Gardeners slug it out with pesky mollusks

Whether brown, yellow, black or spotted like a leopard, slugs all have one thing in common: They can devastate a garden.

Growers in Wrangell have many suggestions on what works to control the slimy mollusks, but they all agree it comes down to garden maintenance.

"Slugs are actually a good creature. They're the cleanup crew of the forest," said Kim Wickman, IGAP technician with the Wrangell Cooperative Association and board member with the Wrangell Community Garden. "They clean up all the things that are dead or dying on the forest floor. Then, of course, as they break it down, it turns into soils and adds nutrients back into the ground."

Unfortunately, Wickman said, slugs also like vegetables and whatever else they can find to eat.

Most species of slugs found in Southeast are considered native or non-threatening, except one: The European black slug. Researchers estimate the black slug arrived from the British Isles in Alaska about 25 years ago and has spread across Southeast and Southcentral during that time. Since native plants aren't used to the black slug, they haven't built up defenses against them, which can be disastrous for the ecosystem.

Slug eggs can be hidden in soil or attached in dark, wet places, making it easy to transport them without knowing it, introducing a species into a new area where they may not have existed before.

Wickman said her family is moving out the road this year and they are trying to leave any garden pests behind. The problem with slugs has been particularly big - to the point where she said she gave up.

"We are leaving all soil at our property when we go," she said. "Any plants that go with us, the soil is staying. It's a new property (where we're moving), freshly developed, so it doesn't have the same pest issues that we have in town."

For gardeners, any species of slug is a nuisance, no matter how beneficial they can be. At the community garden site, beds are covered with netting to repel anything seeking to munch on the plants. But netting isn't the only method used throughout Wrangell.

Input on the Garden of Weedin' Facebook page includes suggestions from an ammonia spray treatment and copper tape to beer traps.

"A plastic container full of beer pushed into the dirt so they just plop in for a swim. They're attracted to the yeast in the beer, and you get the satisfaction of 'collecting' them," one member posted.

"Beer traps are really popular," Wickman said. "The whole idea is you want to get them into the water so they drown. They can be in the water for a long time and crawl out. It's got to be something that's fermented or intoxicating."

Wickman said the Southeast Master Gardeners provide a class that focuses on slug traps, which is putting down a tarp, newspaper or cardboard to provide a protective covering overnight. "In the morning, as the slugs try to hide, they'll go underneath those areas," she said. "Then you can roll your tarp over and dispose of them in whatever method suits you."

Another slug-eradication method, which is ecofriendly but not commonly known, is ducks.

"I've had all types of slugs from monster black ones to banana slugs to the smaller garden destroyers," said Christina Florschutz, a lifelong gardener, who grows on about an acre in Wrangell. "I do not remember how I learned that ducks ate slugs. It's likely I read it somewhere."

Florschutz said she uses a square-within-a-square method. The garden bed - the smaller square - is set up with chicken wire around its perimeter, while a larger square with fencing surrounds the smaller square.

"Ducks are within the larger square but are prevented from entering the garden," Florschutz said. "The space between the squares becomes the slug-free zone. After harvest in the fall, I can open up the inner square and allow the ducks to clean up anything (like slug eggs) that might have escaped their notice during the summer."

Wickman had a neighbor with wandering ducks that would come into her garden to devour the slugs, except there was one problem.

"Those slugs get so big the ducks couldn't eat them," Wickman said. "We'd sit there and watch them trying to eat these giant slugs, and it was not going well for the ducks."

Another natural solution can be certain plants that repel slugs, like peonies and hydrangeas, Wickman said. But really it comes down to maintenance, she said, keeping garden beds clean and removing any dead or dying debris and things slugs can hide on or under.

"It's one of those things where you're never going to get rid of all your slugs, but if you can get a handle on it, then you can manage it," she said.

Carol Fletcher, the IGAP coordinator in Kasaan has been studying soil biology, which she said has helped her understand the attraction of slugs to gardens.

"Slugs, as we all know, are attracted to alcohol," Fletcher said. "When your soil is compacted, it creates anaerobic bacteria and alcohol that attracts them."

The solution is to aerate the garden soil without turning it over to keep it from becoming compacted. One way that can be done, Fletcher said, is by using vermicomposting or worm compost. Worms do all the work of keeping the soil aerated.