Planter’s Row: Insecticidal Soaps

By Jessica Pittman,
Clemson Extension

Insecticidal soaps are a safe, effective, and low toxicity alternative to more toxic pesticides; they have many advantages when compared to other insecticides.  They are inexpensive to use, are among the safest pesticides, leave no harsh residue, are natural products that are nearly non-toxic to animals and birds, and can be used on vegetables up until harvest.  Insecticidal soaps do not typically have a harmful effect on beneficial insects; small, soft-bodied insects like aphids or spider mites are most susceptible to the soaps.  Soaps also can be used as a leaf wash to remove honeydew, sooty mold, and other debris.  Making your own insecticidal soap mixture is an option; however, be aware that there is substantially increased risk of plant injury with a home-made mixture.  Some plants are sensitive to soap sprays and can be seriously injured, so read the label and make sure your plant is not one of them.  Testing for plant sensitivity is always one of the first things you should do.  Simply spray a small area and wait twenty-four hours to see if any damage occurs.  Before applying insecticidal soap, read the label completely, and carefully all directions.  It is important to make sure that both sides of the leaves are sprayed.  Your water quality should also be considered before spraying because hard water reduces the effectives of insecticidal soaps.   Disadvantages of insecticidal soaps include:  the soap solution must wet the insect during application, there is no residual effectiveness because soap dries or is washed away, and there is a potential for phytotoxicity when the soap residue is affected by high temperature.  Insecticidal soaps can be a great method for controlling insects in your garden if you carefully follow all instructions.  Soaps can provide a safe and effective way to grow plants naturally, control many soft-bodied insects, and reduce the amount of harsh chemicals used in your garden.  
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