Abstract
In October of 2001 and 2002, a leaf blight was reported affecting Vidalia onion (Allium cepa) cvs. Pegasus and Sweet Vidalia, respectively, in one field each. Lesions on onion seedlings began as a water-soaked, tip dieback that gradually blighted the entire leaf. Symptoms on onion transplants appeared as elongated, water-soaked lesions that typically collapsed at the point of initial infection. In both cases, disease was very severe on seedlings, and disease incidence was 50% or more in both fields. Warm temperatures combined with overhead irrigation and above average rainfall likely enhanced the severity and spread of disease. Disease was not detected on more mature onions once cool, dry conditions occurred later in the season, and no significant economic loss occurred. Seed was tested from seed lots of the aforementioned cultivars and Xanthomonas spp. were not found. Diseased tissue was macerated in sterile, phosphate-buffered saline, and 10 μl of the resulting suspension was streaked on nutrient agar plates. Yellow-pigmented, gram-negative, rod-shaped bacteria were isolated routinely from diseased tissue. Bacteria were catalase-positive, cellulolytic, oxidase-negative, amylolytic, proteolytic, and utilized glucose in an oxidative manner. Analysis of whole cell, fatty acid methyl esters (FAME) using the Microbial Identification System (MIS, Sherlock version 3.1; MIDI, Inc., Newark, DE) identified four representative strains of the bacterium as a pathovar of Xanthomonas axonopodis (similarity indices 0.75 to 0.83). Known Xanthomonas spp. from onion from Colorado and Texas (1,2) had similar FAME profiles when analyzed by the MIDI system. Onion plants were grown under greenhouse conditions for 2 months and inoculated by injecting the base of a quill with 1.0 ml of bacterial suspensions (1 × 10 7 CFU ml -1 ) of the Xanthomonas sp. isolated from Georgia, and negative controls were inoculated with 1 ml of sterile water. Disease symptoms developed on plants inoculated with bacterial suspensions in 4 to 7 days and Xanthomonas sp. was isolated from the lesions produced. Disease symptoms occurred when the same suspension was sprayed on onion foliage. No symptoms occurred on plants inoculated with 1 ml of sterile water. To our knowledge, this is the first report of Xanthomonas spp. affecting Vidalia onions. References: (1) T. Isakeit et al. Plant Dis. 84:201, 2000. (2) H. F. Schwartz and K. Otto. Plant Dis. 84:922, 2000.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 15
Claim · model-written summary
Leaf blight affected Vidalia onion cultivars Pegasus and Sweet Vidalia in separate fields.
Verbatim
e0“a leaf blight was reported affecting Vidalia onion (Allium cepa) cvs. Pegasus and Sweet Vidalia, respectively, in one field each.”
Claim · model-written summary
Lesions on onion seedlings progressed from water-soaked tip dieback to whole-leaf blight.
- Taxon
- onion
Allium cepae0 - Organ / stage
- seedlingse0
- Outcome
- water-soaked, tip dieback that gradually blighted the entire leafe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lesions on onion seedlings began as a water-soaked, tip dieback that gradually blighted the entire leaf.”
Claim · model-written summary
Onion transplants developed elongated water-soaked lesions that collapsed at the infection point.
- Taxon
- onionAllium cepae0
- Organ / stage
- transplantse0
- Outcome
- elongated, water-soaked lesions that typically collapsed at the point of initial infectione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Symptoms on onion transplants appeared as elongated, water-soaked lesions that typically collapsed at the point of initial infection.”
Claim · model-written summary
Seedling disease incidence was at least 50% in both fields.
- Taxon
- onionAllium cepat0
- Organ / stage
- seedlingse0
- Outcome
- disease incidencee0
- Value
- 50% or moree0
- Setting
- both fieldse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“disease was very severe on seedlings, and disease incidence was 50% or more in both fields.”
t0“onion”
Claim · model-written summary
Warm and wet conditions with overhead irrigation likely enhanced disease severity and spread.
- Taxon
- onionAllium cepat0
- Treatment
- overhead irrigatione0
- Outcome
- severity and spread of diseasee0
- Direction
- enhancede0
- Qualifier
- Warm temperatures combined with overhead irrigation and above average rainfalle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Warm temperatures combined with overhead irrigation and above average rainfall likely enhanced the severity and spread of disease.”
t0“onion”
Claim · model-written summary
Disease was absent on mature onions after cool, dry conditions arrived.
