Harvest Management

Last Update: Tuesday, September 01, 2015 10:29:19 AM

Table of contents

    Important Tips for Best Management

    • Determine the suitability for swathing versus direct combining.
    • Assess each canola crop carefully before choosing straight cutting, based on four factors: crop canopy, disease, hail risk, frost risk.
    • B. rapa varieties may be direct combined because they mature earlier and resist shattering.
    • Optimum stage to swath for both yield and quality: Up to 60% seed colour change. This enables many growers to delay the swathing of their first fields until at least 30% to 40% seed colour change without sacrificing significant yield or quality of their last fields.
    • Time of swathing usually has little effect on green seed levels, except under abnormal situations.
      • To minimize high green seed:
        • Consider swathing B. napus varieties as early as 10 to 15% seed colour change on the main stem in fields that are at high risk of fall frost damage, especially in short season areas where risk of early frost is elevated.
        • Avoid swathing too early in hot, dry weather (30 to 35°C), but assess crop development frequently as seed colour change will happen more rapidly. The heat can rapidly dry the crop resulting in shatter losses from swathing too late or excessive seed shrinkage and lack of curing from premature dry down from swathing too early.
    • B. rapa varieties can be swathed at 40% seed colour change on the main stem.
    • Desiccation dries the crop quickly; glyphosate provides pre-harvest weed control; neither speed maturity.
    • Assess crop after frost using Canola Council of Canada recommendations to determine whether to swath.
    • Green seed is the major downgrade that results from frost.
    • Before combining, use a crush strip to determine the amount of seed that is green inside --No. 1 Canada allows 2.0% distinctly green.
    • To minimize pod shatter at the pickup, adjust pick-up speed so that the windrow will be gently lifted without tearing or pushing
    • Slower combine travel speed can dramatically reduce harvest losses.
    • Use a drop pan to assess harvest losses from the combine.

    Harvest Management

    While good agronomic practices can maximize canola yields and returns, proper harvest management is essential to realizing those yields. Seed and quality losses caused by untimely harvesting, inappropriate harvesting techniques, improper handling, or some combination of these practices, can all result in reduced crop yield, value or both. Therefore, timely harvest will help maximize yield, quality and returns.

    Swathing vs. Direct Combining Canola

    Swathing involves cutting the crop and forming windrows that are laid directly on the cut stubble. This hastens crop drying rate, ensures uniform ripening, and reduces the possibility of seed losses from wind and hail. After the crop dries to uniform seed moisture content of 8 to 10% moisture (usually five to 10 days after swathing), it is may be ready for harvesting if sufficient curing has also taken place to reduce the percentage of green seed to acceptable levels.

    The advantages of swathing canola are:

    • earlier harvest (eight to 10 days) and more uniform seed maturity - this is particularly important in fields where maturity is uneven
    • earlier harvest to avoid fall frost and accelerate dry down, especially in short season areas
    • earlier harvest to allow for double cropping or fall seeding of subsequent crops (e.g. winter wheat)
    • more flexibility for time of harvest with a large acreage since canola typically retains its quality in the swath better than other crops (e.g. cereals), making the timing of harvest less critical
    • reduced shatter losses during the harvest operation - especially in crops infected with Alternaria
    • swathing can be done around the clock (unlike direct combining) which assists with the harvesting of large acreages
    • cutting weeds allows a cleaner and drier sample that will reduce the risk of heating in storage and reduce the number of weed seeds that reach maturity

    The advantages of straight combining are:

    • Reduces manpower, fuel use and equipment requirement
    • May increase seed size and yield
    • May increase oil content
    • Potential green seed reduction

    Field Evaluation

    Carefully assess each canola field to determine the suitability for swathing versus direct combining. In western Canada, B. napus canola is generally swathed because it tends to not ripen evenly and may sustain pod split and pod drop, and shattering losses if direct combined. B. napus can be direct combined with or without a desiccant or pod sealant. 

    Swathing is the standard harvest approach for most canola producers.  Some conditions which make swathing the preferred method include:

    • Immature crop with imminent frost
    • Uneven crop maturity
    • Problems with green weed undergrowth or crop re-growth
    • Reduced effects of alternaria black spot
    • Reduced risk of shattering losses

    The CCC advises growers to assess each canola crop carefully before choosing straight cutting, based on four factors. [1]

    • Crop canopy – The crop should be well knitted and slightly lodged to reduce potential seed loss through pod shelling and drop. If a large proportion of the plants appear to move independently in the wind, they will be at higher risk for shattering loss as the plants senesce and dry down. The plant stand should be thick (hard to walk through). Pod integrity can be affected by frost, drought and insect damage. A uniform crop with minimal green weed growth is also a huge advantage when straight cutting.
    • Disease – The crop should be relatively free from blackleg, fusarium wilt, sclerotinia and alternaria, as these diseases can result in premature ripening, causing the crop to be prone to pod shatter.
    • Hail- Crops affected by hail are poor candidates for straight cutting because the physical damage reduces pod integrity and they normally see greater disease infection. If late season hail is common in a certain area, growers should keep in mind that hail will typically cause more damage to a standing crop than a swathed crop.
    • Frost risk – Canola seed is at significant risk for fall frost damage until seed moisture drops below 20%. This moisture drop will take much longer in a standing crop, and as such, late maturing crops are poor candidates for straight cutting. They will be much more vulnerable to yield loss, and to downgrading from frost damage when standing.

    Additional considerations include:

    • Short, severely lodged, or excessively branched canopies may be candidates as well, because if swathed there would be minimal stubble left to anchor the swaths from moving with wind. In this situation growers should consider the potential for wind damage to the swath relative to shattering risk if left standing.
    • Appropriate combine equipment with experienced operations and settings.
    • Varieties with increased shattering tolerance and lodging resistance.

    In western Canada, B. rapa varieties may be direct combined because they mature earlier and resist shattering. 

    Effect Of Swathing Vs Direct Combining Table

    Other studies have demonstrated that direct combining B. rapa can result in yield gains with 7% greater yield than swathing with seed loss lower than 4% at harvest. [2]

    Pushing canola

    Pushing is a potential replacement for swathing where pod movement is restricted by mechanically lodging the crop and letting the crop mature while still attached to the root system. Pushing can occur at the start of seed color change without any negative impacts on grain yield, green seed and oil quality. Pushing worked best when crop stand and growth were good as well as when canola was pushed at or before 30 to40% of the seeds have changed color and therefore are physiologically mature. [3]

    Contribution margin of pushing was variable in trials compared to straight combining (without pushing) or swathing. [4] Contribution margin is defined as added revenue minus added cost of production. In 2001 and 2002, pushing had lower contribution margin than straight cut canola at all three site-years while having similar yields.

