Hitting the Snail on the Head
What do beer, copper, metaldehyde and this newspaper have in common? Each can be used to combat the voracious hordes of snails and slugs that are now munching their way through Orange County’s gardens and landscapes.
Just when you thought the problems from all the rainstorms had ended, you may well be facing the latest storm damage in your own back yard.
“This is a pretty bad year for infestations from snails and slugs,” said John Cavashema, an environmental horticulturist with the University of California Cooperative Extension Service in Irvine.
“Snails and slugs love moisture, and their eggs have been hatching out in large numbers after these heavy rains,” he said. “Also, they’ve been redistributed as the flooding waters have moved them into different areas.”
If you’ve been controlling snails on your own property, but your neighbors haven’t, the odds are very high that you’ll now have an infestation.
“Even though large numbers of eggs may have been washed out to sea or elsewhere, if even 1% survive to hatch, they can build up their populations very quickly,” Cavashema said. “That’s why they’re pests.”
Fortunately, there are a number of effective methods of reducing their populations.
For many years, the most popular has been the use of poisonous baits.
“This is a highly effective method of eradicating snails and slugs, but it is a poison and should be used with great care if children and pets have access to the yard,” said Rico Montanegro, assistant director of the Fullerton Arboretum.
Cavashema agreed and added: “The use of snail bait is a therapy, not a cure.”
Cavashema is a specialist in integrated pest management, a methodology that advocates using the least toxic methods for pest control. He recommends the following strategies against snail and slug attacks:
* Assess your situation. Look in your garden at night, when snails and slugs are active, and determine the severity of the infestation. Snails and slugs love ivy, agapanthus and the tender young growth of annuals and bedding plants. You may find the population concentrated in just a few areas of your property.
* If the population is exploding and there seem to be snails everywhere, you may want to use snail bait to reduce the numbers until they can be controlled by nontoxic methods.
* If you decide to use snail bait, be sure to scatter the granules rather than piling them up. Follow directions, and put children and pets indoors when you apply the bait, so their natural curiosity won’t lead them taste to it. Place the unused bait in a safe place where children can’t get to it. Be sure to buy the newer types of baits that use metaldehyde, a chemical that paralyzes the snails and slugs, and place it inside the flower beds but near enough to the perimeter so that the paralyzed snails and slugs will die in the sunlight. If the bait is placed too deeply into the planted areas, snails and slugs can recover from the paralysis, seek shelter in dark areas and thrive again.
* If the snails are drawn to just a few plants, try placing copper barriers around them (several commercial barriers are available). Mollusks crawling over the copper surface receive an electrical charge, which repels but doesn’t kill them.
* Try nontoxic eradication methods. One of the simplest is to crush the snails or slugs underfoot. This may be hard for squeamish people, but certainly is the cheapest and simplest method.
Another method is to let them drown in a pool of beer. Pour beer into commercial snail traps, saucers or even empty coffee cans and place in the garden. Snails and slugs are attracted by the yeast and climb in for a drink, which quickly becomes their last. The drawback is the traps must be emptied every day or two. The contents can be flushed down the toilet or tossed on your compost pile (be sure the snails and slugs are dead).
Another successful method is placing rolled-up newspapers in several areas of your garden.
“Snails and slugs are attracted to moist, dark places and will gather inside the paper,” Cavashema said. “In the morning, sweep them into a sealed container and then place it in the sun so they’ll die.”
If they’re crawling out of the container before you can close it up, try putting a little alcohol and water in the bottom to anesthetize them.
Another successful nontoxic control method is to place a hollow grapefruit shell in the garden, upside-down, and on an uneven surface so the mollusks can get inside. The citrus attracts them, and they’ll remain in their cool shelter until daylight when they can be dispatched.
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One of the simplest ways to combat these unwanted garden invaders is to encourage their natural predators.
“We don’t have any problems with snails or slugs at the Arboretum because our ducks eat them,” Montanegro said.
If you can’t keep ducks, you may be fortunate enough to live in an area where opossums forage. Although some people are repelled by their long tails and pointed faces, possums are actually a gardener’s friend because they love to dine on snails and slugs.
Another predator that’s somewhat controversial is the decollate snail. These mollusks with decorative spiral shells eat young snails and slugs but are no match for the larger adults. They will reduce the snail population, but there is some question about whether they, too, damage plants.
“Decollate snails are effective predators of common brown garden snails, and if they start to eat young plants, they can be very easily controlled,” Cavashema explained. “They’re banned in Northern California and states with native mollusk populations because there’s concern that they can endanger the local population, but they can be used safely in Orange County.”
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Once you’ve controlled the snail and slug attack, keep the creatures from returning by practicing good gardening. Don’t over-water or over-fertilize your plants. Tender, lush growth attracts them.
Thin out shrubs or ground cover so sunlight can penetrate and air can circulate. Limit dark, moist spots where mollusks seek shelter.
Many commercial nurseries protect their property by placing copper barriers along the perimeter.
“Snails are among the biggest problems for nurseries because other states have very strict quarantine laws,” Cavashema explained. “If even one snail is discovered, it represents a loss of hundreds of thousands of dollars because the entire shipment will be destroyed.”
Snail barriers will work if your garden is surrounded by fencing, to which the barrier can be attached. If there are lawn surfaces nearby, you’ll have to resort to some of these other methods of snail control.
