My wife and I bought a house last year and there was a citrus tree in the back that we were told is a couple years old (its current dimensions are about 12' tall and 4.5' wide). It has three trunks and on one of the trunks I can see the graft union; however, on the other two trunks, I cannot see any graft union and the bark is the same color all along the trunks (a lightish brown with some green showing through. The same color as the root stock on a orange tree that I just planted last year.) One other difference between the trunks is that the ones without the graft union have really large thorns where the one with the graft union does not have any thorns. My thought is that the people who had the house before us bought a tree in which the rootstock grew up into two other stumps and is now taking over the tree (the two trunks of what I suspect is the rootstock have a much larger diameter than the grafted trunk. The grafted trunk seems to be overwhelmed by the others.). Anyway, does that sound like it is a reasonable theory? Also, is there anyway to somehow salvage the tree if it is basically just a giant rootstock variety?

I have been thinking of digging up the current tree and planting a trovita orange but I would hate to dig up a perfectly good citrus tree. But if I do need to dig it up to get a tree with good fruit (rather than just a hedge), then I would like to get a new good one now so we can start enjoying the fruit sooner.

I am linking some pictures. It was an overcast day so let me know if you would like better ones.

Here is a link that might be useful: Orange Tree Picture Link