Gardeners wage an unceasing war on bugs, fungus and bacteria in their gardens, swinging pruners and sprayers in wide swaths as they defend their tender plants. Bugs are easy to hate. They are clearly the enemy, but the innocuous snail certainly seems harmless enough. Snails are slow-moving and delicate, but, unfortunately, they find all sorts of landscape plants, including trees and shrubs, to be delicious.
The brown garden snail (Cornu aspersum) is the most common shelled mollusk found feeding in gardens. They snails are drawn by an abundance of organic matter from sources such as plant debris, decomposing mulches and rotting compost. Snails are known for helping to break down these materials, but less is said about their destructive tendencies toward plants.
Snails are strong climbers and frequently find their way into the canopy of trees and bushes, especially those bearing fruits with soft rinds. Here, the snails feed on tender new leaves, young bark or ripe fruits by scraping off outer tissues or chewing smooth, irregular holes through leaves and fruit rinds. Because they feed mostly at night, it may be difficult to know for certain that snails are the culprit when your trees and shrubs are attacked, but if you look closely, a dried silvery slime trail will give them away.
Snails that are invading trees are easy to handle if you prune the tree away from and off of nearby structures before applying a 3- to 4-inch wide copper band around the trunk, two to four feet above the ground. You should apply a continuous copper band on the ground around affected shrubs, held up and out of mulch or other plant debris by a temporary wooden frame. Once bands are applied, you can easily pick any stragglers out of trees and shrubs and toss them back on the lawn or into a bucket of soapy water.
Traps and Baits
With their favorite food suddenly out of reach, snails are reasonably easy to trap or bait, although doing both simultaneously will provide faster control. Like their cousins the slugs, snails will readily fall into beer traps and drown, if the trap is kept about half full of beer and buried level with the ground, so it's easy for them to get inside. Many baits are labeled for snails and slugs, but the baits containing iron phosphate are much safer for humans and pets and just as effective as metaldehyde. Iron phosphate-poisoned slugs often hide before dying, so you won't necessarily see bodies when using these baits.
- University of California Statewide Integrated Pest Management Program: Snails and Slugs
- University of California Statewide Integrated Pest Management Program: Brown Garden Snail
- Texas A&M AgriLife Extension: Snails and Slugs
- University of Florida IFAS Extension: Brown Garden Snail
- University of California Statewide Integrated Pest Management Program: Iron Phosphate
- University of California Statewide Integrated Pest Management Program: Metaldehyde
- Creatas Images/Creatas/Getty Images