In this article, we outline critical management factors for a successful canola growing season. A companion article in this eUpdate addresses other planting aspects, such as variety and site selection and seedbed preparation.
Seeding Date
The general rule is to plant canola six weeks before the average date of the first killing frost (28°F) in central and south central Kansas or six to eight weeks for southwest and northern Kansas. This allows adequate time for plant canopy development and root growth to improve the chances of winter survival. Planting too late will result in small plants with inadequate reserves to maximize winter survival. Planting too early may result in excessive growth that can deplete soil moisture. Excessive growth may also elevate the growing point or crown too far above the soil surface, increasing the chance of winterkill. This can also be a problem when heavy residue remains in the seed row without correct management.
Winter canola should be planted in northern and southwest Kansas by September 15 and central Kansas by September 25. In far south-central Kansas (Barber, Harper, and Sumner counties), winter canola should be planted by October 1 to avoid problems with winterkill.
Monitor short-term and long-term weather forecasts to help gauge planting time decisions. The most recent 8-14 day outlook from NOAA projects that normal to above-normal temperatures and normal to below-normal precipitation are likely. The 3-month outlook is for above-normal temperatures and below-normal moisture.
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.
A seeding rate of 3.5 to 5 pounds per acre (approximately 350,000 to 500,000 seeds per acre at 100,000 seeds per lb seed size) is recommended for open-pollinated varieties in narrow row spacing. Because hybrids have higher seed costs and a greater ability to branch out, it is recommended to plant them on a pure live seed basis. The recommended seeding rate is 250,000 to 300,000 pure live seeds per acre in narrow rows.
More producers are experimenting with canola planted in 30-inch rows. Producers can obtain accurate depth control, precision seed metering, and residue removal from the seed row with row crop planters. Generally, yields may be slightly reduced when moving from 15 inches to 30 inches under dryland conditions. However, producers can reduce their seeding rate to 1.5 to 3.0 lb per acre (about 135,000 to 270,000 pure live seeds per acre at a 90,000 seed per lb seed weight). Planting an open-pollinated variety or hybrid with prolific branching will also increase the profitability of canola planted in 30-inch rows.
It is important to check drill calibration. Some drills may require a speed reduction kit to obtain the optimum rate without damaging the seed. Some producers planting at 7.5-inch spacing will plug every other row unit and plant at a 15-inch spacing, so the drill does not have to be slowed as much.
Seed placement is critical for successful germination, emergence, and stand establishment. Optimal germination occurs with seed placed ½ to 1 inch deep. Under drier conditions, canola may be planted deeper (not greater than 1.5 inches), but delayed emergence and reduced vigor may occur. Soil crusting following a heavy rain can result in a poor stand. Canola emergence can be greatly reduced when using a deep furrow opener followed by heavy rain before emergence since soil can fill in the furrow, resulting in a deeper-than-intended seeding depth. To ensure proper seeding depth, producers must plant slower than when planting wheat (preferably five mph or slower). Finally, it is important to check the seeding depth in each field.
Rows spaced between 7.5 and 15 inches allow for rapid canopy closure (improved light interception) and weed control (Figure 1). Yields are similar across these row spacings. Plant-to-plant uniformity at emergence is critical for optimum plant development and growth, overwintering, and weed control.
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 (30 to 40 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) and Potassium (K): No P should be added if the P soil test is above 30 ppm. Additional K should be applied when soil test levels are less than 125 ppm.
- Sulfur: Canola requires S because of its high content of sulfur-containing proteins. Sulfur deficiency is more common in coarse-textured and low-organic-matter soils; however, a sulfur 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. 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.
- Nitrogen: Pre-plant N applications must be carefully balanced, as too little or too much fall-applied N may negatively affect winter survival. One-third to one-half of total N (based on expected yield) should be fall-applied. At least 30 lb/acre but no more than 80 lb/acre of actual N is the general rule for fall applications. Winter survival, plant vigor, and yield potential can decrease without applying fall N.
Weed Management
A clean seedbed is critical to establishing winter canola. 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.
- Before applying any herbicides, care must be taken to ensure that the sprayer equipment does not contain traces of problem herbicides, such as sulfonylurea herbicides.
Insect Management
An insecticide seed treatment is highly recommended to control green peach aphids and turnip aphids through fall and early winter. Monitor canola stands for the following fall insect pests: grasshoppers, diamondback moth larvae, flea beetles, aphids, and root maggots. Several products are labeled and provide good to excellent control.
Disease Management
Careful rotation is the best way to control canola diseases. Canola should not be planted on the same field more than once every three years and should never be planted continuously.
Blackleg (Leptosphaeria maculans) is the most serious disease threat to canola. Maintaining proper rotation intervals, planting disease-free seed, and using fungicide seed treatments are important management practices to slow the spread of blackleg. Damping-off of young seedlings, which resembles the pinching of the stem at or just below the soil line, 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
Ignacio Ciampitti, Farming Systems
ciampitti@ksu.edu
Tags: planting canola winter canola