Cloning a Resistant Elm

[Perkins]

There was the "great british elm experiment" headed by David Bellamy a few years ago. I identified a great number of large elm tree in North Yorkshire, mostly in Hawnby, and offerred to send them some genetic material. They declined.

 

A local nursery up here sells disease resistant elm trees. I've planted a few and they're still growing strong, although not very large yet (16ft tall and perhaps 20cm girth).

 

The nurseryman said that you can send a small twig to a lab (somewhere!) and they will take shavings of the bark, grow these in gel into small trees and send you back 200-300 rooted trees from the parent twig.

 

I never looked into this further but the guy obviously knows what he's talking about.

[woodyguy]

You want to take cuttings 2-3 foot long. You halve the leaves to limit the water loss through transpiration. Keeping them out of bright sun will help. You cut below a leaf point and take off a few lower leaves but cut cleanly. Try some with rooting powder and some without as some species it delays routing. Bigger cuttings are often easier so try different sizes. Yes try layering as it may work. And finally, of course these are clones.

 

Sadly though I've been observing elm trees since the 70's and recently many of the trees that survived the original infection have now died. But as others said, we need to keep trying. By the way, the nursery nationally that sells resistant elm isn't selling English elm but a hybrid.

[agg221]

Where is the best place on the tree to take the cutting.?

How long a twig do I need?

Do I need new growth?

Do I need to cut the twig at a particular point?

Do I need to split or slit the bark at all to help the rooting compound

Is there any benefit in trying to layer the lower branches into the ground where possible?

Why do you need to cut the leaves to half length?

 

Hi Billhook,

 

I don't think it makes much odds where you take the twig from, but woodland grown you get better growth towards the top - open grown it doesn't seem to make much difference.

You want a 4-6" length of this year's growth ideally, although I have had 1" growth take root!

No particular location of cut seems to make it more likely to succeed, although cutting the base at a leaf joint does give more opportunity for cell formation.

No need to split or slit the bark, just dip in the compound, dib a hole in the rooting media with a pencil, drop the twig in and water in.

Cutting the leaves in half is to reduce the area for water loss. They don't need to photosynthesize that much as they aren't trying to make more growth, just sustain life until they root. Also, take any leaves off which would touch the soil as they tend to just rot.

Layering would be great if you can get them in contact with the soil, or water reliably enough to achieve air layering.

 

ELG - hope my response didn't come across as argumentative, I was typing in a bit of a rush to make sure my dinner didn't burn (just had a very nice Thai green curry)

 

Perkins - there have been various bigger 'official' projects, including one in Warwickshire and my local tree officer (Braintree) had a serious interest which is where I learned from. He propagated a few trees through a local nursery, which are now available for sale but at a very high cost. I think the future is likely to be interested individuals just doing enough to keep the surviving strains going. Propagation from bark shavings is the micro-propagation technique which is amazing if you ever see it. The shavings are kept alive through nutrients in agar gel, then hormones are introduced to promote transition to root mass, then further hormones to promote bud growth. It produces really strange, almost alien looking masses of root, followed by perfect, beautiful miniature plants which are cut off and grown on. You can keep it going indefinitely. I did my work experience at East Malling Horticultural Research Establishment in the propagation department in the 1980s when it was just being developed and it was fascinating to watch.

 

Alec

[Billhook]

All very helpful, thank you.

 

Only thing left to do is to try everything and report back!

[Billhook]

By the way, why didn't my pictures come out as a photo on the page. I thought that I followed the instructions after clicking the "post an image" icon

[agg221]

Did you click the 'choose file' boxes and select them so that they showed on the window, the click the 'upload' button?

 

What size were the files (were they within the allowed pixel size for the image type)?

 

Alec

[Gary Prentice]

According to Derr, root cuttings are also quite successful and semi-ripe cuttings do a lot better under mist propagation.

[Billhook]

Alec

 

When I click the "upload an image" icon it tells me to enter the URL of the image which I did copying the one from Flickr. with no result here on the page.

When I upload onto other sites,say Pistonheads, it goes through the procedure you describe and uploads onto its own photo site and all seems very easy and is something I have done successfully many times.

 

 

 

Btggaz

 

The root cutting idea seems to be another option, but I was wondering if there may be a problem with the cloning aspect in the same way as suckers may be from a different root stock, especially since the tree is a "specimen" planted in the middle of parkland in full view of the main house. I do not know how much experimenting went on in Victorian times with different root stocks, but I know that they were keen on their trees around here.

[Alycidon]

I was told that Dutch Elm only attacks things above about shoulder high, so an Elm hedge never gets infected but let it get more than about 6 feet high and bingo Dutch Elm. Mt brothers have a low Elm hedge in front of their farm house and that is relevant to them. They let it get up a bit a few years ago and it got walloped, as soon as they saw the issue they cut it right back and it seems to have at least partly recovered.

 

A

[Billhook]

I rather thought that it was due more to the bark starting to change from smooth to cracking up as the trees grow bigger, say fifteen years without being trimmed. The cracks allow the beetles entry to spread the disease.

If your brother keeps trimming perhaps the bark remains smooth.