I would get another citrus tree and grow it in a container so that if this tree doesn't pull through you have its replacement in hand. If your tree pulls through you will have 2 trees. I don't know how to help with this tree. I had a meteor sour cherry tree bite the compost pile the same way. I did not find out the problem for another 5 years. In my case it was not insects. I am also very much in favor of buying a small tree and have it grow into a good producing tree.

6b Steve

IMO it is nearly impossible to transplant a citrus that large and expect it to survive.

That tree was in a massive pot when we planted it. Why would it be impossible to transplant it? Spain is full of garden centers that sell such trees

5 gallon trees are the best for transplanting. A tree like yours of that size will just go into shock when the roots are disturbed. It has been proven time and time again that a 5 gallon tree will quickly catch up to and surpass the growth of a 15 gallon tree within a couple years. I'd pull it out and ask for a refund and buy a 5 gallon tree instead.

Evan

Any ideas on the bugs? Why is a big tree behaving like this?

I didn't see any bugs. The tree was a large specimen that was transplanted too late in its life. Then, somebody hacked all of the branches off that had leaves that the tree needs to survive and provide itself with food. It might come back in the spring if you treat it carefully through the winter and start watering and fertilizing when it starts to warm up.

Pull the grass a couple feet in diameter. It gives off a bad gas for citrus.

To me that tree looks like somebody hacked it out of their yard, stuck it in a pot a sold it.

I am also shocked that was sold as a container tree- it's huge and looks so mature! But I know nothing of how things are done in your climate to be fair.

This tree's health has absolutely nothing to do with grass. I have seen plenty of citrus trees planted in lawns with zero issues, that bear bounties of fruit annually.

The top half of the trunk is in very bad decline and is dying. Near the base of the tree there are little green growth buds and just above these I would carefully and cleanly saw the tree down for it to resprout with new growth.

My first reaction after seeing that lawn right up to trunk was whether any herbicide was used to treat it. That would severely compromise a newly planted tree/plant. My second thought was that it takes a lot of expertise to prep the ground to accept a large tree like that. And my third reaction (I know I am over reacting) was what was the container that held that tree.

I transplanted some citrus trees with the help of a worker who had done it professionally many times. For a tree with a 2" (5cm) trunk, we tried for a root ball about 18-24" in (61cm), 24" deep and that's a heavy root ball, more than one person can lift. Your tree looks like its 6-8"(15-20cm) in diameter so the root ball (and the pot) must have been pretty large. Around here(S.Calif) when older trees are moved, they have wooden containers built around the root ball, I don't think there are pots that large. And such a large pot would probably be easy to break when moved (with a forklift or a crane). So I also wonder if you really had a root ball appropriate for the size and age of that tree. BTW, my transplanted citrus didn't thrive and died after a few years.

The top of the tree trunk looks mostly dead to me (at least on the right side) and it's hard to imagine spending any time trying to save that part. And I'm the optimistic type who in the past has tried to save half dead trees. I think the bug holes are just another sign of dead wood.

I agree that the buds down near the bottom may be your only chance to save the tree and there's no reason to leave any of the dead/dying parts on. You didn't mention the variety of citrus, but if one of the shoots or branches on the left side is nice and green, maybe you could use it as scion wood and try a bark graft into the remaining stump.

Even if the roots are healthy, it's still going to take some time for those buds to start producing fruit. So buying a replacement tree in a 5 gal container is a good idea. You can leave it in the container for years. In my humble opinion, you can never have too many citrus trees, especially when you live in Spain.

Is that body of water in the back ground by chance contain salt. If so it is probably spraying a salt mist in storms and you will need a special rootstock to handle salt on citrus..

Is it true that the rain in Spain fall mainly on the plane?

I think the rain falls mainly on the plain. Although the plain might be plane. And a plain plane could certainly fall on the plane plain, if there's rain.