Chapter 10 - Integrated Pest Management
Canola Integrated Pest Management
Weeds, insects and diseases can limit the production potential of canola. To minimize their impact on yields, use an integrated control program that includes a combination of prevention and cultural, physical and chemical controls.
An Integrated Control Program
Integrated Pest Management (IPM) uses all the tools that are available for controlling pests. The goal of using IPM is to achieve effective management of pests by using all the tools that are available in the safest manner possible and in a way that enhances the economic viability of the farm. This includes chemical, cultural, mechanical and biological tools. It means not exclusively relying on one technique (for example, using herbicides exclusively for weed control or tillage exclusively for disease control).
IPM is not a new concept. In general, canola growers are using many IPM tools. The challenge of IPM is to pull together better "packages" to improve integration of the IPM tools. IPM is much more than just field scouting to assess pest populations to make a decision to spray or not to spray and is rarely useful when practiced in isolation or in the short term. Growers will be more successful with IPM if steps are taken each year to ensure crop health and to "set up" for individual IPM techniques. There are four steps involved in implementing an IPM program.
- prevention-Practices that reduce the severity of pest infestation or prevent pest build-up
- monitoring and Forecasting-Determining what pests are present and what action is required to manage pests
- intervention-Actions to reduce the economic crop damage from pests
- record Keeping-Maintaining a field record system for effective planning
Underpinning all four of these steps is the grower's ability to accurately identify pests. By knowing the pest and its life cycle, growers can plan control programs to exploit weaknesses in pest lifecycles and use the most effective management strategies.
In canola, IPM means the use of clean healthy vigorous seed, crop rotations, pest monitoring and resistant varieties. It also means using crop protection chemicals judiciously. The goal of IPM is to minimize the impact of pests on the crop, while maximizing the return from using different pest management tools. IPM allows this to be accomplished in a way that takes care of the farm environment.
Table 1. Examples of IPM Techniques and their Value
| Rotation and Seeding Techniques |
|---|
| IPM Techniques | Value |
|---|
| Seed canola no more frequently than one year in three to four on the same field |
Prevents build-up of seed and seedling pathogens, sclerotinia, blackleg, root rot, Alternaria, cleavers, and root maggot. Will help to promote the growth of a healthy vigorous crop |
| Review pest problems on a field before seeding to canola |
Growers can pre-plan and pick the best field for their canola |
| Put canola on fields where there was a "beneficial crop" the previous year |
Avoids disease build-up or volunteer problems carried over from the previous year. Beneficial crops include forages and cereals |
| Use treated, pedigreed seed |
Pedigreed seed is cleaned to high standards with weed seeds and disease presence identified on the tag. Treated seed controls soil borne diseases and some insects. Ensures the emergence of a healthy competitive crop |
| Use resistant varieties |
Varieties are currently available that are herbicide tolerant and blackleg resistant |
| Checking adjacent fields for pest hosts (for example, sclerotinia or flea beetles on mustard plants) |
Checking and controlling pests on adjacent fields adds to the effectiveness of rotation because it cleans up pest hosts. Some pests can readily move from one field to another |
| Early seeding, checking against soil temperature |
Allows for early growth of the crop to maximize crop competition |
| |
|---|
| Soil Testing and Tillage Practices |
|---|
| IPM Techniques | Value |
|---|
| Use soil testing |
Soil testing allows the grower to deliver fertilizer in just the right amount for maximum payback. This ensures good crop economics and minimizes the risk of groundwater contamination. Fertilizer imbalances can increase the risk of pest attack |
| Practise direct seeding |
Helps the grower to minimize soil disturbance, conserves soil moisture and reduces germination of some annual weeds |
| Use light tillage for weed control prior to seeding |
Light tillage can kill off a first flush of weeds prior to crop emergence. This is most effective when the soil is dry, but some risk is involved since tillage may dry out the seedbed |
| Use light tillage but preferably minimum-till or zero till |
Lighter duty tillage equipment can help control some pests (such as shallow germinating weeds) and leaves soil residues in place minimizing soil erosion |
| |
|---|
| Sanitation |
|---|
| IPM Techniques | Value |
|---|
| Clean tillage equipment when entering new fields |
