Integrated Pest Management

IPM Manual for Landscape Pests in British Columbia

Chapter 1: What is Integrated Pest Management?

Learning Objectives

When you have completed this lesson, you should be able to:

1. Define the term 'Integrated Pest Management'.
2. Describe the advantages of IPM programs over scheduled pesticide spray programs.
3. Describe the role of prevention and describe how to design landscapes to prevent pest problems.
4. List the five main steps in an IPM program for an existing pest problem.
5. Describe the importance of identifying pests and knowing their biology.
6. Describe the role of monitoring in an IPM program.
7. Describe the difference between an injury level and an action level in an IPM program.
8. Name and describe five types of treatments used in landscape IPM.
9. Describe problems arising from the use of pesticides to control pests.
10. List items to record in evaluating the success of a pest control program.

Introduction

The intent of this chapter is to clarify what is meant by Integrated Pest Management (IPM), as it applies to landscape pests. IPM is an approach that uses a combination of techniques in an organized program to suppress pests effectively, economically and in an environmentally sound manner. Think of it as a way to manage landscapes to prevent problems and to make decisions about managing pests (for a detailed definition of IPM, see text box).

IPM is an approach that has been used for decades to manage insects and mites in agricultural crops. Over the last two decades, however, IPM methods have also been successfully applied to manage pests of all kinds, including weeds, plant diseases and animals. IPM programs are used in agriculture, forestry, landscapes and parks, home gardens and for structural pests. Most major BC municipalities (e.g., Vancouver, Victoria, Burnaby, Coquitlam, Nanaimo, Penticton, Kelowna, and others) have IPM policies for their landscapes, some dating back to 1990.

In an IPM program, pest managers use regular inspections, called monitoring, to collect the information they need to make treatment decisions. A central idea in IPM is that a treatment is only used when pest numbers justify it, not as a routine measure. Applying pesticides according to a schedule based on calendar dates is rarely, if ever, done in IPM programs. This eliminates unnecessary pesticide use without sacrificing results. It is common to find pesticide use reduced by 60-80% when IPM programs are put in place. For example, since IPM was adopted by the US National Parks Service in the early 1980s, pesticide use has been reduced by over 60%. In addition, parks managers found that they achieved better control of pests. Taking unnecessary pesticide use out of a pest management program also reduces the chance that pest populations will become resistant to pesticides (more on pesticide resistance).

Another important idea in IPM is that it is only necessary to keep pest numbers down to non-damaging levels. It is usually not necessary, or even desirable, to eliminate pests. If treatment is needed, pest managers choose the combination of methods that suit the site and local conditions. As this chapter describes, however, an IPM program is much more than a combination of treatments.

In the short term, developing an IPM program may cost more for labour and for changes in equipment and site designs. Experience has shown, however, that in the long-term, IPM programs can be more cost effective because they prevent future problems, improve the quality of a landscape, and reduce costs related to pesticide use (i.e., for applicator certification, spray equipment, pesticide storage facilities and disposal). IPM provides a way to manage pests that have become resistant to pesticides and to deal with pests in places where pesticides cannot be used. It is important to realize that IPM programs change and improve as people gain experience, and as new products, tools and information become available.

In summary, the advantages of IPM programs are that they:

• provide long-term solutions to pest problems,
• protect the environment and human health by reducing pesticide use,
• reduce costs and liabilities associated with pesticide use,
• prevent pesticide resistant pests from developing,
• enable pest managers to control pesticide resistant pests, and
• give good results where pesticides cannot be used.

Plant Health Care and IPM

Prevention is the true foundation of an IPM program. The key to successful and economical IPM in landscapes is preventing pest problems, mostly by growing healthy plants. An increasingly popular system of managing plants, called Plant Health CareTM (PHC), is one such broad approach to plant management (see Further Reading at the end of this chapter). It emphasizes managing a healthy plant ecosystem and working with nature to provide a flourishing landscape. The excellent results achieved by applying PHC principles often eliminate pest problems entirely.

