Spring
and Winter Canola: Planting and Crop Development
| Author: | OMAFRA Staff
| | Creation Date: | 6
May 2009 | | Last Reviewed: |
6 May 2009 |
| Corn
| Soybeans | Forages
| Cereals | Dry
Edible Beans | | Spring and
Winter Canola | Other Crops |
Soil Management | | Soil
Fertility and Nutrient Use | Field
Scouting | | On-Farm Stored
Grain Management | Weed Control
| | Insects and Pests of Field
Crops | Diseases of Field Crops
| Appendices | Pub
811: Agronomy Guide > Spring and
Winter Canola > Planting and Crop Development Excerpt
from Agronomy Guide for Field Crops Order
OMAFRA Publication 811: Agronomy Guide for Field Crops -
Seed
Quality Know the quality of the seed being planted. Germination
is the major quality consideration used in grading seedlots. Germination standards
test the ability of a seedlot to produce normal seedlings under favourable conditions
of 95%-100% humidity and 25°C. Stress conditions in the field following planting
often reduce field emergence compared to lab results. Certified seed must meet
purity and germination standards. Seed TreatmentsCertified
seed is treated with a fungicide and insecticide. The fungicide controls seed-borne
and early-season soil-borne diseases, including blackleg, seed decay, damping-off
and seedling blight. Insecticide seed treatments contol flea beetles for 2-4 weeks.
Slow seedling development may allow flea beetle populations to build after the
effectiveness of the seed treatement has declined, requiring a follow-up foliar
insecticide treatment (see OMAFRA
Publication 812, Field Crop Protection Guide). Spring
Canola Seeding DateTypically, early seeding produces the highest yields.
In recent years, some growers report good yields from seeding in mid-May. Consider,
though, that flowering generally begins 50-55 days after planting and lasts 10-21
days. Temperature stress (>28°C) during flowering has a greater negative
impact on yield than weather at any other stage. Early SeedingSeed
as early as soil conditions permit. Canola will germinate and grow at a soil temperatures
of 1°C, but 10°C is ideal for rapid emergence. Soil conditions and weather
forecasts should be the ultimate guide, however 3°C or higher is a reasonable
target for planting. Increase seeding rates by 5%-10% when canola is planted very
early to account for slower emergence and increased seedling mortality. Canola
is slower to establish than cereal crops and is less tolerant to spring frost.
When seedlings emerge, the growing point is exposed between the cotyledon (seed)
leaves and can be easily killed by a frost. Early planted canola also has a higher
risk of infestation by cabbage seedpod weevil during the flowering/early pod stage.
If canola growth is slow following planting due to cold weather, flea beatles
may become a problem. Late Seeding If seeding is delayed, it is
critical to conserve soil moisture and to plant into moisture for rapid, uniform
emergence. Avoid seeding after June 1st in areas where swede midge has been identified.
See Swede midge or visit
the OMAFRA website at www.ontario.ca/crops.
Table 6-1. Amount of Seed Required to Meet Target
Seeding Rate 1,000-Seed Weight
(gm) | Target Seeding Rate1 kg/ha
(lb/acre) | Seeds /m1(/ft) |
| 3.5 | 3.63
(3.3) | 20 (6.1) |
| 4.0 | 3.63
(3.3) | 20 (6.1) |
| 4.5 | 4.7
(4.2) | 20 (6.1) |
| 5.0 | 5.2
(4.7) | 20 (6.1) |
| 5.5 | 5.7
(5.1) | 20 (6.1) |
| 6.0 | 6.2
(5.6) | 20 (6.1) |
Winter Canola Seeding Date
Seed winter canola August 15-30
(in Southwestern Ontario, August 20-September 10). Seeding within these dates
results in the canola developing 4-6 leaves and an adequate size root system (approximately
1 1/4 cm or 1/2 in. diameter) to reduce the chances of frost heaving and desiccation
in the spring. Delays beyond these dates greatly increase the risk of winterkill.
If canola bolts in the fall, it will not survive through winter. Heavy competition
from weeds or volunteer cereals in the fall can force canola growth, increasing
chances of winterkill. Seeding RateThe
optimum plant stand for canola is 75-130 plants/m2 (7-12 plants/ft2).
