertani agar (LB) and potato dextrose agar (PDA). Plates were maintained at 22 ± 1°C for 48 h. No fungi were isolated from the leaf spots on LB or PDA. Colonies similar to those of Pseudomonas spp. were consistently isolated on LB. Colonies were fluorescent on King's medium B, levan negative, oxidase positive, potato soft rot negative, arginine dihydrolase negative, and tobacco hypersensitivity positive (LOPAT test). The bacterial colonies were identified as Pseudomonas cichorii (2). The internal transcribed spacer (ITS) region of rDNA was amplified using primers 27F and 1492R and sequenced (GenBank Accession No. FJ534557). BLAST analysis (1) of the 998-bp segment showed a 98% homology with the sequence of P. cichorii. The pathogenicity of one isolate was tested twice by growing the bacterium in nutrient broth shake cultures for 48 h at 20 ± 1°C. The suspension was centrifuged, the cell pellet resuspended in sterile water to a concentration of 107 CFU/ml, and 30 4-month-old healthy coreopsis plants were sprayed with the inoculum. The same number of plants was sprayed with sterile nutrient broth as a control. After inoculation, plants were covered with plastic bags for 48 h and placed in a growth chamber at 20 ± 1°C. Five days after inoculation, lesions similar to those seen in the field were observed on all plants inoculated with the bacterium, but not on the controls. Ten days later, 40% of the leaves were withered. Isolations were made from the lesion margins on LB and the resulting bacterial colonies were again identified as P. cichorii. The pathogen caused the same symptoms also on plants of Dendranthema frutescens (cv. Camilla), Chrysanthemum morifolium (cvs. Eleonora and Captiva), and an Osteospermum sp. (cv. Wild side) when artificially inoculated with the pathogen with the same methodology. The same bacterial leaf spot caused by P. cichorii was observed in 2005 in other nurseries in the same area on Phlox paniculata (3). To our knowledge, this is the first report of bacterial leaf spot caused by P. cichorii on C. lanceolata in Italy. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) H. Bergey et al. Bergey's Manual on Determinative Bacteriology. Williams and Wilkins, Baltimore, MD, 1994. (3) A. Garibaldi et al. Plant Dis. 89:912, 2005.

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First Report of Bacterial Leaf Spot of Spinach Caused by a Pseudomonas syringae Pathovar in California

Plant Disease ◽

10.1094/pdis.2002.86.8.921a ◽

2002 ◽

Vol 86 (8) ◽

pp. 921-921 ◽

Cited By ~ 3

Author(s):

S. T. Koike ◽

H. R. Azad ◽

D. C. Cooksey

Keyword(s):