    Yield and quality trends

    Producers who wait to swath B. napus at 60% seed colour change on the main stem, or straight combine at crop maturity, can potentially maximize both yield and quality [4],[5] That’s a big change from previous recommendations to swath at 30% to 40% seed colour change.

    Yield trends

    The highest yields have been observed when swathing at 60 to 70% seed colour change followed by swathing at 50 to 60% seed colour change. 

    Optimum stage to swath for both yield and quality: Up to 60% seed colour change. This enables many growers to delay the start of swathing on their first fields until at least 30% to 40% seed colour change without sacrificing significant yield or quality.

    Source: (Canola Council of Canada Canola Production Centre reports - 2001, 2002)

    Most of the yield in the trials was captured by the 50 to 60% seed colour change stage.  The slight drop in straight combine yield  relative to the best yields from swathing illustrates that gains from seed filling were outpaced by seed losses between the last swathing stage and straight cutting, but not significantly when averaged over all trials. These losses could occur from shattering and/or pod drop due to mechanical or environmental damage and fall frost damage that could reduce yield and also lead to green seed problems. 

    At Star City, Scott and Swift Current, SK, from 2004 – 2006, B. napus canola did not show any yield difference between swathing and direct combining. [2]

    In western Canada, optimum seed yield and quality were achieved when B. rapa varieties were swathed at 40% seed colour change on the main stem.

    Quality trends

    Once canola plants are swathed, the seed does not continue to fill (Figure 2). [6] Seed swathed before accumulating its full complement of oil and protein will not accumulate any more after swathing, resulting in potential yield loss.

    Figure 2.Figure 2. Effect of Swathing Date on Seed Weight after Swathing

    SOURCE: MCGREGOR, D.J.1992.Swathing canola stops seed filling. Research Letter. Agric. Can. Res. Sta., Saskatoon, Saskatchewan

    Increases in thousand kernel weight, seed size and oil content were also observed for later swathed and straight combined canola. [4],[7]

    Source: (Canola Council of Canada Canola Production Centre reports - 2001, 2002)

    Reductions in seed protein and seed oil were observed when swathing took place before 20 and 30% seed moisture, respectively. Seed oil fatty acids also tend to stabilize near the end of seed development (30% seed moisture), strengthening the argument in favor of delaying swathing to near complete seed maturity. [7]

    Green Seed

    Time of swathing usually has little effect on green seed levels, except under abnormal situations. [8]

    Keep in mind that the distinctly green % cut-offs for No. 1, 2, and 3 Canada canola are 2, 6, and 20% respectively. More information on canola grading can be found on the Canadian Grain Commission website at http://www.grainscanada.gc.ca/oggg-gocg/2013/10/oggg-gocg-10-eng.htm.

    Green seed occurs when the chlorophyll in the seed has not degraded or cleared. Green seed appears to be related not only to variety maturity but also environmental factors. In particular, temperature influences not only the rate of chlorophyll clearing but also the timing relative to seed development, as measured by the decrease in seed moisture content. [9] An inherent difference between the species causes B. rapa to clear its chlorophyll more readily than B. napus during seed ripening.

    The crop needs time to cure after swathing. The enzyme responsible for clearing chlorophyll requires moisture. If moisture in the swath is good and temperatures are moderate, green seed may drop to an acceptable level for combining within 10 to 14 days after swathing. [10] Under dry or cool conditions, curing may take longer.

    Swathing even prior to seed colour change does not increase the green seed levels. [8] Swathing at a seed moisture content over 45% moisture (0-10% seed colour change on the main stem) has reduced average seed size, and immature seed turned a reddish colour. Occasionally, reductions in seed size have been recorded with swathing at 15 to 20% seed colour change on the main stem. However, under abnormal conditions, swathing too early can occasionally result in green seed when plants are under moisture stress and very hot, windy weather dries out the pods and seed in the swath before chlorophyll has had a chance to clear.

    The majority of the canola green seed problem in western Canada is usually the result of frost. Even a light frost can fix the green colour by damaging the enzymes that clear the chlorophyll in higher moisture seed, preventing additional clearing regardless of how favourable weather conditions may become. A killing frost also causes rapid dehydration of seed and plant tissue, which may be just as important for reducing the ability of these enzymes to function properly. The seed enzymes that clear chlorophyll work rapidly at high temperatures but slowly at low temperatures. Freezing temperatures have much less effect on seed chlorophyll content at lower seed moisture levels. Seed at less than 20% moisture should typically be safe from frost damage. Swathing one to three days prior to freezing temperatures may reduce seed chlorophyll levels by allowing for a more rapid seed dry down when compared to standing crops at the same stage of maturity. The time required to dry down the swathed crop to a safe moisture level is always dependent on the weather conditions experienced following swathing. [11]

    To minimize high green seed:

    • Consider swathing B. napus varieties as early as 10 to 15% seed colour change on the main stem in fields at high risk of fall frost damage, especially in short season areas where risk of early frost is elevated.
    • Avoid swathing too early in hot, dry weather (30 to 35°C), but assess crop development frequently as seed colour change will happen more rapidly. The heat can rapidly dry the crop resulting in shatter losses from swathing too late or excessive seed shrinkage and lack of curing from premature dry down from swathing too early.

    Swathing Canola

    Assessing Crop Maturity

    The optimum stage to swath for both yield and quality is up to 60% seed colour change. [4] This enables many growers to wait to start swathing their first fields until at least 30% to 40% seed colour change without sacrificing significant yield or quality on their last fields, and widens the “swathing days” window.

    Seed in all pods on a plant reach physiological maturity and complete filling at about 40% moisture. Physiologically mature seed loses moisture at about 1 to 3% per day. Seeds slowly turn from green to light yellow, or reddish-brown to brown, depending on the weather and variety. This curing process starts from the bottom of the main stem. Seed colour change will then progress up the main stem as moisture content is reduced.

    Seeds colour change will advance an average of 10% every two to three days. Under hot, dry conditions, seed colour change can occur more rapidly but may take longer at cool temperatures. The crop is at the optimum swathing stage for only three to five days under good drying weather.

    B. rapa varieties can be swathed at 40% seed colour change on the main stem, due to their tendency to clear chlorophyll more readily.

    Assessing Your Field

    Figure 29.

    Figure 30. 

    Figure 31.

    Photos by Beth Hoar

    The colour of the seed is a good indicator of seed moisture content and is more important than the overall plant/pod/field colour in determining the stage of crop maturity. Visual indicators will vary between varieties. Some varieties will appear ripe on the outside before the seeds are mature, while others will retain green pod colour after the seed is quite dark. These tendencies may vary depending on environmental conditions.

