scholarly journals First Report of a Leaf Blight of Onion Caused by Xanthomonas campestris in Colorado

Plant Disease ◽  
2000 ◽  
Vol 84 (8) ◽  
pp. 922-922 ◽  
Author(s):  
H. F. Schwartz ◽  
K. Otto
Keyword(s):  
Xanthomonas Campestris ◽  
Acid Methyl Ester ◽  
Tolerance Test ◽  
Tetrazolium Salt ◽  
First Report ◽  
Foliar Blight ◽  
Allium Cepa L ◽  
Northern Colorado ◽  
Similarity Indices ◽  
Scattered Fields

Sweet Spanish onion (Allium cepa L.) cultivars in southern Colorado (Otero and Prowers counties) have been found with symptoms of a foliar blight since 1996, and the same symptoms have been observed in northern Colorado (Weld County) since 1997. This onion disease appears to be identical to that reported from Barbados in 1971, Hawaii in 1978, and Texas in 1998 (1). Leaf blighting in scattered fields began as linear, tan to brown, water-soaked lesions that rapidly coalesced and were often surrounded by chlorotic areas, causing a general discoloration and tip die-back of affected foliage. The disease occurs generally after periods of heavy rainfall or storms. Bulb size may be reduced, and 10 to 15% yield losses have been recorded from control plots in copper-based bactericide screening nurseries naturally infected primarily by this pathogen at Rocky Ford during 1996 to 1998. Disease progression into bulbs has not been observed. Gram negative, rod-shaped, yellow bacteria were consistently recovered from infected foliar and bulb tissues on nutrient agar. The bacterial isolates utilized glucose in an oxidative manner, were catalase positive, oxidase negative, and negative for the tetrazolium salt tolerance test (0.1 and 0.02%). Two strains, one recovered during 1996 and the other in 1997, were identified by Microbe Inotech Laboratories (St. Louis, MO) as Xanthomonas campestris based on fatty acid methyl ester analysis (similarity indices of 0.81 and 0.82). A literature search indicated that classification to pathovar is lacking (2). To prove pathogenicity, a suspension (108 CFU/ml sdw) of one of the strains was sprayed to runoff onto a flat of approximately 100 8-week-old plants. Inoculated plants were placed in a dew chamber for 24 h, and then transferred to a bench and maintained at 25 to 28°C with a 12-h photoperiod and misting period for 14 days. A sample of 10 randomly selected plants with symptoms of water-soaking and discoloration was collected from which X. campestris was reisolated. No symptoms developed on seedlings sprayed with water only. This is the first report of X. campestris from onions grown in Colorado and the western continental United States. References: (1) T. Isakeit et al. Plant Dis. 84:201, 2000. (2) M. Van Den Mooter and J. Swings. Int. J. Syst. Bacteriol. 40:348–369, 1990.

scholarly journals First Report of a Leaf Blight and Bulb Decay of Onion by Pantoea ananitas in Colorado

Plant Disease ◽  
2000 ◽  
Vol 84 (7) ◽  
pp. 808-808 ◽  
Author(s):  
H. F. Schwartz ◽  
K. Otto
Keyword(s):  
Acid Methyl Ester ◽  
Heavy Rain ◽  
Storm Damage ◽  
First Report ◽  
Foliar Blight ◽  
Visual Evidence ◽  
Plastic Bags ◽  
Allium Cepa L ◽  
Scattered Fields ◽  
Physiological Tests

