Just over 6 months ago, I purchased a pear tree that has 5 varieties grafted onto it. It is about 5' tall, and perhaps a little over 3/4" across at the base. It actually had 3 pears on it when I bought it. I pruned 2 of them off, and let the third mature - we actually got a ripe fruit to eat just 5 months after planting it.
The trouble is that the plant itself just sat there - the leaves stayed green, but there was no growth at all this year, even with fertilizer and regular waterings. (when I planted it, I also buried a bag of composted cow manure under it, plus mixed in some of that dehydrated plastic to help it retain water)
When I gave it a closer look, I saw something I had initially missed in my excitement over finding a pear tree that wouldn't need a pollinator. It turns out that the living part of the bark is actually girdled perhaps 66% or 70% of the way around. The bark had a "flaky" or crackled appearance. It didn't look bad from a few feet away, but a very close inspection (what I should have done before purchasing it) it was obvious something was wrong.
I took a knife and scraped away all of the flaky part. Then I used a wire brush to agitate everything until I started seeing a little bit of green here and there. Using a knife, I was able to find that the bark is dead nearly 70% of the way around. No wonder why this thing was sort of just sitting there! At more than $35, I certainly overpaid for it, given the condition. Unfortunately, I also found it at a store that doesn't have a 1 year guarantee, unlike the places I normally buy trees and shrubs. :-(
The big question is whether this thing could ever heal itself. The roots have evidently gotten somewhat established, because it was able to survive through one of the driest summers we've had in a while, and even bore a fruit the first year. However, since the plant itself pretty much just sat there, I am very concerned over its long term ability to thrive. I'm afraid it will become the "zombie plant", that just sits there and never truly grows.
I've seen small trees heal places in their bark, maybe up to 30" of the way around. In fact, my peach tree did that this year - it doubled the size of the trunk, and doubled the height of the plant. However, I think pears grow slower.
I actually went out and bought a really nice looking 5' nectarine tree on sale for $12 at a local store yesterday, with the intention of replacing this pear tree. I hated the idea of throwing out a tree I paid nearly $40 for, but I was of the opinion that if it doesn't thrive the first year, it probably won't thrive the 2nd. I believe a nectarine is a fast growing tree, much like a peach. This one looks vigorous, and doesn't need a pollinator.
My wife threw a fit, though, because she hates the idea of killing a tree that is alive, especially since it did give us a pear to enjoy right away.
Anyone have a good idea what chance a small pear tree like this would have of healing such a large gap in the sapwood? If it was a side branch, it wouldn't be an issue, but this is the main trunk. I think that the missing 70% is a limiting factor in the tree's growth.