Brassica Oleracea ◽

Beta Vulgaris ◽

Pseudomonas Syringae ◽

Leaf Spot ◽

The United States ◽

Nutrient Broth ◽

Bacterial Leaf Spot ◽

First Report ◽

Leaf Spots ◽

Initial Symptoms

In 2000 and 2001, a new disease was observed on commercial spinach (Spinacia oleracea) in the Salinas Valley, Monterey County, CA. Initial symptoms were water-soaked, irregularly shaped leaf spots (2 to 3 mm diameter). As the disease developed, spots enlarged to as much as 1 to 2 cm, were vein-delimited, and turned dark brown. Faint chlorotic halos sometimes surrounded the spots. Death of large areas of the leaf occurred if spots coalesced. Spots were visible from the adaxial and abaxial sides of leaves, and no fungal structures were observed. The disease occurred on newly expanded and mature foliage. No fungi were isolated from the spots. However, cream-colored bacterial colonies were consistently isolated on sucrose peptone agar, and these strains were nonfluorescent on King's medium B. Strains were positive for levan and negative for oxidase, arginine dihydrolase, and nitrate reductase. Strains did not grow at 36°C, did not rot potato slices, but induced a hypersensitive reaction in tobacco (Nicotiana tabacum cv. Turk). These results suggested the bacterium was similar to Pseudomonas syringae. Fatty acid methyl ester (FAME) analysis (MIS-TSBA 4.10, MIDI Inc., Newark, DE) indicated the strains were highly similar (80.1 to 89.3%) to P. syringae pv. maculicola. However, in contrast to P. syringae pv. maculicola, the spinach strains did not utilize the carbon sources erythritol, L+tartrate, L lactate, and DL-homoserine. Pathogenicity of 10 strains was tested by growing inoculum in nutrient broth shake cultures for 48 h, diluting to 106 CFU/ml, and spraying 4-week-old plants of spinach cv. Bossanova. Control plants were sprayed with sterile nutrient broth. After 5 to 8 days in a greenhouse (24 to 26°C), leaf spots identical to those observed in the field developed on cotyledons and true leaves of inoculated plants. Strains were reisolated from the spots and identified as P. syringae. Control plants remained symptomless. The 10 strains were also inoculated on beet (Beta vulgaris), Swiss chard (Beta vulgaris subsp. cicla), cilantro (Coriandrum sativum), and spinach. Spinach showed leaf spots after 8 days; however, none of the other plants developed symptoms. Two strains were inoculated onto spinach cvs. Califlay, Lion, Nordic IV, Polka, Resistoflay, Rushmore, RZ 11, Spinnaker, Springfield, Viroflay, and Whitney. Leaf spot developed on all cultivars, and the pathogen was reisolated. Because the FAME data indicated a similarity between the spinach pathogen and P. syringae pv. maculicola, we inoculated sets of spinach cv. Bolero, cabbage (Brassica oleracea subsp. capitata cv. Grenedere), and cauliflower (Brassica oleracea subsp. botrytis cv. White Rock) with three P. syringae pv. maculicola and three spinach strains. Cabbage and cauliflower developed leaf spots only when inoculated with P. syringae pv. maculicola; spinach had leaf spots only when inoculated with the spinach strains. All inoculation experiments were done twice, and the results of the two tests were the same. To our knowledge, this is the first report of bacterial leaf spot of spinach in California caused by a nonfluorescent P. syringae, and the first record of this disease in the United States. Biochemical characteristics and limited host range of the pathogen indicate the California strains are likely the same as the P. syringae pv. spinaciae pathogen that was reported in Italy (1) and Japan (2). References: (1) C. Bazzi et al. Phytopathol. Mediterr. 27:103, 1988. (2) K. Ozaki et al. Ann. Phytopathol. Soc. Jpn. 64:264, 1998.

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First Report of Bacterial Leaf Spot of Cucumber Caused by Pseudomonas cichorii in China

Plant Disease ◽

10.1094/pdis-02-18-0267-pdn ◽

2019 ◽

Vol 103 (1) ◽

pp. 147

Author(s):

X. Y. Fu ◽

R. Y. Zhang ◽

Z. Q. Tan ◽

T. Liu ◽

Z. Q. Peng

Keyword(s):

Leaf Spot ◽

Bacterial Leaf Spot ◽

Pseudomonas Cichorii ◽

First Report

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First Report of Bacterial Leaf Spot of Swiss Chard Caused by Pseudomonas syringae pv. aptata in California

Plant Disease ◽

10.1094/pdis.2003.87.11.1397b ◽

2003 ◽

Vol 87 (11) ◽

pp. 1397-1397 ◽

Cited By ~ 6

Author(s):

S. T. Koike ◽

D. M. Henderson ◽

C. T. Bull ◽

P. H. Goldman ◽

R. T. Lewellen

Keyword(s):

