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Pesticides

Pesticide is an umbrella term that covers insecticides, herbicides and fungicides.

Although chemical pesticides in dry and liquid forms are widely used, there are other forms of lawn, garden and household insect control. There are a variety of solid insect repellent sticks and special insect traps, such as those used for Japanese beetles and gypsy moths, that are safe to have around a home and effective for their specific uses.

There are three basic types of spray pesticides-inorganic materials such as lead and sulphur; botanicals made from plant materials such as nicotine sulphate, pyrethrin and rotenone, and synthetic substitutes including organo-phosphates (such as malathion) and carbamates (such as carbaryl).

It is these latter pesticides that have caused so much controversy, resulting in bannings and attempted bannings.

THE PROBLEM OF MISUSE

The problem is not only the pesticides themselves but their possible misuse. Many people buy pesticides without realizing their deadliness, despite the fact that every pesticide label includes, by law, one of three indicators to warn of its contents.

The most highly toxic chemicals are required to include the word "DANGER" in red capital letters and the skull and crossbones. Less toxic chemicals are indicated by the word "WARNING" and the least toxic bear the word "CAUTION."

Labels are extremely important. The contents of a label must be approved by the Environmental Protection Agency (EPA) and any claims as to what the product will do must be substantiated by data provided by the manufacturer.

The information contained on the label of a "general classification" chemical, the only kind that can be sold to the general public, includes the product name, which may be generic, or a brand name, the ingredients including the amount of filler material in the container; precautionary statements, which always include the warning to keep out of reach of children; and any other warnings for that particular chemical, and directions for using the chemical.

The problem of environmental contamination-which is of major concern-is often the result of misuse. Too many home gardeners tend to "overkill"-if a little is good, a lot will be better.

Not so with chemicals. Most lawn and garden chemicals are intended to remain on the surface of the plant and eventually kill insects. Saturating the area, especially with chemicals that don't break down, creates a dangerous surplus of poison that will be washed away and end up in natural water supplies. The instructions and recommended uses of the product are the result of careful laboratory research and should be followed to the last letter. You should also use the chemical on the problem area only.

Because of the concern about overuse of chemicals, many gardeners prefer biodegradable (or naturally occurring) chemicals, which break down and work their way back into the soil without contamination. Rotenone, pyrethrin and nicotine sulphate are such chemicals.

PESTICIDE DISPOSAL

Another problem is disposal of unwanted pesticides. All too often homeowners pour concentrated pesticide down the drain, unwittingly contributing to environmental problems.

Some states and cities have enacted specific requirements for hazardous chemical disposal using special disposal sites. Even if not required, sites such as these should be used, if possible. If no other means exist, the chemical should be buried in an isolated, level area where seepage toward the water table will not occur. The EPA is very aggressive in the area of hazardous waste disposal, so take extra care in proper and safe handling and disposal.

USES OF CHEMICALS

Lawncare problems come from three sources-insects, disease, and invasion of weeds.

Although each manufacturer blends individual combinations of basic chemicals into his own formula to remedy certain problems, chemicals can be put into general categories.

Pre-emergence herbicides are applied early, before the weeds break the surface of the soil. Post-emergence herbicides are applied after the plant begins to grow. Selective herbicides kill certain plants and leave others; non-selective chemicals will kill all vegetation they touch.

LAWN INSECT CONTROL

Insects come in all shapes, colors and sizes, but they are really of two general types-surface active (above ground) and soil active (below ground).

Webworms, cutworms, army worms and chinch bugs fall into the surface-active category.

Grubs are typical of soil insects. They feed underground on grass roots, cutting them off just below the surface, killing the grass in patches. Attacked turf can be rolled back like carpet, often exposing the grubs themselves.

White grubs feed on grass roots and become active in the spring when soil warms up. They destroy lawns from late spring to early fall.