- Taxon
- onionsAllium cepae0
- Organ / stage
- more mature onionse0
- Outcome
- Disease was not detectede0
- Qualifier
- cool, dry conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Disease was not detected on more mature onions once cool, dry conditions occurred later in the season”
Claim · model-written summary
The outbreak caused no significant economic loss.
- Taxon
- onionAllium cepat0
- Outcome
- economic losse0
- Direction
- no significante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no significant economic loss occurred.”
t0“onion”
Claim · model-written summary
Xanthomonas was not found in the tested cultivar seed lots.
- Taxon
- onionAllium cepat0
- Organ / stage
- Seede0
- Interactor
- Xanthomonas spp.
_-_Howard_F._Schwartz%2C_Colorado_State_University.jpg?width=60)
Xanthomonase0pathogen - Outcome
- Xanthomonas spp. were not founde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_-_Howard_F._Schwartz%2C_Colorado_State_University.jpg?width=500)
Verbatim
e0“Seed was tested from seed lots of the aforementioned cultivars and Xanthomonas spp. were not found.”
t0“onion”
Claim · model-written summary
Yellow-pigmented Gram-negative rod bacteria were routinely isolated from diseased onion tissue.
- Taxon
- onionAllium cepat0
- Outcome
- Yellow-pigmented, gram-negative, rod-shaped bacteria were isolated routinelye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Yellow-pigmented, gram-negative, rod-shaped bacteria were isolated routinely from diseased tissue.”
t0“onion”
Claim · model-written summary
Four representative bacterial strains were identified by FAME as a Xanthomonas axonopodis pathovar.
- Taxon
- onionAllium cepat0
- Interactor
- Xanthomonas axonopodis
Xanthomonas axonopodise0pathogen - Outcome
- pathovar of Xanthomonas axonopodise0
- Value
- 0.75 to 0.83e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“identified four representative strains of the bacterium as a pathovar of Xanthomonas axonopodis (similarity indices 0.75 to 0.83).”
t0“onion”
Claim · model-written summary
Known onion Xanthomonas isolates from Colorado and Texas had similar FAME profiles.
- Taxon
- onionAllium cepae0
- Interactor
- Xanthomonas spp.Xanthomonase0pathogen
- Outcome
- similar FAME profilese0
- Setting
- Colorado and Texase0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Known Xanthomonas spp. from onion from Colorado and Texas (1,2) had similar FAME profiles when analyzed by the MIDI system.”
Claim · model-written summary
Greenhouse onion plants injected with Georgia Xanthomonas developed symptoms within 4 to 7 days, and the bacterium was reisolated.
- Taxon
- onionAllium cepat0
- Treatment
- inoculated with bacterial suspensionse0
- Interactor
- Xanthomonas sp.Xanthomonase0pathogen
- Outcome
- Disease symptoms developede0
- Value
- 4 to 7 dayse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Disease symptoms developed on plants inoculated with bacterial suspensions in 4 to 7 days and Xanthomonas sp. was isolated from the lesions produced.”
t0“onion”
Claim · model-written summary
Spraying the same bacterial suspension on onion foliage also produced symptoms.
- Taxon
- onionAllium cepae0
- Organ / stage
- foliagee0
- Treatment
- the same suspension was sprayede0
- Outcome
- Disease symptoms occurrede0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Disease symptoms occurred when the same suspension was sprayed on onion foliage.”
Claim · model-written summary
Water-inoculated onion plants showed no symptoms.
- Taxon
- onionAllium cepat0
- Treatment
- 1 ml of sterile watere0
- Outcome
- No symptoms occurrede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No symptoms occurred on plants inoculated with 1 ml of sterile water.”
t0“onion”
Claim · model-written summary
The authors report Xanthomonas leaf blight of Vidalia onions as a first report.
- Taxon
- Vidalia onionse0
- Interactor
- Xanthomonas spp.Xanthomonase0pathogen
- Outcome
- first report of Xanthomonas spp. affecting Vidalia onionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this is the first report of Xanthomonas spp. affecting Vidalia onions.”
The same questions in other papers
application · disease · Allium cepa (onion)Positive and negative results
4 papers in the same direction as this paper · 35 in the opposite direction
- positive
- positive
- positive
36 papers more in this group
See all 40 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.