"Smeckler" wrote in message
It says "Bordeaux mixture" on the pack.
It says it contains copper sulphate BUT the powder inside and the
deposit left on the plants is white. I also thought it would be blue.
Perhaps someone can explain!

I vaguely recall my first ever chemistry lesson at secondary school...

"Copper sulphate crystals were placed in a test tube and heated over a
bunsen flame. A crackling sound was heard and steam was seen escaping.
A white substance remained in the test tube."

The white stuff was "anhydrous copper sulphate", i.e. with all the water
removed...

And, don't forget that BM is a copper sulphate and Lime mixture. I think the
last item might just have something to do with the white colour too.

Anyway, yes we have used it for some years to ensure our tomatoes do crop
but my understanding is that the disease, Tomato Blight, is brought by rain
and as we haven't had any for weeks (only two wet days this summer!) we
haven't bothered spraying yet this year. Will spray before we are due any
though.
Just wash the fruit thoroughly, the chemicals don't enter the fruit, and
they will be OK to use. Skin them if you are paranoid. :-)

We are trying some French variety called "Ferline" that is resistant to
blight (from the "Kitchen Garden" mag) so I won't spray those just to see if
they are indeed resistant. Will let you all know.

--
Bob

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