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Manage garden pests wisely


Lori K. of Santa Rosa asks: I have a few insect problems in my garden, and I don't want to spray harsh chemicals, especially when I don't know what these bugs are.

Are there any guidelines to follow, to help a gardener have a healthy garden with healthy plants?

No matter what's bugging you in the garden, there are a few choices when it comes to waging war on insect pests.

You can start by using an approach called integrated pest management (IPM), which is an ecosystem-based strategy that focuses on prevention of pests or their damage by using biological control, habitat manipulation, modification of cultural practices, and the use of resistant varieties.

Pesticides are used only after monitoring indicates they are needed, and treatments are made with the goal of removing only that particular insect.

Pest-control products are selected and applied that minimize risks to human health, beneficial and nontarget organisms, and the environment.

IPM is a commonsense approach that helps you to choose the most environmentally friendly strategy first.

We need to make smarter biological, cultural, mechanical, and chemical choices to reduce pesky garden problems. Here's a checklist of some IPM practices to guide you.

Know your pest threshhold and identify the insect. Not every insect is a pest. In fact, out of the thousands of species of insects, only a few — about 10 percent — are problem pests to gardeners.

Many of the remaining 90 percent are either beneficial or harmless.

So if insects are simply gnawing on your broccoli's leaves but leaving the broccoli heads alone, you might not need to take any action.

Keep your plants healthy. The healthier the plants, the fewer pests there will be.

Use good cultural practices like selecting disease-resistant varieties, avoid overcrowding, incorporate compost instead of synthetic fertilizers, and water efficiently, using an appropriate drip system.

In the vegetable garden, be sure to rotate crops annually and dispose of diseased plant materials as you see them.

Conduct regular inspections. Careful observation is one of the key IPM practices. Keeping an eye on what's going on in your garden will help you gauge whether the insects you see are causing damage or eating the problem insects.

With regular inspections, you can catch a pest problem early and decide on an appropriate control before it gets out of hand.

Choose the safest (least toxic) action first. When the number of pests outweighs your patience, start with physical and mechanical controls first.

Only go after plants that are affected. Hand pick insects off of plants, use sticky insect barriers and traps, or spray with a strong stream of water.

Plant for predators. Beneficial insects can target specific insect pests and should be encouraged in the garden.

Lady beetles (ladybugs), lacewing larvae and spiders help control pest populations.

The more bugs in your landscape, the more insect predators you'll have — including birds.

Use biological controls. Biological insecticides (like viruses, bacteria, fungi and nematodes) are living organisms that target certain insects. Beneficial nematodes are effective against grubs and cutworms.

Bacillus thuringiensis (Bt) is a soil bacterium that helps control hungry caterpillars. Read the product label to see which works best for your pest problems.

Select the safest chemicals first. Before reaching for the synthetic chemical controls, try the least-toxic method first.

Diatomaceous earth (DE) is a substance made from the remains of fossilized microorganisms.

The powdery substance is usually dusted around the base of plants to control slugs, snails, grubs and other insects.

Other safe chemical controls include insecticidal soaps, horticultural oils and repellents, like Neem oil. Again, read the label to make sure the product won't harm beneficial insects, too — especially the bees!

When all other controls have failed to be effective, you can reach for the least toxic synthetic chemical pesticide that kills on contact.

But if you follow these IPM steps first, you may find you'll never have to use them.

Send your gardening questions to The Garden Doctors at pdgardendoctor@gmail.com. The Garden Doctors, Gwen Kilchherr and Dana Lozano, can answer questions only through their column, which appears twice a month in the newspaper and online at pressdemocrat.com.