Few pests are as frustrating for gardeners as are slugs and snails. They lurk is cool dark places by day and come out night to feed like ravaged stars in a bad horror flick. And it’s so easy to forget they’re there, but they always are. As if decimated seedlings, flowers, strawberries or citrus fruit aren’t enough proof, they’ll leave that disgusting slimy trail, not just to remind you, but seemingly to taunt you.
What’s a gardener to do? We all know about snail baits containing methaldehyde. There’s no doubt they are effective, but they are also poisonous to pets and wildlife, and shouldn’t be used if children are around. For many, that’s reason enough to look for other solutions, and thankfully, there are some good ones.
Effective control of slugs and snails is best done with a combination of techniques. The first step is to eliminate obvious hiding places like under boards, rocks, ledges, pots or whatever cool, moist places they can spend the day. Switching from sprinklers to drip irrigation, will also reduce humidity and moist soil, and discourage their movement. You can also plant snail-proof plants, but what fun is that? Here are some other techniques to protect your plants from snails and slugs.
Handpicking. Get out there with a flashlight on cool, moist nights or early mornings and pick and stomp. Brutal yes, but also cathartic. If you can’t stand the carnage, throw the buggers in a jar of soapy water, or seal them in a plastic bag and put them in the garbage. You have to be persistent to be effective, meaning you’ll have to handpick frequently.
Trapping. Lay out boards or flowerpots where the snails and can congregate, then collect and destroy in the morning. You can drown some snails with the old pan of beer technique (snails are attracted to yeasty fermentations), but it’s a lot work keeping the pan full and fresh, and as the University of California’s IPM website notes, snails and slugs are only attracted within a few feet of the beer.
Barriers. Copper stripping or banding is the most effective barrier to keep snails and slugs out of pots, raised beds or planting areas. You can also use them around the trunks of citrus trees. Supposedly, the combination of copper and slime give the snails a little electrical jolt. Serves them right. Most nurseries and garden centers carry copper stripping. Follow the label directions. Make sure the protected area is snail and slug free before installing and occasionally clean the stripping with a vinegar-water solution.
Predators. For most of us, using geese or ducks to control slugs and snails isn’t very practical. However, if you live in parts of California you can release Decollate snails (many nurseries sell them) to control garden snails. Elsewhere in California (check with your local cooperative extension service), the Decollates are a threat to native mollusks and are illegal to use. Decollates feed on the young snails and over time (often several years) can achieve effective control. Decollate snails will feed on young seedlings, flowers and some other plants, and will be killed by snail baits. In some parts of the southeastern United States, Decollate snails have naturalized but are considered more of a pest than a control measure.
Baits. Iron phosphate, the active ingredient in Natria Snail and Slug Killer Bait, can be used around pets and wildlife. The dual-action bait attracts and kills slugs and snails but it works differently than traditional methadehyde baits. Instead of killing the slugs and snails almost immediately, the pests feed briefly on the bait, quit feeding altogether and crawl off to die. So after using iron phosphate, you don’t see a mess of dead snails. Natria Snail and Slug Killer Bait can be spread in turf, around vegetable gardens and other edibles, and in ornamental plantings. It remains effective even after rain.