Prevents movement of disease organisms or weed seeds from one field to a previously uninfected field |
| Clean seeder after seeding a crop or variety |
Lessens risk of serious volunteer crop problems and minimizes weed seed dispersal |
| Clean out herbicide tank after spraying operations |
Lessens risk of herbicide damage to crops which are sensitive to in-tank residues |
| Clean harvesting equipment |
Lessens risk of transporting weed seeds, herbicide-resistant weeds and dispersing volunteer crop seed from field to field |
| Clean up field edges |
Minimizes spraying in coming years if weeds are kept out of the field |
| Use a chaff collector in harvesting operations |
Minimizes weed seed spread through the field |
| |
|---|
| Careful Use of Crop Protection Chemicals |
|---|
| IPM Techniques | Value |
|---|
| Estimate how much of a crop protection program is composed of chemical techniques and how much is non-chemical |
Non-chemical techniques like crop rotation, sanitation and pest prevention minimize dollars for pesticides and amounts of crop protection chemicals applied |
| Calibrate applicator |
Accurate calibration ensures that pesticides are not wasted through over-application or under-application |
| Spray only when wind conditions are safe |
Spraying under safe wind conditions minimizes off-target drift and impact on non-target organisms |
| Spot spray instead of spraying the whole field |
Spot spraying prevents pests from becoming a larger problem through the field. Spot spraying also controls pests with a minimal amount of pesticide |
| Use "buffers"-no-spray zones around sensitive areas |
A buffer zone prevents pesticide contamination of environmentally sensitive areas like sloughs and woodlands |
| Time spraying to avoid pollinators (bees, etc.) |
Spraying in the evening or when the crop is not in flower prevents impact on pollinators or beneficial insects |
| |
|---|
| Scouting, Economic Thresholds, Record Keeping |
|---|
| IPM Techniques | Value |
|---|
| Scout for pests starting the previous season at key times |
Scouting for canola pests starts the previous fall, and resumes from early spring seeding right through until podding. This alerts growers to problems early |
| In-season, scout fields to check for insects, weeds and disease before spraying |
Scouting can lead to a decision that a field may not need to be sprayed, or may reduce pesticide use through using only spot applications |
| Frequent scouting for insects and disease |
Provides an early warning and allows maximum time to control pests |
| Make a "no spray" decision based on low pest levels |
Allows growers to avoid unnecessary spraying when it is not necessary, does not pay off, or will unnecessarily increase selection intensity for pest resistance |
| Use diagnostic tools, kits and weather monitoring to help in spray decisions |
Assists in decisions to spray or not spray. Excellent kits and disease maps are available for diseases like sclerotinia, grasshoppers, etc. |
| Keep records of pest levels/spray applications |
Allows for a post-season review on how effective the control measure was and allows growers to prepare integrated plans for the next season |
What are 800 of Your Neighbours Doing to Manage Weeds, Diseases, and Insects in Canola
The past few years have been challenging for canola growers as they have worked their way through season after season of trying to protect their crops. They have been battling shifting weed spectrums and pests that are new and unfamiliar to the industry. They have had to learn and perfect new herbicide tolerance systems for their farms. All the while they have had to keep an eye on input costs as commodity prices have swung.
The canola industry conducted a survey on the crop protection techniques used by 881 western Canadian growers to find out how effective they thought their insect, disease and weed control programs have been. The survey provides the opportunity to sift through the collective pest management experience of 881 other growers. The survey also shows where the gaps in an integrated pest management (IPM) system might be.
New challenges mean that it is crucial that we make new strides in implementing better IPM techniques in canola. Why?
- Profitability - There is no doubt that in the past, canola has paid a lot of bills. It has been a lucrative crop for western Canada's growers. In past years, many growers have been able to realize fair returns from their crop despite the costs associated with crop protection and inputs. Nonetheless, during cyclical downturns in commodity prices, growers are looking for new ways of maximizing dollar returns. They want to make sure they are getting maximum effectiveness from their pest control programs.
- Environmental issues - Consumers have shown that they do pay attention to the environmental issues surrounding soil resources and food production. If new strides can be made in IPM and sustainable agriculture, this will assure the public that their concerns are being addressed.
