How to limit damage from slugs
Question: Something is eating the leaves of many of my flowers, including my zinnias, hostas, dahlias and petunias. I don’t see any Japanese beetles or other bugs on them, but there are holes in the leaves or the leaves are eaten in from the sides. Do you know what might be happening?
Answer: With such a wet growing season, it wouldn’t surprise me if slugs were the culprit. The plants you name are all on their list of favorites, and unless you’re willing to visit your garden at night, you’ll seldom see the slugs damaging your plants.
Slugs are a huge problem for Pennsylvania gardeners, especially during prolonged periods of wet weather. The damage they leave behind consists of ragged holes in the leaves or skeletonized foliage. I’m willing to bet that if you head out to the garden at night with a flashlight, you’ll find them in action, nibbling away on your plants.
There are several things you can do to limit slug populations. The first is to space plants properly, giving each one enough room to quickly dry off after rainfall. Slugs love wet, so when you water your garden, try to target the water applications at the soil level to keep the foliage dry. I know this isn’t possible when your irrigation comes from Mother Nature, but if you water by hand during dry spells, water the roots of the plant only.
Second, handpicking slugs can be quite effective. In the evenings, pluck the slugs from your plants, dropping them into a jar of soapy water.
There are also many types of commercial and homemade slug traps you can use to lure the slimy buggers to their death. Beer is often recommended as a lure for these kinds of traps, but personally, I can’t stand emptying the trap when it’s full (gross!), so I skip traps and turn to organic slug baits instead.
Organic slug baits are based on the active ingredient iron phosphate. Iron phosphate-based baits are scattered around susceptible plants where they’re discovered and ingested by slugs. Though the slugs don’t die instantly, they do stop feeding immediately and die soon after.
Chemical-based slug baits should be avoided as they can also harm pets and wildlife, though many brands now include a distasteful ingredient to help prevent accidental ingestion.
There are other slug-deterring products on the market as well, including wool pellets, slug collars and copper tape, all of which have varying degrees of effectiveness depending on how and where they’re used.
And, of course, you should always plan to include many species of plants not preferred by slugs in your garden each season. Plants with highly scented foliage (such as salvias, artemisias, lavender and Russian sage) and plants with fine fuzz or hair on their foliage (such as Brunnera, dusty miller, verbena and Verbasicum) are the best bets.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden,” “Good Bug, Bad Bug,” and her newest title, “Container Gardening Complete.” Her website is jessicawalliser.com. Send your gardening or landscaping questions to [email protected] or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.