Sweet Spanish onion (Allium cepa L.) cultivars grown in southern Colorado displayed symptoms of foliar blight and bulb rotting after bulb initiation in early July of 1997, 1998, and 1999. This disease appears identical to that reported from infected onions in Georgia in 1997 (1). Leaf blighting began as whitish to tan lesions, which rapidly coalesced, causing a general wilt, discoloration, and death of affected foliage. A yellow-cream to light orange discoloration progressed into bulbs, resulting in the rotting of neck tissue and between scales. Infection of more than 70% of onion plants exposed to heavy rain and storm damage after bulb initiation occurred in scattered fields in Otero County. Gram negative, rod-shaped, yellow-colored bacteria were consistently recovered from infected foliar and bulb tissues on nutrient agar during this 3-year period. Physiological tests showed that the bacteria utilized glucose in an oxidative and fermentative manner and were catalase positive and oxidase negative. Two strains recovered during 1997 were identified by Microbe Inotech Laboratories (St. Louis, MO) as Pantoea ananas by gas-chromatography fatty acid methyl ester analysis, with similarity indices of 0.70 and 0.79. A literature search determined that the accepted classification is now Pantoea ananatis Serrano (2). To confirm pathogenicity, a 0.5- to 1.0-ml suspension of bacteria (108 CFU/ml sdw) of one of the strains was injected into firm onion bulbs (7.5 to 10.0 cm diameter). After incubation for 14 days at 22°C in enclosed plastic bags in the dark, bulbs were cut in half and scored for visual evidence of yellow to tan discoloration and initial dry rotting prior to reisolation of the pathogen from five of eight inoculated bulbs. No discoloration or disease developed on eight control bulbs injected with water. To our knowledge, this is the first report of P. ananatis from onion grown in Colorado and the western United States. References: (1) R. D. Gitaitis and J. D. Gay. Plant Dis. 81:1096, 1997. (2) H. G. Truper and L. de Clari. Int. J. System. Bacteriol. 47:908, 1997.

scholarly journals First Report of Leaf Blight of Onion Caused by Xanthomonas campestris in the Continental United States

Plant Disease ◽  
2000 ◽  
Vol 84 (2) ◽  
pp. 201-201 ◽  
Author(s):  
T. Isakeit ◽  
M. E. Miller ◽  
L. W. Barnes ◽  
E. R. Dickstein ◽  
J. B. Jones
Keyword(s):  
United States ◽  
Xanthomonas Campestris ◽  
Acid Methyl Ester ◽  
Leaf Blight ◽  
Nutrient Agar ◽  
Identification System ◽  
Sterile Water ◽  
First Report ◽  
Microbial Identification ◽  
Similarity Indices

In March 1998, a leaf blight of onion (Allium cepa L. ‘1015’) was found on many plants in a plot on the Texas A&M Agricultural Experiment Station in Weslaco. The symptoms were longitudinal chlorotic areas on one side of the leaf, containing sunken, elliptical necrotic lesions. Affected leaves ultimately died. Chlorotic lesions were swabbed with 70% ethanol, and tissue from beneath the epidermis was placed in a drop sterile water for 20 min. Drops were streaked on nutrient agar and incubated at 30°C. Isolations yielded gram-negative, rod-shaped bacteria that formed dark yellow, gummy colonies on yeast dextrose carbonate agar medium, hydrolyzed starch, and had a single, polar flagellum. Analysis of fatty acid methyl ester (FAME) profiles, using the Microbial Identification System (MIS, version 4.15; Microbial Identification, Newark, DE), done at the Texas Plant Disease Diagnostic Laboratory, College Station, identified nine isolates as Xanthomonas campestris (similarity indices of 0.31 to 0.54). Tests at the University of Florida supported this identification: FAME profiles using MIS version 3.9 gave similarity indices of 0.89 to 0.95, and profiles using Biolog GN Microplates, MicroLog database release 3.50 (Biolog, Hayward, CA), gave similarity indices of 0.03 to 0.76. Leaves (15 to 20 cm long) of potted onions (cv. 1015 at the five- to six-leaf stage) were infiltrated with a suspension of bacteria (107 CFU per ml), using a needle and syringe. Plants were maintained in mist chamber in a greenhouse at 24°C. Water-soaking and development of pale green color of the inoculated leaf occurred after 2 days, followed by death after 4 days. There were no symptoms on leaves inoculated with sterile water. Pathogenicity tests on four isolates were repeated once. Bacteria were reisolated on nutrient agar from symptomatic tissue but not from controls. In the field plot, disease severity did not increase as season progressed nor were there any symptoms on bulbs. Symptoms were not observed on onion during the 1999 season. X. campestris was first reported on onion from Hawaii (1). This is the first report of this pathogen on onion in the continental United States. Reference: (1) A. M. Alvarez et al. Phytopathology 68:1132, 1978.

