Integrated Pest Management For Home Lawns
By Anne R. Leslie, U.S. Environmental Protection Agency, Office of Pesticide Programs, Washington, DC
The use of pesticides for home lawn care has become an important environmental issue. To achieve picture perfect green lawns, some homeowners are applying chemicals, and a growing number of people are claiming adverse health effects associated with chemical applications. These critics are raising serious questions:
(1) Are these lawn chemicals necessary?
(2) Do lawn chemicals cause detrimental effects to people and/or the environment?
(3) How much value do these chemicals add to the lawn?
(4) Can we grow healthy lawns without chemicals?
Until such questions are answered, these critics suggest restricting the use of lawn chemicals. Currently some labels on chemical products are being re-examined by the United States Environmental Protection Agency (EPA).
The Benefits of a Healthy Lawn
Turfgrass is the term used to describe grassy plants which-rather than being raised as forage for livestock-are used as a relatively inexpensive, low maintenance surface covering for property. There are many functional benefits derived from turfgrass. Turfgrass acts as a very efficient filter for pollutants in air and water. Grass blades take in carbon dioxide and the worst atmospheric pollutants and give back pure oxygen. The surface area of grass leaves, where this exchange takes place, is greater than that of many ornamental plants occupying the same amount of ground, and its activity may be more extensive because of the length of its growing season. Turfgrass modifies temperature; scientists have estimated that front lawns of just 8 average houses have the cooling effect of about 70 tons of air conditioning. Turfgrass is the safest playing surface for athletic activities. Turfgrass stands up well to foot traffic and protects the underlying soil from wind and water erosion. And finally, turfgrass relates to community beautification and the enhancement of real estate values.
The EPA Integrated Pest Management Program
Once the scientific evidence is examined, few people deny the functional benefits derived from turfgrasses. The basic question centers on whether or not these benefits can be obtained without heavy chemical applications.
EPA has developed a program of minimal chemical input for a healthy lawn. Quality lawns can be achieved with common sense, maintenance rules; proper site preparation; and, the selection of the best grass variety for that site. Extensive scientific testing and breeding programs provides the public a large selection of grass varieties adapted to a wide range of conditions and sites. In addition, scientists have developed a number of promising biological control agents from some of the worst pest problems related to turfgrasses.
The Integrated Pest Management (IPM) program is an important part of that development.1 The goal of IPM is to manage pests and the environment, balancing costs, benefits, public health, and environmental quality. IPM systems use all available technical information on the pest and its interaction with the environment. The programs apply a holistic approach to pest management, taking advantage of all appropriate pest management options, including - but not limited to-pesticides. In summary, IPM is:
A system utilizing multiple methods
A decision-making process
A risk reduction system
Deciding on the Use of a Pest Management Program
The decisions on what is a pesticide problem and how to solve that problem is affected greatly by a community. It is important to know who is included in the IPM problem-solving program. IPM suggests three categories: occupant, pest manager, and decision-maker. Understanding and communication between them is important.
The homeowner is the decision-maker for his or her home lawn. The pest managers who carries out pesticidal action or any alternative that is appropriate, may be the homeowner or a professional lawn care service. Occupants include the homeowner and all members of the family that use the lawn or are affected by decisions about its management. Occupants can also include any neighbors that are affected children that come to play on the lawn, visitors, and any whose property can be affected by a pesticide application. Nonhuman occupants include pets, wild animals, birds and plants.
The basic guideline in planning a pest management program is thoughtfulness toward others.
Basic Decisions Before Implementing the IPM Program
You should decide on your management objectives for your lawn as a basis for planning modifications in its re-design or management. Knowing what you are trying to achieve will help decide the best possible control methods for any pest problem that arises. This can be as simple as determining the primary purpose for the lawn. As a play area, its design and management will be quite different from the lawn that serves as a resource for wildlife or a lawn designed to satisfy the owner's aesthetic sense. Another type of landscape design emphasizes minimal maintenance through limited grass areas and the selection of a less aggressive growing grass with a short growing season and minimal water and nutrient requirements.
