Has anyone any suggestions for a suitable fungicide for botrytis on a
grape vine, please?

My vines are in a polytunnel and suffer from botrytis each year. I
understand that the time to spray them is when in flower, which is now.
Unfortunately, all the treatments mentioned in my books seem to have
been withdrawn from sale and I cannot find one that is indicated for
this mould.

--
Howard Neil

The message
from Howard Neil contains these words:

Has anyone any suggestions for a suitable fungicide for botrytis on a
grape vine, please?

My vines are in a polytunnel and suffer from botrytis each year. I
understand that the time to spray them is when in flower, which is now.
Unfortunately, all the treatments mentioned in my books seem to have
been withdrawn from sale and I cannot find one that is indicated for
this mould.

Bordeaux mixture. You can make it from lime and copper sulphate if you
can't get it. Proportions aren't critical.

I think Murphy's Dinacap (Dinocap? Dynacap?) treats botrytis.

--
Rusty
Open the creaking gate to make a horrid.squeak, then lower the foobar.
http://www.users.zetnet.co.uk/hi-fi/

Jaques d'Alltrades wrote:

Bordeaux mixture. You can make it from lime and copper sulphate if you
can't get it. Proportions aren't critical.

I think Murphy's Dinacap (Dinocap? Dynacap?) treats botrytis.

Thank you very much for the suggestions. I will try the Bordeaux mixture
this year as it looks to be less toxic. I would rather start gently.

--
Howard Neil

I'd have thought that Mildew would also be a problem for grapes in a poly
tunnel.
Again Bordeaux Mixture should work, but you must start spraying BEFORE any
signs of trouble, it will help prevent, but won't cure.

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

David Hill wrote:
I'd have thought that Mildew would also be a problem for grapes in a poly
tunnel.
Again Bordeaux Mixture should work, but you must start spraying BEFORE any
signs of trouble, it will help prevent, but won't cure.


My intention is to start spraying within the next week. How frequently
should I repeat the spraying, please?

--
Howard Neil

On Sat, 8 May 2004, Howard Neil wrote:

David Hill wrote:
I'd have thought that Mildew would also be a problem for grapes in a poly
tunnel.
Again Bordeaux Mixture should work, but you must start spraying BEFORE any
signs of trouble, it will help prevent, but won't cure.


My intention is to start spraying within the next week. How frequently
should I repeat the spraying, please?

Every ten days to a fortnight. I always spray with a mixture of bordeaux
and Dithane. One takes care of downy mildew and the other powdery
mildew. Both these mildews can attack at any time and you can lose the
whole crop.

--
+-------------------------------------------------------+
| Internet: | writing from |
| Fidonet: David Rance 2:252/110 | Caversham, |
| BBS: telnet://mesnil.demon.co.uk | Reading, UK |
+-------------------------------------------------------+

On Fri, 7 May 2004, Howard Neil wrote:

My vines are in a polytunnel and suffer from botrytis each year. I
understand that the time to spray them is when in flower, which is now.

Er, no. When they are in flower is just when you *shouldn't* spray!

--
+-------------------------------------------------------+
| Internet: | writing from |
| Fidonet: David Rance 2:252/110 | Caversham, |
| BBS: telnet://mesnil.demon.co.uk | Reading, UK |
+-------------------------------------------------------+

David Rance wrote:


Every ten days to a fortnight. I always spray with a mixture of bordeaux
and Dithane. One takes care of downy mildew and the other powdery
mildew. Both these mildews can attack at any time and you can lose the
whole crop.

Thanks.

--
Howard Neil

David Rance wrote:

On Fri, 7 May 2004, Howard Neil wrote:

My vines are in a polytunnel and suffer from botrytis each year. I
understand that the time to spray them is when in flower, which is now.


Er, no. When they are in flower is just when you *shouldn't* spray!

The books that I have (including RHS ones) all advise that the time to
spray grapes against botrytis is when they are in flower. Mind you, they
are a little old and advise spraying with fungicides that are no longer
available and make no mention of Bordeaux mixture. What is your reason
for advising against it, please?

--
Howard Neil

On Sat, 8 May 2004, Howard Neil wrote:

David Rance wrote:


Every ten days to a fortnight. I always spray with a mixture of
bordeaux and Dithane. One takes care of downy mildew and the other
powdery mildew. Both these mildews can attack at any time and you can
lose the whole crop.

