Birch with co-dominant stems

[Pieris]

Hi, this is my first time posting on the forum and I’d be very grateful for some advice. I’m not an arboriculturist, just a tree enthusiast.

 

I planted the birch tree pictured below about two and a half years ago. It was sold as a pendula whip, but the habit is not quite like most other silver birches I’ve seen in that it has lost a clear leader and has instead developed several co-dominant stems.

 

Now I’m considering pruning it, but I’ve heard that birches don’t respond too well to pruning. My plan is to remove the co-dominant stem on the left completely. I’d retain the more-or-less central stem, which is in any case fractionally longer than the others, and remove its two competing leaders on the right. Would this be too much? Would I be doing the right thing?

I may also shorten some of the lower lateral branches.

 

I’d like to do the pruning now (I’m too impatient) but the advice I’ve read suggests I should wait because of the risk of excessive sap loss, though opinions differ as to the optimum time to prune birches. Some say late spring or mid-summer; others early autumn; a few suggest mid-winter.

 

Anyway, thanks in advance for any advice on the matter.

Pieris

[Tony Croft aka hamadryad]

dont prune the co dom stem right out, just to a third its former length and to a bud or growth point that leads down and out preferably. This will ensure the tru dominance of the main stem and not leave a wound that is proportionally to main stem on the large side.

[NI Tree]

welcome pieris i would do the above any way but if hamadryad said this i would most defentaly do it, he is very good.

[Arctostaphylos uva-ursi]

Looks pretty small to me. I would prune it right out. Looks like the tree has had no formative pruning? Do you want large long limbs developing 16 inches from the ground?

[Arctostaphylos uva-ursi]

Oh and dont prune it now. If your really desperate to get going, prune it in late summer when the leaves have fully hardened. But if you can wait until winter you will be better able to see the overall shape with the leaves off.

 

Good luck!

[Pieris]

Thanks for the advice; it’s great. Arctostaphylos uva-ursi (intriguing username), you’re right to think the tree has had no formative pruning. I removed a small witch’s broom when it was planted, but that’s it.

 

Most of my interest has focused on wild trees, and in the garden I like to let things take their natural form. Clearly, not always a good idea. Anyway, I have some other birches that have behaved themselves and, with no help from me, produced good trunks with clear leaders.

 

The tree in the picture is quite vigorous, possibly because it’s planted in a slight dip where moisture and nutrients tend to accumulate. I’ve had doubts about its exact nature, since it has shown some characteristics of Betula pubescens; but that's another issue, and one that seems to confuse even the experts. It’s put on a lot of growth since the photo was taken in December. It’s about six or seven feet tall now. I’ll take Hamadryad’s advice and just reduce the co-dominant stem on the left. What I’m concerned about is the possibility of included bark developing on the competing leaders on the right. Do you think it’s ok to remove them completely?

 

Thanks again

Pieris.

[Arctostaphylos uva-ursi]

Yes it’s fine to remove it completely. In fact it is best to do this when the tree is at this stage of growth as the pruning wounds will be small and will callus over quickly.

It’s your tree so prune it for the shape you want to achieve. If you want it to look ‘wild’ then don’t bother pruning it at all. If you want good form then fill yer boots! If you are going to prune it just try to imagine how the limbs will develop as they thicken and grow in length and let this be your guide.

Hope this helps.

[Tony Croft aka hamadryad]

Thanks for the advice; it’s great. Arctostaphylos uva-ursi (intriguing username), you’re right to think the tree has had no formative pruning. I removed a small witch’s broom when it was planted, but that’s it.

 

Most of my interest has focused on wild trees, and in the garden I like to let things take their natural form. Clearly, not always a good idea. Anyway, I have some other birches that have behaved themselves and, with no help from me, produced good trunks with clear leaders.

 

The tree in the picture is quite vigorous, possibly because it’s planted in a slight dip where moisture and nutrients tend to accumulate. I’ve had doubts about its exact nature, since it has shown some characteristics of Betula pubescens; but that's another issue, and one that seems to confuse even the experts. It’s put on a lot of growth since the photo was taken in December. It’s about six or seven feet tall now. I’ll take Hamadryad’s advice and just reduce the co-dominant stem on the left. What I’m concerned about is the possibility of included bark developing on the competing leaders on the right. Do you think it’s ok to remove them completely?

 

Thanks again

Pieris.

 

Pubescens is easy to distinguish from pendula, and at any life stage. look for the fine hairs on the young stems/twigs. it will also remain darker in the maturing bark for longer, and also have little red peelings as it matures. It has a different form when mature too, very little weeping habit compaired to pendula. Pubescens is the proper birch and they tried in vein to re establish it as so, but by then pendula had long been considered the true form.

 

Birches are amoung my fave species, in particular the B. ermanii, and B. nigra or river birch.

[Pieris]

Thanks for the continued advice. I’m now looking out of my living room window at the tree; and, in the words of Lionel Bart’s version of Fagin, “I’m reviewing the situation”.

 

Hamadryad, birches are among my favourite trees too. I agree there are many trees that are clearly either pubescens or pendula; but there are also many intermediate individuals that make life difficult for the amateur botanist. I once read a paper about wild populations of birch in East Anglia. The researchers examined the chromosomal make-up of trees and compared it with their morphology. Specimens with 28 chromosomes (diploid pendula) had strong silver birch characteristics. However, trees with 56 chromosomes (usually classified as the tetraploid pubescens) displayed any range of characteristics, from individuals that looked “pure pubescens” to others that looked “pure pendula”. There was a continuum of variation. On the sites they investigated, the team were unable to find any obvious hybrids – trees with 42 chromosomes – but they concluded the pendula-like pubescens trees were possibly/probably the result of introgression.

 

….Perhaps this subject needs a thread all by itself.

Pieris