Cooperative Extension Service 
Institute of Food and Agricultural Sciences
Hendry County Extension, P.O. Box 68, LaBelle, Florida 33975-0068  Phone (863) 674-4092

Hendry County Horticulture News

Chemicals - Not The Only Solution for Pest Problems

Literally hundreds of chemicals exist for the control of pests.  Research and development of pesticide compounds by chemical manufacturers involves millions of dollars spent on their registration and testing.  Why then, with all the effort expended on the production of effective herbicides, insecticides and fungicides, do we continue to hear complaints and reports of inadequate or ineffectual control of weeds, insects or diseases?

In some instances, development of resistance to a particular chemical by the targeted pest has been documented and may be responsible for the failure to control a particular insect or disease.  More often than not, however, the fault may lie with the gardener or pesticide applicator.  When evaluating the failure of a compound to control a particular pest problem, several areas need to be considered before questioning the effectiveness of a product.  The following three overlapping problems are often responsible for the failure to obtain desired levels of pest control: use of the wrong pesticide, poor application technique, and the overall approach to pest management.  Several concerns must be examined under each of these broad areas.  If these three areas have been carefully considered and ruled out, you can then begin to suspect the development of pest resistance or the efficacy of the pesticide used.

The approach to pest management involves several facets which should be considered.  Timing of application - it is easier to control a small problem than a big one.  Control of an infestation is easiest and more likely to succeed before it reaches epidemic proportions.  Knowledge of the pest life cycle is important, during some stages of development a pest may be more or less susceptible to chemical control.  For instance, many insects are most vulnerable to chemical control during their early larval or nymph stages.  A one time application of pesticide is usually not enough.  Follow-up applications with the same or complimentary chemicals may be necessary to target organisms missed by the first application.

A common mistake is the total reliance on chemicals alone for the control of pest problems.  Healthy plants are normally more resistant than unhealthy ones.  Timing of plantings is useful in avoiding seasons when pests may be most prevalent.  Crop rotation is important to prevent the buildup of a particular pest.  An integrated pest management approach incorporates every pest control technique available and involves manipulation of the host plant, pest and the environment to create a situation unfavorable to the pest.

Application of the wrong material is often at the root of a failure to control a particular pest problem.  Most chemicals are very specific for the insect, weed or disease that they are intended to control.  An insecticide developed for the control of one type of insect may have little or no effect on another insect.  This is also true for herbicides and fungicides used to control weeds and diseases.  This requires that the pest problem be properly identified so that the correct chemical control may be applied.  In addition to failure to control a problem species, use of the wrong chemical may adversely affect beneficial insects or the environment.

Outdated or improperly stored chemicals may lose their potency and fail to provide the desired control.  Label directions should always be adhered to, many problems arise from failure to follow the label precisely.  Certain pesticides may have a phytotoxic effect at high temperatures causing harm to the plants we are trying to protect.  Pesticides are some times mixed together in an attempt to achieve better control or attack multiple problems at the same time.  While this is often an effective strategy, certain mixtures may react reducing their effectiveness.  The pH of the water used to dilute chemicals may adversely affect their efficacy.  A number of pest control compounds lose effectiveness when diluted with alkaline water.  Contamination of a spray mixture may also occur causing unforeseen problems.  This often occurs when a sprayer is used to apply both insecticides or fungicides and herbicides.  Many gardeners have heard disastrous tales of lost or damaged plants when a sprayer previously used to apply herbicide was used to apply a plant protectant compound.

Incorrect application of a chemical may cause potential problems.  Too low a concentration of a chemical will give less than adequate control, while too much may actually burn plants or have environmental consequences.  In addition to the right concentration, the proper amount of spray mixture must reach the plant to provide the desired control.  Generally, for chemicals to be effective they must contact the pest or weed to be controlled. Good coverage will give good control.  Poor coverage will leave areas untreated and pests unaffected.  Weather may have influences on pesticide application.  Rain can dilute or wash spray off plants before it has had a chance to act on pests.  High temperatures may adversely affect chemical performance, while wind may blow pesticides away from target plants.

It can be seen that many factors may affect pesticide efficiency.  Before using any chemical be sure to always read and understand the label.  Further information on pesticide usage and pest identification is available from your local County Extension Office.  It has been said that one of the best fertilizers is a gardeners footsteps - this is also true of pest control.  Frequent scouting of the landscape or garden will enable gardeners to identify pest problems before they get out of control.  Good luck and good gardening.

Gene McAvoy is the horticulture agent with the Hendry County Extension Service.  Direct your horticulture questions to PO Box 68, LaBelle, FL 33975,  e-mail - or phone 863-674-4092 or 863-983-1598.  You are also welcome to visit the Hendry County Extension Office at 225 Pratt Blvd., LaBelle.   Office hours are from 8:00 - 5:00.

The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity - Affirmative Action Employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap or national origin.

Home                   Index