What evidence is there for this?

http://www.telegraph.co.uk/earth/365...ust-warns.html

Or is it the National Trust just scaremongering to get rid of plants
it dislikes?

If oaks have the disease should they not be culled?
Angus Macmillan
www.roots-of-blood.org.uk
www.killhunting.org
www.con-servation.org.uk

All truth passes through three stages:
First, it is ridiculed;
Second, it is violently opposed; and
Third, it is accepted as self-evident.
-- Arthur Schopenhauer (1788-1860)