On 11/01/2014 17:30, Nick Maclaren wrote:
We got no apples this year, because of catastrophic woolly aphid.

Crumbs! How did they manage that? Last year was so good for apples that
the trees were in danger of fracturing branches with the sheer weight of
fruit. You can control but not eliminate woolly aphid on apple trees
with a stiff brush dipped in meths (wear eye protection).

It is in the cracks that they lurk and keep open wounds on the tree. But
even on my parents where woolly aphid is completely out of control I
have never known them prevent an established tree from fruiting.

I have lesser but similar problems with a grey aphid on currants.
The problem is that the infestation causes immediate and severe
enclosure by the distorted leaves, so contact insectides will not
work. I also have chestnut scale on one vine.

Meths will get that too (maybe if you are feeling dodgy with a trace of
unlicensed use tobacco nicotine in it but wear rubber gloves!)

Now, the traditional solution is a tar oil winter wash, but the UK
has banned that for domestic use. There are some organic replacements,
but they don't look at all effective, and I don't want to harm the
plants by using strong disinfectants (e.g. Armillatox or Jeyes'
Fluid) in the absence of advice.

So what would people recommend?

Tar oil winter wash using the modern Jeyes fluid formulation.
(will kill anything green it touches - pretty much is a refined version
of tar oil but lacking some of the more carcinogenic components).

It should be good enough to kill most of the overwintering eggs (but not
all so you have to selectively persecute them with meths on a brush in
spring and encourage the ladybirds). Otherwise pesticide tends to see
off the predators as effectively as it kills some of the prey.

--
Regards,
Martin Brown