start by exposing the root flare ...

https://duckduckgo.com/?t=ffnt&q=tree+root+flare&iax=images&ia=images

you found out about tree time .. which is counted in decades .. two years ago is nothing ...s o it probably dates back to the construction ...

your tree is severely stressed from just about everything that we list as the usual suspects... frost/freeze .. grade changes.. telephone poling ... did i leave anything out ...

whether or not it survives .. in tree time.. is left to prayer ... since we cant undo weather.. nor would we suggest you regrade ... so all we are le=ft with is.. find the root flare ..

its highly stressed.. it is not hungry.. fert is not a response ...

i presume nothing was done on the other side of the fence ... so it doesnt surprise me ... that that side is the unaffected side ...

since you had a major impact to the roots .. you might want to water as deeply as you can.. especially in drought ...

i simply cant fathom what the odds are on it ...

ken

ps: if it were a huge tree hanging over the house;. i might suggest removal if you see further significant decline ... but its a rather small tree and who cares if it takes out some wood fence ... this decision is a few years down the line.. if ever ...

Thanks. I dug down to uncover the root flair, and found another problem: the original sprinkler system hose was wrapped around the roots. I cut most of it away so that it is not wrapped around the entire base, but there are a few areas where the tree has grown around the hose. I was trying to minimize the damage and just left a few pieces in there. Is that okay or should I absolutely remove the hose even if it damages a root? Pics are below:

Here is what I found when I dug down:

Here are the 2 areas that I was unable to cut away the hose:

For some reason I had to split up my pics. Let me know your thoughts on leaving the hose vs removing it, and if there is anything else I need to be doing other than praying to the tree gods.

If the tree has grown tissue around the hose -- leave it. If you've broken up the circle around the trunk to a large extent, you've done a good job.

Not a lot more can be done but you've removed a major problem there.

Now that the strangling effect of that tube is gone and *if* the root flare is at proper depth, the tree should begin to show improvement. But don't expect dramatic results overnight. More like a season or two.

holy moly ... lol ... ..

do no further damage by trying to tear it out of there...

just under the bark is the cambium layer.. its the vascular system of the tree .. water up.. energy down to the roots ... for storage ...

https://duckduckgo.com/?t=ffcm&q=cambium+layer&iax=images&ia=images

you opened 99.999% so you should be in good shape ... in that regard ... where it healed over.. its already fixed the issue.. so dont cut it open to remove the pipe ...

there are the other potential problems.. but give it a few years.. and hope this was the major issue ...

think in tree time.. counted in decades .. so dont expect instant gratification ..

but boy.. do you have a story to tell around the pool ... put the kids to bed.. and give me a beer ...

ken