PREVENTING SHOOT BLIGHT OF APPLE WITH STREPTOMYCIN APPLICATIONS FOLLOWING SIMULATED HAIL INJURY

Shoot blight of apple and pear often occurs after hail storms due to the dispersal of Erwinia amylovora and the invasion of injured tissues.
Bactericide sprays have been inconsistent in preventing these epiphytotics.
Apple leaves were injured with a hole punch to simulate hail and inoculation was made concurrently with and after the injury.
Shoot blight of apple was effectively controlled with an application of streptomycin 4 hours after injury and inoculation of leaves, but streptomycin did not provide control of shoot blight when applied 24 hours after injury and inoculation.
Preventive applications of streptomycin applied 2 hours before inoculation only provided a slight reduction of shoot blight compared to the check.
Inoculated leaves without injury resulted in 4% infection and streptomycin applied 4 hours after inoculation prevented infections when there was no injury.
The polysaccharide ooze produced by E. amylovora sticks to leaves even when diluted and enhances the ability of splash-dispersed bacteria to adhere to leaves rather than run off.

X International Workshop on Fire Blight

S.C. Ockey, S.V. Thomson

Erwinia amylovora, fire blight control, polysaccharide ooze

https://doi.org/10.17660/ActaHortic.2006.704.28