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  • From: "Marge Talt" <mtalt@hort.net>
  • To: "gardenwriters-on-gardening" <gwl-g@lists.ibiblio.org>
  • Subject: Re: [gwl-g] natural slug controls
  • Date: Mon, 12 Apr 2004 23:07:39 -0400

> From: Ellen Zachos <ez@acmeplant.com>
> There was an article in Nature in July of 2002 about the
effectiveness
> of caffeine against slugs and snails. It looked very encouraging
and I
> thought I'd see a commercial product evolve from this but nothing
so
> far. Has anyone else? In the meantime, I'll try your sprayed
> concentrate, Jeff.
----------

I did a bit of looking into this. Without digging out the resources,
as I recall, the study was done using a 2% pure caffeine solution -
not something that normal humans can get their hands on. The study
was done for another purpose; the fact that this concentration of
caffeine also killed slugs and snails was discovered more or less by
accident.

My numbers may be off (since this is delving into what passes for my
memory), but espresso coffee is something like.05% caffeine as
opposed to the 2% solution used in the studies.

Upshot was that coffee grounds and coffee as drunk by humans is not
strong enough to affect slugs although some people use coffee grounds
and swear they do stop slugs; might discourage them but does not kill
them - maybe they actually eat the coffee grounds and like them...who
knows.

Seems I also recall that, at that concentration, there is also
adverse affect on earthworms and some concern about other soil life
(microbes, etc).

The information I found was on the web. If someone is dying to know
more, I can hunt out the links I saved..somewhere.

Marge Talt, zone 7 Maryland
mtalt@hort.net
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