Winter canola can be a profitable rotation crop in Kansas, and success starts with strong stand establishment. This article covers seeding date, seeding rate, seeding depth, fertility, and pest management. For variety and site selection, seedbed preparation, and herbicide carryover information, see the companion eUpdate articles.
Seeding date
The general rule is to plant winter canola about six weeks before the average date of the first killing frost (28°F) in central and south-central Kansas, and six to eight weeks before in southwest and northern Kansas. This allows the crop to develop a healthy canopy and a strong root system for winter survival.
- Planting too late may lead to small, weak plants with a lower chance of winter survival.
- Planting too early may cause excessive fall growth that depletes soil moisture and raises the growing point above the soil surface, increasing the risk of winterkill.
- Heavy residue in the seed row can worsen excessive growth problems unless managed correctly.
Target dates
The planting window for winter canola starts September 1 in Kansas.
- Northern and southwest KS – by September 15
- Central KS – by September 25
- Far south-central KS (Barber, Harper, and Sumner counties) – by October 1
Monitor short-term and long-term weather forecasts to help gauge planting time decisions. The most recent 8-14 day outlook from NOAA, issued August 19, projects below-normal temperatures and near-normal to above-normal precipitation are likely. The 1-month outlook is for near-normal temperatures and moisture. These projections could make for favorable winter canola planting conditions.
Seeding rate, depth, and row spacing
Winter canola will compensate for a poor plant stand; however, it is important to obtain as uniform a stand as possible to facilitate optimum plant development, winter survival, weed control, and uniform plant maturity.
Seeding rate:
- Open-pollinated varieties – 3 to 4 lb/acre (~300,000 to 400,000 pure live seeds/acre at 100,000 seeds/lb) in narrow rows (7.5-inch to 15-inch)
- Hybrid varieties – 250,000 to 300,000 pure live seeds/acre in narrow rows (lower seeding rates than OPs due to higher seed costs and greater plant vigor)
- 30-inch rows – Possible with row crop planters, but yields may be slightly lower under dryland conditions. Seed 1.5 to 3 lb/acre (~150,000 to 300,000 pure live seeds/acre). Use of hybrid varieties may increase yield potential in wide rows.
Depth:
- Optimal – ½ to 1 inch
- Dry conditions – up to 1.5 inches, but this may slow emergence and reduce vigor
- Plant slower than wheat (5 mph or less) for accurate depth control
- Check depth in every field and be aware of crusting risk after heavy rain, especially where the ground has been excessively worked
Row spacing:
- 7.5 to 15-inch rows: rapid canopy closure, better light interception, and weed suppression. Yields are similar across this range. Plant-to-plant uniformity at emergence is critical for optimum plant development and growth, overwintering, and weed control.
- 30-inch rows: may be the best option for no-till producers, but residue must be moved from the seed row. Reduce seeding rate to limit plant-to-plant competition in the row.
Figure 1. Canola established under conventional tillage in narrow rows in south central Kansas. Photo by Mike Stamm, K-State Research and Extension.
Plant nutrition and soil fertility
Soil testing, including a profile sample for nitrogen (N) and sulfur (S), is important in determining fertilizer needs. If you have questions, contact your local Extension office. Canola fertility recommendation programs, based on soil test levels, can be found at http://www.agronomy.ksu.edu/soiltesting/
Fertility needs are similar to winter wheat; however, canola needs slightly greater N and S. Applying high rates of fertilizer in-row at planting is not recommended because canola is sensitive to ammonia and salt damage (phytotoxic effects). However, research by Oklahoma State indicates that a low rate of DAP or MAP (20 to 30 lb/acre of product) is beneficial and not detrimental to yield. The best management practice for banding fertilizer should separate the fertilizer from the seed by two inches to avoid direct contact. Pre-plant broadcast application is also acceptable.
- Lime: Apply lime so that pH is in the range of 5.5-7.0 and early enough so the lime has time to react in the soil.
- Phosphorus (P): No P should be added if the P soil test is above 30 ppm.
- Potassium (K): Apply when soil test levels are less than 125 ppm.
- Sulfur: Apply S based on the soil test recommendation. Sulfate-sulfur (SO4-S) soil tests should be above 10 ppm, or fertilizer should be applied. If no soil test is available, an application of 20-30 lb/acre S is recommended.
- Canola requires S because of its high content of S-containing proteins. Sulfur deficiency is more common in coarse-textured and low-organic-matter soils; however, S application is still recommended for all soil types. Sulfur can be applied at any time from pre-plant until the canola plant breaks dormancy in late winter.
- Nitrogen: Apply one-third to ½ of total N (based on expected yield) in the fall. 30-80 lb/acre actual N is the general rule for fall applications. Winter survival, plant vigor, and yield potential can decrease without adequate fall N.
Weed management
A clean seedbed is critical as small canola seedlings compete poorly with established weeds. However, once a good stand and canopy are established, canola suppresses and outcompetes most winter annual weeds. Regardless of your herbicide program, the most important thing to remember is to control weeds early in the fall.
- Trifluralin and ethalfluralin are effective at controlling winter annual weeds pre-plant, but each requires mechanical incorporation.
- Grass herbicides such as clethodim, quizalofop, and sethoxydim are labeled for cool-season grass control in canola.
- Roundup Ready (glyphosate-tolerant) canola varieties are available, providing excellent control of many problem weeds. Glyphosate is not labeled for application once the plant has bolted after dormancy.
- Clearfield canola varieties are available and provide another herbicide resistance option for controlling winter annual grasses.
Insect management
An insecticide seed treatment is highly recommended to control green peach aphids and turnip aphids through fall and early winter. Several products are labeled and provide good to excellent control. Monitor canola stands for the following fall insect pests: grasshoppers, diamondback moth larvae, armyworm, flea beetle, aphids, and root maggots. A post-emergence application may be necessary in the fall to control these insect pests.
Disease management
Crop rotation is the best way to minimize the introduction and reduce the potential spread of canola diseases. Do not plant canola in the same field more than once every three years, and do not plant canola continuously.
- Blackleg (Leptosphaeria maculans) is the most serious disease threat to canola. Use proper rotation intervals, disease-free seed, and fungicide seed treatments to slow the spread of blackleg.
- Damping-off of young seedlings resembles the pinching of the stem at or just below the soil line. This is caused by several fungi, including Pythium, Fusarium, and Rhizoctonia. A fungicide seed treatment can lessen the effects of these soil-borne diseases.
Additional Resources
Great Plains Canola Production Handbook. Contact your local Extension office for a copy or download it online: https://www.bookstore.ksre.ksu.edu/pubs/mf2734.pdf.
Canola Growth and Development poster is available online at: https://www.bookstore.ksre.ksu.edu/pubs/MF3236.pdf.
Mike Stamm, Canola Breeder
mjstamm@ksu.edu
Tags: canola seeding rate planting date winter canola soil fertility