Erwinia amylovora on Fire Blight Canker Surfaces and Blossoms in Relation to Disease Occurrence

Publisher Website
Google Scholar
Abstract
One pear orchard and 4 apple orchards in Wayne County, New York State [USA], were monitored for the presence of E. amylovora and the occurrence of blossom blight. The pathogen was isolated from holdover canker surfaces in all 5 orchards by a canker-swabbing technique in which 2 selective media were utilized. It was detected in blossoms of 3 orchards 1-3 wk before blossom infection appeared. The pathogen was not confirmed in blossoms from these orchards in sufficient time to indicate implementation of effective spray applications. Although blossom blight developed in all monitored orchards, more developed in the 3 orchards in which the pathogen had been detected previously in blossoms. E. amylovora was detected sporadically throughout the season on cankers that had been produced the previous year. Some cankers apparently were active for most of the spring, others were only temporarily active, and E. amylovora was not isolated from the surface of others. Initiation of canker activity appeared to be positively correlated with warm (> 17.degree. C), moist conditions at least 1 day prior to sampling. Holdover cankers may provide inoculum prior to, or without visible evidence of, renewed canker activity, and that E. amylovora may be detected in pome fruit orchards in New YOrk before the development of blossom infection.

This publication has 0 references indexed in Scilit: