What is IPM?
B.C. Environment is promoting the development and application of integrated pest management, or IPM, for pests in B.C. It is an approach that uses all available techniques in an organized program to suppress pest populations in effective, economical and environmentally safe ways. The concept of IPM was first applied in agricultural systems to control insect and mite pests. It is not new--in fact, some B.C. apple growers have been using IPM for over 15 years and many B.C. greenhouse vegetable growers have been using IPM in their crops since the early 1980's. Over the last decade, the concept of IPM has been increasingly applied to pests of all kinds, including weeds, nematodes, plant diseases and vertebrates. IPM programs are used in forestry, on cattle ranges, in gardens and urban parks, and for household and structural pests.
An IPM program is a decision making process. It gives pest managers the information needed to decide whether or not action must be taken and, if so, to choose the most appropriate combination of control measures. Without such a program, pest managers usually rely on applying preventative sprays according to a calendar schedule. A key idea in IPM is that is necessary to take action against pests only when their numbers warrant it, not as a routine measure. In most cases it is only necessary to suppress pest populations to non-damaging levels, not to eliminate them.
Components of an IPM Program
The first step in developing an IPM program is correct identification of the problem. This is essential because most of the treatments must be tailored to a particular species. Once it is identified, information about the pestís biology can be used to identify the weak points in its life cycle when suppressive measures will have the greatest effect.
The next step is monitoring the pest populations. This is crucial to IPM because it provides the information needed to make decisions about the timing of treatments and whether or not they are necessary. Most monitoring programs are based on a regular inspection for pests or signs of their presence. Pest managers use a variety of methods, such as visual inspections and counts of insects caught in traps or in sweep nets. Growers often find that just by instituting a monitoring program they use fewer sprays. For example, B.C. apple growers who monitor the codling moth numbers in their orchards with pheromone traps, spray only after a predetermined number of moths are captured in a trap. They use about 25% less pesticide than growers who spray according to a calendar schedule. A 1991 B.C. survey found that carrot, onion and potato growers who sprayed only when a monitoring program indicated it was necessary, used an average of 50-60% less insecticide on most of their fields than they had used previously. For most of the carrot acreage, the resulting level of insect control was about the same as in previous years. For onions and potatoes, however, insect control was better on over 70% of the acreage than in it had been before monitoring programs were used.
The third component of an IPM program is the determination of an unacceptable amount of damage, or injury level, for a particular pest. In agricultural crops this is usually an economic injury level. How much damage is tolerable depends on what part of the crop is affected, the cost of the treatments and the value of the crop that would be lost if not treated. It also depends on the cost of negative side effects, such as the loss of beneficial insects that might be controlling other pests in the crop. In urban areas, such as in parks or conservatories, the concept of an aesthetic injury level is often used. In this case, the need for treatment depends on how much damage the public will tolerate, rather than on the harm the pest might be causing the plant. An example is the aphid that attacks maple trees while dripping sticky honeydew onto parked cars below. Although the aphids rarely reach numbers that damage maples, people have a very low tolerance for the honeydew.
The fourth component of an IPM program is the action level. This is the time at which a particular treatment should be applied to deter pest populations from rising above the predetermined injury level. For pesticide treatments, the action level and injury level might be about the same because the spray has an immediate effect. When using a biological control agent, however, the action level usually occurs earlier, when the pest population is still low. This is because predators must be released early enough to give them time to reproduce and build up an effective population. Some treatments are only effective at certain times in the life cycle of the pest, therefore the action level for these occurs when the pest population is in the susceptible stage. For example, a parasitic wasp that attacks moth eggs must be released when the eggs are present, while a microbial spray that infects caterpillars is only effective when they are present.
The fifth component is the treatment. One or several of these treatments may be coordinated into a management program for a target pest or for the entire complex of pests on a crop:
- biological controls, such as predatory and parasitic insects and plant and insect diseases,
- physical or mechanical controls, such as barriers, screens, traps, flame weeders and mulches,
- cultural controls, such as resistant varieties, crop rotation, pruning methods, plant nutrition and sanitation measures,
- chemical controls, including synthetic and naturally derived pesticides, insect growth regulators and other products.
When pesticides are used in IPM programs, they are chosed for their compatibility with other treatments and applied as efficiently as possible. For example, improved applicators for herbicides have been designed that deliver the chemical to the target plant without affecting neighboring vegetation. The substitution of non-toxic controls or management techniques for chemicals is important wherever possible to conserve native beneficial species and reduce impacts on the environment.
Although treating pests is important, IPM programs emphasize making changes in the management of the crop or habitat to prevent pest problems from developing. An integrated approach would include revising aesthetic standards, such as for ornamental plantings or for cosmetic damage to produce, that lead to unnecessary pesticide use. At times other human activities must change as well. For example, managing garbage differently to reduce cockroach populations or restricting use of playing fields to preserve turf from broad-leaf weed invasion.
The sixth component is evaluation of the pest management program. Follow-up monitoring or inspections may be necessary to find out how successful an IPM program has been. It is essential to review records to determine what worked and where improvements should be made.
IPM in British Columbia
In 1991 in B.C., IPM consultants were contracted by growers to advise them on 6000 acres of fruit and vegetable crops. About 1300 acres (nearly half) of the cranberry crop, over 1800 acres of potatoes in the lower Fraser River valley and about 1400 acres of Okanagan apples, pears and other tree fruits were grown under IPM programs. Nearly all of the onions (about 185 acres) and table carrots (about 250 acres) are monitored under IPM methods. IPM programs are also being developed for strawberries, currants, raspberries, lettuce and cole crops. Over 90% of B.C. greenhouse vegetables crops are currently grown using beneficial insects and mites as the primary control for five key pests. Monitoring services cost growers $30-70 per acre depending on the crop. Growers usually find that the monitoring service saves them at least this much in pesticide costs alone, while making it possible to grow a crop of equal or better quality than before.
B.C. is a leader in development of biological control for rangeland weeds and has had an on going program since 1975. Currently 41 biological control agents have been released against 15 target weeds, including knapweed, tansy ragwort, toadflax, Canada thistle and nodding thistle. For many of these species, the biological controls are well established throughout the range of the weed.
An example of IPM in forestry is the program to management of mountain pine beetles infestations. When monitoring determines that beetles are Mountain pine beetle attractant traps developed by B.C. researchers are used monitor the location of an outbreak as well as contain it.
Note: The basic principles of IPM are to are to reduce pesticide use by improving the timing of sprays, to replace pesticides with non-toxic alternatives and good management and to redesign the underlying management system to prevent pest problems and conserve beneficial species.
Courtesy of British Columbia Ministry of Environment, Lands and Parks.
Turf Line News October/November 1999
Back to Turf Line News Article Index click here