"CK" wrote in message
...


"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.

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!

In the extremely thin, powdery, layer on the coloured background of the
tomato, the blue might well not show up. In any case, the Bordeaux mixture
has calcium hydroxide (white) as well.

I put your post more or less where it belongs in the thread. Please don't
top post. It messes up the logical flow of the thread.

| | 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.

[Franz Heymann]