Fatty Acid ◽

Sugar Beet ◽

Pseudomonas Syringae ◽

Leaf Spot ◽

Nutrient Broth ◽

Pcr Analysis ◽

Bacterial Leaf Spot ◽

First Report ◽

Leaf Spots ◽

Swiss Chard

From 1999 through 2003, a previously unreported disease was found on commercial Swiss chard (Beta vulgaris subsp. cicla) in the Salinas Valley, (Monterey County) California. Each year the disease occurred sporadically throughout the long growing season from April through September. Initial symptoms were water-soaked leaf spots that measured 2 to 3 mm in diameter. As disease developed, spots became circular to ellipsoid, 3 to 8 mm in diameter, and tan with distinct brown-to-black borders. Spots were visible from the adaxial and abaxial sides. Cream-colored bacterial colonies were consistently isolated from spots. Strains were fluorescent on King's medium B, levan positive, oxidase negative, and arginine dihydrolase negative. Strains did not rot potato slices but induced a hypersensitive reaction on tobacco (Nicotiana tabacum cv. Turk). The isolates, therefore, belong in LOPAT group 1 (1). Fatty acid methyl esters (FAME) analysis (MIS-TSBA version 4.10, MIDI Inc., Newark, DE) gave variable results that included Pseudomonas syringae, P. cichorii, and P. viridiflava with similarity indices ranging from 0.91 to 0.95. BOX-polymerase chain reaction (PCR) analysis gave identical banding patterns for the chard isolates and for known P. syringae pv. aptata strains, including the pathotype strain CFBP1617 (2). The bacteria were identified as P. syringae. Pathogenicity of 11 strains was tested by growing inoculum in nutrient broth shake cultures for 48 h, diluting to 10 × 6 CFU/ml, and spraying onto 5-week-old plants of Swiss chard cvs. Red, White, Silverado, and CXS2547. Untreated control plants were sprayed with sterile nutrient broth. After 7 to 10 days in a greenhouse (24 to 26°C), leaf spots similar to those observed in the field developed on all inoculated plants. Strains were reisolated from the spots and identified as P. syringae. Control plants remained symptomless. To investigate the host range of this pathogen, the same procedures were used to inoculate three strains onto other Chenopodiaceae plants: five cultivars of sugar beet (B. vulgaris), and one cultivar each of spinach (Spinacia oleracea) and Swiss chard. In addition, five chard strains and strain CFBP1617 were inoculated onto two cultivars of sunflower (Helianthus annuus), and one cultivar each of cantaloupe (Cucumis melo), sugar beet, spinach, and Swiss chard. All Swiss chard, cantaloupe, sunflower, and sugar beet plants developed leaf spots after 7 days. The pathogen was reisolated from spots and confirmed to be the same bacterium using BOX-PCR analysis. Spinach and untreated controls failed to show symptoms. All inoculation experiments were done at least twice and the results were the same. The phenotypic data, fatty acid and genetic analyses, and pathogenicity tests indicated that these strains are P. syringae pv. aptata. To our knowledge this is the first report of bacterial leaf spot of commercially grown Swiss chard in California caused by P. syringae pv. aptata. The disease was particularly damaging when it developed in Swiss chard fields planted for “baby leaf” fresh market products. Such crops are placed on 2-m wide beds, planted with high seed densities, and are sprinkler irrigated. This disease has been reported from Asia, Australia, Europe, and other U.S. states. References: (1) R. A. Lelliott et al. J. Appl. Bacteriol. 29:470, 1966. (2) J. L. W. Rademaker et al. Mol. Microbiol. Ecol. Man. 3.4.3:1–27, 1998.

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First Report of Bacterial Leaf Spot Caused by Pseudomonas cichorii on Thai Basil in Hawaii

Plant Disease ◽

10.1094/pdis-06-18-0995-pdn ◽

2018 ◽

Vol 102 (12) ◽

pp. 2637-2637

Author(s):

B. C. Luiz ◽

W. P. Heller ◽

E. Brill ◽

B. C. Bushe ◽

L. M. Keith

Keyword(s):

Leaf Spot ◽

Bacterial Leaf Spot ◽

Pseudomonas Cichorii ◽

First Report

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First Report of Bacterial Leaf Spot of Basil Caused by Pseudomonas viridiflava in Argentina

Plant Disease ◽

10.1094/pdis.1999.83.9.876b ◽

1999 ◽

Vol 83 (9) ◽

pp. 876-876 ◽

Cited By ~ 4

Author(s):

A. M. Alippi ◽

S. Wolcan ◽

E. Dal Bó

Keyword(s):

