I get lots of questions about pesticides, which leads me to believe that many gardeners and homeowners do not know what an insecticide is, what a fungicide is, what a herbicide is, and what are miticides. And when does one use one or the other, and are there other alternatives to controlling a pest.

          All insecticides, (as well as fungicides, miticides, and herbicides) are pesticides, but not all pesticides are insecticides. Thus, Sevin, Eight, Isotox, and Malathion, are common insecticides, but will not control a plant disease, or kill a weed. A fungicide is also a pesticide and used to control “spots and rots” or plant diseases. Herbicides are pesticides and used for killing or preventing weeds, but does not kill insects or control diseases.  Before buying a pesticide it is important to identify what the pest is. And if an insect, what insect is causing the damage, or if a disease, what the disease is and what caused it. If a weed, what kind of weed. Do not apply chemicals before proper diagnosis. Many symptoms may look the same to an untrained eye. Also remember that a fertilizer is not a pesticide and will not cure a plant disease or plant injury from an insect, but may make the problem worse.

          A PESTICIDE according to the “Federal Insecticide, Fungicide, and Rodenticide Act” is defined as “any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any insects, rodents, nematodes, fungi, or weeds, or any other forms of life declared to be pests.”

          This federal act also requires certain information be on the label.  Be sure and read the label to make sure the chemical you are using is ok for use on your plant.  If the name of your plant is not on the label, don’t use it.  Also the label should tell you if it will control the problem you have, what the proper dosage is, and how often you can apply it. READ THE LABEL BEFORE USE!!!

A pest is defined as anything that:

1.     Competes for food or water,

2.     Injures humans, animals, plants, or possessions,

3.     Spreads disease, or

4.     Annoys humans or domestic animals.

Pesticides include but are not limited to:

1.     Insecticides for the control of insects,

2.     Fungicides for the control of plant diseases,

3.     Herbicides for the control of weeds,

4.     Rodenticides for control of rodents, and

5.     Miticides for the control of mites.

          Some pesticides are combinations.  For example, most fruit tree sprays contain 2 insecticides such as Malathion and Carbaryl (Sevin), and a fungicide such as Captan. A fertilizer, such as Miracle-Gro is not a pesticide that will control insects or diseases.  If a plant looks sick, don’t automatically apply a fertilizer.  This may stress a plant to grow rather than correct what is wrong, and may make the problem worse. Get a proper diagnosis.

          When taking a sample to the garden center or the Extension Office for a diagnosis, please take a big enough sample. One or two leaves or a few blades of grass doesn’t work.  For a tree or shrub cut off about 10 to 12 inches minimum.  For grass a piece of sod about 8 inches square is necessary.  Take the sod from the edge of the problem and include some brown or diseased sod and some green and healthy sod.

          In applying the principles of Integrated Pest Management (IPM), one should look at all other options before applying a chemical. These include

1.                 Planting a pest resistant variety,

2.                 Using biological controls,

3.                 Cultural practices such as mulch and crop rotation,

4.                 Mechanical controls such as traps, hand removal, and sticky traps,

5.                 Sanitation, such as cleaning up your garden in the fall with proper disposal of all waste.

Examples of good IPM include:

1.     Clean up your iris bed every fall as iris borers overwinter in debris.

2.     Overplant with a blend of disease resistant varieties of grass to control summer patch or brown patch in lawns.

3.     Rotate where tomatoes are planted to control tomato blight as the disease spores overwinter in the soil. Also do not water overhead if possible so the blight spores don’t splash up on the lower leaves.  When my tomatoes are about 3 to 4 feet high I take off the lower 8 to 10 inches of branches so I have good airflow.  This helps to prevent blight and powdery mildew.

4.     Use mulch (wood chips or shredded hardwood) under roses to help control black spot which also lives in the soil and can splash up on the lower leaves and infect the bush. Do not use more than 3 inches as plant roots also need air.

5.     Cover young squash, melon, watermelon, and cucumber plants with row cover to prevent insect, especially the squash vine borer, from laying eggs on or near the base of the plant.  Uncover when plant starts to bloom so beneficial insects can pollinate the flower. Row cover can be purchased at most garden centers.  It looks almost like cheesecloth. If you do get squash bugs, pick them off and look for eggs on the underside of the leaves. You can also put a board on the ground and every morning pick up the board and remove the insects underneath and destroy.

Again, before buying a pesticide (spray, dust, or granule) it is important to identify what the pest is, and if an insect, what insect is causing the damage, or if a disease, what the disease is and what caused it. Do not apply chemicals or fertilizer before proper diagnosis.

Thanks to Larry D. Schulze, Pesticide Education Specialist, University of Nebraska Cooperative Extension, for permission to use material that he presents to our the Master Gardeners most every year. For more information you can go to his website at

Copyright 2013