Insecticide, Should You Use? Which? When?

If you find an unfamiliar insect, you should consult your County Extension Office for identification. Correct identification is essential to determine if the insect is a pest and what insecticides will control it.

The decision to use an insecticide in your garden should be based on correct insect identification. Is the insect really a pest? There are many beneficial as well as destructive insects.

You are probably familiar with the usual insects that are a problem in your garden year after year. If you find an unfamiliar insect, you should consult your County Extension Office for identification. Correct identification is essential to determine if the insect is a pest and, if so, what insecticides will control it.

Three basic insecticides

There is no single insecticide capable of controlling all insect pests in your garden. Three insecticides that all gardeners who plan to use insecticides will need are: Sevin, Malathion and Diazinon. These three materials will control most but not all pests in your garden. For example, spider mites, which are tiny insect-like pests, are best controlled with Kelthane. Cowpea Curculios, which sting your peas and beans, are another exception. They require Thiodan for best control.

An insecticide is effective only when it reaches the insect. For insects feeding on the above ground parts of plants; be sure to dust or spray the entire plant, including the uppersides and undersides of leaves.

The bigger they are…

Watch plants closely to detect early damage. Insects are easier to control when they are small. When they grow larger, they are easier to see, but also harder to kill.

You should apply insecticides only when insects are a problem. Unnecessary applications will kill off beneficial insects that feed on insect pests such as aphids and spider mites.

Use caution…

If the insecticide being applied, such as Sevin or Malathion, doesn't kill some pests, such as aphids or spider mites, you may create the very problem you are trying to avoid. When large infestations of destructive insects are present, weekly treatments may be necessary.

Remember to observe all directions, restrictions and precautions listed on the pesticide label. And, always observe recommended intervals between last application and harvest to avoid harmful residues on your vegetables.

For more information on what kind of pesticides to use and when, contact your local County Extension Office.