Rain helps in control of brown garden snails

Now is the best time to keep the brown garden snail from ruining your gardens, trees and shrubs. (Photo by Robin Rosetta.)
Last Updated: 
May 20, 2011

AURORA, Ore. – If you're looking for reasons to celebrate rainy weather, here's a good one – non-native brown garden snails come out from hiding and feed in wet weather.

Rainy weather brings snails into the "slimelight," said Robin Rosetta, horticulturist with Oregon State University's Research and Extension Center in Aurora. Now is the best time to keep them from ruining your gardens, trees and shrubs.

Snails easily adapt to mild conditions in the Pacific Northwest. The brown garden snail is the most well established exotic snail in Oregon and one of the only kinds that gardeners have to worry about as a pest, Rosetta said. A diligent public can help keep the snail in check.

Alien mollusks come into the state in shipments of plants, crops and other goods. If just one brown garden snail shows up in Oregon in a shipment of plants, quarantine ensues.

"It's a real disaster in some situations," Rosetta said. "Exotic snails are getting a toe-hold into the Pacific Northwest. When it comes to alien snails, xenophobia might be helpful. An alert citizenry can help secure our borders."

Slugs and snails are really the same animal, Rosetta said. "Slug evolution diminished its shell to a legacy of a shell hidden beneath its hump-like mantle." Snails, on the other hand, can withdraw into their shells during hot or cold temperatures.

"They seal the opening with a thin layer of hardened mucus and calcium," Rosetta said, "allowing them to 'siesta' until conditions are more favorable, namely warm, moist and humid."

While exotic snails are of great concern, Rosetta reminds us that Oregon's native snails play a vital role in natural systems, including decomposition, and are an integral part of the food chain.

Here are some non-chemical, "least toxic" ways to reduce snail and slug pest populations in home gardens, suggested by the OSU Extension Service Master Gardener program.

  • Irrigate in the morning, rather than in the evening, to reduce favorable conditions for the snails and slugs while they are out at night. Trap snails and slugs under boards, where they can be collected each morning in a bucket of soapy water.
  • Drown snails and slugs in (cheap) beer. Cut a hole in a coffee can or plastic yogurt container with a plastic snap-on lid about a half to a third of the way up. Bury the container to the level of the hole. Pour in about two inches of beer or yeasty water. Cover to reduce evaporation and keep out pets. Check and remove slugs daily and refill with solution.
  • Blockade your raised bed frames with copper stripping, sold at lawn and garden stores. Take care not to trap slugs inside your garden plot.
  • Eliminate yard debris. Mulches usually provide natural places for slugs and snails to hide.
  • Pick snails and slugs off plants after dark when slugs are active or first thing early in the morning. If you are truly dedicated, stalk with a headlamp or flashlight. Drop them into a jar of water with a little detergent or ammonia. Do not put salt on snails or slugs, as adding salt to the soil makes it unsuitable for gardening.

For more information on how to control the brown garden snail, as well as photos of it and its damage to plants, visit Rosetta's IPM website.

Author: Judy Scott
Source: Robin Rosetta