From: pharvey@mipos3.intel.com (Paul Harvey)
Newsgroups: rec.gardens
Subject: Fireblight was (Cydonia problem)
Date: 24 Jul 92 20:12:05 GMT

In article <1992Jul24.102843.25031@lut.ac.uk> 
M.A.Hearnden@lut.ac.uk (MAHearnden) writes:
>I've had a common-or-garden cydonia - with dark red flowers -

That's latin for quince, or in your case flowering quince. Am I right?

>I planted it as a sucker from a bush growing in the garden when we moved in.
>Until about a month ago, when the leaves started turning brown.
>No other plants nearby affected - e.g. ,thyme growing at
>its foot.  No sign of insects.  All the leaves have now dropped off.
>I fed & watered it well as soon as I noticed the problems.

Just be carefull of overwatering. And I don't think I would "feed" a plant
under stress. "Feed" is called for when growth isn't suitable or the leaves
are losing their natural green color or other second order effects like that.
Lack of "feed" will rarely kill a plant, it may make it "anemic". Nitrogen
is more or less a no-no for pears and apples and relatives because it results
in fast, lush, shooty, growth that is prone to fireblight. Quince is a very
tough tree, once popular for that reason. I don't think it would require any
"feed" at all, unless you have an extremely leached soil, like pure sand.

>We've had quite a lot of dry weather here both this year & last year.

Fireblight and relatives mostly strike in hot, wet, tropical weather. 
Fireblight is spread by insects and usually enters from a tip bud or blossom
and moves down the branch towards the roots quickly and looks like someone has
burned the branch. It tends to only take out single branches, but if you
leave it, it will kill the entire tree.

>No sign of regrowth on the existing branches.  Just a couple of
>vigorous suckers growing up from below ground.

Means the roots are still good. Try removing all dead growth and suspect
growth back as close as you can get to the new suckers. Get some new shears
or tools for this purpose and dip them in bleach or alcohol while pruning.
Let the tools sit in alcohol for a few weeks before using them on anything
else. Burn or dispose of the prunings away from where they can spread the
disease. I jumped to a conclusion here. I assumed that the top that is now
leafless is dead. Check it by snaping it and looking for signs of life or
signs of sickness like discoloration of the wood. It's not easy to make the
call of what parts to try to save, I would start with the goal of removing
what I thought was bad and going into some good wood where I could. The goal
is to get the disease out of the plant.

>I've not used weedkiller.  The effect was over the whole 
>plant, not a case of die-back, nor something spreading from the roots.

Sounds like fireblight or something similar.

>I cut back extensively yesterday, to leave a framework.
>When I cut into the branches, they were still green.

Check closely for any discoloration and strips of dead cambium that go
down towards the roots. Don't spread it with your tools.

>Only thing that occurs to me is fire blight: does it behave like
>this? does it affect quinces?  If so, can I do anything to protect
>my pyracanthas?

I think there are some nasty chemicals that may help but you probably
don't want to know about, at least I can't tell you of them. I think
streptomyacin or something like that which is used for humans is sometimes
tried but has lots of problems and side effects. As far as I know, all
you can do is be on the lookout and prune when you see it and keep your
tools clean and avoid nitrogen for most apple/pear/quince relatives.