scholarly journals FIELD EVALUATION OF NEW BELL PEPPER CULTIVARS FOR BACTERIAL LEAF SPOT RESISTANCE

HortScience ◽  
1996 ◽  
Vol 31 (5) ◽  
pp. 745e-745
Author(s):  
Brent Rowell ◽  
Terry Jones ◽  
William Nesmith
Keyword(s):  
Leaf Spot ◽  
Xanthomonas Campestris ◽  
Field Evaluation ◽  
Field Resistance ◽  
Fresh Market ◽  
Bacterial Leaf Spot ◽  
Resistant Varieties ◽  
Bell Peppers ◽  
Race 2 ◽  
Disease Free

Kentucky growers currently produce about 1300 acres of bell peppers worth $2 million for both fresh market and processing. Bacterial leaf spot (BLS) caused by Xanthomonas campestris pv. vesicatoria has been the scourge which continues to limit expansion of pepper production in the state. Fourteen new BLS-resistant varieties and experimental lines were evaluated together with two standard (susceptible) varieties in 1995 at two locations. All entries were exposed to an induced BLS epidemic at one location but were kept disease-free at the second location. Field resistance to four races of BLS was high for all but one of the lines tested, which claimed resistance to races 1, 2, and 3. Cultivars with resistance to only race 2 or races 1 and 2 of the pathogen were no different from susceptible checks in terms of yields and disease resistance. Six entries performed well at both locations; these will be included in further trials in 1996.

scholarly journals Field Tolerance of Bell Pepper Cultivars to Bacterial Leaf Spot under Epidemic Conditions

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 568f-569
Author(s):  
Brent Rowell ◽  
R. Terry Jones ◽  
William Nesmith
Keyword(s):  
Leaf Spot ◽  
Xanthomonas Campestris ◽  
Field Resistance ◽  
Fresh Market ◽  
Bacterial Leaf Spot ◽  
Breeding Lines ◽  
Epidemic Development ◽  
Race 2 ◽  
Free Environment ◽  
Disease Free

Bacterial leaf spot (BLS) caused by Xanthomonas campestris pv. vesicatoria is the scourge that has devastated and continues to limit expansion of both fresh-market and processing pepper production in Kentucky. Fourteen new BLS-resistant varieties and breeding lines were evaluated together with two standard (susceptible) varieties in 1995 at two locations. Twenty advanced lines and commercial varieties were tested at the same locations in 1996. All entries were exposed to an induced BLS epidemic at one location, but were kept disease-free at the second location. Epidemic development was slow and field resistance to four races of BLS was high for all but one of the lines tested, which claimed resistance to races 1, 2, and 3 in 1995. Six entries performed well both under BLS epidemic conditions and in the disease-free environment in 1995. Cultivars with resistance to only race 2 or races 1 and 2 of the pathogen were no different from susceptible checks in terms of yields and disease resistance and were not tested in 1996; combined results form 1995 and 1996 are discussed.

scholarly journals Bacterial Leaf Spot of Lettuce: Relationship of Temperature to Infection and Potential Host Range of Xanthomonas campestris pv. vitians

Plant Disease ◽  
2006 ◽  
Vol 90 (4) ◽  
pp. 465-470 ◽  
Author(s):  
P. E. Robinson ◽  
J. B. Jones ◽  
Ken Pernezny
Keyword(s):  
Host Range ◽  
Plant Species ◽  
Leaf Spot ◽  
Electrolyte Leakage ◽  
Xanthomonas Campestris ◽  
Optimum Temperature ◽  
Fresh Market ◽  
Bacterial Leaf Spot ◽  
Causal Organism ◽  
Potential Host