- Complexity - Pest management in canola is more complicated than it is in cereals, and more expensive. Growers often find themselves steering through waves of pest control decisions relating to everything from blackleg to bertha armyworm to wild buckwheat. Significant decisions need to be made every summer month in terms of one pest or another.
- Changes in pests - Weeds have shifted on farms over the last 20 years. There are more thistle, more cleavers and more buckwheat on some farms. Herbicideresistant weeds are now a factor. New diseases like Alternaria and root rot and new insects like lygus and cabbage seedpod weevil mean that it's time to really pay attention to a pest management approach that takes advantage of all the tools that IPM gives a grower.
Growers are Using IPM Already
In general, growers are using many of the tools that IPM offers. The challenge in terms of IPM is to pull together better "packages" to improve integration of the IPM tools.
The following findings shed light on the current situation in terms of real-life examples of canola IPM. Use the Findings Worksheets on adjacent pages to look at how different practices are being implemented, and how your farming practices compare to over 800 of your farming neighbours. What are you doing to maximize profits from the amount of money spent on pest control? Where do you stand? Answer the questions in the last column. An "IPM Self Scorecard" legend is at the end of the worksheets.
Table 2. Rotation and Seeding Techniques
| IPM Technique | Value to the Grower | What the Study Found | My Assessment of How I Do This on My Farm |
|---|
| Seed canola no more frequently than one year in three to four on the same field |
Prevents buildup of sclerotinia, blackleg, root rot, Alternaria, cleavers, root maggot |
Growers planted canola once in every 3.6 years (AB), 3.83 years, (SK), 3.6 years (MB) |
I seed canola no more frequently than one year in every three to four years
Yes _____ No _____ |
| Review pest problems on a field before seeding to canola |
Allows growers to preplan and pick the best field for their canola |
50% of growers reviewed weeds prior to seeding decision, 11% reviewed insects, and 17% reviewed disease |
I review my weed, insect and disease problems in a given field prior to seeding decisions
Yes _____ No _____ |
| Put canola on fields where there was a "beneficial crop" the year prior |
Avoids disease buildup or volunteer problems carried over from the prior year. Beneficial crops include cereals, alfalfa and flax |
65% of growers put canola on a "beneficial crop," 26% on summerfallow, and 6% "problem crops" (e.g. peas) |
I put canola on a cereal, forage or summerfallow field
Yes _____ No _____ |
| Treated, pedigreed seed usage |
Pedigreed seed is cleaned to high standards with weed seeds and disease presence identified on the tag. Treated seed controls soil borne diseases and some insects |
86% of growers used pedigreed seed. Only 39% checked the tags for weed seed counts. In past blackleg problem areas, 75% check for this disease, 95% use treated seed |
I use certified, treated seed and I check the tag on certified seed
Yes _____ No _____ |
| Checking adjacent fields for pest hosts (e.g. sclerotinia or flea beetles on mustard plants) |
Checking and controlling pests on adjacent fields adds to the effectiveness of rotation because it cleans up pest hosts |
95% of growers cleaned up weeds on adjacent summer-fallow, 41% of these growers used cultural control (tillage), and the remainder used crop protection chemicals or a combination of cultivation and chemical controls |
The year prior to seeding canola I check surrounding fields for pests that might be a problem in next year's canola
Yes _____ No _____ |
| Early seeding, checked against soil temperature |
Allows for early growth of the crop to maximize crop competition |
64% made a special effort to seed canola early (AB); 43% (SK); 40% (MB). About 23% checked soil temperature prior to seeding |
I seed my canola as soon as possible (after I have double checked soil temperature)
Yes _____ No _____ |
Table 3. Soil Testing and Tillage Practices
| IPM Technique | Value to the Grower | What the Study Found | My Assessment of How I Do This on My Farm |
|---|
| Soil testing |
Soil testing allows the grower to deliver fertilizer in just the right amount for maximum payback. This ensures good crop economics and minimizes the risk of groundwater contamination |
Only 34% of growers soil tested the field prior to seeding canola. Of those, only 56% followed the recommendation with 16% applying less than recommended rates and 23% more than the rates recommended |
