Have a grafted fruit tree. Want to have less of one of the fruits

Question

I have a fruit tree whose primary trunk is pomelo fruit and the grafted trunk is Lemon. It's a reasonably large tree (35ft as a guess).

I don't much like the pomelo fruit and don't really eat them. I can't really reach the whole tree, so the fruit drops off and makes a bit of a mess. I get out there and clean up the dropped fruit on the weekends, but it attracts rodents and such as well. All around, a little more annoying than beneficial.

On the other hand, I love the lemons and would hate to lose them. Planting a new lemon-only tree would presumably take a long time to reach the size of this current tree.

How aggressively can I prune the pomelo branches without killing the lemon? Will the lemon be able to support the root/trunk of the tree if I cut back the pomelo completely? Added photo. The left hand 'trunk' is the lemon and the more vertical larger trunk is the pomelo.

Answer 1

I would approach this in a gradual fashion. The requested picture would help, but as a general idea, cut back perhaps 1/3 of the less desired part one year, and repeat. From a growth point of view, lopping it more from the top would be good, rather than just whacking off the lower limbs and encouraging it to grow taller. I should be clear that I don't mean it will all be gone in 3 years - that's still pretty drastic from a tree's point of view. You'll cut less as you have less of the pomelo part.

When you reach a point where the lemon is 2/3 or more of what's left on the tree, you could consider trying to off the pomelo part completely. You might also consider what other fruits you could graft on that you might eat - and that you might consider sooner rather than later.

Specific suggestions for suitable additions would have to be from someone with a better handle on citrus - not too many of those around here.

Answer 2

I recently did this exercise with a sour mandarin tree. I cut back everything on the tree (about the same size as yours) except that I left a small nurse branch to keep the tree alive. I have since been attempting to graft other citrus onto that tree.

In your case the lemon is healthy and can act as the nurse branch. You can completely cut back the pomelo and the lemon should stay alive and thrive. The pomelo will probably produce more shoots over the years. You can leave those to provide shade for the trunk if you live in a hot climate. Alternatively you might want to consider painting the trunk to provide some protection to the exposed bark. Again - only if you live in an extremely hot climate.

Ecnerwal's suggestion of grafting on new citrus varieties onto the trunk is a good one. If you want more lemons than you're currently getting then you can take buds off your existing lemon tree and graft them onto the trunk.