Many methods and principles are common to IPM and Plant Health Care, so whether you call a pest management program PHC or IPM is not important. What is important is learning to think of growing healthy plants as the key to preventing pest problems. Rather than accepting pest attack as inevitable, progressive landscape managers see a pest problem as a sign that there is an underlying plant health problem they need to address.

Prevention

Since the real beginning of an IPM program should be prevention, it is discussed first in this chapter. Following that, the steps in an IPM program for an existing pest problem are described in general. They are described in more detail in later chapters on IPM programs for specific sites (see Chapters 4 to 10).

Anything that can be done to prevent pest problems makes it easier and cheaper to maintain the appearance and function of the landscape in the future. Most prevention consists of the type of planning and management that produces healthy plants (some references call these practices`cultural controls´). At it´s most basic, this means choosing the right plants for the site and giving them the best growing conditions.

Examples of factors to consider in designing a landscape and to improve, if necessary, are:

Ideally, the people responsible for managing a landscape would work with the site planners to choose trouble free plants and "design in" good growing conditions. Most of the time, however, landscape managers take on established sites. These may contain poorly designed facilities or plants with chronic pest problems. The following steps present a process for managing existing pest problems using IPM methods. Once immediate pest problems have been dealt with, however, the landscape manager should look for ways to correct the underlying conditions that led to the problem. This might mean developing a long-term plan to replace problem plants, rebuild sports fields, redesign planters or make other changes.

Steps in a Landscape IPM Program

An IPM program to treat an existing pest problem involves five main steps:

IDENTIFICATION - identify the pest

MONITORING - monitor the pest population and / or damage

ACTION DECISIONS - use injury and action levels to decide when to treat

TREATMENTS - apply a variety of controls

EVALUATION - evaluate results, plan improvements

Identification

It is essential to identify pest problems correctly to plan effective pest management programs. First, it is important to identify whether or not there is a pest problem. In landscapes, plant damage is more likely to be caused by environmental conditions that stress or injure plants (such as drought, flooding, nutrient deficiency, sunscald, frost, salt or wind burn, dog urine, or mechanical damage), than it is from pests.

Once a pest has been identified, the pest manager can look up information on its biology, including life cycle, behaviour, preferred habitat and typical host plants. Knowing about the biology of a species helps to:

• concentrate monitoring efforts when and where pests are most likely to occur;
• use treatments at the right time in the pest life cycle;
• know if the pest has natural enemies that could be conserved or protected; and
• plan preventative measures and improve plant management practices.

It is very important to identify beneficial insects and other natural enemies. This is because they are often mistaken for pests (and sprayed accordingly!) when they are really feeding on the pests. Knowing what beneficial species look like also helps in deciding whether or not controls are necessary. There may be enough natural enemies among the pests to control them in a few days without need for further action.

To identify problems, you usually need to collect insect specimens or samples of plant damage so that they can be compared with reference materials. Tips on where to look and how to sample for common pests are included in Chapters 4 to 10. Before sending samples to identification services, contact them for their recommendations on how to collect and handle samples.

How to identify pests and beneficial species:

• compare specimens with an insect or weed collection
• refer to reference books, fact sheets or resources on the internet
• consult experts for help with difficult or unfamiliar species
• compare characteristics of damage or signs of disease with photographs

Be careful when using characteristics of plant damage to diagnose problems because similar looking damage can have different causes. For example, curled leaves caused by a virus can look like damage caused by thrips, aphids or some kinds of mites. If the symptoms were caused by a virus it would be useless to spray an insecticide or release aphid predators.

Note: Provincial government staff do not provide identification services to the general public, however, landscape businesses and agencies can send specimens to the provincial Plant Diagnostic Laboratory (Ministry of Agriculture and Lands, 1767 Angus Campbell Rd., Abbotsford, B.C. V3G 2M3; Phone: 604-556-3126) for identification and recommendations. There is now a fee for this service. Contact information and a lab submission form are included in Appendix I.

Monitoring

Monitoring consists of making regular inspections or counts and writing down the results. Pest managers need monitoring records to make decisions about whether treatments are needed and when. Such records show where the pest problems are, and whether they are getting better or worse.

