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Caffeine versus slugs & snails
On 23/11/2010 23:56, Bertie Doe wrote:
wrote in message ... In article , Martin Brown wrote: It is more effective just to spread the coffee grounds around sensitive plants like hostas and delphiniums. Turning it into a spray isn't worth the effort. Most things of plant origin that we consume as stimulants and interesting tastes were intended for chemical warfare against plant parasites or fungi. It is sheer good luck that they do us no harm. Not luck! We are evolved from a long history of plant eaters, and have a very high resistance to many such chemicals - caffeine being one. And we don't usually consume the plants which contain ones to which we have no resistance, however interesting they are. I am sure you know what I mean. You have to admire the guy who ate the first chilli or maybe did it the second time knowing what to expect!. Some of the things we can eat are surprising given how bad they are for other mammals - chocolate is lethal to dogs for instance and soya beans and some other legumes wreck most rodents reproduction cycle. I may need your help with the maths here, as it may be less hassle to spray the salad area on the allotment with a gallon of fresh coffee - rather than bothering with saving up old spent grounds. 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. Espresso coffee can contain up to 2g/Litre caffeine which is 0.2%! There's no real need to use 'proper' coffee, as instant coffee lies neatly between arabica and robusta, according to:- http://coffeechemistry.com/index.php...in-coffee.html So to summarise, there are 32 cups (4 oz) in a US gallon. I'm estimating 0.25 oz of instant per cup, so an 8 oz jar would produce a gallon of Nescafe bliss. Make a small adjustment for my 5 litre sprayer etc. If it's effective and a gallon lasts all Summer, then it could prove to be an economic method of pest control. 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. Slug pellets certainly do have the right effect and very quickly. Regards, Martin Brown |
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