Winter Canola Production

The Ultimate Guide to Growing Winter Canola in Ontario

Winter canola seed varieties offering better winter survival and yield potential are renewing interest in the crop in Ontario.

Benefits of Winter Canola include:

There have been a few acres grown during the past decade but larger acreages were grown during the 1980s. The Ontario Canola Grower’s Association sponsored a meeting of researchers, extension, crop consultants and growers to review the production packages of the 1980’s and to update these recommendations to today’s practices. Their recommendations and observations follow.

Winter Survival

Winter Canola in Harriston

Winter survival is and always has been the unknown in winter canola production. The crop is planted in the fall and then reassessed in the spring to see if it has the potential to produce a viable crop. If 30% of the plants survive the winter and are evenly spaced throughout the field, the stand has the potential to produce an economical crop. The remaining plants will branch profusely and fill in the spaces. Many of the management practices are designed to get the crop off to a good start so that the plants will be large enough to withstand the winter and spring conditions. The plant must rely on a strong root system to initiate and sustain spring growth. Winter canola is slightly less winter hardy than winter wheat.

Winter canola can withstand low temperatures during the winter. Winterkill seems to occur mainly in the spring when root reserves are low and heaving causes further damage to the roots. Winds can also desiccate the new leaves putting further stress on root reserves. Ideal conditions are a snow cover that leaves quickly followed by consistent growing conditions. Costs should be kept to a minimum in the fall until you know you have a crop. Nitrogen, one of the largest input costs is applied in the spring when you decide to keep the crop.

Planting & Emergence

This OMAF sheet has excellent pictures and tips for fall seeding and establishment

Site & Rotation Considerations

Winter canola is susceptible to sclerotinia or white mold. For this reason, take caution when grown in less than four years following soybeans, edible beans, canola or tame mustard. Production of canola and tame mustard on the same farm should be avoided. Winter canola normally follows winter wheat in the rotation or a spring cereal crop. The early harvest of winter canola allows for timely winter wheat planting or double crop soybeans. Canola is sensitive to a number herbicides, so it is important to observe herbicide crop rotation restrictions. This information can be found in Publication 75, Guide to Weed Control and by referring to the manufacturer’s label. Volunteer cereals may need to be controlled in a winter canola field to reduce competition during the fall. You will want to promote good healthy fall growth of the canola plant but growth should stop before the plant is ready to bolt or begin flowering. Winter canola will be controlled in a spring-seeded crop with tillage but may remain a volunteer in a no-till situation. Rotations should include effective methods of volunteer control. Winter canola grows best on loam or sandy loam soils. Be aware of root heaving when planting winter canola in poorly drained and heavy clay soils. Sporadic problems with winter canola roots entering tile drains requires further investigation. Winter canola should not be located in areas (i.e. within 5 km) where rutabagas are grown because both crops are hosts for turnip mosaic virus. Serious crop losses have occurred in rutabagas from this disease.

Seedbed Preparation
Winter canola, like spring canola, responds to excellent seed to soil contact. You want to provide a level, firm, slightly lumpy seedbed with moisture within 2.5 cm (1”) of the surface. Canola is very susceptible to crusting. A lumpy soil won’t crust as badly after heavy rains as a pulverized soil. The lumps will help to protect the tiny seedlings. If the soil is too dry, wait for moisture. Also don’t plant when the soil is wet, especially on heavier soils.

Planting Date
You want a large healthy plant going into the winter that has not bolted. Plants overwinter as rosettes and bolt early the next spring. In southwestern Ontario (Essex and Kent) counties August 20 to September 10 is the ideal. In all other areas, aim for August 15 to September 1. Winter canola has a taproot much like alfalfa. The plant has to grow, photosynthesize and accumulate enough sugar reserves in the root to allow it to overwinter. Planting too early, particularly with good growing conditions, can cause stem elongation before winter, which decreases survival. Ideally, plants will have 6 to 8 leaves and a taproot the size of a pencil before a killing frost occurs.

Planting Depth
Plant deep enough so there will still be enough moisture for germination. A depth of 1/2 to 3/4 inch is ideal. If soil moisture is at an one inch then plant to one inch but not any deeper. Packing before planting helps firm the ground to control planting depth and reduce soil moisture loss; packing afterwards will help emergence by bringing moisture up to the surface. If you have packer wheels on the drill, set them firmly and leave the soil between the rows loose to discourage weed germination.

Planting Equipment
Stand establishment has been the most consistent when some tillage is involved. No till is a very attractive option for planting winter canola but it is more difficult to make it work. Even a minimum of tillage such as the tillage from residue coulters on the drills appears to help. Slugs can be a significant problem in no-till stands. No registered controls for slugs are available. When no-tilling into cereal residue, the straw must be removed, and chaff spread evenly. The least amount of residue on the surface is best to help reduce slug damage. Coulters should cut residue cleanly and set shallow to keep the seed opener from placing seed too deep. 15” row unit planters have showed an advantage for emergence due to precise seed depth control. Row cleaners mounted on planters work well however, make sure the back rows are not burying the lead rows with residue.

Broadcasting the seed can be effective if the ground is properly prepared, packed before and after broadcasting and the moisture is adequate. If broadcasting seed with fertilizer, seeding rates need to be increased. Seed can be planted directly through a grain drill or through the small seed box. Metering the seed at the proper rate will be the most important part of the package and will determine what you can use.

Seeding Rate
Seeding rates of 3-4 lbs (1.4-1.8 kg) per acre with a drill or planter and 6-8 lbs per acre with broadcasting are adequate for a good stand. Accuracy of delivering this rate is difficult but cost effective given the price of seed. If soil tests are low seed can be “bulked up” by mixing it with MAP (monoammonium phosphate) to a maximum rate of 10-20 lbs per acre. If background fertility is good, keep seed placed phosphorous out of the seed. Tiger 90 Sulphur works well when placed with the seed (10lbs/ac). These products must have a similar flow rate as the canola to be effective. If you use 10 lbs elemental sulphur and 4 lbs of seed, calibrating the drill is easier due to more volume, also some drills have difficulty accurately metering low rates such as 4 lbs per acre. Other fertilizer types should not be used, because they have a much higher salt index increasing the risk of fertilizer injury.

Spring Assessment

This OMAF sheet has excellent pictures and tips for assessing plant health and stands in the spring

The fall fertility program is very similar to winter wheat. Use a soil test to determine your rate. In general, 50 units of phosphate and 70 units of potash are broadcasted at seeding. Nitrogen and potash materials should not be

Another Winter Canola Field in Harriston

placed in direct contact with the seeds, but should be broadcast or applied in a band at least 2 inches away from the seed. There is some research to indicate that up to 30 units of nitrogen can be used in the fall to stimulate growth as well. This is especially effective on late plantings, very sandy soils, if cool weather results in slow growth, or if cereal residue will tie up available soil N. Nitrate testing could be a good way to determine available nitrogen in the fall. If there is 30-40 lbs of actual nitrogen in the top 12” then do not apply any nitrogen. You do not want to over stimulate growth in the fall.   

Attention must be made to the type of fertilizer used and to its placement so the seedlings do not experience fertilizer burn. The rate of nitrogen fertilizer placed with the seed must not exceed 11 kg/ha (10 lb/ha). The rate for spring application of nitrogen is based on the expected yield and on the price ratio between canola and nitrogen fertilizer. Compared to spring Canola, nitrogen rates need to be higher. A minimum of 140-150lbs/ac actual N is recommended for winter Canola. If the stand is good and has high yield potential, nitrogen rates can be pushed upwards of 3 lbs of N per yield goal. With a 70 bu/ac yield goal that is 210 lbs/ac of actual N. Urea works well but some growers have been using UAN 28% with streamer nozzles and having good success. Canola utilizes more sulphur than other crops, and on occasion sulphur deficiency has occurred. Sulphur is highly mobile in the soil, so deficiencies occur most often on sandy soils, low organic matter soils (< 2%), shallow soils and where soil conditions may limit root growth (e.g. compacted areas). If elemental sulphur was not used in the fall, the most economical method of supplying sufficient sulphur (20 – 30 lbs/ac) is by using ammonium sulphate in a dry program or ammonium thiosulfate in a liquid program. All the nitrogen and sulphur need to be applied before the canola bolts. Another nutrient that canola has high demand for is boron. The most effective way is adding one pound of actual boron in the dry blend in the fall ahead of planting. Aspire could be a good fit for supplying potash and boron. If not applied in the fall, boron can be put on in the spring with the nitrogen program.     

