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Ask a Gardener: Ladybugs, rhubarb juice help kill aphids

Ladybugs are among the most efficient of the beneficial insects, particularly for home gardeners. The adults and larvae feed voraciously on aphids and mites, among other plant pests.
Ladybugs are among the most efficient of the beneficial insects, particularly for home gardeners. The adults and larvae feed voraciously on aphids and mites, among other plant pests. Associated Press

Question: My wife wants to get a bug-light trap. I’m not sure it will do the trick. What do you think?

Answer: What the package information on the bug-lights doesn’t tell you is that the most common insects killed by them are moths and butterflies. UV bug killers do in a fair number of night-flying mosquitoes, but many species of mosquitoes are day-fliers and wouldn’t be drawn to your trap.

I’ve found that the small but distinguishable sounds the insects make as they’re incinerated is off-putting. Here in Whatcom County I’ve never been bothered enough by night insects to warrant the purchase of a bug-light trap.

Q: I had a terrible problem with aphids last year. They seemed to get onto everything. Short of using unwanted chemicals, what can I do to lessen the problem this year?

A: First, develop a very fertile soil and produce healthy plants. Aphids tend to avoid these.

There are dozen of species of aphid, which are also called plant lice. They’re small, soft-bodied and pear-shaped. Most gardeners recognized them on sight — and a frustrating one it is, too, as aphids suck plant sap, causing foliage to wither and plants to lose vigor.

Excess sugar and sap from the aphids is called honeydew and is ambrosia for ants that tend the aphids as people do cows. The ants distribute the aphids from plant to plant, and even carry aphid eggs into their nests only to be carried back out in spring and set on plants.

As incredible and amazing as this symbiotic relationship is on paper, it is frustrating from a gardener’s point of view, as it means aphids are hard to control.

The simplest control is to manually rub the affected leaves, crushing any aphids on them. Or, if the plant is covered with aphids, they can be washed from plants with a forceful spray of water.

Some gardeners swear they control aphids by planting baits.

Nasturtiums are commonly used, and can be so covered by aphids you can’t see the color of the plant. Wait until the nasturtium is covered, and then pull and dispose of the whole thing, aphids and all.

Other gardeners buy ladybugs, the best-known predator of aphids. Problem is, they fly, and won’t necessarily stay where you intended them to stay. But it may be worth a try.

A friend told me of a solution to aphids she’d learned about years ago, and swore by. She boils 1 pound of rhubarb stems in 1 quart of water for 30 minutes, then strains it and adds a squeeze of liquid soap to help it stick to leaves. Then she sprays it on any aphid infestation.

It’s the oxalic acid in the rhubarb leaves that kills aphids. I would try it myself, but I have been spared the scourge of aphids. I have plenty of other pests and wish I could find solutions as simple as rhubarb juice!

Kathleen Bander of Bellingham is a life-long gardener. Her column will appear in The Bellingham Herald weekly through the summer growing season. If you have a gardening question you'd like answered in the column, please email it to newsroom@bellinghamherald.com. For more gardening information online, go to whatcom.wsu.edu/ch/mg.html.

GARDENING EVENTS

Summer Propagation-Softwood Cuttings: Saturday, June 13, 10:30 a.m.-noon, Cloud Mountain Farm Center, 6906 Goodwin Road, Everson. Free. Call 360-966-5859 for information. Propagation of many woody plants is most effective during the summer growing season, and if a few simple guidelines are followed, softwood and semi-ripe cuttings can be very successful. We'll learn how to propagate plants via cloning during the growing season as we discuss timing of cut, condition of wood, and caring for cuttings during and after the rooting process. No registration required. Be prepared to be outside.

From Her Garden: 6:30 p.m., Tuesday, June 16, Community Food Co-Op, 1220 N. Forest St., Bellingham. Cost: $39. Call 360-734-8158 for information. Learn from culinary gardener Mary von Krusenstiern of Loganita Garden who grows special produce and herbs for the famous Willows Inn. Enjoy spot prawns with fresh-from-the garden caraflex cabbage, charred with butter and olive oil, and early summer vegetables stir-fried and grilled. Mary will also field questions on backyard gardening and provide planting and cultivating tips.

Plan your Winter Vegetable Garden Now: 10:30 a.m.-noon, Saturday, June 20, Cloud Mountain Farm Center. Free. Call 360-966-5859 for information. At the peak of summer is the best time to plan and plant a winter garden. Here in the Northwest, it’s possible to grow and harvest vegetable almost year round. We’ll discuss the types of plants you can grow, special fertility and soil requirements for winter gardening, and the use of cloches and frost blankets to extend the harvest. No registration required. Be prepared to be outside.

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