so these are a couple of trees which became infected towards the end of last
summer we left them to fell later this year and because it's at this point that
they're the most infectious you can see there's no foliage on them at all the
bark is drying out making it ideal breeding situation for the Elm bark
beetles they prefer to well they can only lay eggs under dried bark they
can't lay under healthy bark because the sap pressure was too high - too much
water they get flooded out the bark is now starting to come away which is
showing that the bark of the tree has deteriorated enough for the beetles to
use and you can see that there are entry holes where the parent beetle has
drilled in and from here behind there you will find the egg chambers so
there's a central gallery there where the parent beetle has burrowed down and
as she's burrowed down she's been depositing eggs either side
these then hatch and the larvae are out eating all the way growing and growing
and there's one there and these grubs this time of year will stay under the
bark feeding on the dead dying bark until the spring when it's warm enough
and they'll start to transform into adult beetles the first signs of the
disease is the the yellowing the wilting the yellowing of the foliage usually
higher up in the canopy where the beetles are flown in they like to feed
on the younger twig material that then creates a chain reaction within the tree
an immune response which starts closing off all the xylem vessels the water
carrying vessels unfortunately the Elm aren't fast enough to trap the
fungus which is the idea of closing off the vessels so the fungus zips through
the tree the tree keeps tightening itself up creates a torniquet sort of
system and it just begins dying back so hence if you starve something of water
the first sign you'll see is the the wilt and then the very tips will end up
shriveling becoming yellow and then brown and you'll get a sort of a gradual
effect down the branch from there on the tree will start to deteriorate so the
finer twigs will become leafless all the way down through the tree until
it ends up a skeleton like this and it's at this point that the bark has become
dry enough as all the water levels have been shut off the bark is drying out and
that's when the beetles can sense that the pheromones they pick up tell them
this tree is ready that head to it bore in start laying their eggs from an
initially infection from the first time that the beetles hit feed and introduce
the fungus into the tree it can take about twelve months to 18 months to
reach this sort of a situation where the beetles are are in laying eggs it can
depend on the tree its location its size and the weather as well some of these
trees were affected towards the end of last year so or in the program to be
filled this year this winter but due to the warm hot spring that we had the
early spring they've deteriorated a much faster they dried out a lot quicker
early on in the summer so hence now they've they've already been host to one
beetle brood which have you can see signs of areas where they've already
hatched but now we know that there are grubs in here they're still being used
this is the ideal time now to be felling them and taking out next year's beetle
population firewood is a big issue what we aim to do with every tree we fell is
to burn it take out the bark if anything is left
with bark on the beetles can still use it that includes stumps as well so all
the stumps have to be shaved of all the bark we do find often when we're felling
trees on private land that people do ask can we keep the logs you know we have a
wood burner that is fine but so long as the the bark is peeled off the
contractor can do that but it tends to add to the cost the private household of
the land and the tree owner could do that but it's not as easy as it looks it
is hard work and also we need assurances that it's going to be done I can't leave
a pile of logs for a landowner to say that they will do it and come back six
months time file that they haven't and dozens and hundreds of beetles of risk of escape
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