Leaf Spot ◽

Disease Incidence ◽

Tween 80 ◽

Pathogenic Fungi ◽

Soft Rot ◽

Bacterial Leaf Spot ◽

First Report ◽

Arginine Dihydrolase ◽

Pseudomonas Viridiflava ◽

Physiological Tests

In June 1998, during a cool, humid period, typical bacterial spot symptoms were observed on basil plantlets (Ocimun basilicum L. ‘Royal Louis’ and ‘Zaes’) in a commercial greenhouse in La Plata, Argentina. Affected plants had dark brown to black lesions on cotyledons. Spots on leaves were first water soaked, then became necrotic and progressed inward from the margins. Disease incidence approached 30%. Symptoms were similar to those reported by Little et al. (2) on basil affected by Pseudomonas viridiflava. No pathogenic fungi or viruses were associated with symptomatic plants. Bacterial streaming was observed from lesion margins. Bacteria consistently isolated from leaf lesions formed cream-colored, glistening, convex colonies on sucrose peptone agar and a green fluorescent pigment on King's medium B. Bacterial growth produced a distinctive olive green pigment on glycerol agar medium and a pink pigment on T-5 medium (1). Four isolates selected for further study were aerobic, Gram-negative, non-spore-forming rods. In LOPAT (levan-oxidase-potato rot-arginine dihydrolase-tobacco hypersensitivity) tests, all induced a hypersensitive response in tobacco plants, caused soft rot of potato tubers, and were negative for levan, oxidase, and arginine dihydrolase. In addition, strains rotted onion slices and produced a reddish sunken lesion on bean pods. Acid was produced aerobically from D-glucose, mannitol, mesoinositol and sorbitol, but not from D-arabinose, L-rhamnose, melibiose, amygdalin, or sucrose. Bacteria used D-tartrate, pyruvate, and citrate, but not benzoate. The strains did not hydrolyze starch, exhibited an oxidative metabolism of glucose, and did not reduce nitrates to nitrites or accumulate poly-β-hydroxybutyrate inclusions. Negative reactions were obtained with indole, ornithine, and D-tryptophan. Isolates hydrolyzed gelatine, used Tween 80, were positive for catalase, and were unable to grow in the presence of 5% NaCl. Colonies developed at 4°C but not 37°C. Reactions were identical to those of reference strains ICMP 5776 and 12363, which were included in all tests for comparison. Pathogenicity was verified on 35-day-old basil plants by both spraying and infiltration inoculations with bacterial suspensions (108 and 105 cells per ml, respectively). Carborundum was included in the inoculum used for a set of plants inoculated by spraying. Controls were injected or sprayed (with and without Carborundum) with sterile, distilled water. In addition, bean (Phaseolus vulgaris cv. Nag12 INTA) and lettuce (Lactuca sativa cv. criolla), both reported as host plants, were inoculated by spraying with bacterial suspensions of 107 cells per ml plus Carborundum. After 48 h in a humid chamber, inoculated plants and controls were maintained at 23 ± 3°C. Symptoms on basil plants inoculated by injection or spraying with Carborundum were identical to those observed on basil in the field. Symptoms on bean and lettuce were similar to those described for P. viridiflava. The bacterium was reisolated from lesions of all species tested, fulfilling Koch's postulates. No lesions were observed on controls or on plants sprayed without Carborundum, suggesting that bacteria gain entry through wounds. The microorganism was identified by physiological tests and polymerase chain reaction as P. viridiflava. This is the first report of bacterial leaf spot of basil in Argentina. References: (1) R. Gitaitis et al. Plant Dis. 81:897, 1997. (2) E. L. Little et al. Plant Dis. 78:831, 1994.

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First Report of Bacterial Leaf Spot of Witloof, Caused by Pseudomonas cichorii in Korea

Plant Disease ◽

10.1094/pdis-04-13-0436-pdn ◽

2013 ◽

Vol 97 (10) ◽

pp. 1376-1376 ◽

Cited By ~ 1

Author(s):

I.-S. Myung ◽

J.-K. Choi ◽

J. Y. Lee ◽

M.-J. Yoon ◽

E. Y. Hwang ◽

...

Keyword(s):