Implementation of IPM for the Home Lawn
There are four interrelated components to an IPM program. Omission of portions of the system, in EPA's experience, has led to greater, unnecessary dependence on repeated pesticidal treatments. These components are: (1) monitoring; (2) determining injury levels; (3) applying strategies and tactics; and (4) evaluating and redesigning the program.
Monitor the Site Environment and Pest Populations: This step involves an active "down on the knees" examination of the site on a regular basis, looking particularly at any trouble spots identified in previous years for signs of pest problems. Your extension office will have informative publications that will help you identify the common insect and plant pests. Monitoring is also done after a management action is performed to establish whether the action was effective.
Weeds are indicators of poor soil conditions or improper management practices. It is helpful to identify the weed species in your lawn, because this will also help identify the underlying problem.
An area of bare soil will be inhabited by a succession of plants in a natural setting, and we re-create the natural event by our activities. Bare soil in lawn areas compacted by traffic favors weed invasion, as weeds are often the only plants that will grow in this environment. Soil that is poor in nutrients will favor growth of clover, which can give nutrients back to the soil. Certain weeds prefer acid soils, and their population can be reduced by adjusting the pH or acid content of the soil. Grass grows better at a neutral to slightly acid pH. A soil test should be performed once a year for acidity, and additions or "amendments" made to the soil based on the results.
There are many causes of dead spots in a lawn. In addition to damage from insects and fungus diseases, excess nitrogen, dog urine, and vandalism should be considered in the monitoring process. If a disease is suspected, collect a sample of the damaged grass and take or mail it to your local county cooperative extension office, where plant pathologists can diagnose the pathogen. There are sampling strategies for insect pests, such as sticky traps, traps baited with attractants, and applying irritants such as soapy water to a sample to bring insects to the surface.
Set Action Thresholds: IPM for agricultural crops uses economic injury levels to establish action thresholds. This means that a threshold is set at a population below the level that has been found to cause enough injury to the crop to reduce the yield and quality, and thereby profit. This type of action level is more difficult to define for the home lawn. It is based on the consequences of allowing pest damage to the lawn. For instance, Japanese beetle larvae can injure the roots of grass sufficient to cause death, but a healthy lawn can tolerate a certain number of grub larvae per square foot without showing signs of damage. The number will depend on the traffic on the lawn, the health and density of the lawn, and other factors, so the threshold might be quite different for the above scenarios.
Apply Indirect Suppression Strategies and Tactics: The actions in this step can be performed at a pest population below the action threshold, as a part of good general management practices. If the population has reached the action threshold, these actions can be taken in conjunction with direct suppression tactics to effect a long-term reduction in pest numbers. A site that is made incompatible with the pest's survival needs will interfere with population buildup. For example, removal of diseased plant material is an important action that should be regularly performed to avoid further pest invasion.
Weeds are the most common pest problem on home lawns, followed by insects. Most properly cared for home lawns will not be prone to disease problems, except in limited areas of the country.
1. Weed Management practices: Regular aeration, which involves using a machine that lifts out plugs of soil, grass and thatch (the interlayer of dead plant material between the growing grass and the soil), and vigorous raking or verticutting to reduce thatch, will allow air and water to penetrate into the root zone of the grass. A cross-section of a lawn so treated shows a dramatic increase in the grass roots in the areas where the plug was removed. The material in the plugs is broken up and distributed on the lawn and is a good source of nutrients.
Even as simple a practice as raising the mowing height on the lawn mower can effectively prevent invasion of broad-leafed weeds such as dandelions, because they need light to germinate and grow. Although different grasses have different optimal heights, the general tendency is to cut the grass too short and to mow too infrequently. If more than one third of the grass blade is removed at one time, the plant will be stressed.
If the clippings are bagged and removed, not only is a valuable source of nutrient lost, but also a source of microorganisms that help protect the grass plant from disease damage. Mulching lawn mowers will efficiently return the clippings to the lawn.
