Slugs slither into Fairbanks gardens

Slugs slither into Fairbanks gardens

This summer, the real enemy in many Fairbanks gardens wasn't drought or moose - it was slugs.

"I get more calls about slugs every year," said Gooseberry Peter, agriculture and integrated pest management program assistant with the University of Alaska Fairbanks Cooperative Extension Service. Most people calling have never had slugs before, making these slimy critters a major topic of conversation for Fairbanks gardeners this season.

Stephanie Maggard was one of those hit hard by slugs.

At her home in the hills above Fairbanks, she described the scene in her yard. "You can see all the slime marks," she said, describing the shimmering trails slugs leave in their wake.

Slug slime acts as both a lubricant and a glue; it helps the slug stick to a surface when pressure is applied or glide forward when pressure is lifted. The slime allows them to climb vertically - Maggard saw them scale her raised beds, greenhouse tents, metal planter legs and even felted planter bags.

"The slugs are everywhere," she said. "They loved the broccoli and cauliflower, then they started going after the potatoes."

They also damaged her pepper plants, tomatillos and cucumbers. Slugs typically eat the soft tissue between leaf veins, but they will also feed on roots, tubers, seeds and seedlings. Their tongue-like organ, the radula, acts like sandpaper, scraping away layers of plant tissue. They will also eat freshly cut vegetation, fungi and even other slugs or feces.

Joey Slowik, an integrated pest management technicianwith UAF's Cooperative Extension Service in Palmer, says most of the culprits are Deroceras reticulatum, the gray garden slug.

"This slug has been south of the Alaska Range for a long time and probably introduced sometime in the 1930s," Slowik said. "It does sound like things have been more favorable in the last 10 years or so north of the Alaska Range, and they are expanding."

Slowik explained that Fairbanks has always had slugs. The native meadow slug, Deroceras laeve, is found all over Alaska and much of the northern hemisphere. It's a relative of the gray garden slug, but darker and smaller and is rarely numerous. It isn't the pest gardeners are reporting.

In 2022, Slowik realized there was little information about the species and ranges of slugs in Alaska. To remedy this, he created the Alaska Slug and Snail Watch, where Alaskans could report slugs to better track native, non-native and invasive slugs. To report a slug, visit Alaska Slug and Snail Watch websiteor record the sighting on iNaturalist.com.

A new pest for Interior Alaska gardeners

"It's the first year I've seen them at all," Maggard said. She spent her childhood in Delta Junction, where her parents farmed on 150 acres and never saw them there either.

That's a common refrain this year, but Delia Vargas Kretsinger, who has been gardening in the Fairbanks Community Garden since the late 1990s, noticed slugs for the first time four or five years ago. Still, they were never a big issue until this summer.

"I went from maybe one slug last year to a population explosion," she said. "I had a sacrificial cabbage polka-dotted with holes." They also got into her zinnias and rhubarb.

Peter blames human movement for the spread.

"With people moving topsoil, compost, potting soil and plants around, the slugs and their eggs get a free ride to new places," he said.

Slugs are hermaphrodites, meaning they have both male and female reproductive organs. This allows slugs to reproduce asexually or with a mate. Either way, they lay eggs, preferring cool and moist locations. Slugs most often lay eggs in late summer and overwinter, but some lay eggs in early spring.

People have different approaches to getting rid of these stowaways.

"Every time I saw a slug, I snipped it in half with my scissors," Vargas Kretsinger said. For those wondering, cutting a slug in half will not cause it to reproduce asexually; it will kill it.

"I don't kill them," Maggard said. "I just figure everything runs in cycles and there's a reason they're here this year."

Slowik said that "barriers are the most effective method to reduce damage," but nothing works to keep out 100% of the slugs. Because slugs need moisture to survive, dry zones help reduce the number of slugs migrating into an area, but some will still cross them. Electric fences can work in situations like raised beds.

Some people use copper tape as a barrier. Copper may react with the slime, producing a compound similar to copper sulphate, which interferes with slugs' circulatory systems. Other possible reasons include that copper slows slime production, limits how much slugs can eat and harms their ability to reproduce.

"My personal favorite remedy is the cheap-beer-in-the-pie-tin trap. Very effective - and a fun talking point," Peter said. Slugs, attracted to the smell of the yeast in the beer, crawl into a pie tin and drown.

"You can also pick them off plants by hand and feed them to the chickens. Ducks also love slugs," Peter said.

Laura Weingartner is a science writer for the UAF Institute of Agriculture, Natural Resources and Extension.

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