The general public is demanding safe food and water, and an environment protected from contamination. Methods are needed to minimize the potential problems associated with pesticides and fertilizers without adversely affecting the economic viability of Connecticut agriculture the green industries and our quality of life.
The University of Connecticut Cooperative Extension System (CES) in conjunction with the Department of Plant Science has developed and implemented the Integrated Pest Management (IPM) Program to address these concerns.
What is IPM?
Integrated Pest Management (IPM) has been defined in many different ways. Since initial applications of IPM were in commercial agriculture, many of the definitions include references to agriculture, but IPM goes well beyond agricultural applications. In fact, the IPM approach can be applied to virtually any pest situation. Two favorite definitions are:
"Integrated Pest Management (IPM) is the coordinated use of pest and environmental information to design and implement pest control methods that are economically, environmentally and socially sound. IPM promotes prevention over remediation and advocates integration of at least two or more strategies to achieve long-term solutions."
"IPM is a concept that uses a multidimensional approach for minimizing pest damage, empowering farmers, increasing the income and production of the farmer, and restoring a balance to the ecosystem."
Neither of these definitions fits every application of IPM, yet both include the basic principles of the system. IPM is a systems approach. Every decision should be made only after considering its impact on pest management. For example, if we are choosing a cucumber variety to grow in the garden, we might consider whether we want early or late maturity, dark green or lighter green color, vine or bush growth habit. But if we also select varieties that carry natural resistance to powdery and downy mildew, scab and anthracnose, we grow the kind of cucumbers we want and eliminate the need to spray to control four of the most common diseases of cucumbers. If we decide to locate the dog's dinner bowl on a hard, smooth surface that contains spills and can be easily cleaned, we eliminate a potential food source for ants and roaches. Placing the dog's bowl on a porous floor or where spills can roll or be pushed under appliances may create a romantic dining experience for insect pests.
Understand the Pest
To make IPM work we must understand the pest. Knowledge of the pest's life cycle, where it lives and what it eats helps us devise strategies to interrupt its activities by altering management practices rather than by using pesticides. This knowledge is readily available through your Cooperative Extension System.
Knowing that Colorado Potato Beetles over-winter in debris at the edge of gardens and fields and then walk into the garden in search of food allows us to trap them in a simple plastic-lined trench. Trapping the adults early in the season prevents egg-laying and provides a season-long solution for this potato pest without needing to apply pesticides.
It is also important to know that all pests don't have to be controlled. The term "action threshold" is used to describe the level of pest presence that requires control. With plant diseases, action thresholds are frequently the first occurrence of disease symptoms or the occurrence of climatic conditions (usually temperature and humidity levels) that favor development of the disease. With insects, weeds and vertebrate pests, the action threshold is usually linked to the presence of some critical population level or the appearance of feeding damage on a critical number of the plants or the area being protected.
Action thresholds vary considerably from pest to pest. For young cabbage plants, the action threshold for Imported Cabbage Worm is 35 percent infestation. If 35 percent or more of the plants are infested, yield reductions will likely result that will have a higher economic value than the cost of control. By comparison, seeing a single cockroach scurry across your kitchen floor would indicate a need for control measures. Generally, action thresholds are lower where human health or aesthetics are affected and higher where productivity is measured.
The use of multiple strategies greatly increases the effectiveness of IPM measures. If a simple trench trap will prevent most Colorado Potato Beetles from reaching your garden, using floating row covers to enhance early potato development and to prevent potato beetles from feeding on the emerging potatoes raises the effectiveness of control to nearly 100 percent -- all without the use of pesticides.
Pests like Colorado Potato Beetle or Common Housefly have demonstrated a remarkable ability to develop resistance to insecticides. To understand resistance management, you must first understand how a resistant population develops. Think of resistance as "speeded-up natural selection" or as "artificial selection." Natural selection is the process nature uses to select the most fit individuals for survival. Successful individuals pass on genes to their offspring, which are encoded with a certain trait that helps them overcome some specific environmental adversity or hardship. Repeated applications of the same pesticide "artificially selects" for the individuals from the pest population that can detoxify, tolerate or avoid a specific poison. Individuals susceptible to the poison perish, leaving those with resistant genes to reproduce and pass on the beneficial trait. After several generations and repeated exposures, you simply "weed out" all susceptible individuals, and are left with a resistant population. This selection process happens with any type of biotic pest including insects, diseases, and weeds. Resistance develops quickly for pests that have many generations per year, reproduce rapidly, and have few susceptible individuals migrating in from other areas or from wild hosts.
The use of multiple control methods helps prevent the development of resistance. For example, you can slow or manage resistance by alternating between pesticides that use different modes of action (for example, a stomach and a nerve poison). The individual pests lucky enough to possess a gene that can detoxify one material are unlikely to tolerate a second toxin that works differently.
Prevention is the Key
With IPM, the emphasis is always on prevention. Figure (1) illustrates how management efforts might escalate in the face of a severe pest infestation. The basis of control efforts would be a combination of several cultural and mechanical practices intended to make the environment less attractive to the pest or to physically trap or exclude the pest. If the pest were still present in sufficient numbers to cause unacceptable damage to plants, pets or property, to pose a health or safety risk, or cause discomfort to humans, the use of biological controls would be considered. These would include use of natural predators, parasites or pathogens that are usually specific to the pest.
If problems continued, use of the "soft" pesticides would be considered. These materials include highly specific materials such as growth regulators and more general materials, like repellants, soaps and oils. Low human toxicity and a minimal impact on the environment characterize all these materials. Many also have little impact on beneficial organisms that may be present.
As a last resort, conventional or "hard" pesticides may be required to adequately control the pest. If this is the case, the pesticides with the least effect on non-target organisms and the lowest impact on the environment are chosen. Our knowledge of the pest and its habits frequently allows us to gain a high level of control with the use of only small amounts of pesticide through proper placement and timing of the applications.
IPM and the Environment
Finally, IPM empowers you to impact the future of our environment. Agriculture was the first to adopt IPM principles. Government and some industries have followed them. In Connecticut, homeowners manage more land and many apply more pesticides than agriculture and government combined. You can do your part to restore balance to the ecosystem by supporting farms, businesses and government agencies that use IPM. Also, you can take the socially and environmentally responsible action of using IPM in and around your own home.
IPM has been called the common sense approach to pest management. It surely is. IPM costs no more than conventional pest management methods yet it protects the environment, helps maintain or restore the ecological balance while maintaining the productivity, appearance and quality of our environment and adds to our quality of life.
Shouldn't you be using IPM?
By Richard A. Ashley, IPM Coordinator