By Mike Stamm, Canola Breeder
Most of the winter canola crop in Kansas has finished blooming and is filling seed pods. The cooler and wetter weather recently has benefited pod fill and slowed the maturing process somewhat. A return to warmer temperatures will cause seed to turn color quickly. As the crop matures, it is important to consider the harvesting options available and what suits an individual producer best.
It is critical to have a plan at canola harvest, thus it is helpful to review some general principles.
- Seed moisture loss and color change can occur rapidly, going from too wet to dry in a matter of a couple days or even several hours. Harvesting operations must happen in a timely manner.
- Producers should base the decision to commence harvest operations on seed moisture content and visual observations of seed color change, and not plant or pod color changes.
- Moisture content should be 10% or less. Elevators will not accept canola seed that is greater than 10% moisture content.
- The plant matures from the bottom to the top of the racemes.
- Ripe canola must be harvested as soon as possible to prevent losses from shattering.
- Canola can be harvested overnight and at times when it is too damp to be harvesting wheat.
- Cylinder speeds are typically 450 to 650 rpm. Concave clearance should be 3/4” in the front and 1/8” to 1/4” in the rear. Fan speeds are similar to wheat. Combine speed is slower for canola than wheat.
- Always refer to the combine operators’ manual. If there is not a listing for canola, there should be one for rapeseed. Start there and make adjustments according to what is coming into the bin and leaving the back of the combine
- Canola seed can be a little trashy in the bin. If the seed is completely clean, you are probably throwing too much over.
- A producer may want to cut canola before wheat if ready, since canola would be more apt to shatter.
There are four harvest methods for winter canola:
- Direct combining
- Swathing followed by combining
- Pushing followed by combining
Figure 1. Canola in the ripening growth stage.
The preferred harvest method depends on weather and crop conditions, the ability to harvest quickly, and equipment availability. In all cases, it is important to set the combine properly and monitor operations frequently, adjusting for changing crop and field conditions. The primary concerns when harvesting winter canola are to minimize seed loss and to harvest at moisture levels that allow for proper seed storage and handling.
Winter canola can be direct combined with conventional or rotary combines. A few general rules apply to combine set up and operation:
- Canola is an indeterminate crop and will have some immature pods and seeds when it is ready for direct combining.
- In thinner stands, it is not unusual to have more green pods due to branching. This may cause some unevenness in maturity and dry down.
- Seed is ready to harvest before the entire plant is brown looking as the lower stem will remain green. Use a handheld grain tester to check moisture levels.
- Reel speed should match ground speed. Operating the reel too fast will cause pod shatter.
- Raise the reel above the canola canopy to lightly “pull” the crop into the grain table. The reel should be as far back over the grain table as possible.
- Cut standing canola just below the seedpods, which is about 12” or more aboveground.
There are some advantages to direct combining:
- Works well for uniform, tall, interlaced, and thick stands.
- Generally results in the best overall yield and oil quantity because the crop is allowed to ripen completely.
- Lower harvesting costs because no additional machinery is needed and only one pass through the field is required.
There are also some disadvantages to direct combining:
- Canola must be harvested when the crop is ready as shattering risks increase the longer a ripe crop stands in the field.
- If relying upon custom cutters, communication and dependability are critical to getting the crop out of the field in a timely manner.
- Unless a desiccant is applied, canola that is direct combined will likely be harvested at peak wheat harvest.
- Thin stands can result in uneven plant maturity, slowing the harvesting process and increasing the amount of time the crop needs to dry down.
- Standing canola is more susceptible to seed loss from heavy rain, hail, and high winds.
Swathing is the most common harvest method used in the southern Great Plains. The optimum time to swath winter canola is when 40 to 60% of seeds on the main raceme have turned from dark green to a reddish-brown, brown, or black color.
Figure 2. Canola seed color change.
Seeds that have a speckling of brown or black are considered turned. At 50% seed color change, seeds in the lower one-third of the main raceme should have completely turned, the majority of the middle one-third should be turned, and the top one-third should be dark green and firm. The decision to swath should always be made based on seed color change and not pod or plant color change.
Seed color change occurs rapidly, about 10% change every 2-3 days, but can be as high as 50% in 3 days depending on the weather. The key to minimizing harvest losses with this method is to swath at the appropriate crop stage. Swathing late increases the potential for shattering losses and reduced yields. Swathing too early increases the chances for high green seed count and reduced yield and oil content. Windrows will be harvested using a pickup header.
Here are a few general rules to swathing:
- Start monitoring crop stage about one week after flowering. Continue to monitor for proper stage every 2-3 days following.
- Seed color is the key for determining when to swath, not overall plant or pod color.
- Use a draper, belt-style swather. Do not crimp the windrow.
- Try to avoid swathing during the heat of the day (over 85 degrees F). This prevents accelerated seed curing and reduces the potential for high green seed count.
- Swathing during a heavy dew or a light mist will help to minimize potential shatter losses from the swathing operation.
