Government of Nova Scotia Government of Nova Scotia Nova Scotia, Canada


Pests and Pesticides

Frequently Asked Questions

Some Useful Definitions

Pest: A pest is any harmful, noxious or troublesome organism. Pests include any insects, mites, rodents, nematodes, fungi, weeds or other organisms that are injurious to the health of human beings, plants, animals or the environment.

IPM: Integrated Pest Management (IPM) is a means of keeping pest damage below unacceptable levels. This is done by routinely monitoring pest problems and managing them by using a combination of preventive practices and carefully selected control treatments. IPM is based on the principle that a combination of strategies is more effective in the long run than reliance on a single strategy.


We all rely on pest management programs to ensure safe, adequate food and fibre supplies, to protect buildings, structures and stored products, and to ensure public health and safety. Since the discovery of pesticides during World War II, most pest management programs have relied heavily on the use of pesticides to prevent pest damage. Often, these chemicals are applied at specific times of the year according to a pre-set schedule. Years of using pesticides in this way has created a number of challenges for pest managers including pesticide resistant pests, concerns about negative effects of pesticides on beneficial or non-target organisms and environmental health concerns.

Because of these concerns, many progressive pest managers are using Integrated Pest Management (IPM). In contrast to traditional pest management programs, an IPM approach focuses on preventing pest damage. Pest activity is regularly monitored and if pests build up to damaging levels, a number of different techniques (e.g. physical control, biological controls or pesticides) may be used to control them. When prevention, pest monitoring and a variety of control techniques are put together (integrated), the result is a long term approach to pest management that often uses less pesticides and has less of an impact on non-target organisms and the surrounding environment.

In Nova Scotia today, IPM programs are being used in many agricultural crops such as apples, strawberries, cranberries, potatoes, greenhouse vegetables and in processing vegetables such as carrots, peas and beans. IPM is also used in the salmon aquaculture industry, in Christmas tree production, golf course turf management, commercial lawn care and by Nova Scotia Power Inc. for the management of vegetation growing under power lines. Many home gardeners also practice IPM with the help of many publications that are available through Nova Scotia garden centres and the provincial Departments of Environment and Agriculture. Throughout the world there are examples of IPM programs for almost any pest management situation one can imagine from pests in food , fibre and stored products, to pests in structures and even pests in museum collections.

Components of an IPM Program

There are five main components of an IPM program. These are:

  • accurate identification of the pest(s)
  • pest monitoring
  • treatments based on pre-established thresholds
  • use of appropriate pest management strategies
  • evaluation of the program and follow-up

Pest Identification

Integrated Pest Management has often been called knowledge based pest management because pests are managed using information about their biology. To plan an effective pest management program the pest manager must first accurately identify all pests and suspected pests and then become familiar with their biology. Being able to sort out the real pests can be critical to the success of an IPM program in some situations. For example, landscape trees can often harbour many insects, especially in the early season, but only a few of these species may be capable of causing significant damage to the tree.

Treatment Threshold Levels

One of the key concepts of IPM is the fact that the mere presence of a pest does not always indicate a "pest problem."

In conventional pest management programs (non-IPM programs) pesticides are often applied on a set schedule or at a certain time of the year. This results in treatments being applied whether or not the pest is actually present at damaging levels. In an IPM program treatments are applied only when monitoring shows that a pest is building up to an unacceptable level. This is done by establishing a threshold for each pest. The threshold level is the number of a particular pest or the amount of pest damage that can be tolerated in an area before control is required. The area or crop being managed is routinely monitored for signs of the pest to determine if the threshold has been reached.

The threshold level that is selected depends on the pest, the type of damage it does, the value of what is being damaged and the cost of control treatments. When dealing with food and fibre crops this threshold is usually based on economic factors. For example, to decide if a pest control treatment is needed in an apple crop, the apple grower compares the cost of the treatment to the estimated value of the apples that would become unmarketable or be low graded if the pest was not treated.

In comparison, aesthetic criteria are usually used to set thresholds for pests of landscaped areas, turfed areas, or nuisance pests in buildings. In industrial vegetation management programs (e.g. along powerlines and roadsides) thresholds for control of unwanted vegetation are based on the need to ensure public and worker safety. In the food processing industry and in the management of public properties/buildings thresholds are often based on concern for human health and comfort.

Pest Monitoring

Pest monitoring (often called crop scouting in the agriculture industry is the routine, systematic inspection of the areas, plants, animals or stored products where pest damage may be a concern. In a monitoring program, pest populations, symptoms of damage and other factors related to pest development are observed and recorded. Regular monitoring ensures that developing pest problems are caught early and can be treated before they spread to a wider area or high levels of damage have occurred. Pest monitoring provides the pest manager with good information on which to base pest management decisions. Without monitoring the pest manager would have to rely on a pre-set schedule for treatment.

Pest Management Practices

Pest management practices can be divided into long term preventive practices and short term control treatments.

Long term preventive practices may include the use of resistant plant varieties, pest resistant construction materials, appropriate cultural practices, practices which conserve natural enemies of the pest and modification of site conditions to make the area less attractive to pests. Short term control treatments include biological, physical and chemical control.

