K-State Agronomist Offers Canola Planting, Agronomy Tips

Canola growers, here are some things to think about.

Published on: Sep 12, 2007

As Kansas farmers' interest in growing winter canola grows, there are several questions about the crop, says Vic Martin, specialist in annual forages and alternative crops with K-State Research and Extension.

"The last two years have demonstrated winter canola's ability to withstand extremes of drought and cold," Martin says. "There is still ample time to consider planting winter canola this fall as part of dryland and irrigated rotations."

Martin answers a number of agronomic questions for canola producers:

Q: What factors should be considered when selecting a site for canola?
A: Canola will grow well over a wide range of soil textures, provided they are well-drained and the pH range is 5.5 to 7. Avoid planting in soils that waterlog and have standing water. To prevent disease, don't plant canola following canola, sunflowers, soybeans, alfalfa or cotton. However, canola can follow winter and spring cereals and if adequate moisture and timely harvest permit, both corn and grain sorghum. The herbicide program of preceding crops is important. Most winter canola cultivars are sensitive to sulfonylurea and triazine carryover.

Q: What do I need to consider when deciding which variety to plant?
A: Consult Extension offices and seed dealers for advice on locally adapted canola varieties. Consider: winter-hardiness, seed yield, oil content, shatter and disease resistance, maturity, and the potential for lodging. Roundup Ready varieties are available, as is SU tolerance. Treat all seed with an insecticide for fall aphids. Consider selecting two or more varieties with a range of harvest maturities to spread out harvesting activities.

Q: What is the best way to prepare the seedbed?
A: Control weeds before planting; canola seedlings are not competitive with weeds immediately after emergence. Since canola is a small-seeded crop (more than 100,000 seeds per pound), a level, firm seedbed with adequate moisture is best. Avoid large soil clumps or overworked soil. Do apply pre-plant fertilizer and herbicide prior to final tillage.
No-till planting is an option, and is more successful where soil has been no-tilled over a long period of time. Opportunistic no-till planting is riskier. When properly set, no-till planting produces proper stands; however, stand maintenance over the winter with heavy residue cover occurs. So, some producers burn heavy surface residue prior to planting.

Q: What about seeding dates and rates?
A: Plant canola six weeks prior to the average date of the first killing frost in the area, which allows time for the plant growth needed to survive winter, plus provides for canopy development for weed control. Plant too late, and plants don't have sufficient reserves to maximize winter survival; too early and the plant could have excessive growth that depletes soil moisture and nutrients. K-State research suggests that planting earlier, rather than later in the planting window is better for winter survival.
As for population, a rate of 5 pounds per acre (approximately 500,000 to 600,000 seeds per acre) is recommended. Irrigated production can support slightly higher rates. If planting significantly earlier than the optimum date, reduce the rate by 1 pound. Conversely, increase the rate by 1 pound if planting significantly later than the optimum date. Checking the drill calibration is very important. Some drills may require a reduction kit to obtain a 5-pound rate without damaging the seed.
Seed placement is critical to successful germination, emergence, and stand establishment. Ideally, the best germination occurs with seed placed ½ to 1 inch deep. Under drier conditions, canola may be planted deeper, but delayed emergence and reduced vigor are likely. In combination with deeper planting, a heavy rain resulting in soil crusting often leads to a poor stand. To ensure proper seeding depth, you'll have to plant slower (compared to wheat planting). Check seeding depth for each field planting; it's important.
Narrower row spacing is preferable for canopy closure and weed control, although a row spacing up to 15 inches is acceptable.

Q: What do I need to consider regarding fertility management?
A: A soil test, including a profile nitrogen (N) test, is necessary. Fertility needs are similar to those for winter wheat, except in that canola needs slightly higher levels of nitrogen and sulfur. Do not apply in-row fertilizer at planting, as canola is extremely sensitive to ammonia and salt damage. Drills allowing for banding of fertilizers away from the row are normally acceptable, but the safest method is to broadcast pre-plant.
Lime: Apply so pH is in the range of 5.5 to 7.0 (6.0 to 7.0 is preferable). Do so early enough that the lime has time to react.

Phosphorus and Potassium: Soil potassium levels generally are adequate in much of Kansas, but deficiencies are increasing. Phosphorus soil test levels above 30 parts per million (ppm) require no added P. Where needed, broadcast these nutrients prior to planting, according to soil test recommendations.

Sulfur: Canola requires more sulfur than wheat because of its high content of sulfur-containing proteins. Sulfur deficiencies are most common on coarse-textured soils and soils with low organic matter content. Base sulfur applications on test recommendations.
Nitrogen: Pre-plant N applications must be carefully balanced. Too little or too much fall-applied N may negatively affect winter survival, so we recommend basing fall applications on a profile N test. One-third of total N or roughly 30 to 50 pounds N per acre (based on expected yield) should be fall-applied. Applying no fall N can decrease winter survival and/or yield.

Q: What about weed management?
A: Canola does not compete well with established weeds, although once a good stand of canola and canopy is established, canola suppresses and out-competes most annual weeds until harvest. That said, Trifluralin and ethalfluralin herbicides are effective at controlling many common problem winter annual weeds. Several grass herbicides are labeled for cool-season grass control in canola. Roundup Ready (glyphosate-tolerant) canola varieties are available, too, providing excellent nonselective control of many problem weeds, but glyphosate is not labeled for application once the plant has bolted after dormancy.

Before applying any herbicides, take care to ensure there are no traces of problem herbicides, such as SUs, in the spray equipment.

Q: Any recommendations for controlling insects?
A: Seed treatment is highly recommended for fall control of aphids. Other fall insect pests that should be monitored include grasshoppers, army cutworms, flea beetles and root maggots. If necessary, several insecticides are labeled for use on canola and provide good to excellent pest control.

Q: What if I want to graze livestock on canola? Is that possible?
A: Canola can provide excellent opportunistic grazing in late fall and early winter, prior to dormancy. In some years, fall growth will be inadequate for grazing, so producers should not rely on winter canola as the primary focus of their fall/winter grazing program. Planting earlier than normal is recommended. The canopy should be at least 6 to 8 inches tall.

As a rule, grazing canola significantly decreases yield potential. Overgrazing often results in stand loss. And, care must be taken to prevent bloat and monitor for potential nitrate toxicity. With that said, though, canola can often provide excellent grazing for up to two months.

More information about growing canola as a winter crop is available on the K-State Research and Extension Web site: www.oznet.ksu.edu (search for canola).