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mattyboy

pollarding elm success?

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think that's to do with the South downs not that they're pollards

B&H pollard a lot of the street elms about every 4 years if I remember.
I've seen huge elms hacked down to a 5m stump 3-4' across and only a limb or two remaining.
A year later covered in epicormic growth.
They are pretty resilient.

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I thought the beetles needed branches of a certain thickness to make their galleries.. Hence young trees are too small and therefore not affected. Pollarding is not going to help as there will still be thick stems. I also thought that the beetles can sense a pheromone or something that elms release when injured and therefore often get attacked after pruning.. Certainly happened to several mature trees I know about that were healthy, pruned and died the next  year.

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No ones mentioned elm hedges, there are miles of it round Norfolk and Suffolk and I have never seen it with the disease, makes a great hedge many thrashed back heavily every year so as others have said very resilient to regular cutting

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1 hour ago, timbernut said:

No ones mentioned elm hedges, there are miles of it round Norfolk and Suffolk and I have never seen it with the disease, makes a great hedge many thrashed back heavily every year so as others have said very resilient to regular cutting

That's because they do not have any thick wood suitable for the beetles to burrow into and make their homes..

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Round our way in West Sussex it does seem like elms get to a certain diameter (around 20cm DBH) without any harm, then within a couple of years they have got DED. I've never seen a small elm die and never seen a large one survive round this way.

 

My understanding has always been that the Brighton elms are allegedly protected from DED by the South downs to the N, E and W sides and the sea to the S. Whether or not they get pollarded may be due to other factors such as safety issues. Anybody know the TO for B&H council? Maybe get some info.  

 

 

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Didn’t they leave dead elm trunks out to attract any beetles at certain times of year, then remove and burn them before any hatching.

 

Anyway, fair play to them, the LA there do a great job ensuring their survival.

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3 hours ago, Shane said:

Round our way in West Sussex it does seem like elms get to a certain diameter (around 20cm DBH) without any harm, then within a couple of years they have got DED. I've never seen a small elm die and never seen a large one survive round this way.

Because the elm effectively blocks its own sap supply as it reacts to the fungus in it's current years sapwood it can recover if there is some of the current annual ring un infected, you can often see this by cutting through an infected peice and there are black marks within a previous annual ring where the tyloses have formed. This is from feeding activity in the crown. Once the cabium is thick enough to support a breeding gallery then  the fungus  is spread all around the tree and the tree reacts, thus cutting off all its sap supply to the crown.

3 hours ago, Shane said:

 

My understanding has always been that the Brighton elms are allegedly protected from DED by the South downs to the N, E and W sides and the sea to the S. Whether or not they get pollarded may be due to other factors such as safety issues. Anybody know the TO for B&H council? Maybe get some info.  

 

 

Most of the field elms we knew as Ulmus procera, it was known to be an infertile variety, so all the specimens were clones and genetically identical. It also had a high degree of apical dominance and grew long straight poles which was probably why it was selected. One of its unfortunate traits was it was totally dependant on this year's sapwood, hence once that was infected around the total circumference it killed itself.

 

More recently DNA has shown it is in fact a variety of Ulmus minor. The elms in Brighton are a mixture of species and Ulmus minor is one of them and it sets a viable seed, hence it reproduces sexually and there is a variable resistance to the fungus because of these variations. Given a heavy infestation they don't survive so the sanitation felling and hygiene plus the local conditions help the resistance.

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