Articles
WATER RELATIONS AND INFECTION BY ERWINIA AMYLOVORA BASED ON CRAB APPLE BLOSSOM MODEL
Article number
489_90
Pages
521 – 524
Language
Abstract
The effect of water on the interaction between Erwinia amylovora and flower tissue or nectar was studied using crab apple as an experimental model.
Detached flowers were maintained at 24°C with the peduncle submerged in a sucrose solution.
In one test, 0.1–0.2 μl of inoculum suspension (107 CFU/ml) was applied to stigmas of flowers held in 10% sucrose.
After 24 h at 85 % relative humidity (RH), stigmas were wetted with 15 μl of water that flowed over the stigmas and into the floral cup (hypanthium). Flowers were held at 100% RH before drying and returning to 85% RH. After 1 week, only flowers subjected to wetting were diseased, and incidence was 90 to 100% regardless of whether drying occurred immediately or 48 h after wetting.
In another experiment, 0.5 μl of an inoculum suspension (108 CFU/ml) was added directly to the hypanthium and RH ranged from 40 to 100%. In a third test, RH was held at 85 or 100% and sucrose in flower-holding vials was varied from 0 to 25%. Interrelationships of nectar volume, nectar water potential, nectar sugar concentration and population size of E. amylovora were consistent with early reports.
The study also established a relationship between water potential in blossoms and blossom infection caused by E. amylovora. A determination of the full relevancy of results with detached flowers will require further research involving intact plants.
Detached flowers were maintained at 24°C with the peduncle submerged in a sucrose solution.
In one test, 0.1–0.2 μl of inoculum suspension (107 CFU/ml) was applied to stigmas of flowers held in 10% sucrose.
After 24 h at 85 % relative humidity (RH), stigmas were wetted with 15 μl of water that flowed over the stigmas and into the floral cup (hypanthium). Flowers were held at 100% RH before drying and returning to 85% RH. After 1 week, only flowers subjected to wetting were diseased, and incidence was 90 to 100% regardless of whether drying occurred immediately or 48 h after wetting.
In another experiment, 0.5 μl of an inoculum suspension (108 CFU/ml) was added directly to the hypanthium and RH ranged from 40 to 100%. In a third test, RH was held at 85 or 100% and sucrose in flower-holding vials was varied from 0 to 25%. Interrelationships of nectar volume, nectar water potential, nectar sugar concentration and population size of E. amylovora were consistent with early reports.
The study also established a relationship between water potential in blossoms and blossom infection caused by E. amylovora. A determination of the full relevancy of results with detached flowers will require further research involving intact plants.
Publication
Authors
P.L. Pusey
Keywords
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