16S Rrna ◽

Economic Impact ◽

Leaf Spot ◽

Reference Strain ◽

Bacterial Leaf Spot ◽

Pseudomonas Cichorii ◽

First Report ◽

Field Isolates ◽

Original Field ◽

Index Value

In August 2011, bacterial leaf spot was observed on witloof (Cichorium intybus L. var. foliosum) grown in a commercial field with 15% incidence in Injae, Korea. Symptoms on leaves included irregular brown to reddish brown spots in the center. Bacterial streaming from the lesions was observed microscopically. Bacterial isolates (BC3286, BC3287, and BC3308-BC3310) were recovered on Trypticase soy agar from lesions surface-sterilized in 70% ethyl alcohol for 30 s. The isolates were gram negative, urease negative, fluorescent on King's B agar, and had aerobic rods with 2 to 6 polar flagella. Pathogenicity tests were separately performed in different greenhouses located in Suwon (National Academy of Agricultural Science) and Chuncheon (Gangwondo Agricultural Research and Extension Services) in Korea. Pathogenicity was confirmed by spray inoculation of healthy, 10-day-old leaves of witloof plants (two plants/isolate) with a suspension of original field isolate (106 CFU/ml). Sterile distilled water was used as negative control. The inoculated plants were incubated in a growth chamber (25°C and 95% relative humidity [RH]) overnight, then transferred to a greenhouse at 23 to 27°C and 60 to 70% RH. Characteristic leaf spot symptoms were observed on inoculated witloof plants 8 days after inoculation. No symptoms were observed on control plants. The bacterium reisolated from the inoculated leaves was confirmed by analyzing sequence of the gyrB gene with direct sequencing method of PCR products using primers gyr-F and gyr-R (2). The sequence of reisolated bacteria shared 100% similarity with inoculated ones. In LOPAT (1) tests, all isolates and the reference strain of Pseudomonas cichorii CFBP2101T (=BC2595) were levan negative, oxidase positive, potato rot negative, arginine dihydrolase negative, and tobacco hypersensitivity positive, indicative of group III (–, +, –, –, +) of fluorescent pseudomonads. The 16S rRNA (1,408 bp), and gyrB (676 bp) regions were sequenced to aid in identification of the original field isolates as well as P. cichorii CFBP 2101T (=BC2595) using reported sets of PCR primers, fD1/rP2 and gyr-F/gyr-R, respectively (2,4). Phylogenetic analyses based on partial sequences of the gyrB and the 16S rRNA of Psudomonas spp. available in GenBank, the reference strain of P. cichorii CFBP2101T (=BC2595), and the witloof field isolates were conducted using the neighbor-joining method with Juke-Cantor model of distance calculation in MEGA version 5.1 (3). The isolates and the reference strain of P. cichorii CFBP2101T (=BC2595) was clustered in one group with P. cichorii strains in both phylogenetic trees based on the two sequences. Sequences of the 16S rRNA region had a distance index value ranging from 0.000 to 0.001 between the reference strain of P. cichori CFBP2101T (GenBank JX913784) and the field isolates (JX913785 to JX913789), and ranged from 0.000 to 0.001 within the field isolates. Sequences of the gyrB region had a distance index value ranging 0.029 to 0.033 between the reference strain (JX913790) and the field isolates (JX913791 to JX913795), and ranged from 0.000 to 0.041 within the field isolates. To our knowledge, this is the first report of bacterial leaf spot of witloof caused by P. cihorii in Korea. P. cichorii has a wide host range, and an important economic impact on vegetables. The disease is expected to result in a significant economic impact on root production of witloof in Korea. References: (1) R. A. Lelliott et al. J. Appl. Bacteriol. 29:470, 1966. (2) H. Sawada et al. J. Mol. Evol. 49:627, 1999. (3) K. Tamura et al. Mol. Biol. Evol. 28:2731, 2011. (4) W. G. Weinsburg et al. J. Bacteriol. 173, 697, 1991.

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First Report of Bacterial Leaf Spot of Italian Dandelion (Cichorium intybus) Caused by a Pseudomonas syringae Pathovar in California

Plant Disease ◽

10.1094/pd-90-0245a ◽

2006 ◽

Vol 90 (2) ◽

pp. 245-245 ◽

Cited By ~ 3

Author(s):

S. T. Koike ◽

C. T. Bull

Keyword(s):

