[CH] slightly OT: Coffee breaks slugs
peter g (peter.g@telus.net)
Sun, 30 Jun 2002 20:13:32 -0700
Hi folks,
although the locally VORacious slug population pretty-much ignores
my chile plants, i still prefer a veg garden with no pesticide chemicals.
a spray of stale coffee ... or an application of metaldehyde ...
hmmmmm, which will i choose ?!!
*** Coffee breaks slugs ***
Caffeine kills slugs and snails. 27 June 2002
http://www.nature.com/nsu/020624/020624-8.html
Humans have a new weapon in the eternal battle against slugs and
snails - the double espresso.
Slugs and snails hate caffeine, researchers have discovered.
The chemical could become an environmentally acceptable pesticide.
Robert Hollingsworth of the United States Department of Agriculture
Agricultural Research Service in Hilo, Hawaii, and his colleagues
were testing caffeine sprays against the coqui frog, an introduced
species that infests potted plants. They noticed that a 1-2% caffeine
solution killed nearly all the slugs and snails within two days.
Concentrations as low as 0.01% put the pests off their dinner. A cup
of instant coffee contains about 0.05% caffeine, and brewed coffee
has more. Coffee grounds are already recommended as a home
remedy for keeping slugs and snails at bay. Grounds repel slugs,
Hollingsworth found, but a caffeine solution is much more effective, he
says: "Slugs turn back immediately after contacting the [caffeinated
soil]." Caffeine is more effective against snails than the current
commercial standard, metaldehyde. The United States bans
metaldehyde residues in food, but classifies caffeine as safe. It may
even qualify as organic, adds Hollingsworth.
"I would expect caffeine applications to kill small snails and slugs, and
repel the larger ones," says Hollingsworth. He envisages it being used
in orchid greenhouses and on fruit and vegetable crops.
Toxicologist Peter Usherwood, of the University of Nottingham, UK,
thinks that caffeine is best suited for use in domestic gardens. But he
cautions that the chemical's toxic effects are not limited to slugs and
snails. "It's likely to have an effect on beneficial insects," he says.
It's not known how caffeine kills the molluscs. Hollingsworth's team
suggests that the chemical may cause damage to the nervous system -
they report that caffeine-sprayed snails develop weak and irregular
heartbeats, and slugs fall to "uncoordinated writhing" before dying.
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this is worth a try!
regards
peter g