Articles
IMPORTANCE OF SECONDARY SPREAD OF BACTERIAL ANTAGONISTS IN THE BIOLOGICAL CONTROL OF ERWINIA AMYLOVORA
Article number
411_59
Pages
297 – 298
Language
Abstract
Spread of the antagonistic bacteria, Pseudomonas fluorescens strain A506 and Erwinia herbicola strain C9-1, from treated to non-treated pear blossoms, and the effect of their spread on fire blight control were investigated in an orchard block, 10 rows by 4 trees per row.
In 1994, the center two rows were sprayed with a mixture of A506 and C9-1 at 108 cfu/ml at 30% bloom.
Immediately after spraying, antagonists were detected only on treated blossoms.
As bloom progressed, both A506 and C9-1 spread to non-treated blossoms located up to 4 rows distal to the treated blossoms.
At 80% bloom, all trees were inoculated with freeze-dried cells of E. amylovora. After full bloom, the proportion of blossoms with E. amylovora populations> 105 was highest in the outermost rows, and decreased significantly (P < 0.05) with proximity to treated rows.
Diseased blossom clusters decreased from 4.5% in the outermost rows to 2.9% in the treated rows.
In 1995, trees in the center rows were sprayed with the antagonists at 15–20% bloom, but no spread to non-treated trees was detected.
In contrast to 1994, temperatures during early bloom of 1995 were very cool, and this may be one factor that contributed to the poor redistribution of the antagonists.
These results suggest that both A506 & C9-1 have the potential to spread naturally after application, that this spread plays a role in disease control, and that environment may affect the rate of antagonist dispersal.
In 1994, the center two rows were sprayed with a mixture of A506 and C9-1 at 108 cfu/ml at 30% bloom.
Immediately after spraying, antagonists were detected only on treated blossoms.
As bloom progressed, both A506 and C9-1 spread to non-treated blossoms located up to 4 rows distal to the treated blossoms.
At 80% bloom, all trees were inoculated with freeze-dried cells of E. amylovora. After full bloom, the proportion of blossoms with E. amylovora populations> 105 was highest in the outermost rows, and decreased significantly (P < 0.05) with proximity to treated rows.
Diseased blossom clusters decreased from 4.5% in the outermost rows to 2.9% in the treated rows.
In 1995, trees in the center rows were sprayed with the antagonists at 15–20% bloom, but no spread to non-treated trees was detected.
In contrast to 1994, temperatures during early bloom of 1995 were very cool, and this may be one factor that contributed to the poor redistribution of the antagonists.
These results suggest that both A506 & C9-1 have the potential to spread naturally after application, that this spread plays a role in disease control, and that environment may affect the rate of antagonist dispersal.
Publication
Authors
R. Nuclo, K.B. Johnson, D. Sugar, V.O. Stockwell
Keywords
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