    Tips for assessing seed colour change:

    1. Start inspecting your canola field approximately 10 days after flowering ends. The end of flowering is defined as the stage when only 10% of plants have any flowers.
    2. Take time to assess a field. Sample various parts of the field to make an accurate assessment of the overall maturity of the crop. Stand on the road or in the back of your truck box to compare low lying to higher elevated areas of the field, taking note of how each area appears.
    3. Walk out and sample at least five plants in each of those areas.
    4. Use the illustration to assist in determining seed colour percentage on the main stem. Include seeds with small patches of colour (spotting). Most of the seeds in the top pods will be firm, and roll without being easily crushed between the thumb and forefinger.
    5. Once all areas are sampled, average out the percent seed colour change for that particular field.
    6. Continue inspections every two to three days.

    Note: Some fields, or large areas within a field with low plant populations may have plants with numerous branches. Assess not only the main stem, but side branches as well to ensure seeds that have not changed colour are firm with no translucency.

    Click here to View Swathing guide fact sheet.

    Examine only pods on the main stem. Seed in pods on the bottom third of the main stem mature first and will turn colour much sooner than seed in the pods of the top third of the main stem. Make note of how many pods have Alternaria black spot and what percentage of each pod is covered with the disease.

    After assessing the main stem, look at the seed from the pods on the side branches to ensure they are firm with no translucency, especially with low plant populations where the plants have numerous branches.

    Count seed with small patches of colour (spotting) or seeds that have changed colour completely as "colour changed".

    Most of the seed that has changed colour will be from the bottom third of the stem in B. napus varieties, while in B. rapa varieties some of the middle and upper pods will have seed which has changed colour. When seed in the bottom pods has turned colour, seed in the top, last formed pods will be filled or nearly filled. Average seed colour change will typically increase about 10% every two to three days. Under hot, dry conditions, seed colour change can occur more rapidly. When conditions are cool, seed colour change can take longer.

    Assessing thin stands

    In canola stands with low plant populations the architecture of the plants changes and more branching occurs. As plant population decreases, the number of pods per plant increases. [12] Contribution to yield by the main stem is reduced whereas the contribution to yield from primary and secondary branches increases significantly. Canola plants mature from the bottom of the plant up and from the middle outwards. Therefore, this additional branching in stands with reduced plant numbers may lead to a larger proportion of pods containing immature or even translucent seed as the main stems approach the typically recommended swathing stage of up to 60% seed color change. In these cases it is best to consider a whole plant seed color change approach rather than just looking at seed color change on the main stems. Try to delay swathing until seeds in upper and outermost pods are at least firm and green to minimize potential yield loss and green seed, provided this can be done without significant shattering of main stem pods.

    Assessing multiple stage canola fields

    When field topography, soil type and soil moisture levels are uneven, the flat areas of the field may have 30% seed colour change, while the hilltops may be at 70% seed colour change, and the low lying areas may be at 5% seed colour change. This will make the decision of when to swath difficult.

    In canola stands with adequate plant populations but variable maturity resulting from issues like uneven emergence, it will still be appropriate to assess maturity of individual plants based on the seed color change on the main stems. However, optimizing returns will depend on assessing the percentage of plants at each stage of maturity and accurately estimating which growth stage represents the greatest proportion of the yield within the field.

    To start the assessment, first segregate the field into areas with obvious differences in overall maturity. These different maturity zones will often be linked to the topography of the land, but not always in the way we expect. While the hills typically tend to be drier and hence quicker maturing than mid slope to lower level areas, delayed germination on the hilltops in dry spring conditions or excess moisture stress in lowlands can sometimes cause the opposite scenario. A person may want to open up the field and swath a lap around the outside edge or use a quad to travel to the areas selected. Examine those areas and assess the crop based on the following criteria:

    A) Within each distinct maturity area (or zone), look at assessing a smaller 10 X 10 meter area. This should represent a big enough sample area to encompass the varying stages of crop within the larger maturity zone.

    B) Start by pulling some of the ripest representative plants and counting pods on main stem, then on side branches (primary or secondary). This will help determine where the bulk of the yield will be (i.e. main stem vs. branches).

    C) Next start pulling apart pods on the main stem looking at number of seeds per pod and the % of seed color change taking place inside. Then assess the major branches for seed number and color change as well as signs of firmness, which is an indicator of physiological maturity. When rolling the seeds that appear green between your fingers, if they squash easily or a layer appearing like onion skin rolls out, then the seed is still moist and not ready.

    D) If the most mature plants are still too immature for swathing, then note the sample location so you can return in a few days to re-evaluate the maturity. Seed color change will typically increase 10% every two to three days, but will be quicker in hot dry conditions. If the assessment of the ripest plants indicates they are ready, then move to later maturing areas or plants within the sample area, again counting pods and looking at seed color change or firmness. Keep in mind that translucent seeds are very immature and will likely be lost if the crop is not left to mature further.

    E) Once you have completed this, you should have a good picture of the range of maturity in that zone within the field and be able to assess the portion of the seed that is ready vs. the portion that would benefit from delaying swathing.

    F) Finally, sample from many areas within the field to adequately assess the overall readiness for swathing (at least one sampling within each maturity zone identified at the start). This may also help determine if some areas of the field should be managed separately.

    Environmental considerations

    Avoid swathing during hot (e.g. 30°C or higher), dry weather. Very hot and dry, windy weather after swathing may stop chlorophyll clearing prematurely due to low seed moisture from rapid desiccation of the swaths. This may result in some immature seed with green colour. The enzymes responsible for clearing the chlorophyll require moisture. Swath during the cool evening hours, at night, or early morning to allow the seed to dry down at a slower rate. This lowers the chance of green seed and lower oil content. Rain or irrigating the crop will help maintain moisture in the seed. Delaying combining can often allow some of the green seed colour to clear in the windrow.

    If conditions are cool and it is late August or early September and frost is forecast, swath as early as 10% seed colour change to minimize green seed from frost damage. A crop swathed three days prior to a frost will have less potential for frost damage due to more rapid dry down of seeds in the swath versus in the pods of a standing crop (assuming conditions are conducive to drying). However, canola seed does not continue to fill while the plants cure in the swath. If the seed has not accumulated its full complement of oil and protein at the time of swathing, no further accumulation will occur in the swath and some potential yield will be lost from immature seed. This represents the risk if the forecasted frost does not occur.

    Swathing Operation

    Types of Swather

    Swathers can be either self-propelled or power-take-off driven pull-type. The draper belt style of windrower, most commonly used for grain crops, is far superior to the auger style typically used for hay crops because of the greatly reduced crop damage. Self-propelled machines are preferred for their ability to “open fields” and for permitting “back and forth” cutting and in fields  that require greater maneuverability. Regardless of the equipment used, the crop must flow smoothly through the swather without bunching. Stands that are exceptionally tall, thick or lodged and tangled increase the difficulty of laying a smooth, uniform  windrow. Bunching leads to uneven drying and combining problems. As well, bunching can lead to development of diseases such as sclerotinia and stem rot if  weather is wet or humid. At the bottom of bunched or heavy swaths this disease can damage up to 50% of the canola pods.

    Swather design for canola:

    • At least 1.1 m (3.5') depth (front and back) of the table or platform to handle the crop material.
    • A large throat opening (distance between draper belts) of 1.0 to 1.3 m (3.3 to 4.3'). A vertical clearance of 1 m (3.3') for the swath opening to allow large swaths to pass through without interference.
    • A throat opening free of projections that may catch or bunch the swath as it passes through the machine. Ample reel and table adjustments to handle the range of crop stands and conditions.
    • Adjustable draper belt speed.
    • Dividers capable of separating heavy and tangled crops. Difficult crop conditions may require specialized attachments on the swather to assist crop feeding. The vertical knife is one such device. It is similar to the windrower’s sickle bar knife but it is a short section mounted in a vertical position on the swather’s end divider. In a lodged and tangled crop, the vertical knife operates far more effectively than a cone or looped-steel rod divider. This improved crop division reduces plugging and "bunching" problems. There are several types of  powered dividers of which the double knife with two moving blades appears to be the best suited for all crop conditions since it reduces the shatter loss in drier crops.
    • Canola crops do not often lodge badly enough that a conventional swather with a batt reel will not handle them although  a pickup reel is generally preferred as it has less intrusion into the crop and is less likely to be damaged when handling bunches.

    Swather Operations and Setting

    Cutting the crop just under the pods reduces the amount of crop passing through the throat. This leaves a maximum amount of stubble to lay the windrow on. The stubble anchors the windrow to minimize the effect of wind and helps ensure adequate air circulation through the swath. This also minimizes the amount of material that must be handled by the swather and combine.

    If bunching occurs, adjust the width of cut, height of cut and the forward speed of the swather so that the throat of the machine will handle the swath without bunching.

    Swather settings:

    • Set the reel as high and as far forward as possible with the bats at the top of the crop to hold plants gently against the knife.
    • Adjust  reel speed slightly faster than the ground speed of the swather. This minimizes seed shatter and crop tangling but is adequate to keep crop flowing over the knife and helps push the crop out of the opening. Draper belt speed needs to be adjusted to coordinate with ground speed. This means that the crop must flow smoothly in a continuous stream. Too slow a belt speed causes crop to concentrate on the belts and thus create extra loading for the belts and results in a compact bunchy windrow. Using too fast a belt speed can pull the crop away too fast again causing breaks in the windrow uniformity. If the canola has a higher percentage of mature seeds the higher belt speed can contribute to increased shelling.
    • As the windrow passes through the opening and under the windrower (self-propelled), if there is inadequate space or protrusions that engage the windrow bunching can be created.
    • Swath rollers are often pulled behind the swather to push the windrow into the stubble to anchor it so that it is less susceptible to wind scattering the windrow. Rollers often push the windrow forward. Windrows that come out from the swather are often only slightly leaning rearward and the roller pushes them the opposite direction. This at times can become an issue when combining. Since the normal combine travel is in the same direction as the swather travelled it is now trying to pick the swath backwards (stocks first). This becomes an issue if as the combine’s pickup keeps pulling the windrow apart it feeds the combine unevenly, which can affect performance. Set the roller as described below to minimize this effect.

    In areas where light fluffy swaths could be lifted and blown by the wind, a light roller pulled behind the swather will help anchor the swath in the stubble. Set the roller so that it just anchors the swath into the stubble without shelling any ripe pods. Excessive pressure on the roller will produce a swath that is too compact to dry quickly and difficult to pick up without shelling the canola. Leave the swath as high as possible in the stubble so that the combine pickup can slip under it without tearing the cut crop.

    Chemical Desiccation and Pod Sealants

    Growers who decide to straight combine some of their canola may be considering pre-harvest weed control or desiccation, particularly in fields with uneven maturity. While these products can hasten dry down of mature plants, they will kill any immature ones. It is also important to understand that these products are not designed to seal the pods against pod shattering, and in some cases may make the crop more vulnerable to shattering if harvest is delayed. Be prepared to harvest as soon as the crop is ready, because the more rapid dry down will leave the crop vulnerable to shattering sooner than if it is left to mature on its own. If applying pre-harvest chemicals with ground rig sprayers, using crop dividers can reduce the amount of crop loss due to trampling and shattering. In addition, traveling back and forth in the direction of prevailing crop lean will help reduce losses.

    Also remember to use only products that are registered for pre-harvest application. The use of unregistered products may leave unacceptable levels of residue in the seed.

    Desiccation versus pre-harvest glyphosate

    Reglone, a chemical desiccant can produce more uniform crop ripening by chemically drying down all green vegetative growth, but it does not provide perennial weed control. Glyphosate can be applied preharvest for control of perennial weeds and as a harvest aid to help to kill annual weeds, but it does not typically speed drydown. [13]

    Dessication = fast drydown.
    Pre-harvest glyphosate = weed control.

    Neither will speed maturity.

    Growers should assess their needs to determine if they need desiccation or pre-harvest weed control.

    Comparison of Reglone and Glyphosate
    Reglone desiccant Glyphosate pre-harvest
    Contact non-selective Systemic non-selective
    Fast acting (days) Slow acting (weeks)
    Desiccates crops and weeds Kills crops and weeds
    Strong activity on dicot crops Strong activity on monocot crops
    Affects green tissue of all plants Affects meristems of all plants
    Best on senescing plants Best on actively growing plants
    Burns top growth of annual and perennial weeds Kills perennials, inconsistent on annuals.
    Apply when majority of seed is mature Apply at less than 30 percent seed moisture
    Does not affect seed germination Adversely affects seed germination
    Temperature, day length and light intensity affect performance Frost, drought and temperature affect performance
    More expensive Less expensive


    Reglone is the only desiccant registered for use on canola. Reglone rapidly desiccates the leaves and pods of plants, but green seed requires time to mature.

    Canola must be desiccated at the correct stage to optimize yield and seed quality. Reglone can be applied by aerial or ground application, and should be applied when the crop is at 80 – 90% seed turn (green to brown) stage. Combine no later than 14 days after application. [14]

    B. napus cultivars are more prone to shatter than B. rapa cultivars. Desiccation and direct-combining should only be considered for B. napus canola in:

    • heavy crops that lodged early and have weeds grown through the crop
    • crops that mature unevenly due to topography or uneven stand establishment
    • where swathing machinery is unavailable
    • in late maturing fields, which may not mature in time under normal conditions before a killing frost

    For B. napus varieties, a heavily lodged crop canopy may help prevent shatter loss by wind. Check your provincial recommendations for current information on registered desiccants.

