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RETURN TO AGGIE HORTICULTURE
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edited by Dr. Douglas F. Welsh, and produced by Extension Horticulture, Texas Cooperative Extension, The Texas A&M University System, College Station, Texas.
By Dr. William M. Johnson,
 e are becoming more and more aware of the environmental and personal safety aspects of using - or misusing - pesticides. It is encouraging that individuals are showing an increasing awareness of proper use of pesticides. However, as a County Extension Agent, I am especially aware that some misuses of pesticides occur basically because of commonly held myths about their use. Following are examples of such myths and the actual facts:
Fact: While the management of some insects and diseases on certain plants may require timely and regular applications of pesticide, the "wash day" schedule of once-a-week applications is no longer recommended for most applications. Spray only if a problem exists that warrants a pesticide application.
Fact: Application-to-harvest (or days-to-harvest) periods on a pesticide label should be taken seriously. For example, if the label says not to harvest until five days after application, it is not safe to harvest two days after spraying even if your crop is not to be eaten for another three days. If this occurred, the breakdown of pesticides on the crop would be slowed because the harvest took place prematurely. Also, the application-to-harvest period may vary from 0 to 14 or more days for the same pesticide depending on the specific crop involved. Fruits and vegetables picked before the designated harvest time after spraying could contain a higher pesticide residue level than the normal recommended safety levels set by the EPA.
Fact: This myth is not only false but dangerous. Doubling or tripling the dose of any chemical can have disastrous results. Weed killers used in this manner can injure plants you never intended to harm, not to mention leaving long-lived residues in soil. Overuse of insecticides may kill beneficial insects, harm plants, and render vegetables unfit for consumption. Doubling the recommended rate of a pesticide increases the chances of poisoning people by inhalation, absorption through the skin, or ingestion. If you need further convincing, consider also that you’re wasting money!
Fact: Nonselective herbicides are just that - nonselective. They can also injure or kill your ornamental woody plants if sprayed along the border of a planting. Do not apply nonselective, pre-emergent herbicides meant for long-term weed control within the root zone of desired plants. Use "weed-and-feed" type formulations for lawns with caution. They are safe if used according to directions. Remember, the herbicide portion cannot distinguish between good trees or shrubs and unwanted dandelions or crabgrass. Feeder roots of trees can extend to well beyond the drip line, so over-applying "weed-and-feed" type formulations within these areas could endanger a favorite specimens. This also applies for shallow-rooted shrubs such as azaleas which could absorb the herbicide portion.
Fact: It is not only unsafe, it is illegal to dispose of any pesticide, however diluted, down the drain. You could create an environmental hazard in your home by carrying unused pesticides indoors. In septic systems, certain pesticide contaminants can kill the beneficial bacteria in a sewage field, rendering it inoperable. Read the pesticide label to determine how to properly dispose of a pesticide.
Fact: This is a very commonly held belief. Homeowners are sometime puzzled why I cannot provide a blanket answer on how much of a particular insecticide or fungicide to use per gallon of water. It depends primarily on the technical strength of the active ingredient(s). Different manufacturers make different strengths of the same pesticide; moreover, the same manufacturer may make the same pesticide in two or more different strengths. For example, malathion is available as a liquid concentrate in various "strengths" including 25% malathion and 50% malathion. Add to that the fact that different groups of plants will require different rates of pesticides to control different pests, and you understand why reading the label is of utmost importance. Remember, when it comes to using pesticides, don’t "myth with the facts!"
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RETURN TO HORTICULTURE UPDATE
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