In 19-cm (7.5-in.) rows, this is equivalent to 14-25 plants/m (4.5-7.5 plants/ft)
of row. Target seeding rates need to account for large differences in seed size
between varieties. Table 6-1, Amount of Seed Required to Meet
Target Seeding Rate, presents the desired seeding rate for different seed
sizes. Increase seeding rates slightly (5%-10%) on soils prone to crusting, when
seeding very early or very late. Seed BulkingAchieving
target canola seeding rates can be a challenge with some drills. Calibrate seeding
equipment before heading to the field. Ensure that each of the drill's seed cup
openings are set the same. Bulking of seed with pelletized MAP (11-52-0), sulphur
or corn cob grits are options for improving seeding rate accuracy. Do not use
other fertilizers with canola seed, as this increases the risk of reduced seed
germination. Seeding DepthCanola seedlings
expend a great deal of energy to emerge, making quick, even emergence the goal
in seeding. Seed 1.25-2.5 cm (1/2-1 in.) deep, if there is adequate moisture,
and deeper if necessary to plant 0.6 cm (1/4 in.) into moisture, but not deeper
than 4 cm (1 1/2 in.). If the depth to reach moisture is deeper, it is better
to wait for moisture. Press wheels on the drill help place the seed uniformly
at the bottom of the seed trench. Drill bounce is more of a problem at speeds
over 8 km/hr. Increasing speed affects planting depth. If canola is seeded through
the grass seed box, seed tubes should be directed behind openers and in front
of the press wheels. Seeding Rate The seeding
rate can be determined by knowing the 1,000-seed weight in grams found on the
seed tag and using the following formula: Metric Seeding
rate (kg/ha) = (desired plant population/m² x 1,000-seed wt. (gm) ÷
seedling survival rate) ÷ 100 Imperial Seeding
rate (lb/acre) = (desired plant population/ft² x 1,000-seed wt. ÷
seedling survival rate) ÷ 10.4 Seedling survival (final
stand) = % germination (on seed tag) x % expected emergence Sample
Calculation
Using seed size of 5 gm/1,000 seeds, 72% final stand
Seeding Rate (lb/acre) = (7 plants/ft² x 5 gm/1,000 ÷
0.72) ÷ 10.4 = 4.7 lb/acre Seed Drill Calibration
Collect
and weigh (in grams) the seed from a drill opener and use the following formula
to convert to lb of seed/acre using a 7.5 in. row width. Check several openers.
Seeding rate (lb/acre) = gm of seed/opener/30.5 m (100 ft) of travel x
1.54 Seeding ConditionsGood seedbed
preparation is vital, due to canola's small seed size and shallow planting depth
requirements. The seedbed should be level, firm, and crumbly with moisture in
the top 2.5 cm (1 in.) of the surface. A crumbly soil will resist crusting after
pounding rains, allowing the tiny seedlings to emerge. This is critical, since
there is no opportunity to correct crusting. The crust can break the hypocotyl
arch (the seedling stem) that lifts the cotyledons (seed leaves) above the soil
surface. A firm seedbed will help hold moisture near the surface and aid in uniform
planting depth and uniform emergence. PackingLet
soil conditions determine whether to pack the seedbed before or after seeding.
Packing before seeding can help level and firm the seedbed, improving seeding
depth control and reducing soil moisture loss. Packing after planting can improve
emergence and yield, if the soil dries out before emergence. Packing after seeding
may bury the seed deeper if the field was ridged at seeding, thereby reducing
emergence. Broadcast SeedingBroadcasting
of canola seed is a greater risk than seeding with a drill but can still be effective
in some situations. Some growers broadcast canola seed with fertilizer onto a
prepared seedbed. The advantages of broadcast seeding are higher yield potential
because of early seeding date, time savings and low cost. The major disadvantage
of broadcast seeding is uneven planting depth and uneven seed application (if
uncalibrated). Frost injury is also a risk with an early seeding date. Good seedbed
preparation before broadcasting followed by harrowing or packing will keep seed
depth constant and ensure good seed-to-soil contact. Despite this, broadcast stands
can be inconsistent in dry years. Seeding rates should be higher when broadcast
compared to drilled (6-8 kg/ha or 5-7 lb/acre). Replant
DecisionsGenerally, canola plants in thin stands will branch out aggressively
to compensate, resulting in no significant yield loss. Each year, some fields
suffer from thin stands due to poor emergence, frost, insects and diseases. To
make a decision, assess the health and plant population of the surviving stand.
