The front line defense is to choose varieties that have genetic resistance to the disease. Sadly, the disease evolves more quickly than the plant breeders.
One of the characteristic symptoms of fire blight is that the young shoots take on a "shepherd's crook" bend at the growing end.
|Image from Cornell University|
|The next three images are from the tree that was dying in my young orchard. In time this shoot would turn brown (apples) or black (if it were a pear). At that point, a diagnosis of fire blight is a no-brainer.|
|And yet another.|
Fire blight causes wilting by clogging the vascular tissues of the shoot with cells of Erwinia amylovora. It is the vegetable version of anthrax.
|Cornell rated the shoots of Novaspy as highly resistant to fire blight.|
I was not considering a diagnosis of fire blight because the rootstock and the scion variety are both reputed to be "very resistant" to fire blight. I was wrong.
|Image from HERE|
Finally, sanitize your hands and your pruning tools to prevent spreading the disease when you use them later.
|This is what the tree looks like after surgery. The tree is the short stick immediately in front of the post.|
A final note
Young orchards are particularly vulnerable to fire blight because of the abundance of vigorous growth.
|The area circled in red shows where a growing point was pinched out, i.e., dead-headed.|
One of the cultural practices that I was using that contributed to the issue was that I was pinching out the growing points on branches that were not well placed. I did not want to remove the leaves as they contribute by photosynthesizing but I did not want the tree to invest any more resources into a branch that I knew I was going to have to prune later on. I wanted all the energy to go into "keepers".
Pinching out the growing point breaches the plant's defenses exactly where it is most vulnerable to fire blight. Note to self: No more summer dead-heading on young apples and pears.