On 24/11/2010 13:56, Dave Hill wrote:
On Nov 24, 12:30 pm, Martin
wrote:
On 24/11/2010 10:57, Janet wrote:

In ,
says...

I doubt it will last all summer (though it might in a greenhouse) as
caffeine is pretty water soluble and will migrate into the ground. Use
the coffee grounds directly on the soil and you might have a useful
effect. I have tried it and cannot decide if it works or not.

IME certain textures, such as sand, fine grit, wood ashes, and rough
leaves like comfrey and dried bracken, do have some protective
deterrent/ repellent effect as slugs don't like crossing them; maybe
coffee grounds work that way.

Wood ashes are pretty alkaline. Charcoal and the last bits of coke coal
seem to work for a while as slug deterrents. They don't like the rough
surface. But I think the coffee grounds effect is mainly chemical.

Regards,
Martin Brown

Now if coffee would work on Vine weevil

Why not use imidacloprid or one of its analogues?

--

Jeff

"Martin Brown" wrote in message
Bertie Doe wrote

The following are US capacity measurements:
http://preview.tinyurl.com/34gjnw2

"A 4-ounce solution of 2 percent caffeine applied to
the soil of 4-inch
greenhouse pots devastated garden slugs"

I assume they mean 4 oz of coffee contains 2% of
pure caffeine. We have
to speculate as to the strength and type of coffee
and amount used.

I wouldn't assume that at all. 4 oz of coffee will
likely contain 0.03-0.06g of caffeine. Taking 4oz as
roughly ~100g = 0.05% caffeine content. A 2% caffeine
solution would be very very strong coffee the sort
that you could stand the spoon up in.


You're right 2% pure caffeine would give a hippo the
jitters. I think I was getting confused with 2mg which
is your usual consumption in a cuppa Joe.

Espresso coffee can contain up to 2g/Litre caffeine
which is 0.2%!

Agreed, but I still think it's worth persuing further,
the ScienceNews article mentions:-
"Even concentrations of only 0.1 percent caffeine may
prove useful. Sprayed onto such slug-prized cuisine as
cabbage leaves, those concentrations deterred feeding
by 62 percent, respectively, when compared to
uncaffeinated salad greens".

In Spring when I top-up my stash of green unroasted
coffee beans, I'll include 250g of the stronger
(cheaper) robusta, in my order. Somewhere I read that
roasting reduces some of the caffeine content - so I'll
grind, add hot water and leave it to steep for a couple
of days. Filter it, then use it solely on my salad
stuff. The brassicas can look after themselves!!

Bertie

Nick wrote ..
Bob Hobden wrote:
"Bertie Doe" wrote ...

So far, all my spent coffee grinds, have ended up in my
compostor ( I believe there was a thread on ukrg last
year).

After reading the following article, I'll separate the
coffee and use it as a spray next year, on the
allotment. It also mentions tea leaves as a good source
http://preview.tinyurl.com/34gjnw2

The only problem I see is that DEFRA have not given it a licence to be used
as a pesticide, it has not been tested as such, and we therefor do not know
what damage it would cause to the environment as a whole. It might also
kill
birds and others that eat the contaminated slugs for example, it might do
irreparable damage to the soil flora/fauna.

Yeah. And it might super-stimulate the slugs, so they go racing
round the garden, or even sprout wings and fly.

Given the massive experience we have of composting them in open
heaps, the effect on birds is almost certainly nil to negligible,
and we can be certain that it won't cause irreparable damage to
the soil flora and fauna.

And what about Slow Worms, Grass Snakes, Frogs, Toads, Newts, ... sorry if
you think I'm being too cautious but I still think one should be careful
using an untested remedy. For a start evidence seems to suggest amphibians
may have a problem with it!

--
Regards
Bob Hobden
W.of London. UK

wrote:
In article ,
Bob Hobden wrote:
"Bertie Doe" wrote ...

So far, all my spent coffee grinds, have ended up in my
compostor ( I believe there was a thread on ukrg last
year).

After reading the following article, I'll separate the
coffee and use it as a spray next year, on the
allotment. It also mentions tea leaves as a good source
http://preview.tinyurl.com/34gjnw2

The only problem I see is that DEFRA have not given it a licence to
be used as a pesticide, it has not been tested as such, and we
therefor do not know what damage it would cause to the environment
as a whole. It might also kill birds and others that eat the
contaminated slugs for example, it might do irreparable damage to
the soil flora/fauna.

Yeah. And it might super-stimulate the slugs, so they go racing
round the garden, or even sprout wings and fly.

Given the massive experience we have of composting them in open
heaps, the effect on birds is almost certainly nil to negligible,
and we can be certain that it won't cause irreparable damage to
the soil flora and fauna.

In any case, used tealeaves and coffee-grounds have, by definition, been
used. That is to say, extracted with hot water. And I don't think many
varieties of tea have all that much caffeine even before they've been
used, do they?

--
Mike.