Sod webworms are one of the most troublesome lawn pests. They damage lawns throughout the entire growing season by eating grass blades. Small moths flying in zigzag patterns across the lawn are a good indication that sod webworms, army worms or cutworms are present.

Chinch bugs are small and difficult to locate. They begin to damage lawns when temperatures are consistently 80 degree F or above. They attack grass stems and suck out plant juices. Grass attacked by chinch bugs is totally destroyed and these areas must be re-seeded.

A complete list of lawn pests, the problems they cause and how to recognize them is available in an accompanying chart. Use it to help identify the pest that is causing your lawn problems and select the proper chemical.

Trees and shrubbery are susceptible to some of the same insects and fungi that plague the lawn or garden, but they also have their own list of pests. As with pesticide use in the vegetable garden, consumers who want to protect fruit trees will be looking for safe, but effective, chemicals.

Care while spraying trees is of the utmost importance because of the greater potential for long-distance wind drift. In special cases of insect infestations, as with gypsy moths, sex pheromone-baited traps are used. The pheromone, a synthesized sex lure, attracts the male moth to the trap where it is killed by a pesticide strip. By reducing the number of males available for mating, this pest-control method helps to prevent future infestations in an environmentally safer manner than heavy spraying. But, it requires that you understand the life cycle of the particular pest.

LAWN DISEASES

A fungus is a plant that feeds upon another plant. Fungi adhere to the plant, steal food from and/or deposit toxic substances in the cells of the plant. Among the most common fungi are leaf spot, snow mold and dollar spot. Snow mold attacks grass any time from late fall to early spring. Grass turns a reddish color or tan to gray. It can destroy small areas or complete lawns. Use fungicides to kill it. Re-seed the lawn when damage is severe.

Leaf spot results in brown or black spots on leaves and can occur through a wet, cool fall, winter and spring season. Thinning of the lawn may not be noticeable, but leaf activity is quite pronounced. Dollar spot starts in mid-spring, also when weather is moist and cool. When this fungus is most active, a cobweb-like growth can be spotted. Damaged spots are a bleached straw color.

Brown patch hits lawns when temperature and humidity are high. It spreads in a circular area from where it starts.

Some lawn diseases can be controlled with granular chemicals or liquids. A liquid control program is best for small areas or for individual plants, whereas granular treatment is efficient on large areas because it can be applied with a spreader.

Study manufacturer's literature to find the chemicals needed to treat specific lawn diseases.

Because lawn diseases tend to attack one variety of grass at a time, the best defense is to use a mixture of lawn grasses. This reduces the chances of the lawn being totally wiped out by one disease or pest.

Another common lawn problem is excess thatch. Thatch is a buildup of stems and roots, combined with partially decayed leaf, stem and root tissue between the ground and lawn surface. Excess thatch can harbor insects and disease, cause water and fertilizer to run off rather than penetrate the soil and contribute to shallow root systems.

Several factors contribute to thatch buildup-excessive applications of nitrogen fertilizers, too frequent waterings and allowing lawn clippings to lay on and penetrate the lawn after mowing.

WEED CONTROL

Weeds are categorized as grassy, broadleaf, annual or perennial. Grassy weeds are best exemplified by crabgrass. Dandelions and plantain are broadleaf weeds.

Annuals die each year but can re-seed themselves. Perennials live for several years.

Weed seed can remain dormant in soil for several years and germinate only when growing conditions are right. If you have recently added topsoil, compost or manure to your lawn, you may have given those weed seeds new encouragement.

All grass seed formulations contain some weed seeds. It is nearly impossible to get rid of them. Less-expensive formulations may contain more weed seeds than top-quality seeds. Look for the percentage of "crop" seeds listed on the package for a fair estimate of the number of weed seeds.

Spring is the best time to control broadleaf and grassy weeds-they are smaller and more vulnerable, and weed killers are formulated to work best in cooler weather.

Pre-emergence herbicides lay a chemical barrier on the ground to prevent weeds from germinating. If soil is disturbed after a pre-emergence killer has been applied, the protective barrier can be lost. Do not rake or de-thatch lawns after applying pre-emergence herbicides.

