Many gardeners use some type of chemical to control weeds, insects and diseases. The companies marketing these chemicals have spent millions to hundreds of millions of dollars funding extensive tests to determine the optimum application methods for their products.
Unfortunately, many gardeners operate under the premise of “instructions are for others.” There are complaints that the users were unable to control the insect, disease or weed despite the use of the proper chemical.
In almost all incidences, the fault lies not with the pesticide, but with the actions of the pesticide applicator.
There are three overlapping problems which can be considered:
1. Application of the wrong material
2. Incorrect application
3. Poor management
If these three areas have been considered and ruled out, then (and only then) can the manufacturer’s claims and representations about the product be questioned.
Application of the wrong material is commonly credited to an incorrect diagnosis. Many of today’s chemicals are very specific for the pest or problem they control.
It is for this very reason they are good materials to use. The chance of major harmful environmental effects is minimized by specificity.
However, this specificity requires the applicator be certain the problem is properly identified. At the very least, the applicator must know the type of problem being encountered before selecting the correct broad-spectrum pesticide to use.
Label directions are there for a purpose. Many problems occur as a result of not following directions precisely. The old adage “if one works well, two will work better,” does not apply to pesticides. Absolutely do not ‘guesstimate’ measurements.
Pesticide labels are meant to be followed, not ignored.
Chemicals vary in the length of time they may remain active. Environmental factors such as light and temperature may have an effect on viability. Storing chemicals improperly, for example in warm, humid conditions or with other chemicals, may change their effectiveness, usually in a detrimental way.
Manufacturers have good reasons for putting expiration dates on labels. They are legally informing the user their product loses effectiveness after a certain period of time. Outdated materials should be disposed of in an approved, legal manner.
To save time, it is common to mix various chemicals together in a single sprayer. Saving time is an attractive notion, but in some cases, problems may be encountered.
Chemical effectiveness may be diminished, or, worse still, phytotoxicity may occur. It is well worth the effort to find out what is safe before mixing expensive materials or wasting the time applying only to get poor control or injured plants.
Poor equipment cleaning may create tank mixes which were never intended. Even minute quantities of some materials can cause others to clog, become phytotoxic, or neutralize the effectiveness of the spray.
An easy way to prevent problems is to use separate spray tanks for herbicides and insecticides. Clearly marking the tanks for their intended use warns everyone of potential problems.
Label information represents a great amount of testing as to the amount of chemical which should be applied. To prevent possible problems, not only must the concentration of chemical in the spray be correct, but the amount reaching each plant must be correct. Irresponsible application can result in environmental damage and potential liability.
The chemical generally must reach the pests or weed if it is to be effective. Sufficient coverage allows the chemical to reach all affected parts so the problem can be controlled. Poor coverage leaves areas untreated and problems uncontrolled.
Weather can reduce pesticide effectiveness in several ways: rain can wash off the chemical before it has penetrated or high temperatures and/or winds can rapidly dry the chemical before it has been absorbed. These problems can be minimized by properly timing the treatment or at least by recognizing them when they happen.
It is almost always easier to control a small problem than a large one. The control of an infestation is always easiest and most likely to succeed when it is undertaken before the pest reaches epidemic proportions.
Often knowing the pest’s life cycle allows control at a susceptible life stage, even if all other stages are resistant to chemical control. Information about pest biology is usually available at the County Extension Office.
Frequently one application is not enough in pest control. Follow-up treatments of the same or complementary sprays will control the organisms missed the first time.
Some pests may be in a stage resistant to chemical control at the first application but may be susceptible later. If it rains or irrigation comes on too soon after pesticide application, a follow-up is essential since the materials may have been removed.
Without record keeping, each pesticide application is like starting new. Good record keeping should keep track of a product’s efficiency, any harmful side-effects and the development of any resistant strains of the pest.
Applicators need to know the exact response of the target species under the conditions to maximize the spraying’s effectiveness. Each application has its unique characteristics.
Even the most effective chemicals need help. Healthy plants are more resistant to problems than unhealthy ones.
Keep track of pest levels and know the pest biology. This allows treatment when the product will perform at its best.
Integrated pest management (IPM) ensures every pest control option available has been considered. It requires assessing and engaging the pest, the pest host, and the environment to prevent epidemic pest populations from flourishing.
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