I do soil test my canola field prior to seeding and apply fertilizer according to recommendations
Yes _____ No _____ |
| Direct seeding |
Helps the grower to minimize soil disturbance and reduces germination of some annual weeds |
67% of growers seeded canola on stubble and tilled only with a light harrowing |
I seed my canola into stubble
Yes _____ No _____ |
| Light tillage for weed control prior to seeding |
Light tillage can kill off a first flush of weeds prior to crop emergence. This is most effective when the tillage operation does not dry out the seedbed |
74% of growers tilled lightly for weed control just prior to seeding |
I do light tillage for early weed control in the field to be sown to canola
Yes _____ No _____ |
| Tillage equipment used if not minimumtilling or zero tilling |
Lighter duty tillage equipment can help control some pests (such as shallow germinating weeds) and leaves soil residues in place minimizing soil erosion |
% of growers using the following equipment:
60% Harrowing
46% Heavy duty cultivation
31% Medium duty cultivation
8% Disker |
Where possible, I use tillage to control some pests, but I also try to keep enough trash on the soil surface to protect the soil from erosion
Yes _____ No _____ |
Table 4. Sanitation
| IPM Technique | Value to the Grower | What the Study Found | My Assessment of How I Do This on My Farm |
|---|
| Clean tillage equipment when entering new fields |
Prevents movement of disease organisms or weed seeds from one field to a previously uninfected field |
31% of growers used this technique |
I clean my tillage equipment to minimize spread of weed seeds and diseases from field to field
Yes _____ No _____ |
| Clean seeder after seeding a crop or variety |
Lessens risk of serious volunteer crop problems and minimizes weed seed dispersal |
71% of growers used this technique |
I clean my seeding equipment to minimize spread of volunteer seeds and weeds from field to field
Yes _____ No _____ |
| Clean out herbicide tank after spraying operations |
Lessens risk of herbicide damage to crops which are sensitive to in-tank residues |
90% of growers used this technique |
I clean my spray equipment to reduce the risk of herbicide damage
Yes _____ No _____ |
| Clean harvesting equipment |
Lessens risk of transporting weed seeds, herbicide-resistant weeds and dispersing volunteer crop seed from field to field |
53% of growers used this technique |
I clean my harvesting equipment to minimize spread of weed seeds, volunteers and herbicide-resistant weeds from field to field
Yes _____ No _____ |
| Clean up field edges where weeds arise |
Minimizes amounts that will need to be sprayed in coming years if weeds are kept out of the field |
27% of growers used this technique |
I clean field edges to minimize spread of weeds
Yes _____ No _____ |
| Use a chaff collector in harvesting operations |
Minimizes weed seed spread through the field |
1% of growers used this technique |
I use a chaff collector as I harvest to capture weed seeds
Yes _____ No _____ |
Table 5. Careful Use of Crop Protection Chemicals
| IPM Technique | Value to the Grower | What the Study Found | My Assessment of How I Do This on My Farm |
|---|
| Estimate how much of the crop protection program is composed of chemical techniques and how much is non-chemical |
Non-chemical techniques like crop rotation, sanitation and pest prevention minimize dollars for pesticides and amounts of crop protection chemicals applied |
One grower in 10 relies exclusively on crop protection products. About half of growers feel that they rely on crop protection chemicals for 80% or more of their crop protection needs |
I feel that I rely on crop protection chemicals for about ____% of my total crop protection program in canola |
| Calibrate sprayer |
Accurate calibration ensures that pesticides are not wasted through over-application or underapplication |
74% of growers who applied their own crop protection products calibrated their sprayer at least once |
I calibrate my sprayer at least once per season
Yes _____ No _____ |
| Spray only when wind conditions are safe |
Spraying under safe wind conditions minimizes off-target drift and impact on non-target organisms |
70% of growers did not spray if windspeeds rose to moderate. Shields were always used by 27% of growers and used sometimes by 3% of growers |
I shut down spraying in unsafe windspeeds OR I use a shield when windspeeds warrant
Yes _____ No _____ |
| Spot spray instead of spraying the whole field when feasible |
Spot spraying contains pests, preventing them from becoming a larger problem through the field. Spot spraying also controls pests with a minimal amount of pesticide |
82% of growers apply herbicides on a whole field basis only and do not spot treat |
I use spot applications on specific parts of my fields when the infestation allows
Yes _____ No _____ |
| Use "buffers" - no spray zones around sensitive areas |
Maintaining a buffer zone prevents pesticide contamination of environmentally sensitive areas like sloughs and woodlands |
42% of growers use buffers to avoid sensitive areas |
I use "no spray strips" to make sure I avoid contact with environmentally sensitive areas
Yes _____ No _____ |
| Time spraying to avoid pollinators (bees, etc.) |
Spraying in the evening or when the crop is not in flower prevents impact on pollinators or beneficial insects |
Only 9% of growers sprayed during flowering in daylight hours |
I avoid spraying when beneficial insects (bees, etc.) are in the field
Yes _____ No _____ |
Table 6. Scouting, Economic Thresholds, Record Keeping
| IPM Technique | Value to the Grower | What the Study Found | My Assessment of How I Do This on My Farm |
|---|
| Scout fields to check for insects, weeds, diseases before spraying |
May lead to the discovery that a field may not need to be sprayed, or may reduce pesticide use through using only spot applications |
94% of growers (including family members) scouted for weeds and 88% scouted for diseases or insect problems |
I scout my fields (or I make sure someone else does)
Yes _____ No _____ |
| Scout for weeds starting the previous season at key times |
Scouting for canola pests starts the previous fall, and resumes from early spring seeding right through until podding. This will alert growers to problems early |
58% scouted the previous fall; 58% scouted just before seeding; 95% scouted early in crop development; 66% scouted late in crop development |
I check the field that I plan for seeding canola the previous fall and I look for particular pests
Yes _____ No _____ |
| Frequent scouting for insects and disease |
Allows for early alert and maximum time for action in controlling the pest |
11% scouted for insects or diseases daily, 42% scouted twice a week; 24% scouted once a week; and 7% scouted once every two weeks |
I scout my canola fields at least once a week during the time the crop is growing in the field
Yes _____ No _____ |
| Make a "no spray" decision based on low levels of pests |
Allows growers to avoid spraying when it is unnecessary or does not pay off |
14% of growers made a "no spray" decision based on weed population, and 36% of growers made a "no treat" decision based on low insect populations |
I occasionally find that my scouting allows me to skip a spray operation that I thought I would have to make
Yes _____ No _____ |
| Use diagnostic tools, kits and weather monitoring to help in spray decisions |
Excellent kits and disease maps are available for diseases like sclerotinia |
Use of kits and diagnostic services were virtually zero. Some growers occasionally used weather reports in their threshold decisions |
I have used diagnostic tools like petal tests and sclerotinia alerts in the past
Yes _____ No _____ |
| Record keeping for pest levels/spray applications |
Allows for a post-season review on how effective the control measure was and allows growers to prepare integrated plans for the next season |
81% to 91% recorded products sprayed, rates, dates; 50% to 60% recorded weather at spraying and crop stage; less than 50% recorded escapes and effects on pollinators |
I keep records for pests in a given field and refer to them from time to time in subsequent years
Yes _____ No _____ |
Table 7. IPM Self Scorecard
| Number of "yes" answers | Where I Stand |
|---|
| 18 to 26 |
I have most of the elements for an IPM program to function on my farm |
| 14 to 17 |
I am implementing many IPM tactics but may want to wrap them up into a "packaged" approach and review other things that I could implement |
| 0 to 13 |
I have a great opportunity to realize more efficiencies in my pest control program |
Proven Tips and Evidence for 10 Solid Techniques
Using an integrated approach to managing weeds, diseases and insects in canola needs to make sense from a financial standpoint as well as an environmental point of view. Here are 10 techniques where there is evidence (or common sense) indicating that there will be a payoff in using an integrated approach.
Weed Control in the Seasons Before Seeding Canola
Choosing a particular field to seed to canola in the coming year may improve the effectiveness of weed control in all years. The following is one approach, based on work by Alberta scientists.
