"PendletonPR" wrote in message ...
My fifteen year old Silver Birch, planted as a very young tree, is sickly.
It is some 25 feet high and has lost its leaves at its apex and at the
extremities in other places. Other leaves are smaller than they should be
and with evidence of slight choruses. The tree is less furnished with leaves
than it should be. There is no evidence of insect or viral/fungoid
infection. It was planted on the site of a 150 y.o. beech which came down in
the Great Storm. Up to now it has flourished. We are on chalk and it is
surrounded by a beech hedge and shrubs ( buddleia, lilac which are
flourishing), it is some 10 feet from and five feet above a lane which is
heavily trafficked in rush hours. It is three feet above and 35 feet from
our cess pit. It has been gently fed with mild fertilizers to prevent over
feeding and scorch etc and well watered - we are on chalk. We are well up
on the South slope of the North Downs and its position is exposed - but this
has not effected another some 150 yards away at the top of the garden.

Has anyone any ideas/suggestions?

Birches aren't at their happiest on chalk, but it doesn't kill them as
far as I know. And they don't mind exposure.

I imagine you got all the roots of the old beech out before planting,
as there's no sign of fungus. I'm ashamed to say I don't know what
choruses are in this context.

I wonder if it might be root strangulation? If the roots aren't well
spread out when a young tree is planted you may see no ill effects for
several years until finally the crossing roots get big enough to choke
one another. If you think this is a possibility (but you don't sound
like the kind of gardener who would have made such a mistake) it would
be worth scraping soil away just in case you can see what's going on
under there. If there's a visible stranglehold, I'd risk cutting one
of the tangled roots through near the base; but I don't know if it
would work -- anyhow, it would take a couple of years to see any
difference. I wonder if root-pruning, as with fruit trees, might
encourage it to make more small feeding roots near the surface.

Does a birch really need fertilizer? They grow naturally on very poor
soils, after all. I suppose it's possible that it's had a bit too
much, but I rather doubt it. Wonder if it would like a good dose of
sequestered iron in case the chalk's left it a bit chlorotic and sad?
Now might help, and again just before bud-burst next spring, with an
acid peat mulch: it certainly wouldn't do any harm.

They're beautiful things: I do hope we can get this one healthy again.

Mike.