Annual weeds will not be a problem with the August planting. Once established, canola is a good competitor with most weeds. Grasses may be the only escapes in the spring. Venture L or Assure II work well, keep away from Select as crop injury may occur. Fields must be free of twitch grass. Volunteer cereals often need to be controlled in the fall to reduce competition. Volunteer cereals attract aphids, which can transmit turnip mosaic virus to canola. Canola is extremely sensitive to drift from most broadleaf herbicides such as 2,4- D, MCPA, dicamba glyphosate and certain sulfonylurea herbicides (e.g. Pursuit). Precautions must be taken to ensure proper sprayer tank cleanout and avoiding the drift of these herbicides to canola fields. Some chemicals have a two year, or greater, re-cropping restriction for canola, will need to know 24 month prior herbicide history before planting winter canola.

 Insect & Disease Management
Further information on insects and diseases affecting canola can be found in OMAF publication Agronomy Guide or on the OMAF or Canola Council website links listed at the end of this guide. Refer to OMAF publication ‘Field Crop Protection Guide’ for product control recommendations and the product label for specific information.

Insects in Winter Canola

Swede Midge

One of the biggest pest problems spring canola growers face in the province is swede midge. However, with winter canola this pest does not seem to be much of a problem. The reason being, is the flowering date of winter canola compared to spring canola. According to Dr. Eric Page, Research Scientist in Weed Ecology, and Sydney Meloche, Weed Science Technician, AAFC Harrow Research and Development Center, in southwestern Ontario, winter canola reached 50% flowering between April 24 and May 19 2017 (depending on plant date and hybrid) meaning that the vulnerable stages of canola development occurred well before overwintering swede midge could emerge from the soil in late May or early June. Similarly, the advancement of the reproductive phase of development in winter vs spring canola meant that all but their last plant date (i.e., Oct 17 2016) avoided feeding damage from other insect pests including lygus and seedpod weevil.

 Fleabeatle is not as severe a problem in winter canola as in spring canola. Seed treatments give adequate control. Fields should be monitored but damage will generally be insignificant where a seed applied insecticide is used.

 Cabbage Seedpod Weevil (CSW) is a much more serious concern. The population has increased dramatically since 2001. Yield losses can be significant if not controlled. Winter canola and early planted spring canola are at the greatest risk of damage from CSW. In the spring, adults emerge from their overwintering sites (shelterbelts, leaf litter, fencerows and ditch banks) when air temperatures reach 18°C. These newly emerged adults move into winter canola and areas containing other host plants such as wild mustard. After feeding briefly and mating, the female then lays her eggs, typically one per pod, directly into the seedpod itself. The larvae hatch within approximately one week and cause the most damage as they feed on the seeds. Seeds are consumed, pods are susceptible to shatter and diseases can enter more easily through the damaged seeds and pods. Once mature, the larvae mine out of the pod, drop to the ground and pupate in the soil. Adults emerge from the soil 10 days later to feed on cruciferous plants until it is time to enter their overwintering sites.

 How do you scout for them?

Adult weevils can be seen feeding on the upper flower bud clusters. Pods, flower petals, and buds may also have small visible holes. Punctures become more noticeable with time as the tissue around the hole deteriorates or becomes infected with other pathogens. Pods may also appear bent or distorted from the larva developing within. Scouting should be focused on monitoring the adult population before they lay their eggs inside the pod. Insecticides can not penetrate the pods to control the feeding larvae. A sweep net is best used for sampling to determine population numbers. Begin sweeping when the crop enters the bud stage through until after flowering. Take 10 sweeps in 10 locations of the field and determine the average number of adult weevils per sweep.

