Ground-grown Black Alder; what next?

[keyfen06]

Hi all. I have a black alder that I got when I first started in one of those 'Grow Your Own Bonsai' kits. It was pot-grown for the first year, then transplanted into the ground the second year (2022) and now it's become a bit messy.




This is the only tree I've ever ground-grown, so probably not as thick as some other's trees on here but I just wanted to know if it would be wise to cut it back quite hard? I don't want it getting way too big, because I'd like to build some better taper and reduce the straight pole look so I thought I'd ask here before I chop like 70% of it off. The most work it's had is a very rough pruning last year with the wrong tools, so it's been quite neglected.

Is there a recommended amount I should actually cut back the tree to that wouldn't risk it's health too much? Or should I just prune the branches back and let it keep growing to keep thickening the trunk, and cut it back hard in the next few years? Also, would now be a safe time to do this? I think I got away with it in autumn last year, but now that it's early spring I wasn't sure if I could now.



Also, anyone have any idea why this part is very red compared to the rest? Some sort of fungal infection or the wood dying? The buds on it's branches seem healthy enough, but it doesn't exactly look promising.

 

[Wires_Guy_wires]

I would hack it down. Black alder produces a bunch of suckers and side shoots when you hack it.

The red part is dieback to the node. That's what happens if a cut points upwards and can collect water. They shut down the pipes at the closest junction; many plants work like this.
Next time, a sloped cut might be better and closing it off with some cut paste, vaseline or candle wax should prevent deep dieback.

They're swamp trees, so they aren't bothered by 99% of the pathogens we see in other plants.