Japanese White Pine with Rotten Graft

[chansen]

You don't decandle JWP, unless you hate it and want it to die. They don't reliably back-bud like JBP do. So treat it more like a Scots pine. You can break vigorous candles in half, but don't completely remove them. This is a young tree, and if it's growing really strongly it would probably survive. But again, the general practice is not to completely decandle, but pinch/cut the candles as they are growing.

I'd bet you're too late in the season to pinch back the growth, and by looking at the tree you may still need branch extension anyway (tough to tell from the pictures). If you need longer or thicker branches, you don't (generally) decandle or pinch back the growth.

 

[AndyJ]

Thanks Christian. Dam - I thought you’re supposed to wait until the candles shed their sheaths? Evidenced by the brown sheaths on top of the soil/substrate? I want to introduce more branching so was going to pinch the candles to turn one shoot into two .....

 

[penumbra]

Only my opinion, but in your shoes I would put this pine in a large wood box or pond pot and grow it out vigorously for a few years. I might nip it here and there to gently guide it toward my goals, but that is about all. I would let the trunk thicken up and break heal very well.
I would then buy a couple of other more expendable plants to work on to satisfy your needs and revisit the pine your wife gifted you after it has achieved a bit more girth. It would be a shame to destroy your gift tree with all good intentions.

 

[Leo in N E Illinois]

@AndyJ -
you cracked the trunk in July 2019, the trunk will not completely heal for some 5 years or so. It will be stable in about 2 years. No more trying to bend across that spot as it will be forever a weak spot. So now you have 2 areas to avoid putting tension across. The graft union and the point where you cracked the trunk. All future bends have to originate further out along the trunk.

Japanese white pines are single flush pines. They are treated more like a Scotts pine (P. sylvestris) rather than a JBP. Note, actually the techniques for single flush pines originally were worked out with Japanese white pine, so it is Pinus sylvestris that gets treated like JWP rather than JWP being treated like P. sylvestris.

Key is, the "candle removal" of Japanese black pine is NEVER done for Japanese white pine. In general with younger JWP such as this one, no "candle work" is done at all. All pruning is done late summer or even early autumn. And the pruning done is removal of unwanted growth.

The way to get vigorous back budding on a JWP is to first let it grow vigorously without pruning back. It needs to develop strength. The movement of sugars and auxins and other plant hormones as a result of vigorous growth will cause back budding to occur naturally. After 2 or 3 years of vigorous growth, then a sharp pruning back might be needed if buds did not develop where you need them.

So in late summer, early autumn, reduce the numbers of branches at a whorl to 3 or less, ideal is one branch and the branch that is the continuation of the trunk. But if the tree has not been styled yet you can leave 2 branches and the continuation of the trunk. This will leave you choices for when it comes time to formally style the tree. Other than late summer or early autumn pruning I would do nothing else to this tree.

 

[AndyJ]

Thanks for the feedback and the advice. You are right, of course, this tree does need some growth and an opportunity to thicken up a bit. But I am keen to understand what the techniques are and how they are implemented. My plan with this is to gradually ‘up-pot’ it - I think it can stay in this pond basket for another couple of years?

There are a couple of branches that I know I’m not going to need - what I was hoping was that I could practice on these branches to see how they react to the techniques. Or would this not work?