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.

scholarly journals First Report of Rhizoctonia solani AG-2-2 IIIB Causing Foliar Blight on Bletilla striata in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Hao Zhou ◽  
Shuang-Feng Yang ◽  
Shao-Mei Wang ◽  
Ke Yao ◽  
Xiao-Yu Ye ◽  
...  
Keyword(s):  
Rhizoctonia Solani ◽  
Its Sequences ◽  
Nucleotide Sequence Analysis ◽  
Peat Moss ◽  
Its2 Region ◽  
Post Inoculation ◽  
Bletilla Striata ◽  
First Report ◽  
Foliar Blight ◽  
Initial Symptoms

Bletilla striata (Thunb.) Rchb. f. (Orchidaceae), a perennial plant, is a traditional Chinese herb (known as baiji) used to treat hemorrhage, scalding injuries, gastric ulcers, pulmonary diseases, and inflammation (Zu et al. 2019). In May 2019, foliar blight symptoms were observed on approximately 25% of B. striata (cv. Guiji No.1) plants in three plantations (∼4.5 hectares in total) in Ziyuan County, Guangxi Province, China. Initial symptoms were light brown, irregular, water-soaked spots on the plant leaves. Several spots often merged, forming large, irregular, lesions that extended onto the stem after a week and led to leaf abscission, and even plant death. To determine the causal agent, 5-mm squares cut from the margin of 6 infected leaves were surface disinfected in 1% sodium hypochlorite solution for 2 min, rinsed three times with sterile distilled water, plated on potato dextrose agar (PDA), and incubated at 28°C (12-h light-dark cycle) for 3 days. The emerging hyphal tip of a single mycelium was transferred to PDA to obtain pure cultures of the isolates. Twenty isolates were obtained, and 10 isolates (50%) were initially white before turning light brown (∼4 days). Septate hyphae were 4.29 to 10.75 μm (average 6.42 μm) in diameter and branched at right angles with a constriction at the origin of the branch point. Staining with 1% safranin O and 3% KOH solution (Bandoni 1979) revealed multinucleated cells (3 to 9 nuclei per cell, n = 142). This morphology was typical of Rhizoctonia solani Kühn (Meyer et al. 1990). For species confirmation by molecular identification, three isolates (BJ101.6, BJ101.11, and BJ102.2) were cultured on PDA for 4 days, then DNA was extracted from the mycelium using the CTAB method (Guo et al. 2000), and the ribosomal ITS1-5.8S-ITS2 region was amplified by PCR using the universal fungal primers ITS1 and ITS4 (White et al. 1990). Internal transcribed spacer (ITS) sequences of strains BJ101.6, BJ101.11, and BJ102 (deposited in GenBank under accession nos MT406271, MT892815, and MT892814, respectively) had over 99% similarity with those of R. solani AG-2-2 IIIB in GenBank (accession nos JX913810 and AB054858) (Carling et al. 2002; Hong et al. 2012). Phylogenetic analysis using ITS sequences showed that the isolates clustered monophyletically with strains of R. solani AG-2-2 IIIB. The AG of the isolates was confirmed by their ability to grow well on PDA at 35°C, which separates AG-2-2 IIIB from AG-2-2 IV (Inokuti et al. 2019). Based on morphological characteristics and nucleotide sequence analysis, the isolates were identified as R. solani AG-2-2 IIIB. Pathogenicity was tested using 1.5-year-old B. striata (cv. Guiji No.1) plants grown in a perlite and peat moss mixture (1:3) in 7-cm pots. Healthy leaves on plants were inoculated with an aqueous suspension (approximately 1 × 105 hyphal fragments/mL, 100 μL) prepared from cultures of strains BJ101.6, BJ101.11, and BJ102.2, each isolate was inoculated onto three plants; three other plants with sterile water served as controls. All plants were enclosed in transparent plastic bags and incubated in a greenhouse at 28°C for 14 days (12-h photoperiod). Three days post-inoculation, leaves exposed to the mycelial fragments had symptoms similar to those originally observed in the field. No symptoms were detected on control plants. Experiments were replicated three times with similar results. To fulfill Koch’s postulates, R. solani AG-2-2 IIIB was re-isolated on PDA from symptomatic leaves and confirmed by sequencing, whereas no fungus was isolated from the control plants. To our knowledge, this is the first report of R. solani AG-2-2 IIIB causing foliar blight on B. striata in China, and these findings will be useful for further control strategies and research.

scholarly journals First Report of Phytophthora drechsleri Associated with Stem and Foliar Blight of Gynura bicolor in Taiwan