Follow these three steps when applying herbicides:

  1. Remove trash, leaves and excess dead grass from lawn. If power raking (de-thatching) is planned, do it as part of lawn preparation.
  2. Apply the pre-emergence product as directed. Distribute evenly. Spread at half rate in both directions to assure even distribution. This is better than spreading at full rate in just one direction.
  3. After application, water the lawn. Watering moves the chemical into the soil where it can work on germinating weed seeds. In flower beds or around trees and shrubs, weeds can be stopped with weedshields. These are made of heavy-duty plastic and are used under decorative bark or rock.

APPLYING CHEMICALS

The best defense against weeds is a lawn so thick with grass that weeds don't have a chance. However, that seldom happens, so the home gardener needs help from safe, effective chemicals.

The ways in which chemicals can be applied are:

Emulsifiable concentrates - liquids that are diluted with water to proper strength. Most have an oil base.

Wettable powders - very fine dusts that must be mixed with water. They are applied through sprayers as are emulsifiable concentrates.

Dusts - powdered forms of chemicals, usually with the particles noticeably larger than in wettable powders. They are applied with a shaker, duster, etc. and adhere to the foliage to which they are applied.

Granules - similar to dusts, but with still larger particles. In a granule, the chemical becomes available to the living plant by breaking down the granule or by releasing the active ingredient. Granules are usually spread with a lawn spreader. Weather and moisture provide the slower chemical-release action.

Systemic chemicals - available in both liquid and dry form can be used in combination with fertilizers to provide pest control as well as plant nutrition. Systemic chemicals are absorbed by plants or lawn and cannot be washed off by sprinkling or rain.

At least one manufacturer packages insecticide in a one-piece plastic sprayer. The concentrated insecticide is premixed and ready to use, eliminating the chance of getting chemicals on the user's skin. After application, the sprayer is thrown away.

Liquids of the hormone-type weed killers are normally esters or amine salts. Ester formulations may be high volatile or low volatile, which means they do or do not vaporize easily.

Low-volatile esters release a minimum amount of fumes at temperatures below 85 degree F; high-volatile esters give off fumes at lower temperatures. However, air temperature can be somewhat misleading since temperature at the lawn surface can be 20 degree to 40 degree higher.

No ester formulation is safe to use around ornamentals because of vapor hazard. Salt formulations are less hazardous because they do not give off damaging fumes. However, wind movement of spray particles is equal on both esters and salts.

Be sure to check manufacturer's literature for more data on each type of chemical.

Under no circumstances should a homeowner control weeds with highly toxic products bearing the skull and crossbones and the word "DANGER" on the label.

HOUSEHOLD PESTICIDES

In addition to the insects that attack lawns and gardens are those that infiltrate homes. The measures used to control them must be equally as well considered as those used outside, if not more so. Chemicals released inside the house could have harmful effects on families and pets if not applied properly.

Frequently used household pesticides are sprays or fogs, and in some cases it is advisable to leave the house for a few hours while the chemical works. Some of these penetrate into the cracks and crevices of the house where insects nest. Others are sprayed around doorways, windows, thresholds, baseboards, ceilings, moldings, drainpipes, etc., to form a barrier to keep the pests out. If you are using foggers, pay attention to the warning on the label about use around open flame. The pilot lights on gas furnaces and appliances will ignite the insecticide if it reaches a high enough concentration in the home.

Other forms of household pesticides are traps or solid bait, used primarily for mice, rats and roaches. Although they are supposed to be harmless to pets, it is still a good idea to read the package carefully and follow the instructions explicitly.

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Check your state and local codes before starting any project. Follow all safety precautions. Information in this document has been furnished by the North American Retail Hardware Association (NRHA) and associated contributors. Every effort has been made to ensure accuracy and safety. Neither NRHA, any contributor nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this document.

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