[CANUFNET] Root grafting Dutch elm disease

[Philip van Wassenaer]

Sorry but U.americana is not resistant at all to DED, otherwise we would
still have them all over North America.....


Philip van Wassenaer, B.SC., MFC
1248 Minnewaska Trail
Mississauga, Ontario
Canada, L5G 3S5
Tel:  (905) 274-1022
Cell: (647) 221 3046
Fax: (905) 274 2170


www.urbanforestinnovations.com



-----Original Message-----
From: canufnet-bounces at list.web.net [mailto:canufnet-bounces at list.web.net]
On Behalf Of Rowland, Sara
Sent: December-12-11 8:26 AM
To: 'canufnet at list.web.net'
Subject: [CANUFNET] Root grafting Dutch elm disease

Hi,

I used to work in the UK where we were fortunate to have a few isolated
healthy elm trees left. 

Dealing with elm tree hazards - usually after the fact when the tree had
fallen into the highway from a farmer's hedgerow - the concept of root
transfer of the pathogen seemed highly probable as we were dealing with
slender trees that had not yet reached a good size to attract the beetles.
However we could not be sure in all instances that it wasn't re-infection of
coppice growth from an original root system, after the original tree was
removed. But root grafts do occur; there is no reason why the fungus could
not spread from tree to tree in the conjoined vascular systems and we were
assuming that was happening. I imagine the risk increases as the density of
elm increases; generally, we had pretty dense elm all dying at the same time
and about the same size and age. 

In contrast, our healthy trees were isolated and big (80cm dbh+); their
isolation was a factor in their survival, away from other elms. 

Species choice should help reduce the risk; I believe Ulmus americana is
fairly disease-resistant. I would suggest inter-planting with other species,
to help reduce the risk even further. 

Sara
Urban Forestry Planner
City of London


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Sent: Sunday, December 11, 2011 12:00 PM
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Subject: CANUFNET Digest, Vol 83, Issue 4

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Today's Topics:

   1. Dutch Elm Disease (Mike James)


----------------------------------------------------------------------

Message: 1
Date: Thu, 8 Dec 2011 08:27:15 -0800
From: Mike James <mjames at deeproot.com>
Subject: [CANUFNET] Dutch Elm Disease
To: "canufnet at list.web.net" <canufnet at list.web.net>
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	<8CD00EC182639240BA9B8A5AC102D56B45E0E5A6 at VA3DIAXVS4A1.RED001.local>
Content-Type: text/plain; charset="us-ascii"

My client has expressed the below concern.  Is there any science to support
that Dutch Elm is being passed between trees through connecting root
structures?

We are wondering about Dutch Elm Disease. He heard that it spread the
fastest from tree to tree when the roots are touching.We realize this would
preclude us from putting two or more elms in the same tree trench. Have you
ever encountered this? Is it a big concern?


Mike James
DeepRoot Canada Corp.
Tel: 1 800 561 3883
Tel:  (604) 687-0899
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Fax: (604) 684-6744
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