How to remove rootstock from old lemon tree?

[tania3]

 

We have recently moved into our home and have an old lemon tree that was completely overgrown. We have given it a huge cut back. We have noticed that there is some unusual fruit on the tree and I have been told it may be coming from branches that come off of the root stock. I have also read that multiple trunks may be an indicator that the rootstock has taken over the grated lemon tree.  Can anyone tell me from my picture which branches may be from the rootstock that we should remove. 

[MitchellMc]

Welcome to the Bunnings Workshop community @tania3. It's wonderful to have you join us, and many thanks for your question about grafted lemons.
 

Any branches that bear unusual-looking fruit, larger than average leaves or have gnarly large thorns could be coming from the rootstock. These shoots typically come from just above the soil level and grow distinctively sideways out of the rootstock before turning upwards. The best time to locate these branches is prior to pruning them back. Currently, I can't identify any telltale signs that would indicate any of these branches are from the rootstock. Some might be, none might be, or the whole tree might have been overgrown entirely by the rootstock.

Were you able to show our helpful members some of this unusual fruit? If they are fruit from the rootstock, you'd expect to find more skin, pith and pips than actual pulp and juice when you cut them open.

I'll be looking forward to seeing some images of the cut-open unusual fruit and providing further assistance.

Please let me know if you have any questions.

Mitchell

[tania3]

  

  

Morning Mitchell

there isn’t too much fruit on the tree at the moment

from what I can see some fruit is quiet round and others off a different branch are more traditional lemon shape

i have taken a couple of pics to show you the difference

i have also taken a close up of the trunk to show how it has separated down the bottom

[MitchellMc]

@tania3,

That last photo is fairly indicative of what you'd expect to see fruit-wise off rootstock. They'll sometimes produce fruit, but it typically looks quite deformed. Your second photo shows what I would perceive as a normal-looking lemon off the grafted stock. However, to bottom lemon could just be an odd shape.

You have a fused trunk at the base. So if there ever were individual suckers that grew from the rootstock, they look to have well and truly fused together now—likely creating some type of hybrid tree that produces both types of fruits on a variety of different branches.

Let me mention @Noelle, one of our horticultural experts, to see if she has any thoughts.

Mitchell

[Noelle]

Hi @tania3 

I agree with Mitchell regarding your tree.  The right-hand upright growth in your second photo appears to be the grafted part of the tree - the distinct line low down indicates rootstock below and grafted variety above.  The other main "trunks" on the left look exactly the same as the rootstock below the graft union.

The rootstock limbs will be unlikely to ever produce quality lemons so if you want to remove them entirely, do so. That may give the real lemon variety a better chance.