In article ,
says...
"Spider" wrote:

Hi Brian,

You really need to find out if this is a fungal or viral infection.
There's
little point trying to spray plants affected with a virus. The usual
advice
for virused plants is to uproot and destroy by binning or burning; never to
add to a compost bin. Neither can you take cuttings from a virused plant.
Not what you want to hear about your 30 hazels, I know, but it may have to
be faced.

I agree that a large part of the problem is lack of information. I have
searched the web for it without success. Grubbing up and burning seems
to be the single professional answer to any kind of tree disease. I
suppose the scale of most forestry operations makes this the cost
effective option. I wouldn't want to do that unless I was sure leaving
them was a danger to other trees.

Root problems have been suggested before and I was advised to implant
mycorrhizal fungus "spikes" around the trees. I did some as a test,
because again these are far from cheap, but saw no result. That doesn't
rule out a root problem, of course. However, the leaves don't simply
fall prematurely. They have distinct symptoms, brown spots and browned
edges which go dry and crisp, the rest of the leaf yellowing. Later, all
the leaves, including any unaffected ones, go limp and dull, which
*does* sound like roots, so it's all very inconclusive.

I'm fairly sure IT, whatever it is, is airborne, as these bushes are
scattered round a 3-acre site, plus the fact that the prophylactic
Dithane does at least retard it. I suppose, if it forms a barrier by
coating the leaves, it could retard a viral infection too. I've also
found, where the plants are small enough for this to be feasible, that
prompt removal of all affected leaves gives the best protection

Not sure about going back to the supplier. They're a mail-order
wholesaler in Scotland, as these were part of a much larger woodland
plantation, and they were bought 8 years ago. Doubtful, too, about
diseased stock as they grew vigorously for the first 6 years.

You might be on to something when you mention phytophthera pathogens
because alder trees seem to be particularly susceptible to these and
there are alders in the mix. Some of these have a fairly similar leaf
problem to that described for the hazels, though it doesn't seem fatal
for them. But I wonder if they're the source of the problem --or the
carriers, because this problem persists from year to year. The fact that
I seem to be the only person in the area with this problem, and also the
only person growing alder trees, might signify something. I wonder how
closely related alder and hazel are?
Check on Hazels susceptibility to fireblight, as the damage you described
sounds like that.
--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea