Snails and slugs feed on both decaying and living plant material. Wouldn’t it be nice if they’d stick to only eating the decaying stuff?
Wishful thinking aside, if you notice irregularly shaped holes on the flowers and leaves of your plants, if your vegetable seedling are coming up one day and are gone the next, or you find holes in your strawberries, tomatoes or artichokes then the culprit could be slugs or snails. If you notice a trail of silvery slime on the leaves or the ground around your plants then you can be certain the damage is caused by slugs or snails.
These mollusks can do a lot of damage in the garden and they are prolific. A single snail can lay up to 80 eggs at a time, six times a year!
To manage them, its helpful to understand how they live. When its very cold or very hot and dry, they hibernate in small soil cracks or under boards, pots and debris. They prefer moist areas and are active during the night and on cloudy days.
First, you can decrease their numbers by eliminating obvious hiding places like under boxes, sacks, boards and other debris.
You can also choose to grow plants that are fairly resistant to them. Plants like begonias, California poppies, fuchsias, geraniums, impatients, lantana, nasturtiums and purple robe cup flower. Included are plants with stiff and fragrant leaves like lavender, rosemary and sage.
Handpicking. In early evening, moisten your garden with a hose. This will encourage snails to come out and feed after the sun sets. Two hours after dark go out with your flashlight and collect them. You can dispose of them in a bucket of soapy water, a 5-10% solution of ammonia, a plastic bag placed in the garbage, or crush them with your boot and leave them to decompose.
Traps. You can trap slugs and snails by creating lovely hiding places for them. Hiding places where you can easily find them. Start by laying a board or an inverted melon half in your garden. Keep the area moist and leave it for several days then go out and collect them. Repeat as necessary or move the traps to different areas when you notice fewer and fewer slugs and snails.
You can also install beer traps. These can be commercially purchased or by using a container with vertical sides, like a large tuna can. Fill it with beer to within an inch or so from the top. Cover to prevent evaporation but leave a space for the snails to access. Snails are attracted to the beer. When they go for it they fall in and drown.
Barriers. Copper flashing and screens are effective barriers to keep slugs and snails out of your pots or raised beds. You can purchase then at garden centers or on-line. These barriers are believed to work by creating something like an electrical shock which deters them from crossing the barrier.
Natural enemies. Ground beetles and toads are great little eaters of slugs and snails. Create an environment for them by mulching. Ducks, chickens, and geese also eat slugs and snails. However, keep in mind that they may eat your plants as well.
Baiting. Iron Phosphate is sold in hardware stores and garden centers. It works by affecting the snails hunger center. It causes them to stop feeding, they crawl off and starve to death. Iron phosphate is a naturally occurring substance, it is approved for use in vegetable gardens, is non-toxic to animals, and is less affected by moisture than other baits. It comes in pelletized form. Sprinkle as recommended on the label. Do not heap in piles.
For more information refer to UC IPM Pest Notes ‘Slugs and Snails’ at http://ipm.ucanr.edu/PMG/PESTNOTES/pn7427.html
Iron Phosphate. http://extension.oregonstate.edu/gardening/node/995