2. Insect management examples: Three major species account for most lawn insect problems: caterpillars (larvae of sod webworms, armyworms, and cutworms), white grubs (larvae of Japanese beetles, June beetles, black turfgrass ataenius and masked chafers), and chinch bugs ("true bugs"). Management practices for lawns that diminish one pest population may favor another. For instance, chinch bugs and sod webworms prefer lawns with a heavy buildup of thatch and insufficient irrigation often due to soil compaction. Damage may first be noticed in areas close to paving. These conditions also are favored by white grubs, but if the soil is kept constantly moist, it will attract the Japanese beetles to lay eggs.
Reseeding the lawn to a certified endophytic grass (one of the rye or fescue varieties) is one of the most effective controls for sod webworms and chinch bugs, both of which feed on the grass leaves. White grubs feed on the grass roots at varying levels beneath the surface. Biological control by nematodes that infect the grubs is a promising development, but an effective commercial product is not yet on the market. There are many naturally occurring predators of all these pests, which will maintain effective control in a well managed lawn. Some pesticide applications may diminish their effectiveness.
The appropriate use of pesticides means choosing an application with the least possible hazard to the people, property and the environment. There are products available that have low impact on the environment.
3. Fungus disease management: As indicated above, most home lawns are not prone to show symptoms of fungus disease. Disease symptoms are usually the result of a lawn ecosystem being thrown out of balance by various stresses, such as high temperature combined with excessive irrigation and fertilization. The time of day that water is applied (preferably early morning in hot weather) and the frequency and amount of water applied (watering deeply when the grass reaches the "wilt point") are the most important management practices to minimize disease expression. Correcting drainage problems and installing irrigation systems can also be helpful.
When a disease problem is identified, treatment with a fungicide is not the only action that can be taken. With some diseases the lawn will recover without help; with others, e.g. pythium blight, the grass is dead and total renovation or replacement is necessary. Inappropriate application of a fungicide can kill the grass and even correct application may eliminate a population of beneficial fungi and other beneficial organisms.
The most promising biological control is the use of biologically active composted material. Both homemade compost and commercial preparations seem effective, even as preventive treatments. Breeding programs have developed new cultivars of Kentucky bluegrass and other common lawn grasses that are resistant to disease, and these can be introduced to eliminate a recurring problem.
Apply Direct Suppression Strategies and Tactics: Pesticides are only one of many solutions to pest problems. They are a valuable tool, but just as antibiotics are not prescribed by the doctor for every health problem, pesticides are not needed for every lawn care problem. In this section specific recommendations will not be given: ample information is available on the pesticides labeled for use on turf: reference books are maintained at garden centers, and plant clinics run by the Extension Service can offer advice on the right pesticide to use.
The word "appropriate" in the title is the key: If the pest is detected at a stage in its life cycle when it is not vulnerable to the pesticide, there is no point in wasting the chemical. Pre-emergent weed control applied after the weeds have sprouted and have leaves is of no value, and a broadcast application of a post-emergent herbicide in a lawn containing only 10-15% weeds may cause damage to the grass. If the management plan calls for minimizing pesticide exposure, pesticides will only be used as a last resort.
"Appropriate" also means choosing the pesticide with the least possible hazard to the people, property and the environment. There are products available that have low impact on the environment.
IPM does not call for eliminating pesticide use, but in a home lawn there are many alternatives to the use of pesticide. In the face of a severe problem the situation may call for more pesticide to be applied than would be used in a routine calendar type application plan. However, appropriate use of pesticide in this example means making a one-time treatment, to be followed by other measures to prevent recurrence of the problem. For more information on use of pesticides in an IPM framework, see reference 4 below.
Evaluate and redesign program: This is a secondary round of monitoring, and is very important to obtain optimum control. Only by careful attention to the results or habitat modification and pesticide treatment can the homeowner choose appropriate treatment in the future.
IPM is sometimes redefined and renamed Integrated Turf Management or Plant Health Care, but the principles are the same: Management is directed at the crop (grass) rather than an individual pest problem.
The U.S. Environmental Protection Agency (USEPA) defines IPM as follows: "Integrated Pest Management is the coordinated use of pest and environmental information with available pest control methods to prevent unacceptable levels of pest damage by the most economical means, and with the least possible hazard to people, property and the environment." Another definition is given by the Bio-Integral Resource Center: "IPM is an approach to pest control that utilizes regular monitoring to determine if and when treatments are needed and employs physical, mechanical, cultural, biological and education tactics to keep pest numbers low enough to prevent intolerable damage or annoyance. Least-toxic chemical controls are used as a last resort. (Common-Sense Pest Control, 1991.)
