Oriental Lilies - Allelopathy - Caffeine
Kenneth Hixson (Thu, 23 Oct 2008 10:37:00 PDT)
C.J. Teevan wrote:
used coffee grounds
In my experience, coffee grounds do add organic matter, minor amounts
of chemicals, and seems to be attractive to earthworms, at least if
mixed with other composted organic matter. I haven't seen anything
about long term effects on lilies, oriental or otherwise. In my garden,
slugs/snails are a problem while the lilies are emerging and until the
new growth is about a foot high, but when it toughens up, the slugs are
no longer attracted. Unfortunately, the only effective treatment I've
found is the old fashioned metaldahyde baits such as Deadline. Iron
phosphate has been only marginally effective. Others, such as wood
stove ashes, egg shells, etc, are not effective in our rainy spring
weather. I'd love to hear of an organic treatment that works.
The following is on the website of Paghat the Ratgirl, (who is a man),
and a person of definite opinions--which you may or may not find acceptable:
http://www.paghat.com/coffeeslugs.html
The Hilo study has commonly been misrepresented as proving coffeegrounds
kill slugs, when it did nothing of the sort. The Hilo station was first
to establish that a SPRAY of 1-2% chemical caffeine (NOT coffee, certainly
not coffeegrounds merely cast on the soil) dousing the ENTIRE plant will
over time lower the slug population by killing just the BABY slugs &
snails AFTER THE TREATED PLANT IS EATEN. It has zero protective value
except in the long run of controlling the number of slugs that live to
maturity. The use of coffeegrounds per se was shown in other studies to
have little to zero effect, there being only a couple brands of coffee the
FRESH grounds of which would even reach the toxic level required, & spent
grounds already leeched of caffeine would be especially harmless. Even the
effective spray of caffeine in solution required the treated plant to be
eaten to kill the youngest slugs only.
and there are no known problems with other
species.
If one overlooks the harm done to species of plants. Caffeine if used
effectively as a REGULAR application of 1-2% chemical solution sprayed all
over the plants, according to Usherwood's follow-up to the Hilo study, the
plant itself responds to the caffeine, is toxified & damaged. It's true
casting grounds on the soil is pretty much a harmless activity & even
functions as a slow-release acid fertilizer, so no harm done, but also no
harm done to slugs.
Ken