Epidemiological aspects, including optimum temperature for infection and host range of Xanthomonas campestris pv. vitians, causal organism of bacterial leaf spot (BLS) of lettuce, were investigated. The optimum temperature for infection was determined to be 22.7°C based on growth chamber studies. Internal populations were monitored over time in lettuce, tomato, pepper, parsley, cilantro, and beet. Each plant species was infiltrated with the bacterium at 105CFU/ml. Highest populations developed in lettuce (108CFU/cm2) followed by pepper with 106CFU/cm2, whereas the other plant species harbored much lower populations (105 to 103CFU/cm2). Infectivity titration endpoints were similar in pepper and lettuce (103 to 104CFU/ml). For other plant species tested, infectivity titration endpoints were 106 to 107 CFU/ml. Electrolyte leakage data and corresponding internal population data support the conclusion that fresh-market tomato is not a host of X. campestris pv. vitians but, instead, interacts in an incompatible response. Electrolyte leakage from cells of tomato plants inoculated with X. campestris pv. vitians or a pepper strain of X. axonopodis pv. vesicatoria peaked at 48 h, suggesting that tomato is not a host for the BLS pathogen. Both electrolyte leakage and population dynamics results point to pepper as a potential host of X. campestris pv. vitians.

scholarly journals Bacterial Leaf Spot of Zinnia Caused by Xanthomonas campestris pv. zinniae, a New Disease in Korea

Plant Disease ◽  
2012 ◽  
Vol 96 (7) ◽  
pp. 1064-1064 ◽  
Author(s):  
I.-S. Myung ◽  
J. Y. Lee ◽  
H. L. Yoo ◽  
J. M. Wu ◽  
H.-S. Shim
Keyword(s):  
Leaf Spot ◽  
Xanthomonas Campestris ◽  
Negative Control ◽  
Gyrb Gene ◽  
23S Rrna ◽  
Distilled Water ◽  
Bacterial Leaf Spot ◽  
Field Isolates ◽  
Sequence Identity ◽  
Physiological Tests

In September 2011, bacterial leaf spot was observed on zinnia plants (Zinnia elegans L.) grown in a garden in Suwon, Korea. Leaf symptoms included angular lesions that were yellow or brown-to-reddish brown in the center. Bacterial isolates (BC3293 to BC3299) were recovered on trypticase soy agar from lesions surface-sterilized in 70% ethyl alcohol for 1 min. Pathogenicity of the isolates was confirmed by spray inoculation with a bacterial suspension (106 CFU/ml) prepared in sterile distilled water and applied to zinnia plants at the four- to five-leaf growth stage (two plants per isolate). Sterile distilled water was used as the negative control. The inoculated plants were incubated in a greenhouse at 26 to 30°C and 95% relative humidity. Characteristic leaf spot symptoms developed on inoculated zinnia plants 5 days after inoculation. No symptoms were observed on the negative control plants. The bacterium reisolated from the inoculated leaves was confirmed through gyrB gene sequence analysis (3). All isolates were gram-negative, aerobic rods, each with a single flagellum. Isolates were positive for catalase and negative for oxidase. The biochemical and physiological tests for differentiation of Xanthomonas were performed using methods described by Shaad et al. (2). The isolates were positive for mucoid growth on yeast extract-dextrose-calcium carbonate agar, growth at 35°C, hydrolysis of starch and esculin, protein digestion, acid production from arabitol, and utilization of glycerol and melibiose. Colonies were negative for ice nucleation, and alkaline in litmus milk. The gyrB gene (870 bp) and the 16S-23S rRNA internal transcribed spacer (ITS) regions (884 bp) were sequenced to aid in identification of the original field isolates using published PCR primer sets Xgyr1BF/Xgyr1BR (3) and A1/B1 (1), respectively. Sequence of the gyrB gene (GenBank Accession Nos. JQ665732 to JQ665738) from the zinnia field isolates shared 100% sequence identity with the reference strain of Xanthomonas campestris pv. zinniae (GenBank Accession No. EU285210), and the ITS sequences (GenBank Accession Nos. JQ665725 to JQ665731) had 99.9% sequence identity with X. campestris pv. zinnia XCZ-1 (GenBank Accession No. EF514223). On the basis of the pathogenicity assays, biochemical and physiological tests, and sequence analyses, the isolates were identified as X. campestris pv. zinniae. To our knowledge, this is the first report of bacterial leaf spot of zinnia caused by X. campestris pv. zinniae in Korea. The disease is expected to result in economic and aesthetic losses to plants in Korean landscapes. Thus, seed treatment with bactericides will be required to control the bacterial leaf spot of zinnia before planting. References: (1) T. Barry et al. The PCR Methods Appl. 1:51, 1991. (2) N. W. Schaad et al. Page 189 in: Laboratory Guide for Identification of Plant Pathogenic Bacteria. 3rd ed. N. W. Schaad et al., eds. The American Phytopathological Society, St. Paul, MN, 2001. (3) J. M. Young et al. Syst. Appl. Microbiol. 31:366, 2008.

