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 Pesticide Savvy (Synthetic vs. Natural vs. Biological)
Excerpt from Dead Snails Leave No Trails, by Loren Nancarrow & Janet Hogan Taylor
For as long as humankind has existed, insects have generally been regarded as pests. But to be a true "pest," an organism must do one of the following: damage crops, destroy products, transmit diseases, stand in the way of human interests or needs, or simply become annoying. To achieve the goal of eradicating pests, chemical pesticides have been developed to battle the invaders. (A pesticide is defined as any chemical that is intended to kill pests.) Pesticides can be man-made or derived from plants, and care must be taken with all of them. Many scientists believe that no insect pest species has ever been completely eradicated by the use of chemical pesticides, and, in some cases, pest species have become even more of a problem as a result of pesticide use.
Synthetic pesticides are man-made chemicals produced for the sole purpose of killing insect pests and other pests, such as weeds. These chemicals are produced in many forms for different applications. They can be sprayed or dusted on plants and animals, or made into pellets and gaseous forms for application to the soil. The two major groups of synthetic pesticides are chlorinated hydrocarbons (such as DDT) and organo-phosphates (such as Malathion).
Chlorinated hydrocarbon compounds date back to 1874 and have been under great scrutiny in recent years. These compounds were once thought to be miracle cures for many plant pest problems throughout the world. They were used widely to treat everything from lice in Italy (DDT was credited in halting a typhus epidemic carried by lice) to the common cockroach in U.S. homes. Problems arose from some of the residual effects of these compounds; for example, DDT has been linked to such problems as thinning of shells in some birds' eggs. Some of the target insects of these chemicals, such as cockroaches and flies, have even become resistant or immune to them.
Organo-phosphates are basically contact insecticides that were discovered in the course of poison gas research around the time of World War II. Some of these compounds are very toxic to humans and animals, as well as to insects. A real danger of many of these compounds is that they can be absorbed directly through the skin, besides the usual methods of contamination - breathing them in or eating them. Malathion is one of the most used organo-phoshates because it has a very short residual effect in the environment and is also less toxic to non-pest animals. Many species of insects that are resistant to chlorinated hydrocarbon pesticides will be killed by Malathion. In any case great care must be taken when using any pesticide. Always read the label carefully, and follow the directions for applying the pesticide correctly. It's wise to wear full protective clothing during application because nearly all pesticides are absorbed through the skin. The label will instruct you about what minimal protective clothing is required. Professionals often wear rubberized garments and respirators.
Natural controls are those things occurring physically in nature that help keep insect numbers in check. Such controls are found in every backyard and in all parts of the world. Some examples of natural controls are: weather conditions, rainfall levels, the amount of shade in an area, and geographic location. For example, if you live in Alaska, the temperature will keep many tropical insects from taking up residency in your backyard. A wide river might keep a hopping insect from getting to your garden, but it might also be a breeding ground for mosquitoes. People have little effect on natural controls, but in today's age of jets and cars, many an unwanted insect has found its way to a new home with human help.
Biological controls involve those living things that keep insect populations in check. Insect predators, including toads, frogs, moles, birds, and predatory insects, are a good example. Many naturally-occurring diseases, caused by viruses, fungi, and bacteria, also keep insect populations down. It is in this area of natural checks and balances where man has often upset the balance of beneficial and destructive insects.
A pest-management method called biocontrol allows the introduction or augmentation of predatory insects, parasites, or diseases to a pest area in order to reduce the population of a specific pest. This method works best on large one-crop parcels where there is generally one major pest. A good example of this would be the introduction of vedalia, an Australian ladybug beetle, to control cottony-cushion scale, a pest of citrus trees.