Monitoring is used to:

• detect problems while pest numbers are still low
• assess the size and spread of a pest population and extent of damage
• find out if natural enemies of pests are present and in what numbers
• look for conditions that contribute to the pest problem
• find out what effect treatments or natural enemies have had on the pest population

A monitoring program consists of:

• a series of inspections or counts, done at regular intervals, and
• written records of the observations and counts.

Always write down counts and notes at the time they are made so that the information is accurate. Using a well-designed record sheet makes it easy to enter information, saves time and makes sure important information is not left out (for examples, see Appendix II). For efficiency, some companies have staff enter records into a portable computer at the site. Such records can be quickly added to the company's database.

When and Where: The time and place to start monitoring depends on the site, the plants and the pest involved. By learning about the life cycle of various pests, you will know what plants they are most likely to attack and when. For example, an ideal time of year to look for tent caterpillars (Malacosoma spp.) is April, when the hatching egg masses are easy to see on bare branches. There is no point in continuing to monitor for tent caterpillars in mid-summer, because by then the caterpillars have left the trees.

How Often: Frequency of monitoring varies with the pest and conditions. For example, weeds in turf may be counted once or twice a year, whereas monitoring for insects is often done weekly during the time of year they are expected to appear. Monitoring for fungal diseases in turf might be necessary every day or two in damp weather.

What to Record: Examples of information to record include:

• species of plant and location
• weather conditions, such as temperature and humidity
• counts of pests and beneficial species
• counts or notes of damage or symptoms
• notes on site conditions that may be relevant
• growth stage of other plants in the area (called phenology, see below)

Not all of this information is useful in every case. With experience it will be possible to narrow down what information is most useful and suited to the situation.

Landscape managers have come up with short cuts that narrow down when, where and what to monitor, using:

Plant Phenology: Phenology is the relation between climate and biological events — in this case, plant development, such as blooming, leafing out, etc. Plant growth depends on temperature, so the date a particular plant blooms depends on how the weather has been. Although the calendar dates may differ from year to year, plants generally develop in the same relationship to each other. For example, wild cherries bloom before lilacs, which bloom before horse chestnuts; particular cultivars bloom earlier or later than others. Since insect development also depends on temperature, it can be more accurate to relate the appearance of particular insects to plant phenology than to a calendar date. For example, you may discover that aphid populations always seem to develop on poplar in the area at the same time horse chestnuts in the area begin to flower. Using plant phenology as a rough guide (it isn´t perfect) helps you target monitoring to the most likely time to expect the pest.

Indicator Plants: With experience and by keeping good records, you can pinpoint individual plants or particular cultivars or species that are most likely to have a pest problem year after year. Records may also show that there are sites where pests problems show up first in the area, often because they are warmer or more protected than other sites. Plants that are the first to show a problem can be used as indicator plants to focus monitoring efforts. They would be checked first and, as long as they remain pest-free, there would be no need to spend time monitoring other plants.

Key Pests: Because of the wide variety of trees, shrubs and herbaceous plants grown in landscapes, there are many potential pests. In practice, however, there are usually only a few that can be seriously damaging or that appear every year. For example, a 1986 survey of nearly 3000 municipalities in the US found that a group of 10 insects accounted for three-quarters of all the insect problems in their landscapes. Knowing which pests are of the most concern can help the pest manager to focus their monitoring on the most important problems. Information on the most common landscape pests in BC is provided in Chapters 4 to 10 of this manual and in the references listed under Further Reading.

Monitoring Methods: There are many different techniques for monitoring pest numbers and activity. These can be divided into two main approaches: visual inspections and counting methods. As there are many ways to count pest populations, only some examples of the most common counting techniques are described below. For details on other methods, see Monitoring sections in Chapters 4 to 10.

Counting Methods: Counting methods for monitoring pest populations are well developed for only a few problems, such as weeds in turf (aided, no doubt, by the fact that weeds hold still for counting!). The advantage of using counts in monitoring where ever possible is that they give numerical (quantitative) measurements. Unlike visual inspections, such measurements give numbers that can be compared from year to year as long as the same method is used each time.

