It seems
inevitable that every Ash tree in Scotland will become infected with the
disease.
The disease
will kill most of the trees. It will typically take a tree some years to die
completely.
A small
percentage of Ash trees are expected to be genetically resistant to the disease.
This could be 1 or 2 %, or possibly up to 5 %. Such trees will be infected but
will not die, according to the current state of knowledge. (but the disease is
so new that much about it is speculative at present)
Eventually,
over the long term (not in our lifetimes), the Ash population in Scotland will
hopefully recover to something like its present extent, due to reproduction by
the resistant strains of the trees. (which can possibly be aided by planting
seedlings from resistant trees once the resistant strains have been identified)
If recently
planted Ash are found to be infected, the whole planting should be destroyed.
Inform the FC and get further advice from them.
Mature Ash
trees that become infected should not normally be cut down (unless they cause
danger to the public). All Ash trees will eventually become infected, so if the
policy was to cut them down then Ash would be wiped out in Scotland. But if they
are left, the resistant trees will survive and the regeneration can start from
those.
Many insects
and other life forms are dependent on Ash. If Ash disappears, they will too. But
if infected Ashes are spared then these life forms can cling on to existence via
the few resistant Ash trees, and then repopulate the country when the Ash does.
In the case
of mature Ash trees, the disease overwinters in the leaf litter beneath the
tree. If you have a favourite Ash tree that you want to protect, for instance in
your garden, you should get rid of the leaf litter each winter. The way to do
this is to burn it near where you found it. Do not move it somewhere else and
dump it there! - you would just be spreading the disease.
All
infection should be reported to the FC. They will then advise on appropriate
action.
To avoid
spreading disease, do not move any material from Ash trees from one place to
another. After visiting a site with Ash, make sure there are no bits of dead
leaves stuck to your boots. Mud is ok. The fungus is only found on tree
material. So long as this is kept in mind, there is no need to stay away from
Ash trees to avoid spreading the disease; it is much better if people do visit
trees to look for the disease and report it.
The disease
is difficult to recognise, as many other factors can cause similar symptoms. For
anyone interested there is plenty of material online, and I have some leaflets
which will be available at LNHG events. It is easiest to recognise in summer and
I anticipate having a Chalara walk this summer where we can learn what to look
for and see how we get on (for once we'll be hoping NOT to find our target
species!)
Ash in NW
Scotland, which includes our area, is being treated as a high priority by the
FC. This is partly because in this region it has many important associated
organisms, such as Oceanic lichens, and because the disease may behave
differently in the unique west coast climate, and we could get lucky and find it
doesn't do so well there. Also there is more genetic diversity here where most
Ash is native rather than planted, so more chance of finding resistant strains.