Some biological controls that are not so species-specific are gaining popularity among gardeners and farmers alike. One of these is a bacterium called Bacillus thuringiensis. It attacks many species of caterpillars, including tomato hornworms and gypsy moths. Biological controls generally do not completely eliminate a pest, but a natural balance will occur once the control agent becomes established. Biological controls will continue to control the target pest year after year, and may only occasionally need to be augmented. But keep in mind that biological controls do not work overnight. Predators and parasites take time to become established, and insect diseases and pathogens take time to spread and infect new victims. Its difficult to sit back and watch your garden being fed upon when you've just treated it with a biological control, but if you give the controls time to take hold, the rewards will be well worth it.
Back in the 1970s, eradicating pests with chemicals wasn't working well and serious questions were being raised concerning the environment. The term integrated pest management (IPM) was coined to describe a new practice of controlling pests in crops and gardens. IPM is basically a pest management strategy that looks at all aspects of pest management and comes up with a comprehensive analysis of the problem to produce the maximum crop yield and the minimum adverse effects to humans and the environment.
The first step in IPM is to choose healthy plants and give them the best growing conditions possible. Next, use all the available information about crop rotation, eliminating pest host plants, timed plantings, and timed harvests to reduce the severity of crop damage due to pests. After that, if an insect or disease does become a problem, the next step would be physically controlling the pest. Physical control involves hand-picking, traps, and barrier methods of control. If those controls fail, biological controls are added to the program. Finally, if all else fails, chemical controls are used as the last resort. Integrated pest management is based on the knowledge that some damage will occur - the secret of IPM is to know when to act on a problem pest. Many truly "organic" gardeners agree with this practice until chemical measures are used. IPM techniques are mainly common sense approaches, so it's likely that most people have used some form of integrated pest management in their own gardens at one time or another.
In reading the following chapters, you'll find many ideas for your own integrated pest management program. Tailor the program to your own specific problems and needs by observing your garden carefully to understand which insects are pests and which ones are beneficial. If you have questions concerning the identification of insects, start with your local nursery. Most experienced nursery personnel are will versed in entomology (the study of insects) and can identify most pests in your area.
Pesticide Safety
When all else has failed and you feel you must use a pesticide, the following suggestions will help you use the pesticide safely. Remember that even relatively non-toxic pesticides can cause problems if used improperly.
• When choosing a pesticide, choose a product that is registered (government-approved) for your problem pest. Don't try to kill everything with a broad-spectrum pesticide. Be certain the product you choose is intended for the pest and pest life stage you are trying to control.
• Always read the entire label and follow it exactly. Never add more of the chemical than the label calls for. The label is a legal document that tells you everything you need to know when using that product. It spells out exactly the characteristics of the pesticide and its proper use.
• If you have children or pets, store the pesticides in a locked cabinet. Keep the telephone number of the nearest poison control center in the cabinet and by your phone. Never remove the label from the container or pour a chemical into another container that does not have the same chemical label attached to it. You will need this label to tell the doctor exactly what your child got into. Sometimes antidote information is given on the label.
• Wear gloves when handling and mixing the pesticide, and remember that many pesticides can be absorbed through the skin. Always mix a pesticide in a well-ventilated area. The precautionary statement on the pesticide label usually gives important information on the hazards of the pesticide as well as the instructions for handling it. This statement also explains any toxicity to other organisms, such as bees or fish.
• Buy only what you need for the current problem. Some products break down over time and your will not be treating your problem properly if you use a pesticide that has been stored for a long time.
• Spot treatment is better for your environment than a full-scale assault. Use the pesticide on the smallest area possible, keeping in mind that many pesticides kill beneficial insects as well as harmful ones.
• Apply the pesticide when the pest is most vulnerable. If you have to use a pesticide, it's best to do so when it will be most effective, For example, spraying caterpillars, which can't move quickly, will be more effective than trying to spray the flying adults.
• Never apply a spray-type pesticide when it is windy. Most pesticide companies recommend not spraying when the wind is over five mph. Early morning spraying usually works best.
• Never smoke, eat, or drink when applying pesticides, or allow anyone else to do so in the application area.
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