Unfortunately the term pesticide is often misunderstood to refer only to insecticides. The term actually refers to a number of substances used to control pests, such as herbicides, rodentacides, and fungicides, just to name a few.
A pest is defined as a living organism that occurs where it is not wanted and cannot only be an insect, it can also refer such things as a weed, animal, fungus, bacteria or virus. Some might consider dandelions in their lawn a weed, however if dandelions are grown in a garden for their greens it is not a weed for it has been purposely planted there.
Different pesticides attack pests in different ways at different times of their life cycle. Some pesticides must only touch the pest to be effective where others must be swallowed. Systemic insecticides are absorbed by the root system into the plant to be protected. When an insect feeds on this plant it takes in the insecticide designed to kill it. Other methods of liquid application are by a ready-to-use hand-held trigger pump spray or a compressed air sprayer which will require precise mixing of chemicals. If you mix your own pesticides, keep a separate set of mixing cups and spoons for that purpose only. Some pesticides, such as slug and snail bait, come in a granular form.
The package label will list the targeted pests. Some pesticides are labeled as “broad spectrum,” killing a range of pests but also killing non-target and maybe beneficial organisms. Others are labeled as “selective,” killing only a few related organisms.
By law, certain kinds of information must appear on a pesticide label. People who use them have the responsibility to read, understand and use pesticides according to the label directions. When directions are not followed correctly, plants can be injured, pests may not be controlled, health may be impaired, and improper use of pesticides can contribute to soil, air and water pollution.
When trying to eliminate a pest, always consider whether or not a pesticide is really necessary, what the least toxic one would be to take care of the problem, and if a non-chemical solution might be just as effective. Bacillus thuringiensis, often abbreviated as Bt, is a naturally occurring bacteria that makes pests sick when they eat it. Some pesticides derived from plants include neem, pyrethrum and rotenone. They can be a contact or stomach poison or will disrupt certain metabolic processes.
To minimize the dangers of pesticides, use them with the utmost caution and respect.
As always, Happy Gardening!
The Purdue University Cooperative Extension Service can be reached at 499-6334 in LaGrange County.