By Sarah Robertson

Here it is, almost mid-March, and slugs and snails are already well on their way to total landscape domination in my garden.

Drat!

Diligent attempts to stay a step ahead of these pesky mollusks have included the regular spreading of literally hundreds of pounds of least-toxic (and yes, on occasion, undeniably toxic) bait; countless summer evenings with flashlight in hand, gleefully catching the voracious rascals in the act; and hours spent on my knees, attaching copper tape to container plantings and tree trunks.

And then there was the infamous spritzer summer, when I slunk around the garden carrying a spray bottle filled with a five-percent ammonia solution.

Yet it always seems as if I'm starting every spring from ground zero, with every susceptible plant wearing a bull's eye.

Sad to say, I know that I'm not alone. Family and coworkers are in shock over the destruction already evident in their own gardens. The last straw for one friend was discovering a trio of young snails casually inching across her kitchen floor - they'd somehow hitched a ride inside and appeared ready to conquer new territory!

In our neighborhood, snails outnumber slugs four-to-one. They're more destructive, harder to kill and surprisingly devious when it comes to eluding death. Trying to find nontoxic methods of repelling and/or killing either mollusk isn't easy, but this is definitely the time to revisit some least-toxic ways to vanquish these pests.

Remember to reapply regularly, regardless of your method. And start now. Expects recommend baiting all year long in Western Oregon, but it's not too late to make a substantial dent in your local population.

Snail and slug solutions

n Copper sheeting: It sounds like voodoo, but copper sheeting and tape really does repel these mollusks from raised beds, pots and borders. When slime touches copper, it creates an electrical charge. I've actually seen a snail fall to the ground from a terra cotta pot banded with copper tape near the rim - amazing.

You can purchase rolls of flexible copper tape from many garden centers and home improvement stores. Also look for lengths of copper sheeting, which are typically a bit wider and ideal for tacking onto the edge of raised beds. The copper tape and sheeting should work for two to three seasons before it needs replacing.

Copper wire doesn't seem to be as effective, perhaps because it's thin and the mollusks can cross it quickly enough to avoid much of a shock.

Copper sheeting or tape isn't a cheap way to deter snails and slugs, but for gardeners interested in a fairly effective, nontoxic alternative, it's worth a try.

n Diatomaceous earth: This talc-like, white powder is made from the sharp, microscopic fragments of a sea organism called a diatom. The jagged edges puncture the soft underbelly of snails and slugs, causing them to dehydrate.

Because it, too, is fairly expensive, you might want to try using it on just a few of your most vulnerable hostas or similarly susceptible species. Pour a band of the diatomaceous earth in a circle around the plant in question and monitor the results. Test to see whether rainfall ruins the efficacy of your barrier. Some gardeners believe it does, while others insist it doesn't matter if the diatomaceous earth gets wet.

n Beer traps: Corny, but effective. Sink an old pie tin into the soil and fill with whatever beer is on sale. Slugs and snails really do love the stuff and arrive in droves to drown their sorrows in the yeasty brew. Refresh after every rainfall or irrigation cycle - or when the containers are brimming with bodies.

n Commercial bait: Chemical baits (pellets, liquid or grain) are extremely effective. But they're also wickedly toxic to humans, pets, fish and wildlife. Be thoughtful when applying these baits. Avoid areas frequented by kids and animals.

Least-toxic products such as Sluggo or Worry Free contain iron phosphate as their active ingredient, a substance found naturally in the soil. Once ingested, the iron phosphate causes snails and slugs to stop eating. They essentially starve themselves and die within a week.

I've had excellent luck with least-toxic baits early in the season, less so by mid- to late summer. It also seems to work better on slugs than snails. It probably has something to do with the resiliency of our snails coupled with an abundance of susceptible plant material. The result is snail damage by late summer no matter what steps I've taken over the preceding 11 months.

It does, however, pay to be diligent over the course of all four seasons. Here in Western Oregon our mild climate is a haven for these enterprising pests. Gardeners who patrol year 'round insist that, over the course of a few years, even heavily infested gardens can bring their slug and snail populations back into some kind of balance.

And that's really all we can hope for: a state of equilibrium within the garden that leaves enough beauty and sustenance for everyone - even the occasional mollusk.

Sarah Robertson is an avid Willamette Valley gardener.