Pruning large elms

[Garsi]

The Scolytus beetle feeds on 2nd year bark, usually (but not exclusively) high in the canopy. The seemingly coincidental introduction of the Ophiostoma fungus renders the phloem of the host tree perfectly suitable for the beetle to breed for 2-3 years afterwards. This could possibly be described as a symbiosis? which would suggest evolution in action. Fresh, leafy growth and wounding undoubtedly attract the beetles, but a major point would be that the flight muscles of the beetle can only function if the ambient temp is at 72F or above, so pruning would be best carried out after August in most areas, maybe later in the south. As for resistance, nature tends not to wipe species out, so natural resistance in a small number of trees is likely, as is the case of Ash with Chalera. It also seems likely that the Scolytus beetle prefers to feed on English elm over Wych, so again this is likely in relation to other species/hybrids.

Sterilisation of equipment is also an excellent idea, and not just with DED. Dettox spray seems to work well, so does alcohol-based sanitiser and neither will be toxic to trees.

[Gary Prentice]

The Scolytus beetle feeds on 2nd year bark,.

 

Where has this come from? Not being argumentative and personal experience would suggest it's true but I've never heard this as a fact. Have you a reference or a link.

[Graham]

The tree in my avatar is an English elm. A lone survivor from many hundreds of elm that died around it. I fancy trying to propogate from it but reading previous posts I'm not going to take the secatuers to it in summer. What are the chances of hardwood cuttings striking if I take them in Nov? Infact that whole hedgerow is elm.

[Gary Prentice]

I think there's another thread somewhere about elm propagation. If not PM and I'll have a look at Dirrs (which is at work at the moment). I'm fairly sure that the book lists a few methods, I seem to think that root cuttings are successful but may be wrong.

[agg221]

The tree in my avatar is an English elm. A lone survivor from many hundreds of elm that died around it. I fancy trying to propogate from it but reading previous posts I'm not going to take the secatuers to it in summer. What are the chances of hardwood cuttings striking if I take them in Nov? Infact that whole hedgerow is elm.

 

Hi Graham,

 

The tree in my avatar is also an elm - there is a row of three of this form which have survived, despite the ones on the opposite side of the road regularly burning up with elm disease when they hit 15ft.

 

To propagate elm trees there are three ways:

 

The easiest is to trace suckers back to the roots (often very easy as they sucker from big roots near the trunk). Suckers should have the beginnings of a root system already in place. Nick them off when dormant, plant up outside and keep sufficiently watered while the root system develops.

 

Second approach is hardwood cuttings taken in late Jan/early Feb. Plant in a 50 : 50 peat : perlite or vermiculite : perlite mix and keep it somewhere cold, such as the north face of a building, but with a soil heating mat or cable to keep the base at 18degC. This develops roots before the top.

 

Most difficult is softwood cuttings in late May, before the shoots have fully grown for the year. Cut at a leaf joint from a good, stiff, upward or sideward (but not downward) facing bit, then nick off the lower leaves completely, cut the upper leaves in half but leave the last one full. You then need to put them in a similar vermiculite : perlite mix in a dewpoint cabinet. Take rate is very low, but rooting is very quick if they do take.

 

There is a tentative plan hatching to run a proper disease resistance trial on surviving trees. This is what the Spanish did, and managed to identify a handful of truly resistant trees which they are now in the final stages of testing on multiple sites before considering going forward for mass propagation. If this goes anywhere for the UK, it would be very interesting to include your tree. It would need half a dozen or so plants to do it.

 

If the tree has suitable small suckers (definitively from this tree) or some suitable shoots in Jan when they could safely be posted, I would be very interested in some to take forward for this.

 

Alec

Edited July 1, 2014 by agg221

[Gary Prentice]

Alec have you a link to the Spanish research?

[Graham]

Thank you both. I shall have a go with the sucker method and hardwood cuttings.

 

If you want details re. location etc just let me know. The Spanish project sounds interesting.

[Paul Cleaver]

good shout Graham - wonder why its taken so long !!!

[Garsi]

Where has this come from? Not being argumentative and personal experience would suggest it's true but I've never heard this as a fact. Have you a reference or a link.

 

I was informed of this in Tree Pathology lectures in the early 90's, and have had plenty of time and opportunity to check this out 'in the field' since. As you said yourself, what I've seen backs this theory up, so I've no reason to doubt it as fact. Nothing is ever quite 'black and white' in nature though, but thats the beauty of diversity

[Gary Prentice]

Ok. no worries, It would have been nice to have had some research to reference. You need to have some knowledge of just about everything in this job at time.