Bacterial leaf spot of hemp caused by Xanthomonas campestris pv. cannabis in Japan

2013 ◽  
Vol 80 (2) ◽  
pp. 164-168 ◽  
Author(s):  
Osamu Netsu ◽  
Toshio Kijima ◽  
Yuichi Takikawa
Keyword(s):  
Leaf Spot ◽  
Xanthomonas Campestris ◽  
Bacterial Leaf Spot

scholarly journals Report of Bacterial Leaf Spot on Collards and Turnip Leaves in Ohio

Plant Disease ◽  
2002 ◽  
Vol 86 (2) ◽  
pp. 186-186 ◽  
Author(s):  
M. L. Lewis Ivey ◽  
S. Wright ◽  
S. A. Miller
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Xanthomonas Campestris ◽  
Similarity Index ◽  
Acid Methyl Ester ◽  
Bacterial Suspension ◽  
Water Control ◽  
Bacterial Leaf Spot ◽  
Turnip Leaves ◽  
Negative Controls

In 2000, circular water-soaked lesions typical of bacterial leaf spot were observed on leaves of collards (Brassica oleracea L. var. viridis) throughout commercial fields in northwest Ohio. Light brown, rectangular, water-soaked lesions were observed on turnip leaves (Brassica rapa L.). Bacterial streaming from lesions on both crops was observed microscopically. Cream colored, fluorescent colonies were isolated from diseased tissues on Pseudomonas F medium, and eight representative colonies (four from collards and four from turnip) were selected and purified. Fatty acid methyl ester analysis was performed on all of the isolates. Two from collards and two from turnip were identified as Pseudomonas syringae pv. maculicola (mean similarity index = 0.82 [MIDI Inc., Newark, DE]). DNA extracts from pure cultures of the P. syringae pv. maculicola strains were used as template in a polymerase chain reaction (PCR) assay with primers derived from the region of the coronatine gene cluster controlling synthesis of the coronafacic acid moiety found in P. syringae pv. tomato and P. syringae pv. maculicola (CorR and CorF2) (D. Cuppels, personal communication). DNA from P. syringae pv. tomato strain DC3000 and P. syringae pv. maculicola strain 88–10 (2) served as positive controls, while water and DNA from Xanthomonas campestris pv. vesicatoria strain Xcv 767 were used as negative controls. The expected 0.65-kb PCR product was amplified from three of four strains (two from turnip and one from collards) and the positive control DNA, but not from the negative controls. Pathogenicity tests were performed twice on 6-week-old turnip (‘Forage Star’, ‘Turnip Topper’, ‘Turnip Alamo’, ‘Turnip 7’), collard (‘Champion’) and mustard (Brassica juncea L. ‘Southern Giant Curl’) seedlings using the three PCR-positive strains. Premisted seedlings were spray-inoculated separately with each of the three strains (2 × 108 CFU/ml, 5 ml per plant) and a water control. Greenhouse temperatures were maintained at 20 ± 1°C. For both tests, all strains caused characteristic lesions on all of the crucifer cultivars within 5 days after inoculation; the control plants did not develop symptoms. To satisfy Koch's postulates, one of the turnip strains was reisolated from ‘Turnip Topper’ plants, and the collard strain was reisolated from ‘Champion’ plants. The three original and two reisolated strains induced a hypersensitive response in Mirabilis jalapa L. and Nicotiana tabacum L. var. xanthia plants 24 h after inoculation with a bacterial suspension (1 × 108 CFU/ml). The original and reisolated strains were compared using rep-PCR with the primer BOXA1R (1). The DNA fingerprints of the reisolated strains were identical to those of the original strains. To our knowledge, this is the first report of bacterial leaf spot on commercially grown collards and turnip greens in Ohio. References: (1) B. Martin et al. Nucleic Acids Res. 20:3479, 1992. (2) R. A. Moore et al. Can. J. Microbiol. 35:910, 1989.

