IPM Strategies

Clayton Hollier  |  6/23/2006 8:46:14 PM

Integrated Pest Management (IPM) is the judicious use and integration of various pest control tactics in the context of the associated environment of the pest in ways that compliment and facilitate the biological and other natural controls of pests to meet economic, public health and environmental goals. Wherever applicable, IPM uses scouting, pest trapping, pest resistant plant varieties, sanitation, various cultural control methods, physical and mechanical controls, biological controls, and precise timing and application of any needed pesticides.

With IPM, the decision to use pesticides is made when an action threshold for a pest is reached and no other alternative management methods are available that will provide effective control. When pesticides are needed, the safest and most effective materials should be selected for use. The goals of IPM are to achieve the effective management of pests in the safest manner.


Questions to Ask Before Good Pest Management Decisions Are Made

Good pest management decisions can be made only after answering questions such as:
  1. What pests are present, and in what numbers and stages of development?
  2. What conditions exist that may increase or decrease pest problems?

  3. What natural enemies of the pests, such as parasites, predators and diseases, are present that may play an important role in control?

  4. What amount and type of damage are being caused or may soon be caused by pests?

  5. What is the stage of development, condition and value of the crop?

  6. What is the potential for economical injury? How much damage is tolerable? Has the action threshold been reached?

  7. What are the history and severity of previous infestations at the site? How were those infestations managed? What were the results?

  8. What pest management options are available, and how do the advantages and disadvantages of each apply to the situation?

  9. If alternatives are not available, is a pesticide treatment justified for the situation? If so, what is the material of choice?

  10. If a pesticide is not justified, what approaches, if any, should be taken? Field scouting, insect trapping and action thresholds can be used to provide much of the information needed to help answer most of these questions.
Action Thresholds

The action threshold is the level of pest infestation at which treatment is justified to keep an increasing pest population from causing economical losses. Fields should not be treated when pest populations are below the action threshold. Applying a pesticide treatment for such infestations would not be an economic or qualitative benefit.

The action threshold is a key IPM decision-making tool. Thresholds are based on considerable amounts of research and field experience. If an action threshold is approached but not reached, do not apply a pesticide at that time. Instead, rescout the field within a few days to determine the status of the infestation. Pest populations can decline naturally due to mortality from natural enemies and unfavorable weather conditions. Also, many pests, such as caterpillars, change from an active feeding (larva) to a non-feeding stage (pupa) during their development. Such changes will often produce a natural decline in infestations as pupation occurs. Precise timing of needed pesticide applications is extremely important to achieve good pest control. Pest monitoring, action thresholds and a a good knowledge of the life cycles of pests are used to determine the best timing of needed treatments.


There are many methods that can be used to help manage pests. Most often they can be categorized as either chemical or non-chemical methods. Many non-chemical approaches are used to either prevent infestations from initially occurring or to minimize the severity of infestations. When non-chemical approaches such as the use of pest resistant varieties, cultural, physical, mechanical and biological controls are inadequate, chemical control may be justified.

The aims of IPM are to integrate or incorporate all appropriate methods into an approach that provides needed pest control in the safest manner and only use chemicals as a last resort.

Cultural Controls

Cultural controls exploit the factors related to growing the crop, that also may negate or minimize the occurrences of pests. Some examples include: disease-free seed; good sanitation and the destruction of plant residue to limit the spread of pests; optimum growing conditions to minimize stress on the crop; early or late planting and harvest dates to avoid pest losses; crop rotations; and living mulches for weed management.

Physical and Mechanical Controls

Physical controls utilize some physical component of the environment, such as temperature, humidity or light, to the detriment of pests. Mechanical controls involve the use of equipment or manual operations to exclude or disrupt the life cycle of pests. Barriers that exclude pests include fencing, row covers and plastic mulches. Disruptive operations include plowing, discing, hoeing and cultivation.

Biological Controls

Biological control is the use of living organisms which function as parasites, predators or pathogens to help control pests. Such natural enemies are responsible for keeping many pests and potential pests in check. Unfortunately, many pesticides are very detrimental to natural enemy survival. To help promote biocontrol, pesticides should be used sparingly and only when needed. Wherever possible, chemicals that are the least toxic to natural enemies should be chosen. Some pathogens (disease-causing organisms) have been commercially developed for use as biological insecticides. The best know example is the bacterium, Bacillus thuringiensis (Bt), which is effective for controlling certain caterpillars and beetles. Several Bt products are on the market.

Bt is formulated as a bacterial spore powder or a flowable concentrate which should be mixed with water and applied as a spray. The performance of Bt products against caterpillar pests is usually increased when mixed with a spreader-sticker. Bt has no contact insecticidal activity. To be effective, the spores must be ingested by susceptible insects. Good coverage of treated foliage will increase the likelihood of spore ingestion. Once the spores are ingested by susceptible insects, toxins are produced in the gut, feeding ceases within minutes, and death occurs up to 72 hours later. Bts are often excellent choices for pest control because they are very safe to humans, other animals and beneficial insects.