    For B. rapa varieties, desiccation can eliminate the need to swath while drying down green annual weeds.

    Pre-harvest glyphosate

    Glyphosate preharvest translocates within perennial weeds, slowly killing the plant.  Glyphosate affects seed germination and is not recommended on crops grown for seed. On Roundup Ready canola varieties, a pre-harvest glyphosate application will provide perennial weed control, but it will not dry down the crop. For other types of canola, it is critical not to apply the product too early. Apply when the crop has 30% or less seed moisture content. At this stage, pods are green to yellow, and most seeds have turned from green to yellow or brown.

    Seed and foliage moisture drydown are not enhanced by glyphosate treatment. Pre-harvest glyphosate treatments generally have little or no effect on canola seed yields, seed weight, seed germination, green seed content or oil content when applied at the proper stage. [13]

    Extremely cool, wet and/or cloudy weather conditions between the time of application and the anticipated harvest date may slow down activity of this product, thereby delaying crop drydown and harvest date. [15]

    Pod sealants

    Pod sealants were developed to reduce shattering losses by preventing the pods from splitting open during ripening. Pod sealants are relatively new to the Canadian marketplace and limited scientific research has been conducted with these products under western Canadian conditions.

    Preliminary studies with 8-site-years in Saskatchewan show no difference in marginal profit when comparing untreated and pod sealant treatments when straight combining 75% of the time, with marginal profit advantage 13% of the time and a marginal loss 13% of the time.  No significant difference was observed when averaged across all treatments. [16]

    In North Dakota in 2005, a replicated field trial found similar yield for the anti-shattering agent and the control straight harvest treatments. [17]

    As with any new agronomic tool where information on its performance under our environmental conditions is limited, a good strategy is to start small with your own on-farm experimentation. Leave check strips of an untreated area.

    Combine timing is crucial for minimizing shatter losses as the sealant efficacy diminishes with time and from repeated rains. Sealants slow crop dry down and harvest by five to 14 days. This could be a concern in shorter season growing areas.

    Information provided by the manufacturers suggests that application timing should be targeted when the majority of the pods are changing colour from green to yellow but the pods should still be pliable enough to fold over without splitting open. Seed colour change should have occurred within the pods to allow curing and harvesting within the window of protection provided by the pod sealant. The best advice is to consult with company representatives on the ideal timing for your fields.

    Stick with the high water volumes recommended by the company. Thorough coverage of all the pods is very important because these products form a physical coating to seal the pods against splitting open.

    Combining Canola

    The basics of combining include:

    • Gathering: getting the crop into the header, getting it up the feeder and into the separator.
    • Threshing:  the goal is to achieve complete threshing within acceptable limits of seed damage. In most canola crops the biggest concern is seed damage. However, threshing is a major factor in breakdown of the material-other than-grain (MOG). The condition of the MOG will effect separating and cleaning. Unthreshed loss should be negligible in canola.
    • Separating:   Getting the seed out of the MOG without separator loss is the main challenge. However, excessive MOG separation can overload the cleaning shoe with chaff and debris. Separating loss should be less than ½% of the yield.
    • Cleaning:  needs to minimize shoe loss, ideally to less than ½% of yield, the sample cleanliness depends upon the owners tolerance for dockage and issues of handling. Achieving a very clean sample should not come at a cost of shoe loss or extra seed damage. Often in an attempt to maximize cleaning capacity the return tailing is loaded to the point that tailings plugging can become a limiting factor in productivity.

    Consult combine manuals for operational settings.  For auto adjust controls, calibrate and check settings to ensure the combine is operating as indicated.

    General equipment operation and settings

    Before harvest time, check your combine’s mechanical system completely and repair or replace components that are likely to fail to minimize downtime during harvest. As soon as you start harvesting canola pay attention to the following hints.

    Check for leaks.Losses do not always come out the back end. Assess your pickup for source of loss such as between belts, out of the table and the auger throwing seed out of the table. Look for holes and cracks  between the feeder house and pickup, where the feeder house meets the combine, around stone trap doors, past separator covers and access holes, around the clean grain elevator (especially the access door), shoe seals, into the fan housing  and the grain tank. Cover or repair holes or cracks. Duct tape, plastic tape, foam weather stripping  silicon rubber-sealing compound or even paper towels are handy tools. Steady leaks can add up to a significant cost. They can easily exceed the combine’s processing loss of a well performing machine.

    Feed the combine properly.Rotaries work best with a narrower windrow “like a ribbon.” Usually they have relatively narrow feeders so to handle wide heavy windrows the feeders have to work hard to get the material in. This means that the table auger and feeder chain often are run faster than ideal, which results in more front-end loss.  Conventional (straw walker) combines work best with a wider swath that creates an even matt over the full width of the cylinder and walkers.

    Slow down. When a combine reaches its peak processing capability pushing feedrate beyond this level causes the system efficiency to breakdown. Sometimes this is a controlled reduction and sometimes it is catastrophic. The difference between peak efficiency and unacceptable can be a small change in feedrate. It may take just a small decrease in speed — say 0.2 or 0.3 mph — to provide a significant reduction in losses. This is best illustrated by comparing feedrate effect on loss  by looking at a loss curve.  So long as the loss remains fairly flat (at an acceptable loss) increasing feedrate (ground speed) has minimal effect. However, when feedrate reaches a point where the loss curve rises steeply the combine’s capacity has been taxed and efficiency is decreases . When testing to find your combine’s sweet spot, increase your speed in small increments and keep checking  losses. When you observe that loss is increasing noticeably you  getting maximum efficiency at those settings for your particular crop.

    Combine adjustments and operating speed must be fine tuned for conditions in the field.

    Keep combines in good mechanical condition. Worn or misadjusted feeder chain can lead to uneven feeding. A misadjusted clean grain elevator chain can cause seed damage. Make certain that cylinder/rotor rasp bars are in good condition and properly aligned. Concaves must be true and properly adjusted. Straw walker curtains must be in place and in good repair.  Broken, plugged or bent sieves make it impossible to get the best from the cleaning system. The fan inlets and bleed holes must be unobstructed. Worn or misadjusted drive belts can result in poor performance and plugging.

    Table Auger and Feeder
    Adjust the table auger to specifications  and insure that it can travel its full range of float, which should be 5 to 10 cm (2 to 4").  The front elevator needs to carry a  big volume of material so check the tension  and freedom to float.

    Cylinder/Rotor Speed and Concave
    Canola is usually not a difficult crop to thresh.  Under normal conditions  a lot of the seed is threshed  going under the table auger and up the feeder elevator.

