Wise insecticide use in vegetable garden

NICEVILLE, Fla — Should you spray or dust every plant in your vegetable garden at regular intervals to protect your vegetables from insects?

Many entomologists say no. Here’s their reasoning for this answer.

You don’t even need to spray every time you see a bad bug.

But many gardeners make this mistake, which not only wastes chemicals and time, but may make insect problems worse rather than better.

No insecticide will kill all insects. For example, carbaryl (Sevin) will kill many but will have little or no effect on aphids or spider mites (not true insects). Repeated use of carbaryl will eliminate many beneficial insects, such as lady beetles, that feed on these pests. So, you may end up with a much larger population of aphids and spider mites than if you applied no insecticides at all.

What about mixing three or four pesticides together to get one deadly all-purpose brew?

The more chemicals you mix together, the greater the chance of getting some unwanted chemical changes. The chemicals may burn the leaves, become less effective or precipitate in the spray tank.

Unless the label states otherwise, it may be safe to mix two pesticides such as an insecticide and fungicide. But you raise the risks each time you add another chemical to your brew.

There’s a better way – tailor your chemical applications to specific needs.

Most plants don’t need to be covered up with insecticides every week, although a few vegetables may need applications to protect them from specific pests. For example, to prevent serious damage you may need to apply an insecticide preventively to the base of squash plants to protect against the squash vine borer.

The principle strategy here is that those damaging insects that bore into or get inside a plant are best controlled before they enter the plant.

Because most pests feed on the outside, twice weekly inspections of the garden should show when a pest problem is first developing, such as with aphids, mites, bean beetles, tomato and fruitworms.

Treating only those plants infested with the correct insecticide for the pest is the best strategy and don’t treat plants that don’t need it.

Mix up only what you need to treat plants you plan to spray.

The biggest pest in the garden may be the gardener who fills up a three-gallon sprayer. After spraying out half a gallon, the gardener looks over the garden to see where to spray the rest if it “for good measure.”

Spray or dust only when you need to and treat only those plants that need it.

Always follow the label directions and precautions for any pesticide you use.

Larry Williams is the Extension horticulture agent with the Okaloosa County Cooperative Extension Service, University of Florida. Contact Larry at 689-5850 or email lwilliams@myokaloosa.com.