Battling Bugs Expert Offers Tips To Holding Garden Pests At Bay

When gardeners talk gardening, pests often get equal billing with plants.

Bugs are a constant fact of life, some years more so than others. There are many ways of controlling and living with garden pests.

We asked gardening expert Lance Walheim for his best pest tips. Walheim is one of several writers who contributed to “Gardening for Dummies” and “Roses for Dummies” as well as a dozen other “Dummies” home and garden books. He also wrote for Sunset Magazine and was senior editor of the “Sunset Western Garden Book.”

Now the free-lance writer lives on a 17-acre citrus ranch in California, where he grows a large vegetable garden and raises specialty oranges and lemons.

Following are a few of Walheim’s hints for reducing garden bugs:

Q. The aphid population seems to explode in June. Is the only solution to spray them with pesticides?

A. Aphids are usually one of the first pests we see, especially on roses, in the spring. But usually, shortly after you see a buildup of aphids, you get a buildup of predators — ladybugs, lacewings and wasps — that knock the population back. Aphids don’t threaten the life of the plant; they’re just annoying and look bad. Really, you can knock them off the plants with a jet of water. They aren’t a hard insect to control. The predators aren’t too far behind the pests, but a lot of people with aphids just spray right away with something toxic, and it also kills the predators.

Aphids become troublesome if they are near a patio because the sticky honeydew gets on everything nearby, but they are more unsightly than anything. I use an insecticidal soap to knock them back where I need to.

Aphids aren’t very mobile, so it works to use a hose on them. They don’t have a good way to get back on the plant.

Q. Many of the roses get powdery mildew or a black spot in June when the days get warm. Will it harm the rose bushes?

A. The mildew is really weather-related. It goes away as the weather changes from cool, humid nights. But mildew can get pretty bad, and it can cause new growth and the rosebuds to be deformed. There are fungicides that can work, but in general the fungicides are a little more toxic than I like. There’s now an organic product, an oil that’s available at garden centers, that takes care of it.

Gardeners should look for rose varieties that have disease resistance. English roses, in general, haven’t performed as well as they should and don’t have the disease resistance they should. A new rose named Knockout is one that is very good in regions prone to mildew.

Q. Are there common home remedies that work well in the garden?

A. I don’t know if I believe some remedies I have heard, such as chopping up peppers and garlic and mixing it in the flower garden. There are a lot of home remedies listed in “Gardening for Dummies.” Some sound like hocus-pocus, but some are tried and true. With organic approaches, you may have to use them more often, but they are your first line of defense.

For example, for a long time people have sprayed a few drops of dish soap in water on plants, and that’s effective against soft-bodied insects like aphids. If the problem gets more serious, take a more serious approach.

If earwigs are a problem, one thing you can do is put wet newspaper out in the garden, and they will hide in it. In the morning, pick up the paper and toss it. Earwigs look intimidating, but I’ve never been pinched by one. And they are a beneficial insect; they feed on organic matter and they do feed on aphids.

Cutworms can also be a problem, especially with new transplants and young plants. Since they cut off the plant at the ground, I recommend putting a paper cup (with the bottom cut out) or tin can collar around the plant and pushing it into the ground a couple of inches so the cutworms can’t get at the plant. There are also parasitic nematodes that work well; I get them from Gardens Alive catalog (5100 Schenley Place, Lawrenceburg, IN 47025).

Yellowjackets are a tough problem. The little green plastic traps are effective. But mostly I advise making sure you aren’t leaving food or garbage out anywhere for them to feed on. You won’t get rid of them, especially if it’s a bad season for yellowjackets.

Q. Any tips for dealing with mosquitoes?

A. Make sure there is not a lot of standing water around, or use biological controls if you have a water feature, such as mosquito-eating fish. I know people who swear by citronella candles, but they have never worked for me.

Q. The EPA just announced it plans to ban the pesticide Dursban. Will this be a big loss in the arsenal of insect weapons?

A. Dursban and diazinon are part of the old generation of chemicals that didn’t go through EPA testing. We’ve known for a long time that Dursban was suspect and that diazinon is suspect as far as harm to the environment.

I think dealing with pests with organic solutions is where our interest is heading. My approach is organic. I try to control pests with the least intrusive method, using benign products such as predatory pests. In the vegetable garden I don’t do any spraying, and in the yard I don’t do spraying until I need to. If you have a pest problem, you take appropriate measures.

Not everybody has the time to spend in the garden that I do, and not all chemical products are bad. The new generations of products have gone through testing and have better environmental profiles. In a perfect world we would all wake up and go organic, but that’s not going to happen.

If you are going to spray, always make sure to read the instructions on the product label and follow them precisely. And make sure the pest you plan to spray for is one of the pests that’s listed on the label.

Q. Do you patrol your garden daily looking for pests?

A. First you have to decide what you can tolerate. Usually the people who garden a long time learn to tolerate a lot of things. The best way of really keeping on top of pest problems is getting out there every day and looking around. It’s easier to control insects earlier rather than later when they are out of control.

This sidebar appeared with the story: CLIMATE CHANGES Weather affects all insects differently

Do a mild winter and a wet, cool spring add up to a bug explosion? It depends on the insect, says David James, a Washington State University entomologist.

With more water around, there will be more places for mosquitoes to breed. When the temperatures finally warm up, this could be a very bad mosquito year, James says. James works at the WSU Prosser Agricultural Research Station in Prosser, Wash.

“A warm winter stacks the odds in favor of survival,” says James.

A wet spring, though, hinders some insects, such as butterflies and yellowjackets. “Butterflies might have six or seven days as adults to breed and lay eggs. If those six or seven days are cloudy and wet, it stands to reason the butterfly population could suffer.

Only the queen yellowjackets overwinter, and they are well-adapted to severe winters. “But if we have a cool summer and the bees can’t forage and reproduce, the population is not so big at the end of the summer and they don’t get in everyone’s way,” James says.

“Weather affects all insects differently,” James says.

In general, those which need water to breed will likely have large populations this year. Those which need heat, like mites and yellowjackets, might have smaller populations even if it warms up in August. Should the days stay dry and temps rise sooner, well, get out the fly swatter. Susan English