For example, you could count the number of:

• insects per leaf, per stem, or in an area of turf
• weeds in a measured area of turf, or along a length of roadside or sidewalk
• disease spots per leaf or area of turf
• spots of aphid honeydew on sampling cards placed under trees
• insects caught in sticky traps
• insects that drop into beating trays when a tree trunk is struck

Insect Traps: Several types of traps are available for monitoring insect populations. Examples used in landscape ornamentals are sticky traps and pheromone traps. Traps are usually checked weekly and the number of insects caught are counted and recorded. Traps are used to:

• find out when the first adult insects are present, and
• estimate the size and extent of a pest population.

Sticky Traps: Some insects are attracted to bright yellow or other colours, which makes it possible to catch them on coloured cards coated with sticky glue. Yellow sticky traps attract adult whiteflies, flower thrips and fungus gnats. Bright blue traps are also available for flower thrips. Such sticky traps are usually used as a monitoring tool in greenhouses, although they can also be used as a control (see Physical Controls, below). Some shades of yellow sticky traps can also catch beneficial insects, therefore their use is limited outdoors.

Pheromone Traps: Most pheromone traps contain synthetic sex pheromones that mimic the odour given off by female moths to attract males for mating (see text box on semiochemicals). Pheromones are so specific that a different pheromone (or blend of pheromones) is needed for each species. This makes them an excellent monitoring method because they mainly catch just the target insects. The traps are used to find out when the main flights of adult moths occur so that sprays or biological controls can be used at the right time to have the greatest effect.

The pheromone is usually contained in a rubber or plastic lure that is hung inside a cardboard trap, such as a wing trap. The inside of the trap is coated with sticky glue, which catches the insects that enter. To inspect the trap, the pest manager opens it up and counts the captured insects.

Beating: Some insects that would be very hard to find among the leaves of trees or shrubs are easy to knock from the plant by striking the trunk with a padded stick. You can catch any insects that drop by holding a beating tray (usually a square of light-coloured fabric on a frame) under the branch while striking the limb or trunk. The insects can be identified and counted on the spot, or held in sample bags and counted later. Mites and small insects can be sampled by tapping the foliage over a clipboard covered with light or dark paper.

For consistency, the same number of taps or beats should be used for each sample so that the results can be compared between plants or from one date to the next.

Reliability of Counting Methods: The point of counting pests (or pest damage, beneficial species, etc.) is to get an accurate as possible picture of the pest situation. Two main factors determine how reliable counts are in showing the true state of the pest population. These are: sample size and sample randomness.

Sample Size: To be meaningful, it is usually necessary to count between 10 and 50 samples (such as insects on leaves or weeds in squares of turf) and average the results. The more samples you take, the more likely it is that the average will be a true picture of the pest situation, but there is a practical limit, because time spent on monitoring is a labour cost. A way to determine how many samples is enough, is described in the text box.

Sample Randomness: It is usually necessary to make sure that samples are picked at random. This means picking them by chance, without looking at them first and deciding which to take. If you intentionally choose particular leaves or other units to count, the results likely won't give a good estimate of the pest situation. For example, one way to count weeds in a lawn is to lay a 1-metre-square frame on the grass and count the number of weeds inside. If you chose the only weedy spot in the lawn, your records would seem to show the whole lawn was full of weeds. If you chose the only weed-free area on a lawn, the opposite would appear to be true. Only by dropping the frame randomly on the lawn a number of times and calculating the average weed count, would the results be likely to tell you the average weed infestation in the lawn.

One way to take a sample randomly, in the case of the turf example, above, would be to close your eyes, walk a few steps, drop the frame and count the weeds wherever it landed. Another way to ensure randomness is to decide a pattern of sampling ahead of time and stick to it. This removes the temptation to choose where to take a sample after you see the site. For example, you could decide to count the aphids on every 5th branch tip or every 5th plant in a row; you could lay out a grid pattern on turf and count the weeds only at the intersection points.

