Alan Holmes wrote:

I don't want to throw a spanner in the works, but the advice I've read on
walnuts is that they don't respond well to pruning. I can't remember
though what the bad effects are likely to be - maybe the tree just won't
look quite right as it won't put on the new growth you want.


When mine was developing, the branches were at a very low level, and that
became VERY inconvenient, so I cut all the branches off the trunk up to
about 7 feet, the tree has grown massive since then.

So your theory is wrong, at least in my case.

But how do you imagine other growers treat their trees, I'm sure they do not
allow branches to grow at jjst a couple of feet fron the ground.

I have just looked up the details (not my theory but misremembered
advice published by the RHS) and my memory was at fault. The advice
actually says that it doesn't respond well when cut back hard (applies
equally to Juglans nigra and J. regia). I should have looked it up
first. Apologies for the confusion I may have caused.

It does, however, also say that pruning should be kept to a minimum,
because they bleed profusely and that some species should not be pruned
at all (J. californica, J. hindsii, J. microcarpa). There's a fair bit
of detailed advice to do with minimising die-back (by not being careful
not to leave stubs) leaving the collar intact if removing larger limbs.