April 2017 Articles

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Use insecticides only when needed

Use insecticides only when needed Editor: Rick Bogren at 225-578-5839 or rbogren@agcenter.lsu.edu
By Dan Gill LSU AgCenter Horticulturist
Pest problems will become more common as we move into the warmer summer months. Some gardeners still feel that they should immediately get an insecticide and begin spraying when they see insects or some apparent insect damage in their gardens. But just seeing an insect or insect damage is not reason enough to spray. You may end up killing beneficial predatory insects that are eating pests on your plants, and this can actually cause pest problems to develop or become worse. You will have wasted time and effort and destroyed not a pest, but quite possibly a friend.
The insect you see may not be harmful or may not cause enough damage to warrant the use of an insecticide. And if the damage is old and the pest has already come and gone, spraying won’t do any good. Even if using an insecticide is the right course of action, it is very important to use it the right way.
The initial step in deciding how to control a pest is to correctly identify the insect causing the damage, then determine if the insect is currently active or if the damage is old. Finally, decide if the amount of potential damage warrants control and see if there is a way of controlling the pest without the use of pesticides.
Integrated pest management or IPM – also known as least toxic pest management – is the most practical approach for most gardeners. This “middle of the road” method relies on the regular monitoring of pest populations to determine if and when to act. Nontoxic strategies for control are used first, including physical, mechanical, cultural and biological methods. When all else fails, pesticides with the least toxicity and environmental impact are selectively applied.
When using an insecticide, it is very important to identify the insect causing the damage. Otherwise, you may use the wrong material. No single insecticide will control all insect pests.
The pesticides we use are generally short-lived to reduce the chance of environmental problems from residues. Most insecticides break down in a matter of days after application and offer no protection after that. You can’t spray once in the spring and expect your plants to be protected indefinitely. After controlling an insect infestation with an insecticide, don’t be surprised if you need to spray again later in the season. Pest problems can, and often do, recur. It doesn’t mean what you originally used was not effective – you just need to do it again.
It is essential to read the entire label before purchasing a pesticide and again before using it. This is the best way to be certain that it will control the pest situation you are dealing with. If the label does not have specific information regarding how you intend to use the pesticide, put it back and find a product that does.
Say, for instance, you’re told to control a lawn insect with acephate. If the container of acephate you first pick up has information on how to use it on ornamental plants and nothing about lawn applications, put it back and find a product containing acephate that does have information on how to apply it to the lawn.
The label will also tell you how much to use and how to mix and apply the chemical safely. Pay careful attention to 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 cause the plants damage rather than helping them. You should read all of this before you purchase the pesticide.
Also, find out which effective pesticide is 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.
Always buy the smallest available container of a pesticide so you will use it faster. Pesticides lose potency over time, and most of us have too many bottles of pesticides sitting on shelves already. If you are given a recommendation to use something you don’t have on hand, ask if one of the insecticides you already have would do the job. It’s best, whenever possible, to use what you already have.
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 nearby of the same kind. Do not spray everything in your landscape just because a few plants are infested.
If you spray pesticides when they are not necessary, you needlessly introduce toxic substances into the environment. If you decide to use an insecticide, use the right one at the proper rate with the proper applicator. Apply the insecticide according to the label directions and in a manner that will give you the safest most effective control.