Hugo, what phytotherapy book are you talking about? And the
pond you dug, does it have any running water to refresh it, or is it just a large stagnant body of water? I have a 5' deep hole in clay I made during some folly thinking "root cellar", but it is already well on its way to ponding. And close enough to my gardens!
and GAH, I HATE RESTRICTIONS ON INFORMATION. Hugo, you might try a VPN. I will post the text of this important article below my post. KNOWLEDGE IS
FREEDOM, KNOWLEDGE MAKES WISDOM, KNOWLEDGE MUST FREE. The nematode info in the article is also interesting but of less immediate use to us, who must wait for the Products of Industry.
Sebastian, true, ease of dispersal suggests oils are necessary on any large scale. But before the investment I can try the watering can. Should do it for a few months to see what else, if anything, gets disturbed.
And Cristo, THANK YOU! That is wonderful and useful info. We have plenty of ravens and crows waiting for handouts. My only concern is that attracting their attention may lead to other, tastier things than snails (e.g. my crops) being denuded. I think here and in Oregon, slug plagues are an assumed feature of the future, hence the recent hiring of that slug expert prof and the research.
I use pieces of perforated copper foil I got from a scrapyard to make barriers. After 1975, pennies only have 2.5% copper so I'm glad to hear so little works! I've seen slugs reaching over the barriers trying to grab low branches to pull themselves up by herculean muscular effort. So the width of barriers should take the size of your slugs and low-hanging branches into account. I've also used, with varying levels of success:
-coffee grounds (yes the rain is a problem)
-epsom salts (added benefit of getting magnesium in your soil, but rain washes out)
-
diatomaceous earth (also a rain problem)
-ashes (blah blah rain)
-biochar (this in theory should be very effective but trials are ongoing)
Researcher identifies new weapons against slugs
By MATEUSZ PERKOWSKI Capital Press Dec 11, 2018
New weapons are being discovered in the battle against slugs.
Essential oils from thyme and spearmint are proving lethal to crop-damaging slugs without the toxicity to humans, animals or the environment that chemical solutions can present.
An added advantage of these oils is the rapid mortality they cause in slugs, whereas one of the most common chemical molluscicides used by Oregon farmers, iron phosphate, simply causes them to stop feeding, said Rory McDonnell, Oregon State University’s slug specialist.
“The oils were essentially just as effective as metaldehyde,” another common molluscicide, McDonnell said during the Oregon Seed League’s annual meeting, held in Salem, Ore., on Dec. 10-11.
Thyme and spearmint oils achieved 100 percent mortality at a concentration of just 0.25 percent, most likely through direct contact with slugs — though it’s possible their volatile emissions could also serve as repellents for the pest, McDonnell said.
Because they’re natural compounds, these oils would be exempt from the U.S. Environmental Protection Agency’s registration and residue tolerance regulations for conventional pesticides, he said.
Before they could be commercialized as biological pesticides, data would need to be submitted to the Oregon Department of Agriculture proving they’re not toxic to humans or non-target organisms, though this should not be a big obstacle, McDonnell said.
“I’ll eat my hat if it’s toxic,” he said.
McDonnell was hired by OSU in 2016 after Oregon farmers told the university’s leaders that more research was needed to fight slugs, which have become increasingly destructive in recent years.
Another positive development from McDonnell’s research is the discovery of a nematode that’s naturally parasitic to grey field slugs — phasmarhabditis hermaphrodita — on OSU’s campus in Corvallis, Ore.
The location if the discovery was ironic given that McDonnell had traveled thousands of miles around the state searching for the species, which is native to Europe and used in slug control there.
“The darn thing was a stone’s throw from my office,” he said.
Since then, McDonnell has discovered two other nematode species in Oregon that show promise as biological control agents.
In the United Kingdom, the phasmarhabditis hermaphrodita nematode is sold as a commercial biopesticide that’s been shown to reduce slug damage in winter wheat by 85 percent, he said.
The nematode finds a hole in the back of a slug’s head, then vomits up a bacterial soup that’s toxic to the gastropod. As the slug’s body decomposes, the nematode’s offspring
feed on its corpse.
The BASF chemical company also markets the nematode in Europe, producing it in enormous vats through a secret process, McDonnell said.
Before the nematode can be commercialized in the U.S., BASF or another pesticide manufacturer would need to demonstrate to USDA that it’s not harmful to other species, such as the native banana slug.
“I think that would be a major stumbling block,” he said.