Pseudomonas Syringae ◽

Leaf Spot ◽

Late Summer ◽

Hypersensitive Reaction ◽

Cichorium Intybus ◽

Nutrient Broth ◽

Bacterial Strains ◽

Bacterial Leaf Spot ◽

First Report ◽

Leaf Spots

Italian dandelion (Cichorium intybus) is a leafy, nonhead forming chicory plant that is eaten as a fresh vegetable in salads. During the late summer (August through October) of 2002, in the Salinas Valley (Monterey County) in California, a previously unreported disease was found in commercial Italian dandelion fields. Early symptoms were angular, vein delimited, dark, water-soaked leaf spots that measured 2 to 7 mm in diameter. As disease developed, spots retained angular edges but exhibited various irregular shapes. Spots commonly formed along the edges of the leaves; in some cases these spots developed into lesions that measured between 10 and 30 mm long. Spots were visible from adaxial and abaxial sides and were dull black in color. A cream-colored pseudomonad was consistently isolated from leaf spots that were macerated and streaked onto sucrose peptone agar. Fungi were not recovered from any of the spots. Recovered strains were blue-green fluorescent when streaked onto King's medium B agar. Bacterial strains were levan positive, oxidase negative, and arginine dihydrolase negative. Strains did not rot potato slices but induced a hypersensitive reaction on tobacco (Nicotiana tabacum cv. Turk). These data indicated that the bacteria belonged to LOPAT group 1 of Pseudomonas syringae (1). Pathogenicity of six strains was tested by growing inoculum in nutrient broth shake cultures for 48 h, diluting to 106 CFU/ml, and spraying onto 12 6-week-old plants of Italian dandelion cv. Catalogna Special. Untreated control plants were sprayed with sterile nutrient broth. After 10 to 12 days in a greenhouse (24 to 26°C), leaf spots similar to those observed in the field developed on all inoculated plants. Strains were reisolated from the spots and identified as P. syringae. Control plants remained symptomless. These inoculation experiments were done twice and the results were the same. Amplification of repetitive bacterial sequences (repetitive sequence-based polymerase chain reaction [rep-PCR]) demonstrated that all Italian dandelion strains had the same rep-PCR fingerprint, which differed from fingerprints of P. syringae pv. tagetis and P. syringae pv. tabaci. Additionally, toxin specific primers did not amplify tagetitoxin or tabtoxin biosynthesis genes from Italian dandelion strains. To our knowledge, this is the first report of bacterial leaf spot of commercially grown Italian dandelion in California caused by a P. syringae pathovar. Because fields were irrigated with overhead sprinklers, the disease was severe in several fields and as much as 30% of those plantings were not harvested. Reference: (1) R. A. Lelliott et al. J. Appl. Bacteriol. 29:470, 1966.

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First Report of Basil Leaf Spot Caused by Pseudomonas cichorii in Louisiana and Cultivar Screening Results

Plant Disease ◽

10.1094/pdis.1998.82.11.1283d ◽

1998 ◽

Vol 82 (11) ◽

pp. 1283-1283 ◽

Cited By ~ 2

Author(s):

G. E. Holcomb ◽

P. J. Cox

Keyword(s):

Leaf Spot ◽

Screening Tests ◽

Minor Importance ◽

Bacterial Cells ◽

Bacterial Leaf Spot ◽

Pseudomonas Cichorii ◽

First Report ◽

Sweet Basil ◽

Leaf Spots ◽

Cultivar Screening

A leaf spot of basil, Ocimum basilicum L., was observed on container-grown and field plantings of cultivars Aussie Sweet and Sweet Basil. The disease was of minor importance under field conditions, but was of potential economic importance in seedling production. Gray to black, watersoaked, necrotic spots commonly developed at leaf margins. Large numbers of bacteria were released from cut lesions when viewed by light microscopy. Single colony bacterial isolates were established on nutrient dextrose agar (NDA) and yeast extract-dextrose-calcium carbonate agar (YDC). Pathogencity tests were performed by misting a water suspension containing 104 bacterial cells per ml on healthy basil plants. Plants were held for 24 h in a dew chamber at 26°C and then moved to a greenhouse for observation. Typical leaf spots developed on inoculated plants in 2 days, but not on healthy control plants, and the bacterium was reisolated. The bacterium was characterized as a gram-negative, motile rod, negative for potato rot test, positive in tobacco hypersensitivity test, and oxidase positive. Isolates were identified as Pseudomonas cichorii according to the Biolog Microplate system (similarities ranged from 0.937 to 0.995). Screening tests were conducted by inoculating 15 basil cultivars, six replicates each, and rating them for disease severity based on a scale of 1 to 5 in which 1 = no disease and 5 = dead plants. Cultivars most resistant to bacterial leaf spot (ratings in parentheses are averages of two tests and those followed by the same letter are not significantly different according to Tukey's Studentized Range Test, P = 0.05) were Green Bouquet (2.0 a), Piccolo (2.2 a), Mrs. Burn's Lemon (2.2 a), Genovese (2.4 a), and Dark Opal (2.5 ab). Moderately susceptible cultivars were Bush Green (2.8 abc), Sweet Basil (2.8 abc), Large Green (2.9 abcd), Lemon (3.1 abcd), and Mexican Spice (3.6 bcd). The most susceptible cultivars were Lettuce Leaved (3.8 cd), Thai (3.8 cd), Napoletano (4.0 de), Green Ruffles (5.0 e), and Purple Ruffles (5.0 e). Bacterial leaf spot of basil caused by P. cichorii was first reported in the U.S. from Florida (1). Other bacterial diseases reported on basil include leaf blight from Egypt caused by P. syringae (2) and leaf necrosis from California caused by P. viridiflava (3). This is the first report on the occurrence of basil bacterial leaf spot in Louisiana and the first reported information on cultivar susceptibility. References: (1) S. M. Burgess et al. Proc. Fla. State Hortic. Soc. 99:249, 1986. (2) S. A. M. El-Sadek et al. Assiut J. Agric. Sci. 22:2, 1991. (3) E. L. Little et al. Plant Dis. 78:831, 1994.