scholarly journals Pathogenic variability of Pseudocercospora griseola isolates from two provinces of Ecuador

2017 ◽  
Vol 101 (1) ◽  
pp. 107-119
Author(s):  
Diego Rodríguez ◽  
Laura Vega ◽  
Ángel Murillo ◽  
Eduardo Peralta
Keyword(s):  
Leaf Spot ◽  
Field Resistance ◽  
Angular Leaf Spot ◽  
Grain Legume ◽  
Phaseolus Vulgaris L ◽  
Breeding Lines ◽  
Resistant Varieties ◽  
Pathogenic Variability ◽  
Pseudocercospora Griseola ◽  
Sown Area

Common bean (Phaseolus vulgaris L.) is the most important edible grain legume in Ecuador. The Ministry of Agriculture, Cattle Raising, Aquaculture and Fisheries of this country estimated that 71,600 hectares were cultivated in 2012; of the sown area, 53% was dedicated to dry grain and the remaining 47% to fresh grain. Beans are an important source of income for farmers and food for thousands of Ecuadorian families. Crop performance and yield are affected by diseases such as angular leaf spot caused by Pseudocercospora griseola (Sacc.) Ferraris. The best alternative for disease control is to use resistant varieties. However, durability of field resistance will depend on the knowledge of angular leaf spot variability. In Ecuador, detailed and systematic studies on the variability of the angular leaf spot pathogen have not been conducted. For this reason, the pathogenic variability of 21 isolates of angular leaf spot, collected from the provinces of Carchi and Imbabura in the Ecuadorian Andes, was studied. Thirteen different pathotypes were identified, five of them showed compatibility with only the group of Andean differentials and the remaining eight showed compatibility with two groups of differentials (Andean and Mesoamerican). Race 63:0 was the most frequent and race 31:63 was the most virulent. None of the isolates were compatible with differential Cornell 49-242. Therefore, bean breeding lines in Ecuador would benefit by incorporating the Phg-2 resistance gene present in differential Cornell 49-242 .

scholarly journals First Report of Bacterial Leaf Spot of Rieger Begonia Caused by Xanthomonas campestris pv. begoniae in China

Plant Disease ◽  
2013 ◽  
Vol 97 (2) ◽  
pp. 282-282 ◽  
Author(s):  
L. H. Zhou ◽  
G. H. Ji
Keyword(s):  
Leaf Spot ◽  
Xanthomonas Campestris ◽  
Infection Process ◽  
Leaf Spot Disease ◽  
Leaf Margin ◽  
Bacterial Strains ◽  
Bacterial Leaf Spot ◽  
First Report ◽  
Initial Symptoms ◽  
Phosphate Buffered Saline