Technique 1 - Wild oat control
Evidence: IPM and wild oat control using economic thresholds
Dr. John O'Donovan of Agriculture and Agri-Food Canada (AAFC), Beaverlodge, AB, ran a two-year study where he sprayed wild oats in farmers' fields only when it paid to spray. He found that he could skip a spray for wild oats far more often in cereals (especially barley) than in canola (Table 8). Note that in these actual farmers' fields barley was almost twice as likely as canola to require no sprays.
Table 8. Percentage of Fields Where Farmer Could Skip A Wild Oat Spray
| Crop | % |
|---|
| Canola |
39 |
| Barley |
77 |
| Wheat |
55 |
Source: Dr. J.T. O'Donovan
Technique 2 - Volunteer cereals/crops control through fall tillage
A light tillage in the fall while the soil is still warm (above 6°C) will give close to 90% germination of volunteer cereals. Seed has had the majority of its dormancy bred out. Use this to an advantage by encouraging it to germinate in the fall. Let the fall frosts and winter snow control the bulk of volunteers and save a herbicide decision in the spring.
Technique 3 - Winter annuals including cleavers, stinkweed, shepherd's purse
These are "canola unfriendly" broadleaf weeds because they either have no control methods in canola or are expensive to control in the crop. Light tillage in the fall will give 80 to 90% control of fall-germinated weeds.
Technique 4 - Canada thistle control through partialfield treatments
Canada thistle is one of the five most common weeds in canola fields. The latest weed surveys on thistle are shown in Table 9. Note that thistle is in about half of all fields and it generally covers only a little over 20% of the land within a field, normally within patches or on headlands.
Table 9. Canada Thistle Survey (Averages)
| Thistle Infestation Characteristics | Alberta | Saskatchewan | Manitoba |
|---|
| Percentage of total fields where thistle is found |
53 |
46 |
59 |
| Percentage of individual field infested with thistle |
24 |
22 |
21 |
| Number of shoots within the patch |
2.5 |
2.7 |
2 |
Source: Weed Survey Series, Dr. A.G. Thomas, AAFC Saskatoon Research Centre
Map thistle patches while doing field work in preparation to seed canola. Check headlands in June and mow in the prebud stage to maximize the impact on root carbohydrates. Also spot treat with glyphosate or with a product containing clopyralid (such as Lontrel in canola or Curtail M in cereals.)
As harvest approaches, check the field to see if infestation is widespread enough to warrant using the pre-harvest rate of glyphosate as the label indicates. Pre-harvest or patch herbicide applications to thistle the year before canola will save blanket spraying the entire canola field with in-crop thistle mixes. It may be possible to leave thistle spray out of the canola herbicide tank mix.
Disease Control in the Seasons Before Seeding Canola
Technique 5 - Crop rotation for disease control
Crop rotation is a good defence against all canola diseases (Figure 1 and Table 10). The key to disease control lies in planning on a multi-year basis
Figure 1. Impact of Rotation on Canola Diseases 
Table 10. Effect of Rotation on Canola Diseases
| Disease | Rotation Recommendation | Limits to the Effectiveness of Rotation | Additional Measures Needed |
|---|
| Blackleg |
Three seasons of no canola in the field |
Spores can blow in from adjacent fields, can come in as a seed contaminant |
Scout adjacent fields for hosts the year before seeding canola, grow resistant varieties |
| Sclerotinia |
Three seasons of no sclerotiniasusceptible crops |
Spores can blow in from adjacent fields |
Scout adjacent fields for hosts the year before seeding canola, use test kit to determine problem in crop |
| Alternaria |
Three seasons of no canola in the field |
Alternaria spores are widespread and can exist on many hosts, can blow in from adjacent fields and can come in as a seed contaminant |
Scout adjacent fields for hosts the year before seeding canola (See recommendations on swathing, variety selection) |
| Brown girdling root rot |
Three seasons of no canola in the field |
Four years only reduces the level of infection within a field |
(See recommendations on seeding and variety selection) |
| Staghead |
Three seasons of no B. rapa canola varieties in the field |
Can come in as a seed contaminant |
(See recommendations on variety selection, seed selection) |
Source: Canola Growers Manual
However, rotating crops is not 100% effective. Disease spores can blow in from adjacent fields or arrive in a field courtesy of infected seed. The reasonable approach is to throw up a farm-wide disease shield that consists of rotation, clean seed and patrolling bordering fields the year before seeding to look for disease hosts
Evidence: Crop rotation does work
Recent data from the Agriculture and Agri-Food Canada (AAFC) Brandon, MB Research Centre shows how effective rotation is in controlling sclerotinia and especially blackleg. Rotation is less effective in managing sclerotinia because it is more "mobile," entering fields from neighbouring fields via wind.
