MSU Extension Field Crops

Crop progress update

Dry weather in September allowed for quick canola planting progress this year, but some growers have seen uneven emergence due to low moisture conditions. Most canola fields following wheat have already been planted across Michigan, while fields following soybeans will have a later start date. The time before a killing frost is crucial for the canola crop to survive the winter. For the best overwintering success, canola should be seeded into well-drained fields with low clay content.

The following are some best management practices to help ensure uniform winter survival.

Planting population

The target planting population is 175,000-350,000 plants per acre.

The most common row spacing is 15 inches, though 30 inches is also an option when adapting a corn planter with canola seed plates. Lower seeding rates (175,000-200,000 per acre) should be used for the wider row spacing (30 inches).

Most canola is approximately 80,000-150,000 seeds per pound. To achieve a target 250,000 planting population, the seeding rate from a drill or planter will be around 2-4 pounds of pure live seed. It can be challenging to adjust the drill to consistently drop seed at such a low seeding rate. Bulking seed with elemental sulfur or even cover crop seed that will winter kill can help get a consistent rate from most drills.

Planting above 250,000 plants per acre can be risky. Seedlings experiencing competition in the fall can have reduced canola winter survival. Whether competition comes from high seeding rates or weeds, canola in a highly competitive environment will have thinner stems, less robust root growth, and may set the crown too high above the soil surface.

Planting timing

While wheat planting in Michigan occurs in late September and into October, the recommended planting window for winter canola is quite a bit earlier, between Aug. 20 and Sept. 20. Canola is most likely to survive winter if there is enough growing degree days to reach the rosette stage with at least six to eight leaves before going into winter dormancy.

With this timing, winter canola is best suited as a crop following corn silage, wheat or very early soybeans or dry beans. However, too much crop growth in the fall, or bolting, can overexpose the canola’s growing point to winter conditions and increase the chance for crop injury or winter kill. Planting into moisture can also help with even emergence.

Planting depth

The recommended seeding depth is 0.5-1 inch.

Residue management at soybean/wheat harvest is important. Because seed is getting planted shallow, seed disks can have a hard time opening the seed furrow and achieving consistent depth/soil contact in heavy residue. Even distribution of residue from the combine can help prevent emergence issues.

Though tillage is not necessary to establish a strong canola stand, canola seedlings can be sensitive to residue and seed to soil contact. It is beneficial in no-till situations to have the planter or drill successfully clear residue from the seed trench.

In addition to crop emergence, residue management is also a key consideration for pest management in canola. Green vegetation (weeds or poorly terminated cover crops) close to the emerging seeds may also create optimal conditions for insect pests or slugs to feed on emerging seedlings.

Seed treatment and fall weed control

Canola can be established without seed treatment, but seed companies offer both fungicide and insecticide treatments, which can be beneficial in certain situations. Emerging seedlings can be susceptible to insect and slug feeding, or diseases including black leg or downy mildew. Research is needed in Michigan to establish the economic return on canola seed treatment.

For fall weed control, start with a weed free field using pre-emerge burndowns. Few residual products are available and are safe or labelled for canola. Some varieties of canola are Clearfield, which can have Beyond (imazamox) applied post-emergence. Other varieties have tolerance to glyphosate or glufosinate. Grass herbicides such as clethodim can be sprayed post emergence to control volunteer wheat and annual grass weeds.

Canola can be a valuable addition to diversified cropping rotation, but trying out a new crop can bring challenges. For more information about growing canola in Michigan, listen to Brook Wilke, associate director of the Kellogg Biological Station Long Term Agroecosystem Research, and Benjamin Butcher, ADM account manager, on “In the Weeds” podcast from Michigan State University Extension.

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