Rieger begonia are collectively referred to as a begonia hybrid group. Its global annual sales is 90,000,000 cutting seedlings. It is one of the top ten potted plants. In the summer of 2011, serious outbreaks of a suspected bacterial leaf spot disease were observed on five Rieger begonia cultivars (Dark Britt, Rebecca, Blitz, Barkos, and Borias). These plants were grown for potted cutting seedling production in commercial nurseries located in Shilin county of Yunnan Province, China. The initial symptoms of the disease were small circular or polygonal water-soaked needle spots on leaf margin that later these spots expanded and joined together, forming bigger inverted V-shaped necrotic specks (4). Yellow-pigmented bacterial colonies were consistently isolated from diseased leaves and stems on NA agar medium and incubated at 28°C. Twelve bacterial strains were isolated and used for further studies. All the isolates were Gram-negative, rod-shaped, motile, aerobic, and non-sporing. All of the bacterial strains isolated in the present study were identified as Xanthomonas campestris pv. begoniae (Xcb) based on biochemical and physiological identification (Biolog carbon source utilization analysis) and 16S rDNA sequences analysis and further pathogenicity determination (1). The results show that the sequence homology rate of HT1-1 (GenBank Accession No. JN648097) and X. euvesicatoria (syn. X. campestris pv vesicatoria) (GeneBank Accession No. AM039952) is 99%. This strongly suggests that the Rieger begonia isolates belong to X. campestris pv. begoniae (2). For Koch's postulates, 10 surface-disinfected young leaves from five susceptible Rieger begonia plants (cv. Dark Britt) were inoculated by spraying a phosphate-buffered saline suspension of each bacterial isolate (3.0 × 108 CFU/ml) onto the leaves (3). Controls were inoculated similarly with phosphate-buffered saline solution. All inoculated plants were covered with polyethylene bags for 24 h at 25°C and then put in the greenhouse. After inoculation, water-soaked and necrotic symptoms were observed on inoculated Rieger begonia leaves within 7 to 9 days. No symptoms were observed on controls. Bacteria were reisolated and confirmed to be identical to the original isolates by the methods described above. To our knowledge, this is the first report of Xcb causing leaf spot on Rieger begonia plants in China. The infection process of Xcb on Rieger begonia plants and rapid detection of this pathogen are underway. References: (1) M. R. Gillings et al. PNAS 12:102, 2005. (2) C. L. Oliver et al. Plant Dis. 4:96, 2012. (3) H. Ornek et al. New Dis. Rep. 13:40, 2006. (4) O. Pruvost et al. Plant Dis. 4:96, 2012.

scholarly journals A New Pathotype of Xanthomonas campestris pv. armoraciae That Causes Bacterial Leaf Spot of Radish

Plant Disease ◽  
1997 ◽  
Vol 81 (11) ◽  
pp. 1334-1334 ◽  
Author(s):  
F. Sahin ◽  
S. A. Miller
Keyword(s):  
Leaf Spot ◽  
Xanthomonas Campestris ◽  
Acid Methyl Ester ◽  
Organic Soil ◽  
Bacterial Leaf Spot ◽  
North Central ◽  
Fame Analysis ◽  
Acid Methyl ◽  
Black Spots ◽  
Similarity Indices

A previously undescribed pathotype of Xanthomonas campestris pv. armoraciae was found in 1995 on radish plants grown on organic soil in north central Ohio. Radish foliage developed numerous small, circular, water-soaked black spots, eventually with yellow halos, on the underside of the leaves, giving the foliage a yellowish, ragged appearance. Spots were also visible on the upper surface of leaves and on petioles. Yellow xanthomonad-like bacteria were consistently isolated from the lesions and confirmed as the causal agent of the disease by fulfilling Koch's postulates. All five strains purified were gram negative, rod shaped, motile, aerobic, oxidase negative, catalase positive, amylolytic, and pectolytic. They were identified as X. campestris pv. armoraciae by fatty acid methyl ester (FAME) analysis (similarity indices [SI] range = 0.21 to 0.39), the Biolog 95 GN reaction (SI range = 0.31 to 0.36), and serological reactions with X. campestris pv. campestris/X. campestris pv. armoraciae-specific monoclonal antibodies X9, X11, X21, A11, and B35 (1). All strains caused bacterial leaf spot on collard, kale, radish, horseradish, and cabbage but not on tomato or pepper. These strains were different from X. campestris pv. raphani, which is pathogenic on kale, radish, cabbage, tomato, and pepper, but not on horseradish. These strains also differed from other previously reported strains of X. campestris pv. armoraciae that do not cause infection on kale and radish (1,2). This is the first report on the existence of a different pathogenic group within X. campestris pv. armoraciae that can cause bacterial spot on kale and radish. References: (1) A. M. Alvarez et al. Phytopathology 84:1449, 1994; (2) H. E. White. Phytopathology 20:653, 1930.

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