Ensuring samples are random doesn't mean that you have to sample over a wide area or in places where the pest are not likely to be. It is most efficient to concentrate on sites, plants or parts of plants, where the pests are most likely to appear (a good reason to learn about their biology). For example, to monitor aphids in the spring, inspections would start with growing tips and plant shoots. If you just want to know whether or not aphids have arrived, this non-random checking would be fine. If you want to know the average number of aphids per shoot, or the average number of shoots that have aphids, then you need to take random samples and average them. You could still target your sampling to plant shoots and tips to make it most efficient, but you would take samples randomly from among all the possible shoots and tips.

Note: It is meaningless to compare counts from random sampling with counts from non-random sampling. The same sampling methods must be used each time if you want to be able to compare results from one week to the next, or from year to year.

Action Decisions

In IPM programs, determining when to apply treatments really involves two concepts. In most descriptions of IPM programs, these are called:

• injury level (or injury threshold), and
• action level (or treatment threshold)

The injury level is the level of the pest population that causes an unacceptable amount of injury or damage. A few aphids on a tree or a weed or two in a lawn are not a problem, but at some point, the numbers could reach a level that is intolerable. This is the injury level; it depends on such factors as:

• what part of the plant is affected
• what pest is involved and the risk of permanent injury or death to the plant
• overall health of the affected plant (vigorous plants tolerate more damage)
• location of the plant in the landscape
• attitudes and perceptions of people who use the site
• cost and effectiveness of treatments

There are generally only a few pest problems, such as boring insects, root weevils and some plant diseases, that are life threatening to landscape plants. Most pests damage the appearance of plantings, often only temporarily. Since landscape plants, however, are grown to provide pleasing surroundings, the visibility of the damage will be important in setting an injury level. For example, even slightly damaged roses in front of city hall would be noticed, while heavily damaged leaves at the top of a tree in a naturalized park probably would not.

Because aesthetics are involved, the attitudes and values of the site users play a large part in setting injury levels. These perceptions can change through education. For example, when someone learns about the benefits of clover in lawns (i.e., it adds nitrogen to the soil and is drought tolerant), their attitude can shift from wanting to get rid of clover to appreciating it. When people know more about pest biology, their tolerance of cosmetic damage can also increase. For example, if people know that trees will soon replace the leaves damaged by tent caterpillars, they are less likely to feel they need to spray to protect the trees.

The action level or treatment threshold. This is when a particular control should be applied to keep the pest numbers from reaching the injury level. When to take action depends on factors such as:

• how fast the treatment works
• what growth stage of the target organism the treatment acts upon
• time of year or weather conditions that affect the treatment
• cost of negative side effects of treatment (such as loss of beneficial insects that might be controlling other pests)

You need to know what kinds of treatments are going to be used before you can set an action level. This is because how the treatment works will be a factor in deciding when to use it. For example, chemical insecticides are generally fast acting, so the most cost effective time to apply them might be just before insect populations reach the injury level. In practical terms, when pesticides are used to treat a landscape pest problem, the injury and action levels are often considered to be about the same. Most biological controls agents, on the other hand, usually need time to reproduce and build up their numbers, so they would be released well before the pest population reaches damaging numbers.

Other examples of treatment characteristics that affect when they can be used are:

• herbicides that work only on actively growing plants
• microbial sprays that only work on the caterpillar stage of moth pests
• oil sprays that can only be used on dormant trees

To decide whether or not treatment is required, you would compare the records from a regular monitoring program to the action levels you have established. Often there is no need to take any action, either because the expected pest is not found or because it remains at numbers well below the action level. When pest numbers rise higher it may be clear when they are reaching action levels and that treatment is needed. Sometimes, however, it is necessary to monitor more often or more widely to be able to make a decision.