    Set the cylinder/rotor speed at about 50 -60% of that used for cereals. Set at 600 to 800 rpm for small diameter (46 cm, 18") cylinders/rotors, and 450-700 rpm for mid-size diameter (61 cm, 24") cylinders/rotors and 400 to 650 rpm for larger cylinders/rotors (71 cm – 28in). Excessive cylinder speed causes seed cracking and skinning.  A high cylinder/rotor speed smashes  pods and stems, which may generate increased chaff that can hamper separation and/or increases the shoe load. Slow cylinder/rotor speed increases the chance of plugging and puts more strain on the cylinder/rotor drives. Generally use as high a cylinder/rotor speed as possible that still provides an acceptable amount of seed damage.

    The concave is generally set quite wide open as compared to cereal crops. The concave should not be set wide open so that if plugging occurs there is still an opportunity to lower the concave to make backing the slug out easier.  For combines where the concaves can be easily changed it is often preferable to have narrower spaced wire concaves to minimize the amount of stems being pushed down to the cleaning shoe.

    Straw Walkers
    Excessive pods, broken pods and stems separated by the walkers can overload the cleaning system and tailings return. In some cases wire mesh over the walker surface has been successful in reducing excessive trash separation. Others have removed the straw walker risers to help material move over the straw walkers faster. However, most operators reduce the threshing aggressiveness with cylinder and concave adjustment.

    Wind Adjustment, Chaffer and Clean Grain Sieve

    QUICK TIP: For a given chaffer and sieve setting:

    • Have operator just feed crop in at 0.5 to 1.0 mph. Start at the low to mid–range of recommended fan speed.
    • Monitor if and where seed is coming off the chaffer and if minimal.
    • Increase fan speed (50 rpm increments) until full seeds start to carry over. (This usually is the air speed that is capable of suspending seed over the chaffer until it exits).
    • Increase feedrate in steps and keep monitoring loss over the chaffer
    • As loading increases air speed decreases slightly so maximum acceptable blown over seeds at low speed is usually less at normal harvesting rates.
    • This setting technique is based on chaff fluidization (air moving through the entire chaff mat).

    Proper fan and sieves adjustment is important since canola seed can be easily  blown out of the combine or remain mixed with the chaff and carried out. However, it is necessary to use enough wind to maintain a "live" sieve.

    Two things are important for a cleaning system to work effectively:

    • The shoe must be fed evenly from side to side, and
    • The air must be distributed reasonably uniformly.

    Uniform material delivery to the shoe is most affected by separation and this is most noticeable in rotary combines. There is a tendency for seed and chaff to load heavier on one side. Sometimes distribution can be improved by rotor speed and concave adjustment, but more often concave blanks or diverter panels are required to get more uniform distribution. Often the best way to check for distribution uniformity is to shut the combine down as quickly as possible while it is under load. This is called a “kill stall”. At the same time the chaff distribution of the chaffer sieve needs to be checked. The front ¼ of the chaffers should be chaff free. If longitudinal channels of the chaffer are blown clear or piled higher with material it is important to verify if this corresponds to the material separated under the rotor. If they do not correspond it is likely that there is an uneven air distribution pattern. Typically, very little can be done to correct uneven air patterns, unless it is due to fan or fan inlet plugging. However, the distribution must be matched to the air pattern with more material directed to where the strongest air blast is. There is a complex  relationship between fan speed and sieve (pre-cleaner, chaffer, tailings and cleaning) openings. It is first important to recognize that it is much easier to blow air through seed and get to the chaff than it is to blow chaff through seed. This is why preparation floors shake the separated mixture to get the grain to the bottom before feeding onto the sieves. Pre-cleaners use a strong air blast to get chaff above the seed.

    Generally closing the chaffer sieve directs air from a more vertical direction to a horizontal path. This causes seed and chaff to move rearward more quickly, reducing the time it is in the cleaning area. This also tends to align straws in the horizontal plane. When the chaff load is dry and light a fairly wide chaffer openings (15 -22mm (9/16”-7/8”)) can provide maximum capacity as the material moves slower and has more time to separate. The chaff mat is also dispersed so that there is less restriction for the seed to fall through the mat. However, when chaff has larger pieces of stem or becomes damp or green, too wide an opening results in stems and pod pieces in the sample or stems “spearing” in the sieves. The wide chaffer sieve setting can in some conditions result in an overloaded tailings system. In these instances the chaffer must be closed more (12 mm (1/2”)).

    Closing the cleaning sieve has a similar effect, but because it is below the chaffer sieve this also affects the air flow to the chaffer. In canola the cleaning sieve is often closed to 2-3mm (3/32”-1/8”) but can also operate at times up to 6mm (1/4”) open. Running a closed sieve can limit the air flow along the entire length of the chaffer sieve which means there is a chance in some machines that material will settle on the chaffer and ride out, taking seed with it.

    Adjusting the lower sieve tight to obtain a very clean seed sample in the grain tank can at times send clean seed into the tailings return, which in turn may lead to extra seed damage.

    If too much trash is in the grain tank and closing the sieve is not an option try increasing the fan speed slightly or reducing the chaffer sieve opening. Often the tailings section at the rear of the chaffer sieve is opened wider than the main chaffer sieve. In canola this can be problematic. Unlike coarse grains there are typically few unthreshed pods to be caught. Opening the tailings section often overloads the tailings system with trash that should have been carried over the tailings section. The wide tailings section also provides an easy escape for air between the chaffer and cleaning sieve, which further reduces the air flow up through the chaffer sieve towards the rear of the chaffer.

    If you can’t achieve acceptable shoe settings it is possible that you can go back and readjust your threshing and separating components. Sometimes this means more aggressive threshing to get rid of pieces of stem that can be broken to a size that the air can deal with, or it may mean decreasing the threshing aggressiveness so that the larger pieces stay in the separator and the chaff load is lighter.

    Harvesting Swathed Canola

    Assessing crop maturity

    Swathed canola is ready to harvest under normal conditions about five to 14 days after cutting - when moisture content has dropped below 10%, which is the official limit for “dry” canola. However, for safe longer term storage canola should probably be around 8%, so if harvesting at 10% or above some conditioning or even drying may be required. Most seed will be mature with little or no green colour. Use a properly calibrated moisture meter to ensure correct assessment of moisture content.

    Green seed evaluation

    If there is green seed present, allow a few more days in the swath for further colour change. Green seed may change colour in the swath but does not change significantly once combined and stored.

