MONITORING OF EPIPHYTIC ERWINIA AMYLOVORA AND THE INCIDENCE OF FIRE BLIGHT OF APPLE AND PEAR IN SOUTHWESTERN ONTARIO

Monitoring of apple and pear orchards for epiphytic Erwinia amylovora on blossoms and leaves could not be relied upon to predict the occurence of fire blight disease outbreaks in southwestern Ontario.
Epiphytic E. amylovora was detected in only four of 19 apple and pear orchards, although fire blight occurred in all of them later in the season.
Disease severity as measured by new infections in the individual orchards ranged from 0.15 – 8.90 strikes per tree for apples and 0.29 – 2.31 strikes per tree for pears.
In contrast, hold-over cankers were more numerous in pears than in apples.

II Symposium on Fire Blight

W.G. Bonn

https://doi.org/10.17660/ActaHortic.1981.117.4