By Doug Oster/Pittsburgh Post-Gazette
A long brownish-orange slug slowly slides across a cabbage leaf, pausing occasionally to feed on the tender foliage in my garden. Usually they attack under a shroud of darkness, causing gardeners to wonder what’s causing the holes in their plants’ foliage.
“During the day, they are underneath debris or mulch. Then at night they come out and feed,” says Matthew Quenaudon, integrated pest management specialist at Phipps Conservatory and Botanical Gardens.
“A slime trail is also a good indicator.”
This is the third wet summer in a row and has the potential for being the worst we’ve seen for slugs in as many years.
The conservatory doesn’t have a serious slug problem since most of its rooms are changed out regularly for seasonal flower shows. That doesn’t give the slug population a chance to grow. When the pests do attack, Mr. Quenaudon’s reaches for an organic bait called Sluggo whose active ingredient is iron phosphate,
“That’s safe for people and pets,” he says.
Once slugs have ingested the bait, they stop feeding almost immediately and die within several days.
Mr. Quenaudon discourages gardeners from reaching for chemical slug pellets. “You might be hurting other things in soil, including toads and frogs.”
There are lots of predators that eat slugs and chemicals can negatively affect them, too. Slugs are a food source for everything from ground beetles to small mammals.
Mr. Quenaudon’s best tip to keep slug damage to a minimum is to keep the garden free of debris and weeds, two things slugs love. Cultivating under and around the plants will also help, he says.
Slugs are soft-bodied snails without a shell. Mr. Quenaudon has some fun facts about the slimy garden raiders.
“They have two sets of antennae. One set is for seeing the other is for smelling.” If one of the antennae is lost, it can regenerate. Slugs are also hermaphroditic and will reproduce prolifically in wet conditions.
If the rains ever stops, water in the morning, he says. The foliage and soil will have time to dry out during the day, making it a little harder on the slugs.
Handpicking is also an option but always use gloves -- slugs emit a sticky slime as a defense mechanism that is hard to wash off. Mr. Quenaudon recommends heading out into the garden for 20 minutes at night when slugs are most active with flashlight in hand.
When the ground does dry out, he says gardeners can use diatomaceous earth to keep the slugs at bay. It’s sharp on the microscopic level and punctures the slugs as they crawl over it. During rainy weather, the powder would need to be applied after each soaking.
Another technique is trapping the pests with beer. Place a grapefruit rind or a bowl in a hole at soil level. Fill the trap with stale beer. Slugs attracted to the yeast will crawl in and drown at the bottom of the trap. It's a disgusting chore to clean out the dead slugs each morning, but it does make quite a dent in the population.
Darcy Kennedy, manager of Penn Hills Lawn and Garden, is carrying a brand-new organic product called Slug Gone. It’s 100 percent natural and made of wool pellets which are applied under and around plants. When the pellets get wet, they swell to form a barrier. Slugs don’t like the texture and won’t crawl on it. The mat also acts as mulch for the plants.
Ms. Kennedy said one customer who bought some in May came back to report success.
“She used it first around her hostas and then decided to use it in her containers” with petunias and other annuals.” The barrier stopped slugs and weeds, she said.
A 1-liter bag of Slug Gone costs $7.99 and a 3.5-liter bag is $17.99 at Penn Hills Lawn and Garden.