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Caffeine versus slugs & snails
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 |
Caffeine versus slugs & snails
"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 |
Caffeine versus slugs & snails
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 |
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