A Keiffer on Cally in its 3rd leaf had severe fire blight all year. Only pear out of 20 to have this problem. It’s a third the size it was in March, after all my hacking.
I Suppose it had something with all the nitrogen I was feeding it, getting it up to size. 
I used lots of nitrogen.
Anyway do you suppose the fire blight is gone? Or maybe I should remove it to keep it from infecting other trees?
All your other pear trees, are they FB resistant varieties? Why do you think only this got FB? Did you give it more nitrogen than other trees?
If I had one out of 20 infected I would get it completely out of my orchard. Just my opinion but I would stop the heavy nitrogen applications. My pear trees grow off pretty fast with very little fertilizer added.
I tend to agree with the heavy nitrogen usage. I happened to fertilize my trees during the drought we had. I used a high nitrogen fertilizer. Then I started having FB issues on my trees. I have NEVER had FB before in my orchards over the years. I had one tree that I had to take out because the trunk was split and weeping.
I learned my lesson.
I’m not sure why my Keiffer reacted so strongly. No problem with the other pears which have varying degrees of fb resistance. Yeah the heavy nitrogen applications are done, most trees have grown quickly. The Keiffer didn’t have any problems 1st couple years, but then it bloomed…
Now I just have to decide whether to take the Keiffer out, in case the fb is stuck to the tree; or maybe its run its course
I would at least wait and see. I was going to let the FB tree run its course until I saw the one trunk split and ooze. I figured it was not going to come back since it was split and oozing all the way around.