Thanks.

In fact, I have my doubts as to whether Bordeaux Mixture will be of any
use with botrytis (grey mould). I can find no recommendations to its use
for botrytis in any of my books or on the web. Instead there seems to be
greater emphasis on cleanliness of the soil and the vine, i.e. don't
leave any dead leaves around. My advice would be to remove the
polytunnel when the grapes are approaching ripeness because it is then
that they are most prone to botrytis developing.

Of course, you still need to spray regularly against powdery and downy
mildews.
--
+-------------------------------------------------------+
| Internet: | writing from |
| Fidonet: David Rance 2:252/110 | Caversham, |
| BBS: telnet://mesnil.demon.co.uk | Reading, UK |
+-------------------------------------------------------+

On Sat, 8 May 2004, Howard Neil wrote:

Er, no. When they are in flower is just when you *shouldn't* spray!

The books that I have (including RHS ones) all advise that the time to
spray grapes against botrytis is when they are in flower. Mind you,
they are a little old and advise spraying with fungicides that are no
longer available and make no mention of Bordeaux mixture. What is your
reason for advising against it, please?

"Spray the vines with the above mixture (Bordeaux Mixture, Dithane and
Maxicrop) every two weeks until flowering when all spraying must cease."
- Growing Grapes in Britain by Gillian Pearkes.

--
+-------------------------------------------------------+
| Internet: | writing from |
| Fidonet: David Rance 2:252/110 | Caversham, |
| BBS: telnet://mesnil.demon.co.uk | Reading, UK |
+-------------------------------------------------------+

On Sat, 8 May 2004, David Rance wrote:

In fact, I have my doubts as to whether Bordeaux Mixture will be of any
use with botrytis (grey mould).

Hmmm, I've just checked in one of my German books on viticulture
(Weinbau by Vogt & Götz, 1979) - "Copper, and many of the hitherto
organic, fungicides are not effective or, at least, not completely
effective, against botrytis." Of course, Bordeaux Mixture is based on
copper.

--
+-------------------------------------------------------+
| Internet: | writing from |
| Fidonet: David Rance 2:252/110 | Caversham, |
| BBS: telnet://mesnil.demon.co.uk | Reading, UK |
+-------------------------------------------------------+

On Sat, 8 May 2004 00:20:07 +0100, "David Hill"
wrote:

I'd have thought that Mildew would also be a problem for grapes in a poly
tunnel.
Again Bordeaux Mixture should work, but you must start spraying BEFORE any
signs of trouble, it will help prevent, but won't cure.

There are EU/UK restrictions on the use of Bordeaux Mix, because it
contains copper sulphate, see www.ruralni.gov.uk/pdfs/publications/
Bulletin%20Summer%2002.pdf
and
http://www.organic-research.com/Laws...ection_eu1.asp

Google for more info.

David Rance wrote:

In fact, I have my doubts as to whether Bordeaux Mixture will be of any
use with botrytis (grey mould). I can find no recommendations to its use
for botrytis in any of my books or on the web.

I had a search yesterday when Bordeaux mixture was first suggested. I
managed to find a couple of references to it being useful against
botrytis. In the absence of anything else, I am willing to give it a
try. At the very least it should protect against mildew.

Instead there seems to be
greater emphasis on cleanliness of the soil and the vine, i.e. don't
leave any dead leaves around. My advice would be to remove the
polytunnel when the grapes are approaching ripeness because it is then
that they are most prone to botrytis developing.

This is not an option. The polytunnel is 65ft x 17ft and the poly is
correctly stretched and anchored under the ground. There would also be
an issue with other plants in the polytunnel.
--
Howard Neil

David Rance8/5/04 10:05

snip

"Spray the vines with the above mixture (Bordeaux Mixture, Dithane and
Maxicrop) every two weeks until flowering when all spraying must cease."
- Growing Grapes in Britain by Gillian Pearkes.

Totally irrelevant to the subject but she was the sister of our Rector!
In the Lots we saw vineyards growing rose bushes at the end of each row of
vines as they give the earliest hint of problems. But there, everything was
covered in a bright blue mixture of some sort ?colldodial copper? This
would have been around July or August, IIRC.
--
Sacha
www.hillhousenursery.co.uk
South Devon
(remove the weeds to email me)