- Swath parallel to the prevailing wind direction to reduce potential for movement of the windrows.
- Canola should be swathed just below the lowest pods and windrows should be placed on top of standing stubble. This allows for air circulation around the windrow.
- A roller attachment is necessary to push the windrow into the standing stubble, further protecting it from the weather.
- The crop can be in windrows for 7 to 10 days. If conditions are hot, dry, and windy, then it may be closer to 4 days.
There are several advantages to swathing:
- Typically earlier harvest because dry-down is accelerated by cutting off the plant from grain fill.
- Better ability to manage large acreages of canola.
- With earlier harvest, it may increase double-cropping opportunities by a week or more.
- Helps dry up any weeds present in the field that might increase seed moisture content.
- Proper swathing with good, tight windrows can withstand heavy rain and some wind with minimal yield loss.
- Helps control uneven maturities in fields.
- Fewer risks associated with severe weather than with direct combining.
There are also disadvantages to swathing:
- Potential for yield loss and low oil content from cutting off the plant prematurely when swathed prior to the optimum stage.
- Potential for yield loss from shatter when swathed later than the optimum stage.
- Swathing during hot, dry conditions (over 85 degrees F) can result in seed shrinkage.
- More time, investment, and labor involved.
- Tall, tangled, or lodged stands can be difficult to swath.
- If not placed properly into standing stubble, strong winds can move windrows.
Figure 3. Canola following desiccation.
Desiccants are now labeled to aid dry down and can be used prior to direct combining. Desiccants should be applied at 75-80% seed color change. There are three products available: Reglone Desiccant (diquat dibromide), Nufarm Diquat SPC 2 L (generic diquat), and Sharpen (saflufenacil).
Diquat should be applied at a rate of 1.5 to 2 pt per acre, with a minimum 15 gal per acre spray volume by land and 5 gal per acre by air. A seven day pre-harvest interval exists. Add a nonionic surfactant containing 75% or greater surface active agent at ½ to 4 pt per 100 gal of spray volume. Diquat is a contact herbicide that is activated by sunlight and will only desiccate the plant materials that it touches, so coverage is important. It may also be applied on cloudy days or in the evening to allow it to spread more evenly over the plant. Diquat is typically the fastest acting desiccant.
Saflufenacil should be applied at a rate of 1.0 to 2.0 fl oz/a with a minimum 10 gal per acre spray volume by land and 5 gal per acre by air. A three day pre-harvest interval exists, but depending on weather conditions, seven days may be required for optimal desiccation. Include a methylated seed oil (1.5 pt/a) plus ammonium sulfate at 8.5 to 17 lb/100 gal of spray solution as additives. Saflufenacil is typically a slower acting herbicide than diquat and desiccation of the crop may not be as complete.
Producers may consider using a desiccant under the following conditions:
- To get the crop out of the field quicker when direct combining.
- Heavy, tall, and dense crop canopies exist.
- Heavy weed infestations caused by thin stands and excessive rainfall prior to harvest.
- Excessive lodging, making it harder to push or swath.
- Uneven crop maturity due to thin stands, low spots, wet holes, sandy knobs, or excessive rainfall making it harder to push or swath.
Pushing was developed as an alternative to swathing. It is designed to provide the advantages of direct combining while minimizing some of the risks associated with direct combining or swathing. Pushing is still a new concept in the southern Great Plains, so experience and equipment are limiting factors.
A pusher is a roller hydraulically mounted on the front of a tractor which is driven at high speeds through the field. The pusher force lodges, or “pushes,” the crop over without cutting the plants off from the root system. The concept is to prevent yield losses from weather events by laying the crop over, allowing the crop to mature normally.
Vertical sickles are located at both ends of the pusher/roller and directly in front of the tractor tires. These are designed to ensure a clean cut between passes and reduce the amount of canola crushed by the tires. Once the canola is ripe, it can be combined in the opposite direction it was pushed. The header width of the combine should match the width of the pusher.
There are advantages to pushing:
- Reduces susceptibility to shattering from wind and storms.
- Allows the crop to ripen completely.
- Works in fields with high yield potential and tall, heavy, and thick plants.
There also are disadvantages to pushing:
- Shorter, thinner crops do not push well.
- Pushing equipment is scarce in the region.
- Harvesting is typically slower than direct combining and swathing due to the amount of material entering the combine.
- Dry down of the pushed crop is typically slower than direct combining because the crop canopy has been compacted, reducing air flow.
Canola producers have a several avenues to assist them with canola harvest and getting their crop out of the field. Whatever harvest method is chosen, the keys to success are planning ahead and performing all operations in a timely manner.
For more information on these harvest methods, see the K-State publication MF-3092, Harvest Management of Canola. For general information on canola crop growth and seed color staging, see publication MF-2734, Great Plains Canola Production Handbook. Both publications can be found at www.bookstore.ksre.ksu.edu.