Cloning a Resistant Elm

[Billhook]

On the farm here in Lincolnshire we have been devastated by the Dutch Elm disease mainly in the 70s and 80s. There are many Elms in the hedgerows and woodland that are still going strong until they are about fifteen years old and the bark cracks and the beetle invades again, but they keep coming back from the suckers, I suppose waiting for the time when either the beetle or the fungus mutates.

However in the middle of this Elm disease ridden woodland are two large mature trees one of which seems to be touched by the disease in the crown every Autumn to the same degree and this has been the case for some years. The one in the photo stands in open parkland whereas the other similar sized is in a hedgerow, but it has shown no signs at all of the disease.

Several questions about cloning these trees.

1. Where is the best place to take a cutting, presumably away from the suckers.

2. What time of year or growth stage should this be.

3. What is the most successful method of turning the cutting into a tree

 

 

[agg221]

Cuttings can either be taken in late June or in autumn after the leaves fall. You want this year's growth.

 

If you take them in June you need to cut the leaves to half their length and pot in a 50:50 sharp sand:potting compost mix, burying a couple of inches. It is best if you use hormone rooting compound. You also ideally put them in a propagator with bottom heat, but putting the lot in a clear plastic bag on a North or East facing windowsill is also OK.

 

If you take them in autumn, just use hormone rooting compound and compost as above but put them outside somewhere sheltered.

 

You should get a slightly higher success rate with the former than the latter, but don't expect either to be good.

 

Once rooted, pot up for a year and then plant out to grow on, either lined out about a foot apart until they are about 3' high, or in their final planting place if it is well protected from rabbits and weed growth.

 

Alec

[easy-lift guy]

Billhook, taking cuttings from an existing tree is not really cloning from a genetic stand point. If you are trying to grow an example of an elm that is not showing the signs of Dutch Elem disease ATM that is fine. Just remember that actuall cloning takes place in a lab under specific growing conditions usuall by groups of trained plant biologists, botanist, and plant

genesists. I am sure work continues on this problem where ever the elm tree grows or has grown. Genetics will altimately be the cure or solution to many problems in the horticultural

And Arborcultural world, however everything is always changing in order to survive.

Just the nature of nature.

easy-lift guy

[burrell_]

We have quite a few large elms round this way witch u believe are called huntingdon elm most of them are 3ft across the bottem of the trunk to 6ft

 

There is a massive one on one of the sites I'm at quit often and keep on about taking cutting but never get round to it

Strange thing is there is loads of Dutch elm round the tree for many years and it still lives

I will see if I can get a pic

[sandspider]

Billhook, taking cuttings from an existing tree is not really cloning from a genetic stand point.

 

Surely it is? The resulting tree will be genetically identical to the parent plant, i.e. a clone?

[agg221]

Surely it is? The resulting tree will be genetically identical to the parent plant, i.e. a clone?

 

Yes, it is cloning, just not normally termed as such. Plants are easy to clone, from simple cuttings to layers to complex micro propagation techniques using complex hormonal environments as ELG describes.

 

Cloning animals is much harder because the cell types needed and their interrelationship is much more complex.

 

Genetic modification for disease resistance is another thing altogether.

 

Alec

[easy-lift guy]

Yes, it is cloning, just not normally termed as such. Plants are easy to clone, from simple cuttings to layers to complex micro propagation techniques using complex hormonal environments as ELG describes.

 

Cloning animals is much harder because the cell types needed and their interrelationship is much more complex.

 

Genetic modification for disease resistance is another thing altogether.

 

Alec

 

Actually I believe the OP may have been referencing the taking of cutting and growing a resistant strain of elm that will not hopefully acquire Dutch Elm disease. If cloning was that simple the problem would have been resolved long ago. Two primary causes of DED is a fungus and Native elm bark beetle,and smaller European elm bark beetle. Genetically speaking once and if the Two species of beetle are deleted from the habitat I believe the spread of this disease will disappear as well.

easy-lift guy

[agg221]

Actually I believe the OP may have been referencing the taking of cutting and growing a resistant strain of elm that will not hopefully acquire Dutch Elm disease. If cloning was that simple the problem would have been resolved long ago.

easy-lift guy

 

Yes, that's also my interpretation of the OP's intention, which is cloning the tree in question through cuttings.