Plant Disease ◽  
2011 ◽  
Vol 95 (7) ◽  
pp. 874-874 ◽  
Author(s):  
Y. M. Shen ◽  
C. H. Chao ◽  
H. L. Liu
Keyword(s):  
Disease Incidence ◽  
Morphological Characteristics ◽  
Hyphal Growth ◽  
Pathogenicity Test ◽  
Distilled Water ◽  
First Report ◽  
Foliar Blight ◽  
Dual Cultures ◽  
Phytophthora Drechsleri ◽  
Gynura Bicolor

Gynura bicolor (Roxb. ex Willd.) DC., known as Okinawa spinach or hong-feng-cai, is a commonly consumed vegetable in Asian countries. In May 2010, plants with blight and wilt symptoms were observed in commercial vegetable farms in Changhua, Taiwan. Light brown-to-black blight lesions developed from the top of the stems to the petioles and extended to the base of the leaves. Severely infected plants declined and eventually died. Disease incidence was approximately 20%. Samples of symptomatic tissues were surface sterilized in 0.6% NaOCl and plated on water agar. A Phytophthora sp. was consistently isolated and further plated on 10% unclarified V8 juice agar, with daily radial growths of 7.6, 8.6, 5.7, and 2.4 mm at 25, 30, 35, and 37°C, respectively. Four replicates were measured for each temperature. No hyphal growth was observed at 39°C. Intercalary hyphal swellings and proliferating sporangia were produced in culture plates flooded with sterile distilled water. Sporangia were nonpapillate, obpyriform to ellipsoid, base tapered or rounded, and 43.3 (27.5 to 59.3) × 27.6 (18.5 to 36.3) μm. Clamydospores and oospores were not observed. Oospores were present in dual cultures with an isolate of P. nicotianae (p731) (1) A2 mating type, indicating that the isolate was heterothallic. A portion of the internal transcribed spacer sequence was deposited in GenBank (Accession No. HQ717146). The sequence was 99% identical to that of P. drechsleri SCRP232 (ATCC46724) (3), a type isolate of the species. The pathogen was identified as P. drechsleri Tucker based on temperature growth, morphological characteristics, and ITS sequence homology (3). To evaluate pathogenicity, the isolated P. drechsleri was inoculated on greenhouse-potted G. bicolor plants. Inoculum was obtained by grinding two dishes of the pathogen cultured on potato dextrose agar (PDA) with sterile distilled water in a blender. After filtering through a gauze layer, the filtrate was aliquoted to 240 ml. The inoculum (approximately 180 sporangia/ml) was sprayed on 24 plants of G. bicolor. An equal number of plants treated with sterile PDA processed in the same way served as controls. After 1 week, incubation at an average temperature of 29°C, blight and wilt symptoms similar to those observed in the fields appeared on 12 inoculated plants. The pathogen was reisolated from the lesions of diseased stems and leaves, fulfilling Koch's postulates. The controls remained symptomless. The pathogenicity test was repeated once with similar results. G. bicolor in Taiwan has been recorded to be infected by P. cryptogea (1,2), a species that resembles P. drechsleri. The recorded isolates of P. cryptogea did not have a maximal growth temperature at or above 35°C (1,2), a distinctive characteristic to discriminate between the two species (3). To our knowledge, this is the first report of P. drechsleri being associated with stem and foliar blight of G. bicolor. References: (1) P. J. Ann. Plant Pathol. Bull. 5:146, 1996. (2) H. H. Ho et al. The Genus Phytophthora in Taiwan. Institute of Botany, Academia Sinica, Taipei, 1995. (3) R. Mostowfizadeh-Ghalamfarsa et al. Fungal Biol. 114:325, 2010.

scholarly journals CHEMICAL CONSTITUENTS OF Bischofia javanica

2017 ◽  
Vol 55 (2) ◽  
pp. 188
Author(s):  
Nguyen Thi Mai
Keyword(s):  
Methyl Ester ◽  
Gallic Acid ◽  
Nmr Spectra ◽  
Methanol Extract ◽  
Chemical Constituents ◽  
Acid Methyl Ester ◽  
First Report ◽  
Acid Methyl ◽  
Bischofia Javanica ◽  
Reported Data

