Re: Another chemical question

Gemcopley@cs.com wrote:
> 
> Moira, thank you so much for the recipes for sprays. I realise that the time
> you spend in front of the screen is time lost to other things including the
> garden, so please don't feel obliged to answer, however......if you have the
> time, what can you tell me about copper sulphate ? It is inexpensive and used
> a great deal here, some people even put it in their swimming pools, and this
> concerns me a little. TIA. Jennifer

Hi Jennifer
The recipes I sent you came originally from Cornell University, courtesy
of OG. I am always delighted to  be able to recommend remedies so safe
they can be mixed in the kitchen with one's ordinary cooking utensils!

Regarding the copper sulphate. I am surprised it is so cheap with you as
in NZ it is distinctly pricey. We use it in the form of compressed
"pills" which we put down our toilet during summer. This is because we
seem to be unable to keep the roots of a neighbouring jJapanese maple
from trying to invade our old glazed terracotta drainpipes. Apparently
the copper sulphate will frizzle off the ends of invading roots and
mostly keep the pipe clear (though we still have to have it cleared
manually very occasionally).

Copper is always present in healthy soils as it is an essential trace
element, but it is only safe when present in minute amounts. Some soils
do naturally have excess and are poisonous to many plants and other
organisms. Sulphur is another essential element, but can safely be
present in much higher concentrations, before it causes any problems.

As I mentioned above, concentrated copper sulphate is obviously toxic to
roots. Both concentrated copper and sulphur are also toxic to fungi.
That's why they are used in fungicides. Copper is also toxic to algae
(which I think is why people put copper sulphate into swimming pools)
and at higher concentrations to worms. There is a warning on the tablets
we have to keep them from eyes and skin as they will cause irritation
and any copper compound is dangerous if swallowed and calls for medical
intervention. One would obviously need to be very cautious how much one
put into swimming pools if one was not at least to suffer sore eyes. It
can apprently be used very dilute to control algae, which must be
super-sensitive.

Copper sulphate is however less biologically active than other copper
compounds and would not normally be used straight as a fungicide. Other
copper compounds such as the oxychloride and oxide are more effective.
They can both be used as a spray to protect leaves against leaf spots
and particularly rusts, but it is a good thing to take precautions to
prevent a lot of runoff spray reaching the soil, as this could harm
worms. Many people now find they can cut down on the use of both copper
and sulphur in the garden by using alternative protective sprays based
on compost extracts and other simple biological materials.

Hope this covers what you wanted to know.

Moira


Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata, New Zealand. (on the "Ring of Fire" in the SW Pacific).
Lat. 41:16S Long. 174:58E. Climate: Mediterranean/Temperate
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