    Before combining, use a crush strip to determine the amount of seed that is green inside. A small percentage of green seed will reduce grade (No. 1 Canada allows 2.0% distinctly green, while No. 2 Canada and No. 3 allow 6.0 and 20.0% respectively). The use of wide swathers on tall, heavy crops can result in very large swaths that can take longer to cure, especially at the centre of the windrow. Bunching in the swaths also may contribute to a green seed problem as the crop dries out and cures unevenly. Canola swaths tend to dry more quickly than cereal swaths after a rain or heavy dew so combining can begin sooner. The chances of taking off top grade canola are much better under rainy conditions than with cereals, as canola typically retains its quality better in the swath.

    Windrow Pick-Up

    Windrows are picked from the stubble using  rubberized draper belts, or an aluminum reel fitted with fingers. The draper belt pick-up with plastic fingers is preferred in canola as they provide a more gentle action, which helps to reduce shatter losses. The aluminum reel style pick-up is more open so must be run slowly to ensure minimal loss.

    To minimize pod shatter at the pickup adjust pick-up speed so that the windrow will be gently lifted without tearing or pushing. Set the pick-up height to run just under the swath. If the pick-up is run too high or too fast, the swath will be abruptly lifted onto the table which may cause shatter loss. On the other hand, if the speed is too slow, the swath will be pushed again causing shatter loss and cause crop to feed in bunches which hampers combine operation.

    Direct-Combining Canola

    Canola is ripe when the pods are dry and rattle when shaken. Seed is dark brown to black or yellow in colour at maturity depending on variety. Stems may still be partly green at this stage. Bottom pods on the plant ripen first and at harvest some of the small top pods may still be greenish. Green pods will usually pass through the header unthreshed. Start harvesting when overall seed moisture has fallen to 10% moisture or less and green seed is minimal.

    At 10% moisture and above, seed in storage can heat rapidly on hot days, particularly if there is a significant proportion of immature seed. To avoid shatter losses, harvest B. napus varieties without delay when green seed levels are low and seed moisture reaches 10%, but be prepared to aerate or dry the seed as needed. The longer a ripe B. napus crop stands in the field, the greater the potential for shatter losses. Rain on a standing crop increases the potential for shatter losses as it promotes saprophytic organisms growing on the pods.

    Reduce shatter losses by combining:

    • a ripe crop at higher seed moisture levels and drying the seed
    • in the cooler part of the day
    • at night when pods are damp from dew
    • at night during periods of very hot weather

    However, seed moisture levels must be continuously monitored to ensure they do not exceed safe storage levels.

    Dividers and Reels

    A major problem in direct combining tall canola is dividing the crop at the end of the header as it is traveling through the standing crop. Vertical powered dividers can be effective in preventing crop blockages.

    A normal bat reel can be satisfactory in some lighter crops, but in heavy and lodged crops a pick-up or finger reel is desirable. To minimize shatter losses, setting reel speed is critical. The reel isn’t for clearing the cutter bar but rather to ensure that the crop keeps moving rearward until the draper or auger can carry the crop to the feeder.  Reel height is usually set so that just the fingers enter the crop. Reel fore-aft position is typically set just ahead of the cutterbar so that in heavy crop it doesn’t start restricting sideways flow on the table

    Environmental issues

    A killing frost will reduce quality, and leaving the crop standing or swathing will not improve quality after a killing frost. Immature seeds (moisture content higher than 20%) will be damaged.

    Green seedis the major downgrade that results from frost.

    Frost effects on maturation

    The degree and duration of frost and moisture content of the canola seed influences the type and amount of damage. Canola seed drier than 20% moisture will not normally be damaged by frost. Frost in excess of -5 degrees C at high seed moisture contents is generally lethal, resulting in non-viable seed. Such frosts are lethal due to formation of ice crystals that physically disrupt structures such as membranes and enzymes. Pods of immature canola crops frozen at lethal temperatures have been observed to turn black, whereas mild frost turns pods white or white-speckled. Lethal frost at seed moisture content greater than about 45% will cause seed shriveling since dry matter accumulation is not complete. [18]

    Mild, non-lethal frost damages canola seed by interfering with chlorophyll degradation, thus creating green seeds. Initially, mild frosts were thought to damage the de-greening enzymes, but research has shown that chlorophyllase activity is activated and synthesized following frost. Peroxidase activity is inhibited following sub-lethal frost and could be partly responsible for degreening failure.

    The main effect of mild frost is to cause an accelerated desiccation, which forces a premature transition from the grain-filling or pre-desiccation stage. After a mild frost, there is a rapid moisture loss from pod walls, followed by rapid moisture loss from seeds. De-greening enzymes thus are not able to complete pigment degradation. [19]

    For example, canola plants subjected to -5 degrees C at 50-75% seed moisture dried rapidly to 12-15% in 8 days whereas control plants lost little moisture over that time period. Seed from the frozen plants lost a little chlorophyll in the first 4 days after the frost, but none after that. In comparison, the control plants lost 70-80% of chlorophyll in the 8 days. In some experiments, pigment synthesis was actually renewed for a short period after a mild frost.

    Green seed has been created by rapid drying in the lab or field, which supports the “desiccation by frost” theory. In addition, re-hydrating frost-induced green seeds to 20% moisture for 7 days led to 25% reduction in total pigment content. Germination was not stimulated since the active stage of germination begins after the seed has imbibed enough water to reach 40% moisture. [20]

    Freezing of immature canola seed causes subtle effects on oil and protein compared to pigments. If the seed moisture content is higher than 55% at the time of mild frost, oil contents can actually be increased since protein synthesis continues later than lipid.

    Assessing frost damage

    If frost hits a standing canola crop, note the temperature and duration of the frost in the morning and monitor crops closely. The amount of frost damage depends on various factors including crop stage, degree and length of frost, relative humidity, and presence of rain or dew. In many cases, a light frost will damage the outside of pods but seeds can continue to mature — increasing yield and quality — if the crop is left standing.

    For a light frost, above -2 degrees C:
    Hold off swathing.  Check in the afternoon immediately following the frost.  Speckling on the stem and pods may be observed, but are not a concern if the plant is still alive.  If the plant is wilting, this is indicative of heavier frost damage that may have killed the plant.

    If no wilting, leave the crop standing and check daily:

    • If the majority of the seeds remain turgid, delay swathing to allow for further seed maturity.
    • If the pods are severely damaged and are beginning to desiccate, swath during periods of dew or high humidity to reduce the amount of pod shelling and pod drop.

    For a heavy frost, below -2 degrees C:
    Check in the early afternoon and assess the damage. Canola may wilt and desiccate quickly after a heavy frost, depending on factors such as crop stage, duration of frost and field topography. Check pods for a white, wilted appearance. Damaged pods turn translucent quickly, and will desiccate and possibly shatter within a day, especially with warm sunny afternoons. If pods are desiccating rapidly, swathing right away will preserve as much yield as possible.

