Be careful when considering insecticide use

Richard Bogren, Gill, Daniel J.

Io moth caterpillars are stinging caterpillars that feed on the leaves of a variety of landscape plants, such as this crape myrtle. They should be controlled with appropriate insecticides when you see them. (Photo by Dan Gill. Click on photo for downloadable image; right click to save.)

For Release On Or After 05/17/13

By Dan Gill
LSU AgCenter Horticulturist

As the weather warms up, insect problems increase. Many gardeners still feel they should immediately get an insecticide and begin spraying when they see insects or some apparent insect damage in their gardens or landscapes. But just because you see an insect is not reason enough to spray.

The insect you see may not be harmful or may not cause enough damage to warrant control. It may even be a beneficial insect that eats other pests and helps keep them under control. Even if you are correct in thinking that you need to control the insects, it is imperative you do it the right way.

The initial step in deciding whether to spray is to correctly identify the insect causing the damage. Once it’s identified, find out if there is a way of controlling the pest without using chemicals. Many techniques can be used to control particular insects without using an insecticide.

If you don’t properly identify an insect pest, several things could go wrong. If the damage was caused by insects that have already come and gone, spraying won’t do any good.

For example, in spring you may notice that areas of your grass do not green up with the rest of the lawn. In many instances the damage was caused by chinch bugs the previous summer. But even though chinch bugs were responsible, they are not active in spring, so treatment then would accomplish nothing.

Indiscriminate spraying can kill beneficial predatory insects that are eating other insects on your plants. This can actually cause insect problems to develop or become worse. You will have wasted time, money and effort and destroyed not a pest but quite possibly a friend.

If insecticides are needed, without proper identification you may spray the wrong material or use it the wrong way. Remember, no single insecticide will control all insects, and some can even make the problem worse. For instance, spider mites can become even more damaging if they are treated with the insecticide Sevin.

Also, insecticides for gardeners are generally short-lived to reduce the chance of environmental contamination from residues. Most insecticides break down in a matter of days or weeks after application and offer no protection after that. You can’t spray once in the spring and expect that your plants are protected indefinitely. Pest problems can, and often do, recur.

It is essential to read the label before purchasing and using an insecticide to be certain that it will control the pest. It will also tell you how much to use and how to mix and apply it as well as the safety precautions that must be taken, such as wearing protective clothing. Some pesticides have restrictions for use on certain plants and at certain temperatures that, if not followed, might damage the plants rather than help them.

If you need to use an insecticide, find out which ones are the safest and least toxic. Check the label of the pesticide container for one of three words. “Caution” denotes the least-toxic category of pesticides; “Warning” appears on the label of the next-most toxic category; and “Danger” is on the label of the most toxic category of pesticides. If several insecticides would be effective and appropriate to use, choose the one that is least toxic.

Choose the right formulation. Different types of pests are controlled better with different types of insecticide formulations, such as baits, sprays or granules. Some insecticide formulations are more effective than others on particular pests, and you need to choose the right one. Always buy the smallest available container of a pesticide so that you will use it up more quickly. Pesticides lose potency over time. Also, consider the convenience of purchasing insecticides that are premixed and ready to use.

The control method must be directed toward the pest. If the insect lives and feeds on the underside of the foliage, your spray should be directed there. If it lives on the trunk and branches, a light spray on the foliage will not be effective. Only spray infested plants and those of the same kind nearby. Do not spray everything in your landscape just because a few plants are infested.

When making applications of insecticides, keep kids and pets out of the area. You need to read and carefully follow any safety precautions indicated on the label. Always wear rubber gloves when mixing and spraying insecticides. Also, wear closed shoes, long pants and a long-sleeved shirt to minimize your contact with the spray. Goggles or eye protection is also recommended when using some insecticides.

Be wise in your use of insecticides. If you spray insecticides when they are not absolutely necessary, you needlessly introduce toxic substances into the environment. Before you start spraying, be sure you properly identify the insect and use the right pesticide at the right rate with the proper applicator. Always apply the insecticide according to the label directions and in a manner that will give you the safest, most effective control.

Rick Bogren
4/30/2013 8:11:54 PM
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