By Brent Flaten, PAg, CCA, Crops Extension Specialist
What is Integrated Pest Management?
Integrated pest management is defined as a decision making process that combines multiple strategies (cultural, chemical, mechanical and biological) to suppress pest organisms, such as damaging weeds, diseases or insects. These strategies are based on being effective, economical and environmentally sound. Integrated pest management makes agronomic and economic sense in the long term, especially when considering issues such as pesticide resistance and breakdown of crop genetic resistance to various pests.
Social licence is society’s trust in, and acceptance of, modern food production. As consumer scrutiny of producer practices increase, utilizing an integrated approach and not solely relying on any one strategy helps build public trust in our prairie food production.
The steps to integrated pest management include:
1) Prevention: reducing pest numbers primarily through cultural practices.
2) Monitor and forecast: includes identifying pests, knowing pest life cycles, and using predictive tools particularly for diseases and insects.
3) Intervention: scouting fields, knowing economic thresholds and various management strategies that suppress certain pests.
4) Evaluation and record keeping: knowing what works and doesn’t work is essential for future planning.
Integrated pest management does not rely on one management strategy in these steps, but utilizes an integrated approach.
What management strategies should be included?
- Cultural strategies are preventative and involve managing ecosystems to minimize pest organisms from causing significant economic crop damage. Examples include crop rotation (which can include biennial or perennial crops), crop timing (such as fall versus spring seed crops), and variety selection (some of which may compete better with weeds or have better tolerance to certain diseases or insect pests).
- Chemical strategies are the use of synthetic pesticides, including herbicides, fungicides and insecticides. A continuing issue with using this strategy exclusively, or at least too often, is the ever expanding pest resistance to pesticides. Resistance is due to the inherent genetic variability, often referred to genotypes, within any species which is nature’s basic survival mechanism. Because of this genetic variability, a small portion of the pest population may be able to tolerate the pesticide. The tolerant population then reproduces and over time makes up a growing portion of the general population. This is what we call selection pressure towards resistance. Selection pressure is a concern when relying on any one pest management strategy, so it is not an issue only related to pesticide use.
Another concern that is important to both the agriculture industry and to consumers is the proper use of pesticides. Safe residue levels include significant safety margins that are based on using registered products, at the registered rates, on the registered crop and pest stages and that follow the registered pre-harvest intervals. Proper use of pesticides also includes using appropriate technology to reduce any spray drift and follow labelled buffer zones to minimize movement of pesticides off target. To keep society’s acceptance of pesticide use as a pest management strategy, their proper use is vital.
- Mechanical strategies include tillage, mowing of weeds, grain cleaning and milling of weed seeds. Over use of tillage is not sustainable for our soils, but direct seeding with too much reliance on pesticides combined with a lack of attention to other integrated pest management tools is not likely sustainable either. Again, a combination of various management strategies is needed. When using tillage, steps should be taken to reduce erosion risk and keep organic matter levels up.
- Biological strategies can include natural parasites that impact weeds, insects and diseases. For example, many of our weeds were introduced here from Europe. Natural occurring parasites weren’t always brought over along with the seed. So by re-introducing these parasites here on the prairies some suppression on pest growth may be possible; although survival in our environment, such as overwintering, is required for this to work. Also bulking up natural occurring biological agents found here on the prairies can be utilized to apply to soil or pests for suppression. Examples of this include the biological fungicides called Contans and Serenade. Recognize and look for the existing beneficial organisms that play an important role in controlling certain pests, for example ladybugs, lace wings and syrphid flies that kill certain insect pests.
It is important to monitor pest and beneficial organisms by scouting fields regularly. Determine any pest population changes and their potential damage to crops. Look for insect and disease forecasts or alerts by Saskatchewan Agriculture or private industry agronomists. Consider environmental conditions. Weather can have profound effects on pest and beneficial organism populations.
Use economic thresholds when deciding when to take control measures for pests. Refer to the Guide to Crop Protection and other literature for these thresholds. Eradication of pests is rarely a realistic goal. Saving pesticide applications for when pest numbers are above the economical threshold is a cost effective strategy while reducing pesticide exposure, removal of beneficial organisms and risk of pesticide resistance.
Evaluate various strategies used in the past to help with future decision making. Be open to tweaking or changing strategies as required. Utilizing a mix of integrated pest management strategies works for farmers and can satisfy increasing consumer scrutiny of food production resulting in a win/win scenario.
It is important to note that repeated and over use of any one strategy, or tools within that strategy, imposes selection pressure favouring slight different genotypes of that species. This occurs with all strategies, not just the chemical strategy. To quote Neil Harker, with Agriculture and Agri-Food Canada in Lacombe, “Repeating a successful practice is not a problem in the world of assembly lines and machines, where all “genotypes” are defined. But living systems with inherently high levels of variation and diversity, rapidly adapt to repeated practices. Adaptation is more difficult when practices are diverse.”