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Integrated Pest Management: controlling weeds, insects and diseases

Integrated pest management (IPM) is simply the process of integrating the use of pesticides with cultural, mechanical and biological controls in a planned and systematic approach to control weeds, insects and diseases.

Ideally, we don’t want to kill plants, animals, insects or other organisms unless they are causing or likely to cause crop damage or loss. But cropping practices such as soil tillage, use of certain crop rotations or use of pesticides can inadvertently affect non-target

Most pest control programs focus on the use of chemical pesticides. Typically, pests are identified in the field to estimate their potential population and damage potential, then a decision on type of pesticide, time of application and application rate is made. Unfortunately, this commonly used approach neglects to anticipate future effects due to use of the pesticide.

Pest control chemicals often kill non-target organisms. For example, an insecticide application will kill non-target insects, many of which are beneficial. Destroying the predators and parasites of crop pests can cause a rapid rebounding of the crop pest in numbers even greater than before application. Repeated use of an insecticide year after year can lead to development of insect tolerance or resistance to the insecticide.

Fungicide application can effectively aid in controlling fungal crop diseases. But, repeated use of a fungicide will lead to adaption and tolerance to the fungicide, causing it to become less effective. Repeated applications of fungicides and insecticides over years may adversely affect soil microbial populations. Promoters of pesticides rarely mention this, but in the long-term, repeated applications could have significant effects on native soil organisms, which are critically important for soil health.

Herbicides have become very important for weed control. Frequent and repeated use of the same herbicide groups, however, has gradually resulted in development of herbicide-resistant weeds – a very serious problem for many farmers across the Prairies.  

We must be very mindful and carefully consider both the positive and negative impacts of every practice we use to achieve optimum crop yields. Farmers must constantly try to balance short-term benefits to increase crop yield with long-term impacts on future crop production. The goal of IPM is to try to combine chemical, cultural, mechanical and biological controls together in a pro-active crop production system to try to enhance long-term sustainable crop production.  

Use preventive treatments only when needed
This is the first step in IPM. Often, chemical treatments are used on a scheduled basis. For example, spraying canola for cabbage seed pod weevils is often done at a scheduled time, rather than scouting, sweeping and monitoring fields to decide if and when to spray. Scouting and monitoring is time consuming, but chemical treatments are only applied in response to identified need if the insect is at a critical threshold level and chemical application is carefully selected for least disruption of the natural environment.

IPM does require more careful pest monitoring. A farmer must constantly monitor fields, develop action plans and analyze the results of treatments. Ideally, a farmer needs to understand why various pests are present in fields. For example, how were new weed types introduced onto the farm? How could this be avoided in the future? How can new weeds be managed? For some diseases, could cultural controls such as using a more diverse crop rotation to break disease cycles reduce the presence of the problem?

For some diseases and insect pests, could the use of a tolerant or resistant crop variety be an option? To consider control options, farmers must develop a very good knowledge of the various pests in their region and understand the biology and life cycle of each pest. Awareness of changing pest trends is also important. To do this, careful recording of information for each field and crop is required every year on your farm.  

Detailed field record keeping is time consuming, but over time this practice can provide valuable information on changing trends on your farm. Pest occurrences in a field or on the farm often occur due to events earlier in the season or the previous year. Most farms are large and the combination of numerous fields, crops, events and treatments are often complex and difficult to remember without the help of well-organized, detailed field records. Using an electronic record-keeping system can be important for analyzing your IPM program.

There are many IPM practices a farmer can consider. I have summarized some important factors.

Seed and seeding:
There is no substitute for excellent seed.

  • Have you selected the best regionally adapted crop variety for your area? Disease resistance is constantly breaking down in older varieties, but breeding advances are constantly improving disease resistance and agronomic characteristics. Be sure to constantly review new varieties available that are well-suited for your region and suit your growing requirements.
  • Is your seed source free of weed seeds? A number of plant diseases are present on seed (seed-borne diseases). Be sure to use seed that is disease free and weed free. Ensuring seed is cleaned and tested for disease is very important. Using certified seed is a very good practice to consider.
  • Make sure to select the most disease-resistant varieties for the diseases present in your area. This will help to reduce the need for fungicides.
  • Treat seed with the fungicide or fungicide/insecticide combinations for cost-effective control of pests present in your fields.  

Crop rotations
Wisely rotating crops is extremely important for reducing pest problems.
  • Rotating crops will help control less mobile insects.
  • Rotating crops will reduce the presence of residue-borne fungal and bacterial diseases. Having a break of several years between crops susceptible to the same disease will reduce disease potential.
  • Long-term crop rotations that include annual crops and perennial forage crops in the rotation are ideal. Forages are excellent for lowering disease risk of annual crops in a long-term rotation, and also reduce the presence of weeds. Forage crops are also very helpful to improve soil quality and build soil organic matter.
  • Shorter term crop rotations using annual crops ideally should include at least two or three crop types, such as cereal, oilseed and pulse crops.  Ideally, don’t grow the same crop more than once every four years.
  • Don’t grow different crops susceptible to the same disease back to back.  Sequence crops to your advantage. After growing a nitrogen-fixing crop such as pea, grow spring or durum wheat to take advantage of nitrogen release from pea residue to increase grain protein. A good diverse rotation can interrupt weed, disease and insect cycles. Rotating crops makes it easier for a farmer to rotate different herbicide groups to reduce the potential of developing herbicide-resistant weeds.
  • Alternating winter wheat and spring wheat, with different life cycles, in a diverse crop rotation helps to disrupt the life cycle of weeds to help control weed problems.
Conventional versus zero tillage
Reduced and zero tillage across Western Canada has contributed to soil moisture conservation, reduced fuel costs, reduced wind and water erosion, and greatly improved soil quality and soil health. Zero tillage also means weed seeds are not incorporated into soil, which is helpful in terms of cultural weed control. But in situations when considerable disease infected crop residue remains on the soil surface, the use of tillage to bury diseased residue will promote residue decay to prevent infecting growing plants. There are times when tillage may be appropriate to assist with disease control, but always keep in mind the importance of soil conservation.

Sanitation is key for pest control. Practice excellent equipment sanitation by cleaning farm equipment to prevent spread of weed seeds and disease organisms from field to field. Insist custom application equipment, industrial equipment and vehicles or ATV’s of visitors that enter your farmland be thoroughly cleaned to prevent importing weed seeds or disease organisms onto your land.

This article just scratches the surface of the potential for IPM. Think of the many things you can do on your farm for good pest management. Do your own research to understand as much as possible about the pests on your farm and the various control options. Search for excellent sources of good information to help you understand the pests on your farm and understand all the things you can do to protect your crops and at the same time ensure the long-term sustainability of your farm.

May 17, 2017  By Ross H. McKenzie PhD P.Ag.

IPM requires more careful pest monitoring


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