It is easy to overestimate the extent of the injury and underestimate the ability
of seedlings to recover. A uniform stand of 11-22 healthy plants/m2
(1-2 plants/ft2) will have a yield that is 90% of a full stand. Assess
populations using the hula hoop method to determine plant populations (see Appendix
K, Hula Hoop Method for Determining Plant and Pest Populations, on page 268). Plant
DevelopmentSpring canola is a cool-season crop that grows best at temperatures
above 10°C and below 30°C (optimum 20°C - 25°C). Crop development
is closely related to the amount of sunshine received, although temperature also
is a factor. Table
6-2. Approximate Growing Degree Days to Reach Various Stages of Development
Growth Stage (decimal code system) | Description | Growing
Degree Days (Base 0ºC)1 | | 0-1.0 |
Emergence | 152-86 |
| 1.1-1.2 | 1-2
leaf stage | 282-324 |
| 1.4-1.6 | 4-6
leaf stage | 411-463 |
| 3.0-4.0 | Bud-first
flower | 582-666 |
| 4.9 | Late
flower | 759-852 |
| 8.1 | Maturity2 |
1,432-1,557 | 1Adapted
using research data from AAFC, Scott and Swift Current. 2Occurs
when seed begins to mature, 10% seed colour change. Development of
canola is more closely aligned with growing degree days than crop heat units,
similar to that of spring wheat. Canola matures in approximately 90-100 days in
southern growing areas, and 110-120 days at New Liskeard. In northern growing
regions, longer day length can partly compensate for lower temperatures. Drought
and heat stress will shorten the days to reach maturity. The approximate GDDs
to reach various stages of development is presented in Table
6-2, Approximate Growing Degree Days to Reach Various Stages of Development.
High temperatures at flowering cause flower and pod abortion. Maturity differences
among varieties is typically less than 7 days. Principal
Growth Stages of CanolaRosetteGermination of canola is similar
to other dicots - seedlings emerge with the growing point contained between cotyledons
(seed leaves). A 5-6-leaf rosette forms, with larger, older leaves at the base
and smaller, younger leaves developing in the centre. Leaf area development is
directly related to growth rate and final yield. Stem Elongation (Bolting)
Lengthening days and rising temperatures trigger bud formation in the
centre of the rosette and the stem rapidly "bolts". The main stem reaches
30%-60% of its final height at the start of flowering. A large leaf area (especially
upper leaves) at this stage strongly influences pod set and final yield. FlowerFlowering
begins with the opening of the lowest bud on the main stem and continues upward
on both main and secondary branches. Flowering continues for about 14-21 days.
Table
6-3. Nitrogen Recommendations for Spring Canola N:Canola
Price Ratio ($/kg N:$/kg canola) | Recommended N Rate
(kg/ha) | | 2 | 119 |
| 2.5 | 108 |
| 3 | 96 |
| 3.3 | 90 |
| 3.5 | 85 |
| 4 | 74 |
100 kg/ha = 90 lb/acre To use this table, the price of canola
must be known or estimated. Canola at $450/t and nitrogen at $1.50/kg results
in a price ratio of 3.3 (1.50/0.45). At these prices, use 90 kg/ha of nitrogen. Fertilization
occurs within 24 hours of pollination. The maximum plant height is reached at
peak flowering. Typically, flowering begins 50-55 days after planting (582-666
GDD). Temperature stress (>28°C) during flowering causes flower abortion
and is detrimental to yield at this stage (Plate 33).
Canola can either self-pollinate or cross-pollinate, depending on various environmental
factors. Plate
33. Heat blast. Hot temperatures during flowering (especially spring varieties)
can cause heat blast and reduce seed yields.

RipeningThe
leaf, stem and especially pod surface area are major food sources for the developing
seed. Seed filling is complete about 30-40 days after flower opening. Pod ripening
occurs from bottom to top of the plant. When seeds have turned green, leaf senescence
begins, and the pod wall becomes the major source of food, although the stem is
also important. When 30%-40% of seeds on a plant have started to change colour,
seed at the top of plant will be nearly mature, and the average seed moisture
will be 30%-35%.
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