This does not mean that rotation is ineffective as a sclerotinia control method. Studies done by AAFC scientists in Saskatchewan show that sclerotinia risks are higher if growers tighten up their rotation and if moist weather prevails at the time of disease infection.
Table 10 outlines the effectiveness of crop rotation in controlling canola diseases. It also provides some additional cultural tools that can be used to supplement rotation in managing these diseases.
Insect Control in the Years Before Seeding Canola
Technique 6 - Scout for insects the year before
Many canola insect pests are difficult to anticipate the year prior to seeding. Some can fly long distances, like the diamondback moth, or occur only cyclically, like bertha armyworm. However, it is easy to prepare for insects like the flea beetle. This is especially true in areas that experience flea beetle problems from time to time.
Evidence: Manage flea beetles the year before seeding canola
Get the field ready for next year's flea beetles the year prior to seeding canola. Why the year before? Look at the data in Figure 2. Note how quickly flea beetle populations increased in a newly sown canola field. This is evidence that work is required in advance to avoid being forced to react to the pest.
Figure 2. Flea Beetle Trap Counts 
Individual canola seedlings can weigh as little as 0.15 g when they are young and vulnerable to flea beetle attacks. This is not much tissue and this pest can devour it in a single warm afternoon. That's another reason why IPM work the year before is so crucial.
The following practices will help shield against flea beetle invasions in next year's canola:
- Leave standing stubble in the field to be seeded to canola. The stubble will trap snow, maximize moisture and allow early seeding. The earlier canola is seeded, the better the plants will withstand flea beetle activity. This insect eats and moves much more slowly in cool weather.
- Check the areas adjacent to the field for flea beetle populations in late summer and early fall. Lots of flea beetles on wild mustard plants or other mustard family weeds is a signal that there are going to be flea beetles overwintering in leaf litter and around the field.
- If there have been flea beetles in the area in the past and if fall populations signal potential trouble ahead, plan to seed canola first. The canola will get off to an early start thanks to the extra moisture trapped by the stubble. The canola will be past the five- to six-leaf stage before the beetles will become the most active. Beetle feeding will be less of a problem.
Also plan for other insects the year before seeding canola. Insects like diamondback moth fly great distances. Bertha armyworm and grasshopper infestations follow cycles of several years. The best preparation to manage these pests is to read up on the biology and control of each insect. Also keep in touch with extension services and the agricultural research community to watch for forecasts of how serious these pests are likely to be in the coming year.
Following Through on IPM: The Canola Year
In the seeding year, follow through on in-crop IPM techniques. Approach pests as a group (weeds, diseases and insects) and pull together all of the tools in an integrated way to manage the pests.
Technique 7 - Choose seed variety and source carefully
Evidence: Seed selection and source counts
There are marked differences between varieties in terms of blackleg resistance. Choose varieties with at least an "MR" rating for at least some fields within a blackleg zone. Choose varieties that offer the best package of options for weed control as well as yield potential.
Buy certified seed and check the specifications on the lot purchased to make sure it does not have blackleg infections or high levels of cleavers or other weeds.
Recently, two studies (one Canadian and one Australian) looked at the performance of bin-run seed versus certified seed (Table 11). In both canola growing areas, there was a rise in the use of bin-run seed as seed costs rose. Both studies show a remarkably similar loss in net profit averaged over a number of sites. This was due to variable quality and seedling vigour. This says nothing about the catastrophic losses that would occur should bin-run seed contain hidden levels of blackleg inoculum or cleavers seeds.