Many of the pest management practices that are used in IPM programs are outlined below. It is important to note that not all practices are appropriate for all situations.

Manipulating Site Conditions to Prevent Pest Damage

Pest problems can often be reduced by changing the site conditions that support high pest populations. For example, the severity of many plant diseases can be reduced by decreasing shade or relative humidity and increasing the air movement around plants.

All organisms including pests require food, water and shelter. As a result, many structure invading pests can be controlled by modifying their habitat (e.g. decreasing the humidity in the structure) or by denying pests access to shelter, food sources or water.

Pest Resistance

In agriculture and in the landscape trade, the use of plants that are resistant to certain pests is a common pest management tool. Proper selection of plants such as nursery grown native plants (for use in landscape plantings) or plants that have been bred to be resistant to the common pests in the area can effectively reduce pest damage.

When dealing with structure invading pests or pests of stored products the choice of construction methods, materials and maintenance practices can influence the amount of pest damage that occurs. Where practical construction methods and materials should be selected that are suited to the site, climatic conditions and the level of maintenance that the structure will receive.

Cultural Practices

Cultural control is the oldest and most widely used method of reducing pest damage.

It is based on the fact that healthy vigorous plants and animals are less susceptible to damage from pests. Healthy plants and animals can also tolerate higher pest populations without suffering permanent damage and can recover more rapidly.

Cultural practices include any practice that involves manipulation of the growing conditions to make the system less favourable to the growth or survival of pests and more favourable to the growth of desired species. A common example of cultural control in agriculture is crop rotation. Crop rotation reduces the likelihood that diseases and insects will carry over in the crop residue from one season to the next.

Conserving Natural Enemies

In many IPM programs, steps are taken to conserve the natural enemies of the pest. This is done by identifying the factors that the natural enemy needs in its environment to be successful. Where practical conditions that promote populations of the natural enemy are provided. For example, the natural enemies preferred food source might be provided or undisturbed buffer strips may be left around managed areas to allow populations of natural enemies to build up.

If pesticide treatments are required, products and application methods with the least potential impact on the natural enemies are selected. As well, affected areas are often spot treated. This allows pockets of the natural enemies to survive outside the treated area so they can recolonise it more quickly.

Physical (Mechanical) Control

Physical controls are methods used to exclude or remove a pest from an area or host plant. Examples include barriers such as screening materials, sticky tree bands to prevent insect movement into landscape trees and water permeable geotextile mulches (landscape fabric) to suppress weed growth in landscaped areas.

Physical control also includes hand pulling or mowing of weeds and cold or heat treatments to destroy pests of fabric and other stored materials. Sanitation practices such as the removal of fallen leaves and pruning of diseased or dead branches can also be an effective way to control many pests. Sanitation removes the waste and debris that may provide a food, shelter or overwintering site for pests.

Biological Control

Biological control is the control of pests by other living organisms such as predators, parasites, disease causing organisms or organisms that compete with the pest for food, shelter or space.

There are two main ways in which biological control can be used to manage pest populations: classical biological control (where a natural enemy is imported, reared and released to control a pest of exotic origin) and augmentative biological control (the collection, rearing and release of native natural enemies to build up populations). In practice, biological controls are only commercially available or practical for use against a limited number of pest problems.

Chemical Control

In most cases, pesticides are used as a backup in an IPM program. Pesticide treatments are made when monitoring shows that preventive measures have not kept pest populations below the threshold level and other pest control methods such as physical or biological controls are either not available or not appropriate for use in the situation.

When a pesticide application is prescribed by the monitoring program, the pest manager will select a pesticide that is compatible with the other treatments in the IPM program and ensure that it is applied as efficiently and safely as possible using accurately calibrated equipment. Some IPM programs also make use of new, highly specific pesticides such as insect growth regulators and pheromones (chemicals that interfere with an insect’s ability to find a mate).


Education is a key component of many IPM programs, especially those in commercial and public health situations. Effective education efforts include everyone that may be involved in or concerned about pest management. For example, in a commercial setting, staff who are informed about the goals of an IPM program are more likely to support it. As well, when staff who perform daily or routine maintenance tasks are given training in pest identification they can play an important role in spotting the initial build up of a pest problem.

In areas where the public has a stake in pest management programs (e.g. public properties and buildings) or where private properties are abutting the areas where the pests are being managed, public education is an important part of an IPM program. Providing information about real and/or imagined pest problems can reduce apprehension about the presence of pests and reduce requests for unnecessary or mis-directed efforts to control them. In addition, when the public is informed about the IPM program there is often less concern about the overuse and/or misuse of pesticides when they are required.

Program Evaluation and Follow-up

In an IPM program the effectiveness of all the treatments is regularly evaluated. At the end of each season the whole program is reviewed to evaluate it’s overall success. This review enables the pest manager to adjust thresholds, identify additional information needed, determine if new preventive practices should be included in the program, and incorporate new products an technologies that may be available in the marketplace. Through these reviews the pest manager can continuously improve and refine the IPM program as knowledge and experience are gained, making it a truly knowledge based approach to pest management.