Snail/slug control - The never ending battle

The first thing to think about is a mechanical barrier. They must "walk" into the container to get to the plant, so if you can block that pathway, they simply cannot do damage. There are many ways to accomplish that.

Copper foil (often sold in a self-adhesive tape form) is the old classic, wrapped around bench legs, or whatever stand or platform the plants are sitting on. A salt perimeter is also very effective, but must be replaced when it gets wet. There is a gel in a tube called "Tree Tanglefoot" that is also quite effective.

As far as eliminating those that have already gotten to the plants, a metaldehyde bait is the most effective. Marni turned me on to Deadline MPs, but it is quite toxic to mammals, so is best used where access can be restricted.

 

Use the "Beer Trick" - in the evening, go out to the plants with a flashlight, hammer, and a bottle of beer. Using the flashlight, when you find a slug (or snail), you slug it with the hammer, then have a slug of beer.

You won't get them all, but after a little while, you won't mind.

 

Hi, I have used Slug-Fest and know a couple commercial growers as well who do...because it does work on the snails. There is the increased hazard potential when spraying, so not for the casual user as metaldehyde is quite toxic

Marni - I don’t know where you got the instructions for keeping the plants dry, unless an older formula? The intent is to spray after watering (or rain for outdoor crops) when things are wet and preferably in the evening so the critters are most active.

The following is from the manufacturer’s promotional literature

Slug Fest® All Weather Formula
Slug-Fest All Weather Formula contains 25% metaldehyde in a liquid formulation. This is the only liquid sprayable slug and snail control in the world. Slug-Fest is highly efficacious as a slug and snail eradicant. This product is best applied right after it has rained so you know the slugs or snails are active.

 

I was interested in counter-measures against bush snails, so I read a little bit about different methods. I thought that the toxicity of Metaldehyde seems to be reasonable. The warning seems to come from pets eating pellets. But according to Wikipedia (here, and the reference here), the toxicity level is similar to acetaldehyde, which is a fairly "natural" molecule. There doesn't seem to be too much mutagenic effects (long term effect), so the danger is acute toxicity if someone eat it. Also, MH breaks down rapidly in soil and in water, so it doesn't accumulate. I probably shouldn't say that it is safe (especially after seeing people lacking common sense since Nov. 2016), but I have been considering that it is relatively mild.

I think that this (whether you need to keep them dry after application of MH) doesn't seem to be completely set. For example, Hollingsworth (2003, p.121) mentioned that snails recover better from MH poisoning under moist environment (citing a couple papers). When snails are exposed to MH, they excrete bubbly mucus. Some people think that this causes the dehydration and death. Then, it is more effective to suppress the subsequent watering after application.

More recently, I was reading a book, Molluscs as Crop Pests by G. M. Barker (ed.)(amazon link), and they mention that the exact mechanism of how MH kills snails is not known yet. They also mentioned that there appear to be other mechanisms than dehydration, and MH can work under moist environment.

So recently, I'm not keeping them dry after application. Similar to Marni, I noticed that some plants become unhappy if I dry it after MH application. But if I don't do extreme driness, I don't see any Phytotoxicity even if I overdose. Several papers also reported no phytotoxicity (e.g., here), which is a good thing.

Ref to Hollingsworth's paper.
Hollingsworth, R.G. and Armstrong, J.W., 2003. Effectiveness of products containing metaldehyde, copper or extracts of yucca or neem for control of Zonitoides arboreus (Say), a snail pest of orchid roots in Hawaii. International journal of pest management, 49(2), pp.115-122.

 

Great information Naoki, The only crop I could find where watering was mentioned was grass: “reduce watering” of grass being grown for seed for two days. In Florida, the State used it to combat the Giant African Land Snails, so its likely that moisture in the ground was quite cyclical in a 24 hour period. The REI is 12 hours, so if you apply in the evening when moist and hold off watering until mid-morning the next day, that would seem to be enough contact time. I have seen one study where mortality was around 65% within 12 hours. I’ve only used it about twice per year without modifying my watering routine with no issues and great results...of note, the manufacturer does state that leaf tip burn has been reported in some “sensitive” orchids.

I will have to look up the source (I think UFL), but I believe that Slug Fest was actually more effective that the old Measurol in field trials.

Regarding toxicity, what I was referring was the opportunity for human exposure to 4% metaldehyde in a granular bait form vs a sprayed liquid metaldehyde in a closed up hobby greenhouse.

 

It is hard to find distributors...I think a place called something like Seed Ranch was one.

 

To stop slugs or snails attacking the flowers on my plants I fasten cotton wool around the stems. Be careful when killing these pests, their relatives are to be found at their funeral.

 

Dredging up this old thread:

Does anyone have new recommendations for dealing with slugs and snails? I'm thinking to try Sevin. I've heard of some success from spraying caffeine, and metaldehyde of course. One of my biggest constraints is that the plants are all indoors, and I keep them in the same room as a bunch of frogs, so I'm hesitant about using the really heavy duty stuff.
But - I'll consider anything at this point. The slugs are wreaking havoc and my nightly searches aren't doing the trick.

 

If you use metaldehyde granules, it shouldn’t be any problem unless they are in the the same tank as the frogs.