This is a companion file for the Canola Diagnostic Tool. The diagnostic tool asks questions to come up with a short list of potential causes for an observed problem in a canola field. The more questions you answer, the more refined the search. Going through this checklist ahead of time will make answering the questions easier and more accurate.
The diagnostic tool is an objective way to assess a field, and helps you to avoid making assumptions about symptoms. Note that while visual symptoms can narrow the list of possible causes of poor canola growth, rarely will you be able to identify a single primary cause based on symptoms alone. Additional information and/or follow up sampling and testing is often required to further refine a short list of possible causes. Data collected through this checklist can be used to sort through the list of causes and find the few most likely.
Step 1—Collect background information
Collect as much background information on the history and characteristics of the field as possible. Use these details to refine the diagnosis if the tool comes up with a number of possible causes: Record:
1. Crops grown on the field the previous 3 years
2. Soil test results (including organic matter, pH, salinity)
3. Fertilizer blend and placement
4. Seeding date
5. Seeding rate
6. Seed depth, and type of seeding tool
7. Packing system
8. Seed source (Certified, bin run, variety, treatment)
9. Soil temperature and moisture at the time of seeding
10. Crop emergence timing and uniformity
11. Weather conditions through the season (moisture, wind, hail, frost)
12. Herbicides applied this year and previous years, including products and rates
Step 2—Field observations
Start with an overall look at the field, and then hone in on the general appearance of affected plants. Collect the following details:
1. Patterns of damaged or missing plants in the field. Describe the patterns and note locations
2. State of volunteers or related weeds outside the field perimeter
3. Plant stage (germination, rosette, bud/bolting, flowering, ripening/harvest)
4. Plant population per square foot or square metre
5. Parts of the plant that are damaged
6. Discoloration of plant or plant tissue compared to normal. Note the colour and where it appears (stem, leaf, leaf veins, etc.)
7. Lesions present, with specifics on lesion location, colour, shape and other features
8. Abnormal growth compared to unaffected plants. Look for stunted, twisted, wilted or lodged plants. Look for missing or abnormally formed plant parts
9. Describe the damage. Chews, rips, nips, broken stems, etc.
10. Dig in bare patches to look for seeds and insects
11. Dig up unhealthy plants to check roots
Scout fields weekly from crop emergence to maturity, to check canola for any damage and for the kind and number of insects present. If yield-limiting problems have been identified, or if canola is more vulnerable to pests and disease due to field and weather conditions, increase the frequency of scouting to daily. Scouting every two weeks is sufficient later in the season as long as conditions are not favourable for pest thresholds.
In canola fields of less than 100 acres, scout a minimum of five locations. In fields greater than 100 acres, assess 10 locations. Scouting patterns depend on pest distribution and field configuration, but in general should include all parts of the field and scouted locations should vary unless a problem has been identified. If a problem has been identified, note the location and follow-up on those sites to monitor its development. At the scouting location, examine the canola canopy for discoloration and plant damage. Examine the leaves and roots of the canola plant. Dig out the plant instead of pulling, so as not to lose root material and any pests which may be close to the root system. Collect samples for any disease or insect that cannot be identified and take them to an agronomist or diagnostic lab. Sample labels should include grower’s name, date, field location, distribution of symptoms and crop history, noting information on chemical/fertilizer use and any extreme weather conditions.
For insect thresholds that depend on sweep net counts, be sure to use the proper technique. Improper sampling can result in over- or under-representation of pest population. Click here for a Canola Watch article or check with your Canola Council of Canada agronomy specialist, provincial agricultural representative, or guides to crop protection for economic thresholds and control recommendations.
A complete scouting kit should contain:
10X magnifying glass to differentiate disease lesions, and to identify small insects and other types of damage. Purchase ones with a protective cover so the lens will not get scratched. Source: Hardware stores, and hobby (geology) stores.
Standard sweep net for identification and collection of insects, both pests and beneficials. The standard size has a 35” long handle and a 15” (38 cm) diameter net. Source: UFA in Alberta, Pro Metal Industries in Regina, or insect monitoring equipment supply companies.
Clippers for cutting canola stems to look for disease. Clippers provide a nice clean cross section. Purchase ones that are stainless steel (avoid carbon steel) so they can be disinfected and will not rust.
Hand trowel to evaluate roots and to look for cutworms. Plants should always be dug out as this prevents the loss of root material and insects located close to the roots. In dry soil, cutworms can be found at a depth of 8-10 cm. (4”). Purchase a stainless steel hand trowel.
Seed depth finder to ensure the placement of canola seed at the recommended half inch to one inch depth. Source: Often available as promotional items from seed suppliers or Hume Seed Depth Finder.
Containers for samples of plant material and insect specimens can include paper bags and large perforated Ziploc bags and other containers (old film canisters) for collecting specimens. An aspirator can help isolate insects into vials. Vials or plastic containers are good for transporting insects for identification. Source: Hobby (entomology) supply companies.
Grease pencil or Sharpie for labelling specimen containers.
Flags for measuring or to mark areas with potential problems.
Measuring device, either a hoop, meter stick or a two-sided square. The number of insects and plants per square meter determine management decisions. Source: Folding squares at hardware stores.
Disposable booties to prevent transmission of disease and noxious weeds from affected fields to healthy fields. If disposable booties are not available, remove loose dirt from boots and disinfect with diluted Lysol or bleach solution. Source: Veterinary or industrial safety supply companies.
Spray bottle of sterilizer for cleaning boots and equipment between fields.
Garbage bags for disposal of booties or to wrap contaminated equipment.
Resources. Factsheets, disease publications and crop disease pictures for identification of disease, pests and deficiencies. Source: Canola Council of Canada
Notebook and pen to record details of areas to return to for monitoring, noting distribution of disease, sampling, etc.
Smart phones have become an invaluable tool for scouting: Taking photos, keeping records and communicating with others. Photos can be sent to agronomists for assistance with quick identification purposes.
Lightweight bag for carrying these items.
Click here for more details on the scouting toolkit.