Ken, I've also gone down the caffeine track for slug/snail control. I'll send you that paper in a separate private email in a few minutes - I have it somewhere. At the time USP caffeine was pretty cheap online so I just bought a bag as a way of quantifying results (coffee varies so much). We used it mostly as a drench on plants that were particular slug/snail targets, rather than as a spray because it's also toxic to amphibians (they used to use it to kill Coqui frogs in Hawaii, though I don't know what concentration) and I'm very fond of all the tree frogs in our greenhouse. It was very effective, and cost effective, in that mode to kill slugs and snails hiding in the pots, but as you'd expect there was little or no residual effect so it had to be repeated off and on as new populations moved toward those plants. We also used the iron phosphate pellets on the floor of the greenhouse, and between the two, at this point the molluscs are only a minor irritation. But there were a few plants, not geophytes, that apparently were so ambrosial to slugs and snails that no deterrent was sufficient (Dendroseris was one). I've also seen a paper which concluded that spent coffee grounds used as a top dressing, or added to the top layer of soil, did indeed reduce depredation by slugs and snails as well as improving plant growth but I haven't read the whole paper. Steve On 8/22/2023 1:42 PM, ken isaac via pbs wrote: > On Tue, Aug 22, 2023 at 11:45 AM Marc Rosenblum via pbs < > pbs@lists.pacificbulbsociety.net> wrote: > >> Leigh, >> >> I usually try to avoid using poisons. >> > Caffeine? > Yes, I wish there were more options for slugs and snails. BETTER options > for us, and our planet (except the slugs and snails!) > I'm not talking about all the blogs that say "use coffee grounds," as I > need real, measurable control. > > Caffeine? > Headline in NATURE journal: "Caffeine as a repellent for slugs and > snails. At high concentrations this stimulant becomes a lethal neurotoxin > to garden pests." > (follow this link and find the "download" button to read it.) > https://digitalcommons.unl.edu/icwdm_usdanwrc/470/ > > I saw that article 2 decades ago and thought at the time "finally!" and > waited for the dirt cheap slug/snail control with a "safe chemical" I > already consume. But two decades and nothing more than "throw your coffee > grounds in your garden?" No researcher said "hey, let's test it by adding > kaolin clay (AKA: Surround) or pinene (AKA bonide's 'wilt stop') to the > caffeine solution and spray on your hostas," or tried soaking wood chips or > alfalfa pellets in caffeine as bait? > > The actual research study link is here: > Annals of Applied BiologyVolume 142, Issue 1 p. 91-97 > "Caffeine as a novel toxicant for slugs and snails" > https://doi.org/10.1111/j.1744-7348.2003.tb00233.x > > But- it costs money or an institution log in to view. I've requested a > copy from the USDA.... > https://ars.usda.gov/research/publications/… > > Why do I get the impression the slug and snail lobby has repressed this > caffeine research? Seriously, if anyone has tried caffeine for real, let's > talk! > > Ken- > in cool, wet slug/snail weather- in Utah > _______________________________________________ > pbs mailing list > pbs@lists.pacificbulbsociety.net > http://lists.pacificbulbsociety.net/cgi-bin/… > Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> > PBS Forum https://… _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> PBS Forum https://…