Articles
MOVEMENT OF ERWINIA AMYLOVORA FROM FIRE BLIGHT CUTTINGS AFTER CHOPPING
Article number
800_122
Pages
899 – 906
Language
English
Abstract
A Bartlett orchard was used in May 2004 to evaluate the movement of Erwinia amylovora (E.a.) bacteria after chopping blight cuttings.
Cuttings were placed in piles in an alley; each was 2 m wide x 20 m long x 0.4 m tall, containing 250 blighted branches.
A flail chopper chopped the cuttings on a day with a gentle breeze.
Petri plates containing Modified Miller-Schroth medium were placed in trees just before chopping and left open for 30 min.
Downwind trees had over double the number of E.a. colonies per plate than upwind trees.
There were no differences in blight incidence.
In another trial 2 weeks later, cuttings were chopped in four piles: two with 120 strikes/pile, and two with 30 strikes/pile.
Plates in trees downwind of the larger piles recovered substantially more E.a. cells than those of the small piles.
Counts tapered off in the fifth downwind row.
No blight strikes were found.
The movement of airborne bacteria through the orchard poses a threat, however, the relative numbers of cells recovered on dishes was relatively small (only about 10 cells/dish). Thus, the recovery of about 10 E.a. cells/dish suggests that very few of the flowers that were open during chopping had received even one cell.
Weather conditions conducive to further multiplication of natural inoculum would likely be far more important in causing new strikes than the small increase in inoculum in flowers that would result from chopping.
Cuttings were placed in piles in an alley; each was 2 m wide x 20 m long x 0.4 m tall, containing 250 blighted branches.
A flail chopper chopped the cuttings on a day with a gentle breeze.
Petri plates containing Modified Miller-Schroth medium were placed in trees just before chopping and left open for 30 min.
Downwind trees had over double the number of E.a. colonies per plate than upwind trees.
There were no differences in blight incidence.
In another trial 2 weeks later, cuttings were chopped in four piles: two with 120 strikes/pile, and two with 30 strikes/pile.
Plates in trees downwind of the larger piles recovered substantially more E.a. cells than those of the small piles.
Counts tapered off in the fifth downwind row.
No blight strikes were found.
The movement of airborne bacteria through the orchard poses a threat, however, the relative numbers of cells recovered on dishes was relatively small (only about 10 cells/dish). Thus, the recovery of about 10 E.a. cells/dish suggests that very few of the flowers that were open during chopping had received even one cell.
Weather conditions conducive to further multiplication of natural inoculum would likely be far more important in causing new strikes than the small increase in inoculum in flowers that would result from chopping.
Publication
Authors
C.A. Ingels, S.E. Lindow, R. Koutsoukis
Keywords
pear, ¿Bartlett¿, inoculum
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