 

The hope is that any trees of good size which still survive in areas where DED has not been actively managed have a high probability of being resistant, either because the beetles are not attracted to them or they show resistance to the disease itself. Either would have the net effect of the tree surviving.

 

'Cloning' is that simple, however its simplicity does not result in easy resolution of the DED problem. This is because there is no straightforward way to screen for resistance to the disease (there are lab based culture tests but they aren't very practical) and no way at all to screen for resistance to beetle attack. As such, the only practical option is to wait until the disease has run through and see what's left.

 

Many elms lack fertility and hence are genetically identical clones, grown from suckers. This results in very high loss of population (cf. the outbreak of Chalara fraxinea in Denmark for contrast). The consequence is that to resolve the problem you need:

 

a) Someone to notice that not all the elms have died and identify surviving trees.

b) Someone to work out how to propagate elm from cuttings.

c) Someone who is prepared to take cuttings from the surviving elms.

d) A way of putting a), b) and c) together.

 

Pre-internet, the above was very difficult to achieve. The surviving elms being very scarce and often not visible from a point of public access made them hard to find. If you found one, would you notice, and if so, what would you do about it? Even if you wanted to do something about it, pre-internet where would you go to communicate the information (your local public library was not likely to be much help on this).

 

Given the above, I don't think it is surprising that realisation of the number of surviving trees is pretty recent, and efforts to propagate them even more so. Hopefully it will work, just as previous natural regenerations post-DED have been successful. The reason some human intervention is justified in my view is that human intervention has reduced the likelihood of natural regeneration by reducing the opportunities for large elms to develop.

 

Alec

[treecreeper arb]

Yes, that's also my interpretation of the OP's intention, which is cloning the tree in question through cuttings.

 

The hope is that any trees of good size which still survive in areas where DED has not been actively managed have a high probability of being resistant, either because the beetles are not attracted to them or they show resistance to the disease itself. Either would have the net effect of the tree surviving.

 

'Cloning' is that simple, however its simplicity does not result in easy resolution of the DED problem. This is because there is no straightforward way to screen for resistance to the disease (there are lab based culture tests but they aren't very practical) and no way at all to screen for resistance to beetle attack. As such, the only practical option is to wait until the disease has run through and see what's left.

 

Many elms lack fertility and hence are genetically identical clones, grown from suckers. This results in very high loss of population (cf. the outbreak of Chalara fraxinea in Denmark for contrast). The consequence is that to resolve the problem you need:

 

a) Someone to notice that not all the elms have died and identify surviving trees.

b) Someone to work out how to propagate elm from cuttings.

c) Someone who is prepared to take cuttings from the surviving elms.

d) A way of putting a), b) and c) together.

 

Pre-internet, the above was very difficult to achieve. The surviving elms being very scarce and often not visible from a point of public access made them hard to find. If you found one, would you notice, and if so, what would you do about it? Even if you wanted to do something about it, pre-internet where would you go to communicate the information (your local public library was not likely to be much help on this).

 

Given the above, I don't think it is surprising that realisation of the number of surviving trees is pretty recent, and efforts to propagate them even more so. Hopefully it will work, just as previous natural regenerations post-DED have been successful. The reason some human intervention is justified in my view is that human intervention has reduced the likelihood of natural regeneration by reducing the opportunities for large elms to develop.

 

Alec

 

:thumbup1:Very good response.nice one:thumbup1:

[Billhook]

Thank you Alec for the detailed reply and yes what I want is a clone of the tree that I have observed now for several years recovering from a little sniff of the disease each Autumn.

 

Just need a bit more detail here

 

"If you take them in June you need to cut the leaves to half their length and pot in a 50:50 sharp sandotting compost mix, burying a couple of inches. It is best if you use hormone rooting compound."

 

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?