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First Report of Pseudomonas cichorii Causing Bacterial Leaf Spot on Sweet Basil (Ocimum basilicum) in New Jersey

Plant Disease ◽

10.1094/pdis-04-19-0895-pdn ◽

2019 ◽

Vol 103 (10) ◽

pp. 2666-2666

Author(s):

N. Patel ◽

D. Y. Kobayashi ◽

A. J. Noto ◽

A. C. Baldwin ◽

J. E. Simon ◽

...

Keyword(s):

New Jersey ◽

Leaf Spot ◽

Ocimum Basilicum ◽

Bacterial Leaf Spot ◽

Pseudomonas Cichorii ◽

First Report ◽

Sweet Basil

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First Report of Bacterial Leaf Spot of Basil Caused by Pseudomonas viridiflava in Hungary

Plant Disease ◽

10.1094/pdis-09-11-0726 ◽

2012 ◽

Vol 96 (1) ◽

pp. 141-141 ◽

Cited By ~ 4

Author(s):

A. Végh ◽

M. Hevesi ◽

Zs. Némethy ◽

L. Palkovics

Keyword(s):

Leaf Spot ◽

Sequence Similarity ◽

Soft Rot ◽

Hypersensitive Reaction ◽

Bacterial Suspension ◽

Bacterial Leaf Spot ◽

Biochemical Tests ◽

First Report ◽

Arginine Dihydrolase ◽

Pseudomonas Viridiflava

In April 2011, typical bacterial spot symptoms were observed on sweet basil plantlets (Ocimum basilicum L.) in a supermarket in Budapest, Hungary. Affected plants had dark brown-to-black lesions on the cotyledons. Spots on the leaves were first water soaked and then became necrotic and progressed inward from the margins. Symptoms were similar to those reported by Little et al. (3) on basil affected by Pseudomonas viridiflava. Bacteria consistently isolated from leaf lesions formed mucoid colonies with a green fluorescent pigment on King's B medium. Strains were gram negative. In LOPAT (levan-oxidase-potato rot-arginine dihydrolase-tobacco hypersensitivity) tests (2), all induced a hypersensitive reaction (HR) in tobacco (Nicotiana tabacum L. cv. White Burley) leaves (1), caused soft rot of potato tuber slices, and were negative for levan, oxidase, and arginine dihydrolase. Biochemical tests, API 20NE and API 50 CH (Biomérieux, Marcy l'Etoile, France), were also used for identification. The pathogenicity of three isolates was tested twice by injecting 20-day-old healthy basil plants with a bacterial suspension (107 CFU/ml). Controls were injected with sterile distilled water. Plants were kept at 25 to 28°C and 80 to 100% relative humidity. Forty-eight hours after inoculation, dark brown-to-black lesions were observed only on inoculated plants. The bacterium was reisolated from lesions of all plants tested, fulfilling Koch's postulates. No lesions were observed on controls. To identify the pathogen, a PCR technique was used. The 16SrDNA region was amplified with general bacterial primer pair (63f forward and 1389r reverse) (4) then the PCR products were cloned into Escherichia coli DH5α cells and a recombinant plasmid was sequenced by M13 forward and reverse primers. The sequence was deposited in GenBank (Accession No. HE585219). On the basis of the symptoms, biochemical tests, and 16SrDNA sequence homology (99% sequence similarity with a number of P. viridiflava isolates), the pathogen was identified as P. viridiflava. To our knowledge, this is the first report of bacterial leaf spot of basil in Hungary, which can seriously affect the basil production. References: (1) Z. Klement. Nature 199:299, 1963. (2) R. A. Lelliot et al. Appl. Bacteriol. 29:470, 1966. (3) E. L. Little et al. Plant Dis. 78:831, 1994. (4) A. M. Osborn et al. Environ. Microbiol. 2:39, 2000.

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