Young elms - what to do

[Mercadante]

We have several young Cornish (I think) elms around the place - one close group (or possibly two) of clones and then a couple of trees a little way away. So of course we are in dread of Dutch Elm Disease, which I have read is sweeping the country killing off all the suckers that have been growing since the last major outbreak, and Cornish elms are said to be very susceptible.

Last year the oldest tree showed possible signs - a couple of branches started dying from the top. We cut it down and burnt the branches immediately to try to stop any spread.

I have lots of questions. First, someone who practises as a tree surgeon told us that the bark ridges shown here indicated DED. But all the pictures I have seen online of bark beetle damage are quite different - isn't this just normal?

Second, would keeping all our elms short stop them getting the disease, or is it something else about them getting older that attracts the beetle?

Third, is there an easy way to tell if a tree that looks a bit sickly actually has DED?

Fourth, if the tree that we felled last year had the disease and it had spread to the root, are all the clones doomed, or could they go on being chopped down and then growing new suckers for years?

And finally, if anyone has any general advice, we'd be grateful.

[Adam Cheeseman]

The only way I have managed to keep reasoonable sized elms at a place where I work is to keep them pollarded below a height of 11 feet. I have been told, but don't know how exact this is, that the beetles only bore into elms above this height. It has been a successful method so far, so I would personally reccommend it.

I think the days of elms susceptible to DED reaching standard size are gone, and the only way to conserve them is as a hedgerow species or as a low pollard.

Cheers,

Adam

[Adam Cheeseman]

Originally Posted by Mercadante

Third, is there an easy way to tell if a tree that looks a bit sickly actually has DED?

Fourth, if the tree that we felled last year had the disease and it had spread to the root, are all the clones doomed, or could they go on being chopped down and then growing new suckers for years?

Usually, when a tree is a bit rough the topmost branches start to show rapid die-off of the leaves, which rapidly spreads to the lower branches. Once it has a hold, the bark starts to fall away quite quickly too and the tree will be dead by the end of the summer.

Strictly speaking when a tree dies of DED it is supposed to be felled and the root dug up and the whole lot burnt on site. This is rarely done in practice by council contractors though.

Cheers,

Adam

[Mercadante]

Thanks very much for the tips! I think our elms are probably still under 11 feet, but one or two must be nearly there, and as they're growing out of the tops of Cornish hedges perhaps I should cut them back a bit further. Looks like they might have a chance after all.

[tufftie]

There was a problem with this round here a few years back but as I can't remember most of it here's some quotes from a RHS book: To go with Adam's description there's also this ''Dark brown streaks maybe visible when the bark and outer wood are peeled back from affected branches.''
This might also be of help to you; ''In situations such as hedgerows where root transmission may be an important means of spread, healthy trees maybe protected by digging a trench aprox. 15 cm wide and not less than 60 cm deep midway between the trees and diseased neighbours.''
Hope you manage to save them

[Frimsley]

The bark ridges are entirely normal on this species and absolutely nothing to do with DED.

The impact of DED has been to change the form of elm in the landscape. Young trees grow, often suckering from the stump of a tree that was felled. After a time they succomb and die. New suckers replace them. The reality is that except for a few isolated mature trees which are actually worth making a big effort with, this is how things are these days, and is how things have been in many parts of the country for getting on to 30 years. No point in fighting it. I'm afraid your trees will probably die. But they will be replaced.

[Mercadante]

Great, thanks for the confirmation on the bark.

It'll be a shame if all our trees die, but if we can keep suckers coming up that will be something.