Treatments

Ideally, treatments are only needed where preventative measures have not solved a pest problem. Often, however, an IPM program starts with an existing pest problem that must be dealt with before the landscape manager can plan a prevention program. Controls used in landscapes fall under five general types:

• cultural
• physical
• mechanical
• biological
• chemical

Other categories could be added to the list, especially as research develops new treatments. In agriculture and forestry, insect semiochemicals (see text box, pg.7) have been developed to affect insect behaviour on a large scale so these are often called behavioural controls. Some methods fit into two categories (i.e., sanitation can be considered either a cultural or a physical control). Therefore, categories aside, the important thing to know is that pest managers have a wide variety of treatment "tools". These can be used separately, or in combinations, to give the required level of control. Using a combination of treatments is usually more effective than relying on any one treatment. This is because each measure contributes to reducing the pest population­even if the effect of each measure is small, all together they add up to effective control.

In choosing treatments, select methods that are:

• least hazardous to human health
• least toxic to non-target organisms
• least damaging to the environment
• most likely to produce long-term results
• most cost-effective over time

Cultural Controls

Cultural controls include many of the methods discussed under Prevention that are aimed at producing healthy plants. Sanitation methods are also generally included as cultural controls.

Sanitation: This mainly involves removing potential breeding sites for pests and destroying sources of infection. Examples include:

• Pull weeds that act as hosts for insects and diseases around nurseries and greenhouses.
• Correct drainage problems in greenhouses to remove breeding sites for fungus gnats.
• Remove trash and plant debris that harbour rodents, overwintering insects or disease organisms.
• Cut weeds before they set seed and spread to other areas.

Physical Controls

Physical controls include manual techniques, such as hoeing or pulling weeds and pruning out branches with tent caterpillar nests or fungus infections (this could be considered a sanitation practice). Some controls can be considered as either physical or mechanical, therefore they are usually grouped together in the Treatment sections of Chapters 4-10 of this manual. Physical controls also include passive techniques, such as barriers and traps.

Barriers: These simply stop pests from reaching their food supply. Examples include:

• insect barriers, such as screens on greenhouse vents or floating row covers on nursery plants
• weed barriers, such as mulch mats, landscape fabric or mulches of leaves or bark that smother germinating weeds (discussed in more detail in Chapter 3)
• animal barriers, such as deer fences, bird mesh or copper strips to keep out slugs

Traps: These attract and catch pests, removing them from the population. The same type of sticky traps used to monitor for insects can be a physical control when they are used to catch a large part of the pest population. Examples include:

• sticky tree bands catch female winter moths crawling up tree trunks before they can lay eggs
• sticky yellow traps catch adult whiteflies or fungus gnats in greenhouses
• baited traps catch slugs, yellowjackets, flies or rodents

Mechanical Controls

Mechanical controls are machines or devices used to control pests, such as vacuum equipment for insects and cultivators, mowers and line trimmers used to control weeds. Other examples include: heat applicators, such as propane flamers, hot-water or steam applicators and infra-red radiation equipment, used to kill weeds growing in cracks in hard surfaces, under fence lines and along roadsides animal repellers, such as devices that squirt water when activated by a motion sensor to frighten deer, raccoons and other animals.

Biological Controls

Biological control is the use of natural enemies of pests to control pest populations. Many are beneficial insects and mites, but they can also be larger animals, such as birds and snakes, and microorganisms, such as fungi and bacteria.

Landscape managers employ biological control by:

• protecting and attracting the many natural enemies that are native to B.C., and
• using natural enemies from commercial suppliers.

Protecting Natural Enemies: The most important way to protect beneficial species is to avoid using pesticides as much as possible, especially those that affect a wide range of species or that are very long lasting. If pesticides are needed as part of a pest management program, then:

• choose the most selective products with the lowest toxicity and / or shortest residual effect, and
• limit applications to only those plants or areas that are infested.

Attracting Natural Enemies: Native beneficial insects can be attracted to landscapes by plants that provide them with pollen and nectar. Many female beneficial insects need to eat pollen or nectar in order to have enough energy to lay eggs. Once the females are attracted to the area, they are likely to stay and lay eggs. When the eggs hatch, the larvae attack the pests. Studies in agricultural crops have shown that providing flowering plants for beneficial insects results in better control of pests. In landscapes with few flowering plants, or where mainly showy flowers with little or no nectar are grown (e.g., roses, geraniums, etc.), it is a good idea to include some plants for the beneficial insects (see text box).