From the methanol extract of Bischofia javanica leaves, five compounds including 5'-b-D-glucopyranosyloxyjasmonic acid methyl ester (1), 2-(4-hydroxy-3-methoxyphenyl)ethyl-O-β-D-glucopyranoside (2), hexyl-O-β-D-glucopyranoside (3), friedelan-3-one (4), and gallic acid (5) were isolated. Their structures were elucidated by NMR spectra as well as in comparison with previous reported data. This is the first report of 1 and 2 from Bischofia javanica.

scholarly journals First Report of Anthracnose of Onion Caused by Colletotrichum coccodes in Ohio

Plant Disease ◽  
2014 ◽  
Vol 98 (9) ◽  
pp. 1271-1271 ◽  
Author(s):  
F. Baysal-Gurel ◽  
N. Subedi ◽  
D. P. Mamiro ◽  
S. A. Miller
Keyword(s):  
Leaf Tissue ◽  
Its Region ◽  
The United States ◽  
Tween 20 ◽  
Colletotrichum Coccodes ◽  
Academic Press ◽  
Conidial Suspension ◽  
First Report ◽  
Allium Cepa L ◽  
Total Dna

Dry bulb onion (Allium cepa L. cvs. Pulsar, Bradley, and Livingston) plants with symptoms of anthracnose were observed in three commercial fields totaling 76.5 ha in Huron Co., Ohio, in July 2013. Symptoms were oval leaf lesions and yellowing, curling, twisting, chlorosis, and death of leaves. Nearly half of the plants in a 32.8-ha field of the cv. Pulsar were symptomatic. Concentric rings of acervuli with salmon-colored conidial masses were observed in the lesions. Conidia were straight with tapered ends and 16 to 23 × 3 to 6 μm (2). Colletotrichum coccodes (Wallr.) S. Hughes was regularly isolated from infected plants (2). Culturing diseased leaf tissue on potato dextrose agar (PDA) amended with 30 ppm rifampicin and 100 ppm ampicillin at room temperature yielded white aerial mycelia and salmon-colored conidial masses in acervuli. Numerous spherical, black microsclerotia were produced on the surface of colonies after 10 to 14 days. To confirm pathogen identity, total DNA was extracted directly from a 7-day-old culture of isolate SAM30-13 grown on PDA, using the Wizard SV Genomic DNA Purification System (Promega, Madison, WI) following the manufacturer's instructions. The ribosomal DNA internal transcribed spacer (ITS) region was amplified by PCR using the primer pair ITS1 and ITS4 (2), and sequenced. The sequence, deposited in GenBank (KF894404), was 99% identical to that of a C. coccodes isolate from Michigan (JQ682644) (1). Ten onion seedlings cv. Ebenezer White at the two- to three-leaf stage of growth were spray-inoculated with a conidial suspension (1 × 105 conidia/ml containing 0.01% Tween 20, with 10 ml applied/plant). Plants were maintained in a greenhouse (21 to 23°C) until symptoms appeared. Control plants were sprayed with sterilized water containing 0.01% Tween 20, and maintained in the same environment. After 30 days, sunken, oval lesions each with a salmon-colored center developed on the inoculated plants, and microscopic examination revealed the same pathogen morphology as the original isolates. C. coccodes was re-isolated consistently from leaf lesions. All non-inoculated control plants remained disease-free, and C. coccodes was not re-isolated from leaves of control plants. C. coccodes was reported infecting onions in the United States for the first time in Michigan in 2012 (1). This is the first report of anthracnose of onion caused by C. coccodes in Ohio. Unusually wet, warm conditions in Ohio in 2013 likely contributed to the outbreak of this disease. Timely fungicide applications will be necessary to manage this disease in affected areas. References: (1) A. K. Lees and A. J. Hilton. Plant Pathol. 52:3. 2003. (2) L. M. Rodriguez-Salamanca et al. Plant Dis. 96:769. 2012. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

scholarly journals First Report of Black Rot Caused by Xanthomonas campestris on Arugula in California

Plant Disease ◽  
2018 ◽  
Vol 102 (5) ◽  
pp. 1025
Author(s):  
E. R. Rosenthal ◽  
L. Ramos Sepulveda ◽  
C. T. Bull ◽  
S. T. Koike
Keyword(s):  
Xanthomonas Campestris ◽  
Black Rot ◽  
First Report
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