 What are the thresholds?

No thresholds have been established for Ontario yet however, in other jurisdictions with similar yield potential as Ontario, thresholds are 2-4 adults/sweep. Spraying should be timed to when the crop is in the 10 to 20% bloom stage (2-4 days after flowering starts) to control adult weevils before they can lay eggs.


Timing of control is when weevils reach threshold numbers which generally is at early flower(10 – 30% bloom), since the weevils are attracted too the yellow flowers. Matador is the only product currently registered for CSW. The insecticide will not control the larvae within the pod and must be applied before egg laying. Experience the last several years has been that control last 7 – 10 days. Re-application may be required if threshold numbers are reached again. See product label for further details and restrictions.

Continue to monitor both your winter and spring canola to ensure that this pest does not affect your yield this year.


Sclerotinia or White Mold can severely infect winter canola, as the crop grows very thick and dense. In moist conditions an infection can cause economic damage. Heavy crop canopy and exposure to continuous wetness and temperature between 15 and 20 degrees C for more than 48 hours presents the greatest risk. Initial infections begin with a soft watery rot on leaves and stem, followed by a white fungal growth. Eventually the plant wilts, dies and stems appear bleach coloured. The disease also affects soybeans, edible beans and sunflowers. Rotation of at least 4 years with non-host crops can help to reduce the severity. In areas where the disease is widespread, crop rotation is not enough to control it. Treatment with a fungicide may be advisable when conditions favour white mould, but the fungicide must be applied before symptoms appear. If controlling Cabbage Seedpod Weevil with an insecticide, this could be a good time to tank mix a fungicide to help manage white mould.  

Appearance: Initial infections begin with a soft watery rot on leaves and stem, followed by a white fungal growth. Eventually the plant wilt and dies, and stems appear bleach coloured. The disease also affects soybeans, edible beans, and sunflowers. Rotation of at least 4 years with non-host crops can help to reduce the severity. In areas where the disease is widespread, crop rotation is not enough to control it.

Turnip Mosaic Virus (TuMV) can be a problem in canola, especially in areas where rutabagas are grown. The disease is transmitted to canola in the fall by several species of aphids that migrate from other host crops. The disease causes leaf mottling (yellow or light green areas surrounded by normal green colour) and wrinkling or puckering of the leaf tissue between the veins. Spring growth is slow. Severely infected plants are stunted, twisted and generally light green or yellow in colour. Pods are distorted and a significant proportion of the seeds are poorly filled. The disease appears to be more severe in areas where other cruciferous crops are grown and in fields where pressure from weeds and volunteer cereals is high. Volunteer crops of winter canola often have high levels of TuMV infections.

Manage Pests & Harvest Tips

This OMAF sheet has excellent pictures of flowering and ripening stages of winter canola

Harvest and Storage

Harvest – Almost all the winter canola grown is direct harvested. The crop is quite shatter resistant and easier to handle with a direct cut head rather than swathing. Manuals will detail how to set up the combines for best seed harvest. Be sure that your machine is capable of handling the volume of this crop.

Storage and Marketing – Traditionally canola moves directly to market from the combine. You will need special aeration floors in bins and care must be taken to keep the canola from heating. Storage is also available through local elevators who in turn deliver the seed to the crushers. Seed should be delivered at 10% moisture or less. Canola may drop quickly in moisture in the field once it nears harvest moisture. A drop of 1% an hour is not uncommon.

Crop Insurance – The attached map outlines the areas where winterkill coverage is provided for winter canola. Outside of these areas, the winter canola is insured against all other perils with the exception of winterkill. The deadline to apply and report acres is November 8. These acres are grouped together with spring canola acres, so the invoice for the winter canola acre is sent in the spring and premium is due July 10. The yield from both winter and spring canola acres are grouped together for a single average farm yield.

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