Anne R. Leslie is a chemist in the Office of Pesticide Programs of the U.S. Environmental Protection Agency (USEPA). She has been a member of the Environmental Division for eight years, is now serving as Social Chairman and member-at-large on the Executive Committee, and has served as Chairman of the Agrochemical Subcommittee of the Council Committee on Environmental Improvement (CEI). She is currently a member of the Meetings and Expositions Committee of ACS. Anne is a chemist in the Integrated Pest Management (IPM) Section of the Field Operations Division in EPA's Office of Pesticide Programs. In conjunction with her work at EPA, she has developed three Environmental Division symposia on IPM at ACS meetings and was Co-Chair of a symposium on residue sampling in groundwater, co-sponsored by Agrochemicals and Environmental Chemistry. Anne is a past chairman of the Chemical Society of Washington and a Councilor for the Section.
Sources of information on IPM techniques, biological control and appropriate use of pesticides.
1. The most available source of accurate information to the homeowner on IPM techniques and good management practices is the County Extension Office. The Cooperative Extension Service offers training in several States for extension agents, and often localities will offer courses for the general public. Unfortunately some States do not provide as much information on home lawns as they do for agricultural crops.
2. The U.S. Environmental Protection Agency has an Integrated Pest Management program within the Office of Pesticide Programs. The primary thrust of this program is to promote transfer of new technologies, to develop informational materials about IPM techniques, and to catalyze their implementation wherever there are pest problems. The USEPA also supports a Pesticide Hotline which can provide information on the proper use and toxicity of pesticides and give referrals on poisoning problems. The National Pesticide Telecommunications Network (NPTN) is located at Texas Tech University Health Sciences Center, School of Medicine, Dept. of Preventive Medicine, Lubbock, TX 79430. The 24 hour hotline number is (800) 858-7378.
3. The Bio-Integral Resource Center (Address: BIRC, P.O. Box 7414, Berkeley, CA 94707), headed by William and Helga Olkowski and Sheila Daar, has published much useful information on home lawn IPM in their newsletter, The IPM Practitioner, their journal, the Common Sense Pest Control Quarterly, and an excellent new book, Common Sense Pest Control (1991). This private foundation began as a cooperative contract with the National Park Service, funded by the USEPA, to develop alternative ways of managing pest problems in our national parks, particularly in areas where vulnerable populations (children, pregnant women and the elderly) would be exposed to any pesticide used.
4. A book cited by the Olkowskis in the above reference as being the best basic discussion of pesticide composition, behavior, toxicity and appropriate methods of use currently in print, is The Safe and Effective Use of Pesticides by P. J. Marer, published in 1988 in Davis, CA by the University of California Statewide Integrated Pest Management Project, Division of Agriculture and Natural Resources (Publication 3324, 387 pp.) It is written for professionals but is accessible to the layperson, and it contains practical advice for the use of pesticides in an integrated pest management framework.
5. Research on new biological controls as well as safer pesticides is generally carried out by the U.S. Department of Agriculture and at land-grant universities.
6. The largest library collection of research work on turfgrass is at the Turfgrass Information Center, Library W-212, Michigan State University, East Lansing, MI 48824-1048. As a project supported by funds from the U.S. Golf Association, this library has developed a computer-accessible Turfgrass Information File (TGIF), but literature searches can also be requested by phone or mail from Peter O. Cookingham, the Project Manager, at (517) 353-7209.
7. An interesting book published by Wiley Interscience presents and early review of the British research on "amenity grassland," which is defined in a report published by the Natural Environmental Research Council in 1977 as "all grass with recreational, functional or aesthetic value and of which agricultural productivity is not the primary aim." The book is: Rorison, I. H. and Roderick Hunt. Amenity Grassland: An Ecological Perspective. 1980. John Wiley & Sons, Ltd., U. K.