CANOLA STRAIGHT COMBINING OR SWATHING
Producers traditionally have swathed rather than straight combined canola; however, straight combining is an option for canola. Straight combining can save time and money, and result in improved seed quality. Heavier canola stands are better suited for straight combining than thinner stands because of the decreased likelihood of shattering from wind. Straight combining has resulted in yield losses of 8 to 54 %, as reported by the Canola Production Center in Canada. These losses primarily were from preharvest shattering and combine shattering losses. Studies conducted with farmer-size combines at Minot in 2005 and 2006 demonstrated that timely straight combining can achieve similar or better canola yields compared to swathing. Straight-combined canola tended to have lower harvest moisture, darker seed color, lower green seed, and higher test weight. About 15 to 20 % of canola in North Dakota is currently straight combined successfully by the growers.
Presently, Diquat is the only product labeled for use as a preharvest desiccant in canola. Growers can maintain excellent yield and quality if the Diquat application is timed properly and the crop harvested in a timely manner. Diquat should be applied when 60 to 75 % of the seeds have started to turn color. Canola seeds mature in the bottom pods first, while the last seeds to mature are in the top pods. Apply the desiccant when seed in the middle pods (or 60 to 75 %) have started to turn color. Research has shown that when the desiccant is timed properly, crop quality parameters, including yield, test weight, oil content, seed loss, green count and grade, generally were similar for desiccated canola compared with swathing.
Diquat applied too early may result in lower yield and seed quality, with a trend toward higher green content. Diquat requires a seven-day preharvest interval. Canola harvested 14 days after application will have lower green content than canola harvested seven days after application. Fields with excessively lodged canola may be difficult to desiccate because the spray droplets may not be able to penetrate the canopy. Therefore, swathing may be the better choice for lodged canola.
Swathing canola at the optimum stage of ripening reduces green seed problems and seed shatter losses, and ensures the quality required for top grades and prices. Swathing can begin in canola at 60% color change (http://www.canolacouncil.org/chapter11.aspx ). When canola plants consist only of stems, stem branches and pods, the crop probably is very near the optimum time for swathing. Seeds in all pods on a plant complete filling (physiological maturity) at about 40 % moisture and then slowly turn from green to light yellow or reddish brown, brown or black, depending on the variety. In hot (90 degrees F), dry weather, canola seed can go from 10 to 50 % seed color change in just three to five days or less. Once filled, seeds rapidly lose moisture at about 2 to 3 percentage points or more each day, depending on the weather.
Inspect fields every two to three days when some color change occurs in the first-formed pods on the bottom of the main stem. To determine when a field of canola is ready to swath, examine plants from different parts of the field. The stage of maturity in an evenly maturing field will vary from plant to plant and from area to area within the field. When examining the plants, take into account varying soil types, low-lying areas, available soil moisture and exposed early ripening areas.
Examine only pods on the main stem. Seeds in pods on the bottom third of the main stem were formed earlier and will turn color much sooner than seeds in the pods on the top third of the plant. When the overall moisture content of seed from the total plant averages 30 to 35 %, about 30 to 40 % of the seeds in pods on the main stem will have changed color or have started to change color. Seeds with only small patches of color should be counted as color changed. The color of the seed is more important than the overall color of the field in determining the stage of maturity. Most of the seeds that have changed color will be from the bottom third of the main stem. When seeds in the bottom pods slightly turn color, seeds in the top, last-formed pods are filled or nearly filled.
For more information see: http://www.ag.ndsu.edu/pubs/plantsci/crops/a1171w.htm
Hans Kandel - Extension Agronomist Broadleaf Crops firstname.lastname@example.org
Brian Jenks, NDSU Weed Scientist Brian.Jenks@ndsu.edu
Strategies Optimizing Canola Yields
Below are listed some key management suggestions for getting high canola yields:
- Select a variety/hybrid that has a proven high yield potential in university and company trials. Obtain data from trials from several locations in your respective growing region. Results from the NDSU canola variety trials can be found in publication A-1124 , which is also available at county extension offices in N.D.
- Field selection is important to obtain high yields. Canola does well following small-grains or fallow in a rotation. With canola in a crop rotation there should at least be two cropping years with other crops before canola is seeded again. Avoid crops such as sunflower, dry bean and other sclerotinia (white mold) sensitive crops in close rotation with canola. Select fields that are free of troublesome weed problems.
- Plant seed with a high germination percentage and with good seedling vigor. Planting seed treated with both an insecticide and fungicides for seedling protection is recommended.
- Canola is a cool season crop and can be seeded mid April through early May. Research has shown that yield potential may be reduced with delayed planting. This is mostly a result of the increased potential of high temperatures during flowering when the crop is seeded late. Hot conditions during flowering shorten the time the flower is receptive to pollen, as well as the duration of pollen release and pollen viability. This can decrease the number of pods that develop on the plant and the number of seeds per pod, resulting in lower yields.
- Canola should be planted into a firm seedbed and seeded at a uniform depth. Recommended seeding depths are ¾ to 1 inch. A seeding rate of around 700,000 live seeds per acre (16 live seeds per square foot) should result in a established plant stand of 10 to 12 plants per square foot (435 to 522,000 plants per acre), which would be adequate for high yields. Varieties and hybrids differ in the number of seeds per pound.
- Canola responds well to applied fertilizer. Nitrogen, phosphorus and sulfur are the key nutrients for high yields. Always have a soil test done to help in knowing how much to apply for high yield goals. Nitrogen recommendations are based on the following formula: Supplemental nitrogen is the yield goal (lb/a) times 0.065 minus soil nitrate in the 0 – 24 inch depth (from soil sampling). If the previous crop was a legume, a N-credit can be subtracted from N fertilizer application rate. Growers in cooler, moister areas of N.D. should consider a maximum 150 lb/a N cap recommendation rate, while growers in the drier, warmer areas of the state should use the 120 lb/a N rate cap (for the Soil N +Supplemental N). Canola does better with P fertilizer banded at seeding than broadcast. The amount of N will limit the rate of P fertilizer applied, so many successful growers have seeders that separate banded fertilizer from the seed. The sulfur soil test is so inaccurate that S is recommended regardless of test result. Sulfer use results in the greatest returns in lower organic matter soils in rolling terrain, but yield increases have also been documented in heavier, higher organic matter soils. A soluble sulfate fertilizer like ammonium sulfate or gypsum is recommended. Elemental sulfur of any kind is not recommended. For detailed information see publicaton SF 1122.
- Control weeds as early as possible since a lot of competition early during the growing season can reduce yields very quickly. Herbicide tolerant canola hybrids usually show little if any herbicide crop injury if the herbicide is applied according to the label. Monitor for any late emerging weed flushes that were missed during first application.
- Monitor for any flea beetle pressure and other pest problems especially the first three weeks after emergence during the early development stages of canola. Be prepared to apply an insecticide if the seed treatment does not hold long enough or the insect pressure is too great.
- As canola gets near the bud stage or early bloom, start monitoring the NDSU Canola Disease Risk map for Sclerotinia stem rot (white mold) potential. Be prepared to get a fungicide applied to the crop should the sclerotinia risk be high.
- Swath the canola at the optimum time to insure maximum yield and quality. If the canola is allowed to get too ripe, shattering can be a problem and reduced yield will result. If cut too early then green seed problems can result in discounts when the canola is sold.