Resistant Varieties

Planting resistant varieties can prevent or minimize pest infestations and injury.

Chemical Controls

Pesticides are chemicals that are used to destroy, repel or otherwise lower pest infestations to protect crops from damage. Though pesticides pose many potential risks, they also provide the following important advantages and benefits:
  1. Pesticides are readily available and easy to use.

  2. Where resistance is not a problem, pesticides are generally highly effective for controlling pests.

  3. Pesticide treatments can be rapidly implemented as needed with minimal lag time.

  4. Pesticides can be used over large areas to control large populations of pests.

  5. Pesticide treatments are often cost-effective, especially if the alternatives require large increases in human labor.

  6. No effective, reliable, non-chemical alternatives are available for many pests, and chemical pesticides are the last resort.
Pesticides are used in IPM programs when no effective alternatives are available to keep pest populations from reaching damaging levels. The emphasis is to maximize the benefits and advantages that pesticides offer while minimizing any potential risks.

Whenever a pesticide treatment is needed, selection of the chemical should be consistent with the pesticide label and all state and federal laws and regulations. Additional considerations include: effectiveness against the target organism, compatibility with the host plant, effects on beneficial organisms, degree of environmental and user safety, and cost. Wherever possible, use a material that is least toxic to humans and other non-target organisms and is least likely to contaminate ground and surface waters.


During the years following World War II, many new synthetic pesticides became available for use. They were widely used and quickly became the standard tools for combating pest problems. Pesticides were easy to use, inexpensive and initially provided rapid and highly effective control of a wide variety of pests. However, several problems and limitations have now become apparent by relying solely on pesticides. Some of the problems include: pest resistance to pesticides; increased costs; toxicity to fish, wildlife, beneficial natural enemies of pests and other non-target organisms; concerns about human health and safety; ground water contamination; and overall environmental quality.


Pesticide Resistance

Because of attempts to achieve better or total pest control, resistance problems have increased because pesticides are applied more frequently and at higher dosage rates. These tactics have resulted in increased selection pressure. Naturally resistant individuals in a pest population are able to survive pesticide treatments. The survivors breed and pass on the resistance trait to their offspring. With each passing generation, the pest population becomes more difficult to control with the same pesticides as compared with earlier generations. Reducing pesticide use and alternating among classes of pesticides with different modes of action can help to lessen the possibility of pest resistance. Managing pest resistance is very important in helping to prolong the effective life of needed pesticides.

Toxicity to Natural Enemies and Other Non-target Organisms

Natural enemies of pest species can be very helpful in keeping pest populations at lower levels. These beneficial organisms are often other insects that serve as predators, parasites or competitors to the detriment of the pest species. For example, gypsy moths do not reach pest levels every year throughout the Northeast because many different natural enemies help to keep them in check. Unfortunately, many broad-spectrum, non-selective pesticides are more detrimental to numerous beneficial species than to the pests. The use of such pesticides often causes a resurgence in pest populations and at a much faster rate compared to the natural enemies. Without the natural controls, primary (established) and secondary (new) pests are often free to reach damaging levels at faster rates. An increase in pest levels usually results in additional pesticide treatments, which further depress or eliminate the natural enemies and further encourage the potential for pest resistance. Using pesticides as little as possible and selecting effective alternatives that are less toxic to non-target organisms will increase natural enemy survival and overall effectiveness of pest control.

Public Health and Environmental Concerns

The public has become increasingly concerned about the use of pesticides and the possible adverse effects on human health, wildlife, ground water and overall environmental quality. Pesticide exposure from drift to non-target areas; contamination of ground and surface waters; and residues on food are topics of concern to the general public. Applicators should be especially concerned because they may have the highest potential for exposure and thus may have the greatest health risks. All applicators must be sensitive to public concerns about pesticide use and apply materials only in a safe and judicious manner. This is particularly true for vegetable growers, who are often viewed by the general public as being responsible for providing safe and nutritious food. If pesticides are misused, this trust is violated, resulting in negative public relations and serious liable.

Cost of Pesticides

The cost of developing new pesticides has risen at an increasingly rapid rate. Many pesticides are petroleum-based products, and their costs increase with oil prices. Government regulations and more stringent registration requirements have also slowed the rate of development and increased the costs of new products. Concerns about potential product liability have discouraged companies from introducing new products. Increasing problems with pest resistance have likewise resulted in shorter market lives for many pesticides than in the past. All of these factors result in higher costs and potentially lower profits for chemical companies. In turn, this leads to higher prices for pesticide users. Many pesticides are very expensive. When including the costs of fuel and labor, every pesticide application made by the grower is a substantial expense. Imagine the savings a grower could realize if even one unnecessary pesticide application can be eliminated without increased damage to the crop. Maintaining the economic viability of agriculture is also one of the goals of Integrated Pest Management.

Reprinted from Northeast Sweet Corn Production and Integrated Pest Management Manual. 95-18. Roger G. Adams and Jennifer C. Clark, eds.
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