You need to post this in the citrus forum in addition to this forum. It looks like it got some freeze damage a long time ago and rot is setting in the freeze damage. It also looks like it needs a sunnier location.

Thanks for the comments, very helpful!

i also dont do citrus ...

but to my eye.. the injury was long ago ... either thru bad pruning.. opening wounds or perhaps the weather issues indicated above ... or both

the bugs just came along .. once the tree started to rot ... or to take advantage of the open wounds .. and in tree time.. that could have been 5 or 10 years ago?????

since you dont seem to have any particular attachment to the tree [aka.. grandpa planted it .. ] ... then you might just think about getting rid of it ... and if you want to dabble in citrus... just get a new young plant ...

in my world.. warped as it is .... im not going to spend a couple hundred bucks getting expert opinions and expert tree service ... for a tree i can replace for 30 to 50 dollars ... its the old cost benefit ratio ...

ken

ps: in that first pic.. it looks like some new trees are planted awful close to the fence .... that will be a problem in the future .. that you will take care of.. thru pruning the plants.. so the trees stay away from the new wood fence ... all of which wont be any big deal.. if you stay on top of it ...

I'd remove the tree and start over with a variety that you know you love.

Replacing it seems to be a good option... Also, thanks for the extra comments on distance to the fence!

Out of curiosity, where are you located?

That’s in San Jose, California