"brian mitchell" wrote


Having spent over two hours picking diseased leaves off my blackcurrant
bushes (I have a few), this interests me. I believe they are two
unrelated issues.

I have an ongoing situation with the premature yellowing and dropping of
leaves. It began with hazel bushes a couple of years ago but seems now
to have spread somewhat promiscuously to a range of woody plants. I'm
seeing it this year on elder, blackcurrant, briar rose, silver birch, an
ornamental cherry plus the original hazels. So the first thing I'd say
is to look around your neighbourhood to see if you can see it anywhere
else. If it's the same thing I've got it's quite noticeable as the
yellowing leaves also go brown and dessicated at the edges.

In the case of the hazels and the silver birches, whatever it is
eventually kills the plant over two or three years. There is die-back
along the twigs, progressively fewer leaves, and those which do come out
hang rather listlessly. I don't yet know if other species are as
susceptible. Because of the very humid conditions last summer, and
because whatever it is on the hazels spread to adjacent shrubs such as
hawthorne and field maple, I thought it was some kind of fungal disease.
Now I'm not so sure and think it might be bacterial/viral. This matters
because there are preventative treatments available for fungal problems,
such as Dithane, but not for the others.

What I've also noticed about this is that the first growth of leaves,
those that break out of the winter buds, are mostly unaffected but new
leaves following are nearly all affected, so most of the yellowing and
dropping leaves are small, not fully formed. Is this what you're seeing
on your plants?

As to surrounding trees or shrubs becoming affected, it seems to depend
on the species. I have apples and plums and it hasn't so far migrated to
them, but watch this space. I'm about to send some leaf samples to a lab
for a report and if you think what I'm describing fits what you're
seeing I'll post the results here. Whether they'll be useful is another
matter. By the way, I wonder where in the country you are? I'm in S W
Wales. I have seen the same symptoms in hazels in the surrounding
hedgerows, so it not just me --unless I was the source of the outbreak!

brian mitchell

Hi Brian

Thanks for the comprehensive response.
The yellowing leaves I am seeing are more mature and formed leaves, but they
are also developing a brown fringe before dropping.
I can't help thinking that the fruit size and yield are down.
But I discovered that the majority of new shoots and leaf clusters are being
attacked by aphids - will this cause the yellowing leaves?
Went round last night with the fairy liquid spray and doused them all
thoroughly.
I only have 3 blackcurrant bushes, but a couple of redcurrants also seem to
be affected (more by the shrivelled leaves due to aphids than the yellowing
leaves).
http://www.eewinerycoop.com/docs/blackcurrants.pdf gives details of pests
and symptoms, though I expect you've done the google bit to death already.
I am just hoping that the cause isn't reversion, as this means discarding
bushes and starting again.
As the blackcurrant bushes are almost touching apple and plum trees (small
garden - needs must) it will be bad news if the problem does spread.
I am in east yorkshire (3 miles from the Humber Bridge) - elevated location,
clay soil with some chalk.
If you could email me next time you post any further info from your tests it
would be appreciated (pscull at europacrown dottcomm) - I am an occasional
URGLER only.

Phil