Articles
CRAB APPLE BLOSSOMS AS A MODEL SYSTEM FOR FIRE BLIGHT BIOCONTROL RESEARCH
Article number
411_57
Pages
289 – 294
Language
Abstract
Nonseasonal availability of pomaceous flowers could permit the greater use of flowers for pre-field detection and testing of biocontrol agents for fire blight of pear and apple.
Crab apple trees were selected as a model system because of their high flower productivity on 1-year wood, high susceptibility to fire blight, and availability from nurseries.
Nursery trees (‘Manchurian’ and ‘Snowdrift’) were manipulated to bloom once by periodically transferring dormant trees from a cold room to a greenhouse and a second time by defoliating trees and applying with brush a 1% solution of cytokinin to the buds.
By forcing two bloom periods per tree, flowers were available in all but 1 mo (July) during a 12-mo period.
Twelve bacterial strains with a range of activity against Erwinia amylovora were selected to test the reliability of crab apple as a model for predicting the field performance of organisms as biocontrol agents.
These bacteria were tested on detached blossoms of crab apple in the laboratory, on blossoms of intact crab apple trees in the greenhouse, and on blossoms of intact pear and apple trees in the field.
In each case, flower stigmas were treated with the test strains (0.5μl of suspension at 108 cfu/ml), inoculated after 24 or 48 hr with E. amylovora (0.5 μl of suspension at 107 cfu/ml), and then excised after an additional 24 or 48 hr for population determination.
The negative effect of test strains on populations of E. amylovora were similar in all tests involving blossoms.
The bacterial strains were also tested using the immature pear fruit assay, which was found to be less effective than tests with crab blossoms in predicting results of field tests.
The study supports the idea that crab apple blossoms could serve as a suitable model for year-around evaluation and study of microorganisms as potential biocontrol agents against fire blight.
Crab apple trees were selected as a model system because of their high flower productivity on 1-year wood, high susceptibility to fire blight, and availability from nurseries.
Nursery trees (‘Manchurian’ and ‘Snowdrift’) were manipulated to bloom once by periodically transferring dormant trees from a cold room to a greenhouse and a second time by defoliating trees and applying with brush a 1% solution of cytokinin to the buds.
By forcing two bloom periods per tree, flowers were available in all but 1 mo (July) during a 12-mo period.
Twelve bacterial strains with a range of activity against Erwinia amylovora were selected to test the reliability of crab apple as a model for predicting the field performance of organisms as biocontrol agents.
These bacteria were tested on detached blossoms of crab apple in the laboratory, on blossoms of intact crab apple trees in the greenhouse, and on blossoms of intact pear and apple trees in the field.
In each case, flower stigmas were treated with the test strains (0.5μl of suspension at 108 cfu/ml), inoculated after 24 or 48 hr with E. amylovora (0.5 μl of suspension at 107 cfu/ml), and then excised after an additional 24 or 48 hr for population determination.
The negative effect of test strains on populations of E. amylovora were similar in all tests involving blossoms.
The bacterial strains were also tested using the immature pear fruit assay, which was found to be less effective than tests with crab blossoms in predicting results of field tests.
The study supports the idea that crab apple blossoms could serve as a suitable model for year-around evaluation and study of microorganisms as potential biocontrol agents against fire blight.
Publication
Authors
P.L. Pusey
Keywords
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