Canola success starts with a uniform stand of five to eight plants per square foot. Canola counts at the two- to four-leaf stage provide a check up on the seeding operation and if canola is on track to achieve its full yield potential.
The following article was written by Jason Casselman, an agronomy specialist and plant establishment lead with the Canola Council of Canada.
How to count
Take a few counts across the field to come up with an average plant density for that field. Two counting options are:
Hula hoop. The hoop toss adds randomness to the count. A hoop with an inside diameter of 19″ covers two square feet. Count the number of plants inside the hoop and divide by two to get plants per square foot.
Metre stick. Count the seedlings per metre of row. Multiply the count by 100 then divide by the row spacing in cm to get plants per square metre. Divide by 10 for an approximate conversion to plants per square foot.
Citizen science – Canola Counts
The Canola Council of Canada (CCC) is running its Canola Counts citizen science project again in 2022. We would like farm families, agronomists and crop scouts to count canola plants at the two- to four-leaf stage and enter results at canolacounts.ca. People can enter as many fields as they want. The program provides a summary email for each entry, and participants can review Canola Counts maps at the end of the season to compare their fields to regional averages. The CCC uses the data to compare typical canola populations by region. If the farm uses drone or satellite imagery, the plant count process is a great opportunity to ground-truth different areas of the field that might be indicating different levels of biomass or range in the vegetation index.
Common causes for low counts
Boots on the ground to count and ground-truth give growers and agronomists clues to lower-than-expected results. Causes for missing or weakened plants can include:
- Dry seedbed. With limited seedbed moisture, canola seeds may not germinate or seedlings may dry up shortly after germination.
- Excess moisture. Flooded soils can stop root function and kill canola seedlings within days.
- Rain after seeding can cause the topsoil to crust, which stops emergence.
- Frost damage. Dried up seedlings may be difficult to find a few days after a frost.
- Strong winds can shear off canola seedlings or blow away topsoil and seed.
- Fertilizer toxicity. Mortality from seed-placed fertilizer tends to be higher if seeding equipment has low seed bed utilization and soils are dry.
- Seedling disease. Risk increases for canola seeded too deep into cool, moist soils.
- Insect damage. Cutworms and flea beetles can remove a lot of seedlings before anyone notices they’re gone.
- Seed rate. Without calibrating for seed size and target stands, plant populations can be lower than expected.
- Seeding depth. Deep seeding can reduce emergence rates and increase seedling disease. Shallow seeding can also reduce emergence, especially in dry conditions.
- Seeder issues. Repeatable patterns in rows or sections usually suggest a mechanical issue with the seeding tool.
Canola stand establishment is an essential step in profitable canola production. By scouting at the two- to four-leaf stage to count plants, growers and agronomists can identify problems that could be fixed immediately – like insect feeding or reseeding – and establishment problems that could be improved with a new plan for next year.
For more details, read “Evaluating the stand” in the Plant Establishment section at canolaencyclopedia.ca and “Plant populations: How to count? Why low?” at canolawatch.org/fundamentals.