Many annual and perennial ornamentals are good insect plants. For example, yarrows, various daisies and calendula are good pollen sources for lady beetles. Making the landscape attractive to beneficial insects can be as simple as providing an edging of sweet alyssum around a rose bed or adding a few good insect plants to a display garden.

Using Commercial Natural Enemies: Beneficial species sold by commercial suppliers for use in landscapes include microorganisms ("microbials") and nematodes as well as insects and mites. These are discussed in more detail in Chapter 3 of this manual.

• The most widely used microorganism is Bacillus thuringiensis kurstaki (BTK), which is used to control caterpillars. Microbial products are legally registered as pesticides.
• Insect parasitic nematodes, which are microscopic worms that attack insects, are available in commercial products. The nematodes are mixed in water and applied to the soil to control root weevil larvae, leatherjackets and other turf and nursery pests.
• Most species of beneficial insects and mites are sold to control pest insects and mites in commercial greenhouses; only a few are recommended for use outdoors.

Pest managers interested in buying natural enemies should be aware that:

• most only attack particular species of pests, therefore the pest must be correctly identified first; supplier instructions must be followed carefully to ensure good results
• these living organisms are very perishable; they must be handled with care and released promptly

Chemical Controls

A large variety of chemicals (and some microorganisms), are registered as pesticides in Canada. Pesticides are any substances used to kill, control, repel, or manage insects, rodents, fungi, weeds and other living things considered to be pests. Pesticides vary greatly in their toxicity and the way they work. In IPM programs, pesticides should only be used after careful assessment shows that they are the best control for the situation. Applying pesticides only when monitoring shows that the action level is reached is economical and eliminates unnecessary pesticide use.

When a decision is made to use pesticides, pest managers must choose the most suitable formulations and methods of application. They must take all possible precautions to prevent the exposure of people and non-target organisms to the pesticide. Ways to limit negative effects of pesticides include:

• choose "preferred pesticides" where possible (see below)
• choose application methods that limit the amount of pesticide used
• limit treatments to only the plants or sites where pests are a problem
• notify anyone who might enter a treated area so that they can avoid exposure

Preferred Pesticides

Preferred pesticides, as described in this manual, are generally those that:

• present the least short- and long-term health risk to humans
• have the lowest environmental impact, usually because of short residual effects or because they specifically affect target pests

The characteristics of specific preferred pesticides are described in Chapter 3 of this manual.

Other Pesticides

Products containing toxic and/or persistent chemicals, such as organophosphate and carbamate insecticides are registered for some landscape pests. These may be necessary in some cases, particularly as a short-term measure. Generally, however, these products should not be used when preferred pesticides or non-toxic methods are available. This is because there is greater risk of harming non-target organisms and the hazards associated with improper storage and disposal are higher with these products than with preferred pesticides.

It is worth nothing that federal review processes for organophosphate pesticides in the US and Canada are underway. This may result in restrictions on some commonly used products within a few years.

Problems with Pesticide Use

Much of the interest in promoting IPM is a result of problems with using pesticides, including:

• development of pest populations that are resistant to pesticides
• development of new pest problems when the natural enemies that were keeping them in check
• are destroyed by pesticides
• exposure of humans, pets and other non-target organisms to pesticides
• environmental contamination with pesticides

In comparison to other types of controls used in IPM programs, pesticide use:

• provides short-term control, but rarely a long-lasting solution to pest problems
• requires effort and expense for service companies to provide adequate training, safety equipment and pesticide storage facilities
• requires careful planning and use of application techniques that protect people and the environment
• causes inconvenience (and concern) to site users who want to avoid treated areas

Pesticide Resistant Pests

Pesticide resistant pest populations are a major problem in agriculture and, to a lesser extent, in other sectors. Resistance appears when a pest population is repeatedly treated with the same pesticide. A few individuals in the population may survive a spray because they have genetic characteristics that make them resistant. When they breed, they produce offspring that are more likely to survive the next time the pesticide is used. As each spray kills the susceptible individuals, the resistant individuals continue to reproduce. Eventually, the whole population is made up of individuals with resistance to the pesticide. Pesticide resistance has been found in insects, mites, weeds and rodent populations.

