"Kay Easton" wrote in message
...
In article , Franz Heymann
writes

"Steve Harris" wrote in message
...
In article ,
(Franz Heymann) wrote:

There is no constituent in Bordeaux mixture which is organic. Its
two
components, copper sulphate and calcium hydroxide, are both quite
strictly *inorganic*.

Similarly, don't use an inorganic mental hoe to deal with weeds, use a
nice organic herbicide like 2,4 D :-)

The proliferation of weeds in my garden must be due to the use of a
mental
hoe rather than a metal hoe. {:-)

You're not using the right mental hoe, then. A really efficient one
would leave you with wild flowers, not weeds ;-)

Like everything else about me, my mental powers are regrettably on the wane.

Franz

"Kay Easton" wrote in message
...
In article , Franz Heymann
writes

"Pam Moore" wrote in message
.. .
I have just picked my first tomatoes for 5 years, having lost all to
blight for the last 4 years.
This year for the first time I have used Bordeaux Mixture which is
suggested as the nearest organic control.

There is no constituent in Bordeaux mixture which is organic. Its two
components, copper sulphate and calcium hydroxide, are both quite
strictly
*inorganic*.

In the chemical sense that is absolutely true. In the gardening sense,
BM may well be as organic as rainwater ;-) Wouldn't it be nice if
different subjects didn't use the same words to mean different things?

Agreed.

Franz

In message , CK
writes
What makes you think that the white deposits on the tomatoes are in fact copper
sulphate?
Last I heard was that copper sulphate crystals were blue!

Tiny crystals of almost anything (except carbon black) appear white. And
the results of Bordeaux mixture spray dried onto leaves does look white.
And at least in part due to the other components of the mixture (lime).

"Nick Maclaren" wrote in message
...
|
| In article ,
| Pam Moore writes:
| | I have just picked my first tomatoes for 5 years, having lost all to
| | blight for the last 4 years.
| | This year for the first time I have used Bordeaux Mixture which is
| | suggested as the nearest organic control.
| | Now I am concerned about the white copper sulphate deposits on the
| | fruit.
| | Is copper sulphate toxic?
|
| Yes, but not catastrophically so. You need micrograms of copper
| a day, the odd few milligrams on occasional will almost certainly
| do no harm, and the lowest lethal dose recorded is of the order
| of a gram.
|
| | Does anyone know how thoroughly I need to wash them?
|
| Moderately. No need to panic, but do wash them.
|
| | Has anyone else used BM? Advice is to spray weekly.
|
| Yes, on potatoes, where the problem doesn't arise. Weekly seems
| a bit excessive, but the issue for tomatoes is whether there has
| been heavy rain since you last sprayed.

Weekly seems a bit excessive. Build up of copper in the soil and/or
groundwater is a problem in wine growing regions where it is heavily
used.

Regards,
--
Martin Brown

"Nick wrote in message ...

:
| What makes you think that the white deposits on the tomatoes are in
fact copper
| sulphate?
| Last I heard was that copper sulphate crystals were blue!

Bordeaux mixture is not just copper sulphate, and looks whitish
when the spray dries.


And don't forget the lime, Bm is a copper sulphate and lime mixture.

--
Bob

www.pooleygreengrowers.org.uk/ about an Allotment site in
Runnymede fighting for it's existence.

In message , CK
writes
What makes you think that the white deposits on the tomatoes are in fact copper
sulphate?
Last I heard was that copper sulphate crystals were blue!

Tiny crystals of almost anything (except carbon black) appear white. And
the results of Bordeaux mixture spray dried onto leaves does look white.
And at least in part due to the other components of the mixture (lime).

"Nick Maclaren" wrote in message
...
|
| In article ,
| Pam Moore writes:
| | I have just picked my first tomatoes for 5 years, having lost all to
| | blight for the last 4 years.
| | This year for the first time I have used Bordeaux Mixture which is
| | suggested as the nearest organic control.
| | Now I am concerned about the white copper sulphate deposits on the
| | fruit.
| | Is copper sulphate toxic?
|
| Yes, but not catastrophically so. You need micrograms of copper
| a day, the odd few milligrams on occasional will almost certainly
| do no harm, and the lowest lethal dose recorded is of the order
| of a gram.
|
| | Does anyone know how thoroughly I need to wash them?
|
| Moderately. No need to panic, but do wash them.
|
| | Has anyone else used BM? Advice is to spray weekly.
|
| Yes, on potatoes, where the problem doesn't arise. Weekly seems
| a bit excessive, but the issue for tomatoes is whether there has
| been heavy rain since you last sprayed.

Weekly seems a bit excessive. Build up of copper in the soil and/or
groundwater is a problem in wine growing regions where it is heavily
used.

Regards,
--
Martin Brown

"Nick wrote in message ...

:
| What makes you think that the white deposits on the tomatoes are in
fact copper
| sulphate?
| Last I heard was that copper sulphate crystals were blue!

Bordeaux mixture is not just copper sulphate, and looks whitish
when the spray dries.


And don't forget the lime, Bm is a copper sulphate and lime mixture.

--
Bob

www.pooleygreengrowers.org.uk/ about an Allotment site in
Runnymede fighting for it's existence.

"Franz Heymann" wrote in message ...
"Mike Lyle" wrote in message
om...
[...]
We lumpen-peasants do actually know that Bordeaux mixture is not of
biological origin, just as we know that water is a chemical compound.
But it's perfectly understandable and entirely forgivable if people
use "organic" to mean "approved for use on organically-grown crops".

What exactly is the purpose of these objections? If it's the promotion
of good precise written English, then I'm with you all the way. If, on
the other hand, it's an attempt to disprove the theoretical basis of
organic crop-production, then (a) it doesn't, and (b) why do you want
to do that?

What I mainly object to is the amount of bullshit and unsubstantiated
folklore which is part and parcel of organic crop production.

Irritating to have this discussion so fragmented across threads. I've
already mentioned The Soil Association elsewhere; along with such
outfits as The Henry Doubleday Research Association it deals in
rationality and experimental evidence. Organic crop production is how
many hard-pressed businessmen actually make their livings: they have
no time for bullshit -- except in the literal sense! -- or folklore.

The store of expertise built up over millennia is what drove *all*
farming until about a hundred years ago when industrial processes for
the extraction of nitrogen etc began to make an impact. What on earth
is objectionable about the Norfolk four-course rotation? I can't begin
to understand how anybody can regard this verifiable technical
knowledge as "bullshit".

If people who think parsley seed won't germinate for a hen-pecked
gardener, or that a Christmas cactus will grow better if you play it
Mozart, are what's annoying you, fair enough; but that's a bit like
saying democracy's a waste of time because Reagan's wife consulted an
astrologer -- no, wrong: actually it's like saying democracy's a waste
of time because a few *voters* consult astrologers. It's entirely
irrelevant, and if you really think these things are "part and parcel"
of sustainable agricultural systems you can't possibly have done your
reading.

Mike.