I have to say I haven't been diligent in removing those rootstock stubs.
Does this usually happen if you leave it behind or is this more of an anomaly? Either way I plan to take a closer look and start removing them.
Will, this is very bad because the upper part is growing faster then the underpart.
This is the cause of the grafter which used the wrong understock.
The grafting union will get weaker by the year and some day it will break off because it can't carry the (heavy) weight anylonger...
Will, I got rid of a Pp ' Blue Totem' for the same reason.
Sounds like this only happens if you have low vigor or the wrong understock then?
This one is Pinus mugo 'Zundert' so not the largest growing conifer at least yet. So I'll likely let it roll until I find something to replace it with.