Table 11. Comparison of Bin-run Seed Performance
| Source | Certified Seed | Bin-run (% of Certified Yield) | $ Loss/ac* |
|---|
| Australian data |
100 |
92 |
$13.48 |
| Western Canadian data |
100 |
93 |
$13.48 |
* At 30 bu/ac and $5.00/bu canola Source: S.J. Marcroft, Victoria Institute of Dryland Agriculture
Technique 8 - Fertilizer placement helps manage weeds
Evidence: Fertilizer planning helps in wild millet control
A fast growing, healthy crop can fend off pests in the early few leaf stages where the seedling is vulnerable to insect damage or weed competition. Getting the crop out of the ground quickly, then through the first leaf stages is key. Apply a balanced package of plant nutrients-it's the best way to stimulate rapid growth. Band these nutrients to give the crop preferential access and help the crop battle pests.
Instead of wild millet increasing as fertility increases, banding nitrogen (N) actually decreases the level of wild millet. As shown in Figure 3, the weed was manipulated into oblivion by using minimum disturbance seeding and banding the fertilizer close to the crop so it could out compete the weed.
Figure 3. Effect of Fertilizer Banding on Wild Millet Levels 
Strategic placement of fertilizer makes sense from a weed control point of view because it produces healthy, fast growing crops more rapidly than broadcast fertilizer. Table 12 shows how side banding N and drilling phosphorus (P) with the seed produces a much better yield.
Table 12. Effect of Fertilizer Placement on Yield
| Fertilizer Placement | Yield (bu/ac) |
|---|
| Both P and N broadcast |
22.0 |
| N broadcast and P drilled in |
24.4 |
| N banded and P drilled in |
34.8 |
Technique 9 - Good crop establishment
Evidence: Seeding rate, row spacing, depth and date help seedlings grow quickly and fend off weeds, insects and diseases
Good establishment of a crop and fast canopy closure means that weeds will be shaded early. Figure 4 shows how bumping up the seeding rate of canola can reduce wild oat competition.
Figure 4. Effect of Seeding Rate on Wild Oat Levels 
Do not bump up the seeding rate by 50% to control wild oats. Use a seeding rate that results in a final plant count of 96 to 145 plants/m2 (80 to 120 plants/yd2)-a healthy early closure of the crop canopy will help battle pests.
Follow these seeding rules:
- Seed early. Seeding early gives the crop the jump on pests that do better under warmer weather conditions (like wild millet and flea beetles). It also allows the crop to choke out "flushing weeds" that are not controlled by a single herbicide application.
- Seed shallow to moisture. This allows rapid crop establishment.
- Seed near nutrients. Banding N close to the seed and putting P close to the seed gives the crop better access to nutrients than the weeds.
Technique 10 - Frequent scouting is crucial Scouting canola early is key to making sure problems are nipped in the bud. It also can save the cost of inputs because scouting very often can lead to a reduced number of spray passes.
Provincial pest control guides have excellent scouting instructions. It is important that each time the field is scouted, the scout stays alert for weeds, diseases and insects (as well as fertility issues). Table 13 is a summary of how often scouting should be done and what to look for when scouting a field.
Table 13. Reasons to do In-season Scouting
| Stage of Canola at Scouting Time | What to Watch For | Advantages |
|---|
| Emergence to cotyledon stage |
Early flushes of cool season weeds |
May allow to plan for control of early season weeds before they inflict damage |
| Flea beetle damage |
Warm conditions and heavy flea beetle pressures can destroy a crop in hours |
| Cotyledon to six-leaf stage |
Weed inventory |
May allow for lower pesticide rates based on species in the field or to skip a spray if economic thresholds are not attained |
| Rosette to early bolting |
Check for effectiveness of weed control. Watch for red turnip beetles, diamondback moth larvae and early blackleg lesions |
Spot weed control misses early and watch for early insect problems so that control strategies can be planned |
| Bud stage |
Begin watching for lygus bug and cabbage seedpod weevil |
Early warning so that control strategy decisions can be made |
| Flowering |
Check for sclerotinia and early stages of Alternaria blackspot |
Examine infection levels and check for the economic benefits of spray/no spray decisions |
| Flowering to late podding |
Watch for bertha armyworm and cabbage seedpod weevil |
Early warning allows for planning of control and economic threshold decisions |