I would be interested to see photos of what you think is fire blight. I have seen what I am sure is fire blight on pears locally in spring but I have also had what I suspect is a later fire blight on my Fuji Apple. I think it would be an interesting thread and really informative for a lot of members.
This is what it looks like Late season Fireblight
What I think is fire blight on my Fuji was not that advanced but it looked similar. I pruned it out today. Thanks for the link.
There are at least two kinds of blight- the blossom blight in spring and later twig blight in summer. Not sure if they are the same organism.
Do you have photos of the later type of firebli?
Fireblight in blossom or shoot form is caused by the bacteria Erwinia amylovora. Some strains seem more aggressive than others. The same as rabbits one grows faster than the other but a cottontail is still a cottontail. It sometimes seems like there is more than one type because the bacteria needs perfect conditions and when it has them it’s highly aggressive. Fireblight is not well understood. We think we understand it but we don’t. When humidity is 65% and temperatures are 65 degrees we think Fireblight will occur and then it doesn’t happen. Then we assume it’s additionally hormones that set it off when the tree begins producing fruit and again no Fireblight. This year I had a strike on a callery pear with a FB resistant pear grafted to it. No bloom, no perfect temperatures, no insects, nothing tangible besides the new graft had been pruned. We know fast growing tissue is something Fireblight is drawn to because it only attacks growing tissue. Fast growth caused by Fertilizer and rain in my experience are very dangerous more so than any other factor. Fireblight can devastate an orchard at times and in some locations every year. People assume one place is the same as the other but it’s not true soil is another factor. Health of the tree etc. is determined by soil minerals and that is a factor on susceptibility to Fireblight. Boron deficiencies can be a factor in blossom blast which is confused with Fireblight http://www.tfrec.wsu.edu/pages/cpg/Boron
In my experience I believe there are different strains of the same disease. Some of those can be real nasty. Some people discuss Fireblight resistant pears but it might be worth it to look at this post Pear tree Fireblight research so you dont have to . My hope is the disease will become smarter over time as most do. A good bacterial disease does not kill it’s host. This is a stupid bacterial disease because once it kills it’s hosts it has nothing to live on.