The best way to prevent the development of pesticide resistance is to use non-pesticidal methods whenever possible. This also ensures that when pesticides must be used, they will still be effective.

Pesticide Risks to Humans and Non-target Organisms

Many common pesticides are broad-spectrum poisons. If used improperly, they can harm or even kill people and other non-target organisms, such as pets, plants, beneficial insects, wildlife, birds and fish. Generally, broadcast applications of residual pesticides pose the most risk.

Many people are concerned about possible long-term effects of pesticides on their health. Some people are sensitive to certain pesticides, or to the carriers or other ingredients in the formulated products. They may have adverse reactions from exposure to very low levels of certain products. Also, there is increasing concern that some chemicals, including some pesticides, may disrupt hormone functions in humans and animals (these are known as endocrine disrupters). These concerns can be addressed by using alternatives to pesticides and least-toxic products wherever possible.

Evaluation

Evaluation is an essential part of every IPM program because it helps the pest manager:

• determine what worked and what didn't
• identify ways to improve the program
• assess the costs and benefits of the program
• identify changes to site design and management to prevent future problems

To evaluate an IPM program, the pest manager needs accurate records of treatments and results from:

• monitoring records of pest numbers and locations before treatment
• treatment specifics, including date, time, product names and rates used
• monitoring records of pest levels after treatment
• feedback from clients or site users

Accurate records of labour and other costs should also be kept so that the pest manager can set a fair price for IPM services.

Conclusion

As described in this chapter, the basis of a landscape IPM program is prevention of pest problems, mainly through growing healthy plants. If controls become necessary, the IPM approach gives the pest manager a step-by-step process for managing pest problems. The emphasis on monitoring pest populations before making treatment decisions differs from the practice of applying pesticides based on a calendar schedule. Clients who are used to such scheduled pesticide applications may think that it is the only way to deal with a pest problem. The challenge to the landscape manager is to promote IPM to such clients so that they will accept the long-term, safer solution, instead of a short-term, 'chemical bullet'.

An increasing number of clients are demanding an IPM approach because they are concerned about pesticide use and environmental safety. Landscape companies who are used to selling the scheduled pesticide approach will need to upgrade their skills to serve such clients and adapt to changing markets and government regulations. Over the next few years, using IPM methods will become a condition for receiving a service license from the British Columbia Ministry of Environment to apply pesticides on public lands.

Further Reading

___ 1997. Plant Health Care for Woody Ornamentals: A Professional´s Guide to Preventing and Managing Environmental Stresses and Pests. International Soc. Arboriculture and University of Illinois. 223 pp. (From: University of Illinois, ITCS, 1401 South Maryland Drive, Urbana, IL 61801. Tel: 800-345-6087

Bobbitt, V., A. Antonelli, C. Foss, R. Davidson, R. Byther and R. Maleike. 1996. Pacific Northwest Landscape IPM Manual. Washington State University. 206 pp. (From: WSU, Cooper Publications Bldg., P.O. Box 645912, Pullman, WA 99164-5912. Tel:1-800-723-1763

Daar, S., H. Olkowski & W. Olkowski. 1992. IPM Training Manual for Wholesale Nursery Growers. Bio-Integral Resource Center, Berkeley, CA. 80 pp. (From: BIRC, PO Box 7414, Berkeley, CA 94707. Tel: 510-524-2567

Dreistadt, S. H. 1994. Pests of Landscape Trees and Shrubs: An Integrated Pest Management Guide. Pub. # 3359. University of California. 327 pp. (From: ANR Publications, Univ. of Calif., 6701 San Pablo Ave., Oakland, CA 94608-1239. Tel: 800-994-8849

Olkowski, W., S. Daar, & H. Olkowski. 1991. Common Sense Pest Control. Taunton Press, Newtown, CT. 715 pp. (From: Bio-Integral Resource Center, PO Box 7414, Berkeley, CA 94707. Tel: 510-524-2567