Garden Plot: There’s more than one way to get rid of slugs

There are non-toxic granular slug-killers, but beer works fine too. (Thinkstock)
Plant and water plants in the evening

Mike McGrath | November 14, 2014 7:01 pm

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WASHINGTON – Lourdes in Silver Spring has a slimy problem. She writes: “Please help me get rid of the slugs that feed on my hostas. The plants look so perfect, healthy and strong when they emerge in the spring, but once the slugs start feeding they look like they’re in a war zone!”

Hostas are slug candy, Lourdes. And the fact that they’re shade-loving plants makes them easy prey for these moisture-loving slimers, who only hunt at night and prefer damp, shady spots.

Put half-pint containers filled with fresh beer out at dusk, the slugs will crawl in and drown overnight. Don’t use the often-recommended stale beer. Slugs like stale beer less than I do. And don’t put the beer traps out until the sun starts to go down so it will still be nice and fresh when the slimers come out to play.

There’s also a great non-toxic granular slug killer available that’s very effective. Sold under brand names like “Sluggo” and “Escar-Go!,” the active ingredient is iron phosphate wrapped in a yeasty bait. The slugs are attracted by the yeast, but can’t metabolize the iron, which kills them. But the bait is totally harmless to people, pets and wildlife.

Ants away!

Tom in Huntingtown writes: “Ants are coming into the house from a shady area under our deck. Is there something I can plant or apply down there to keep them away? I’ve heard that mint does wonders, and I’m trying to avoid using pesticides.”

Good for you, Tom!

Now, plants don’t repel insects by just growing in the ground, but their leaves and essential oils can be used for that purpose. And mint is a popular ingredient in many non-toxic insecticides designed to control ants, so try spraying an organic insecticide whose active ingredient is mint around the door and other entry areas.

Or use bay leaves – they’re reported to be highly repellent to ants. Just crush up a bunch of the leaves and spread them around the invaded area.

But the sure cure for ant invasions is boric acid bait traps. Harmless to us, boric acid is deadly to ants if you use it correctly. The traps, which use a very low dose of boric acid in a sweet bait, are widely available. Look for boric acid, sodium tetraborate or some other form of the element boron as the active ingredient. Then you must allow the ants to come and go after you set out the baits. Don’t kill any of the ants. The low dose of boric acid will take several days to sicken the first ants, but by then those workers will have fed the bait to the queen – and that will wipe out the entire colony.

Get your dog offa my lawn

Bill in Woodbridge has an all-too-common complaint. He writes: “How can I keep the neighborhood dogs from ‘using’ my yard? Are there chemicals or something natural that will make them walk right on by?”

There are repellants designed for this purpose, Bill but I wouldn’t bet on their effectiveness – and repellants have to be applied weekly and/or after every rain, which can be tedious and darned expensive.

If the dogs are running loose, call animal control.

If thoughtless dog walkers are allowing this, put up a low fence and “Don’t poop here!” signage. Some great pre-made signs are available. You’ll find lots of free, printable designs online. And here’s a company that offers a variety of styles on long-lasting metal.

If that fails, set up a motion-activated sprinkler to chase them off with a blast of cold water. Motion-activated sprinklers are very effective, and also keep deer, cats and thoughtless people off your property. Here’s the official website for the model that I use to ward off Evil Squirrels. The sprinklers are also available at retail at better garden centers, and online for a lower price at Amazon (what a shock!).

Is that a caterpillar on your roses? Or is your sawfly happy to see me?

Tom in Manassas writes: “What do I use for caterpillars on roses? Are horticultural oils safe and effective?”

If they are true caterpillars, you’d spray the plants with Bt, Tom. This organic and non-toxic pesticide (available under brand names like Dipel, Thuracide and Green Step) kills any caterpillars that eat the sprayed plant parts, and it only affects caterpillars that eat the sprayed plant parts, nothing else.

But Bt would not affect the rose sawfly. The larval form of a weird little wasp that looks remarkably like a caterpillar. (Here’s a site to help you ID them.) If sawflies are the problem, a light “summer spray” horticultural oil would be a great solution. (Don’t use a dormant oil. Those heavyweights are for winter use only.)

But, as with insecticidal soap, horticultural oils work by smothering, and must be sprayed directly on the pest to be effective. Spraying the plant itself would only give you a shiny plant.

Stop stinkbugs now – Because the cicadas won’t

Those nasty, tomato-sucking stinkbugs will soon be appearing in area gardens, unless you prevent them. Tape a mirror to the end of a hoe and begin using it weekly to search the undersides of the leaves of your plants for their very distinctive barrel shaped eggs, which are laid in fascinating geometric clusters, like double rows and triangles. Destroy these eggs early in the season and you’ll really cut their summertime numbers.

Because, unfortunately, Joe in Middletown’s terse email titled “Dream from stink bug central: Wouldn’t it be nice if cicadas ate stink bugs?” is just a dream.

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