unknown citrus

[eb]

Hello,
We have a citrus tree that was in our yard when we moved in 5.5 years ago.  Last year it produced for the first time and had less than a dozen fruit.  This summer it produced several dozen.  I have no idea what it is, so I'm turning to you expert growers.  Initially when the fruit began to appear in Spring, I thought it was related to kaffir lime, but it does not have the same leaves.  Then I thought maybe it was yuzu, but again, leaves are not the same.  Leaves are in cluster of 3, and has HUGE thorns.  Fruit on my tree is golfball size and smaller.  Lots of seeds and little juice.  Is this edible?  Worth saving the plant? Looking to clear some space in that part of the yard.  Pardon the brownish/gray on the skins of the fruit.... ash from the wildfires here on the West coast.
Thanks,
EB

[Laaz]

What you have is Poncirus Trifoliata. Very cold hardy & used as a rootstock. Won't kill you if you eat it, but not very pleasant...

[ash]

Don't kill it use it as a rootstock and graft something worth while onto it.

[zap]

I would say graft that baby over to something delicious!

{{In California it may only be grafted during the full moon, wearing a rubber chicken costume, & burning incense ...}}

Seriously in CA; grafting is restricted to Certified germplasm obtained from a registered source. But you can buy Oranges full of black necrosis at virtually any supermarket!

Good news is that C.trifoliata is resistant to a lot of citrus pests.
If you purchase a small citrus tree from a local nursery?   The tree should have been produced with registered germplasm, and be disease free.

But I believe it would be a violation to bring it home, and graft buds from it onto your existing rootstock. Or to use a branch from your own yard, or your next door neighbor's tree.

What would be VERY Bad would be to compost nasty black oranges down, and put compost near your tree. (or touch an infected orange at the supermarket, and prune your tree later ... that same week?)

Graft it! You can do it!