    In areas hit by successive heavy frosts, growers planning to straight combine should reconsider that decision unless the crop had dried down naturally prior to the frost. If pods were already leathery, the frost may have little effect on shattering risk. Frost damage to green crop will leave those pods in jeopardy of both shattering and pod drop. Waiting to straight cut green crop hit by heavy frost may mean considerable losses.

    Green crop hit by heavy frost should be swathed, and probably right away. Immature, watery seed will see little if any advantage from waiting. With frost damage, this seed probably won’t finish filling even if the crop is left standing. For seed near maturity, frost has locked in chlorophyll and it likely won’t clear. Look for seeds that are brown on the outside but dark green inside. Mature seed is ready.

    Minimizing grain loss during harvest

    A loss of 1 kg/ha (0.02 bu/ac) is equal to 23 seeds of B. napus and 42 seeds of B. rapa per square metre remaining in the field. Average harvesting losses in the field can range from 10 to 50 kg/ha (0.2 to 1 bu/ac), but losses can reach up to 5 bushels per acre.

    Benefits of reducing losses

    Increased margin: Loss can be measured in several ways including operating costs, time, and revenue.  For many farmers, the actual value will be a combination of these measurements.  The last bushels in the grain tank are also more valuable from a margin perspective. If you subtract the number of bushels of yield needed to cover production expenses, there may be only a few bushels for margin. At this level, every bushel lost becomes a much higher percent of the profit compared to total yield. Instead of 2% to 3% it might be 20% to 50% or more.

    Reduced operating cost:  From an operating cost comparison, slowing down combine travel speed to reduce grain loss can improve net revenue per acre.  For example:

    Scenario 1:  Combine @$250/hr.  Harvesting at 4 mph will take 12.5 hours for 160 acres.  Cost of operating is 12.5 hr x 250/hr = $3,125. 

    Scenario 2: Combine @$250/hr.  Harvesting at 3.5 mph will take 14.5 hours for 160 acres.  Cost of operating is 14.5 hr x 250/hr = $3,625.

    If 1 bu/ac additional yield was captured because of slower harvest speed, 1 bu @ $8.50/by x 160 acres = $1360.

    Scenario 1 cost of operating is $3125 plus $1360 = $4485.  Scenario 2 cost of operating is $3625, for a low cost of $860 over scenario 1.

    Integrated weed management: An average yield loss of 1 bushel per acre can return 1200 seeds per square metre back to the soils.  These seeds can volunteer the following year, putting large pre-seed and in-crop weed pressure on the subsequent crop.  Reducing combine losses means lower weed competition.

    Measuring actual losses

    Canola producers can lose up to five bushels or more per acre if the combine isn’t adjusted properly. The amount of loss that is acceptable is up to each farm manager.  However, the amount of loss a combine produces depends on combine adjustments and how it is operated.

    A combine grain loss monitor, suitably adjusted, can be effective for monitoring loss in canola. The loss monitor can warn of changes in the grain loss rate but does not accurately measure the amount of loss.

    Step 1. Measure losses

    Electronic loss monitors will not accurately measure losses out the back of the combine. They give you an indication whether losses are going up, but won’t tell you how many bushels per acre are thrown over. An increase in the meter reading is a signal to reduce the feed rate by slowing down. A reduction in the meter reading is a signal that the feed rate may be increased in order to improve productivity. Changes in crop conditions often occur during the day. The loss monitor will indicate when combine adjustments are necessary to compensate for changing weather conditions.

    Measuring actual  loss out the back of the combine requires a drop pan. There are three drop-pan options:

    1. Drop Pan: Les Hill, manager of business development and technical services with the Prairie Agriculture Machinery Institute (PAMI) in Humboldt, Saskatchewan makes a large metal pan to match the full width of a combine’s discharge area. The pan attaches under the belly of the combine and releases with the pull of a lever. The pan is divided into sections so losses from the   shoe and separator are collected as the combine passes over, providing the chopper and spreaders have been removed.  The sections help identify whether losses are concentrated on the sides or in the center.

      AgriTrac Equipment in Westlock, Alta., has also developed a full-width pan that attaches by magnet to the belly of the combine. To release the pan, the combine operator unplugs the magnet cord from its power source — the cigarette lighter in the cab. Without power, the magnet releases and the pan drops. VB Enterprises Ltd of Morinville AB also makes a drop pan mechanism.

      With the pan dropped, the operator can measure how much seed is thrown over. Convert weight of seed captured in pan into bushels per acre using Combine Seed Loss Tables.
    2. Stick Pan: Make a stick pan with deep sides that you can hold under the back end of the combine as it goes by. Deep sides will limit seeds from bouncing out of the pan. The Canola Council of Canada produced some seed loss kits (pictured below), which included a deep-sided stick pan with threaded receptacle for a paint roller handle. The CCC pan attached to the handle on a right angle. That way the user can stand behind and to the side of the combine, and still keep the pan square to the separator. The CCC pan was exactly one square foot, which made it easy to use the conversion table shown later in this article. With a homemade pan, measure its dimensions and be ready to convert losses into a one-square-foot equivalent.
    3. Throw Pan:  Throw a pan under the combine. The lid to the CCC deep-sided pan is also one square foot. You can throw it ahead of the rear wheels to capture losses as the combine passes over it. The risks with throwing the pan are that it won’t land flat in the stubble (and not capture a true one-foot sample) or it will land in the path of a rear wheel.

    How to take a sample

    Once the collection tool is chosen, here are the simple sampling steps:

    1. Disengage the chaff spreader and straw chopper and move them out of the way. That way, all straw and chaff drop straight down into  the pan. This is important for calculations. Also, with the spreader off, the person holding the pan isn’t pelted with straw and seeds and dust.
    2. Drop the pan, throw the pan, or hold the pan. When using the stick pan, the ideal is to move the pan into position upside down so it doesn’t gather any losses ahead of time. To position the pan, walk behind and to the side of the rear wheels and extend the pan so it’s in front of the chaff and straw discharge area. Once the pan is in position, quickly flip it over and stop walking. Stand still until the combine has passed over the pan. With this procedure, you get the same result as though you’ve dropped or thrown the pan on the ground, but the handle gives you far more precision when it comes to placement. A long handle helps keep you out of the dust. (The old method of walking alongside the combine using a scoop shovel is flawed in two ways. First, lightweight seeds such as canola will bounce off the shovel or roll out, so the sample is not a true representation. Second, timing becomes a factor when walking while sampling. For example, if you took a sample for four seconds, then made an adjustment to the combine settings and checked the losses again but only held the shovel in place for three seconds, you didn’t get a fair comparison.)
    3. Remove the straw and chaff and preserve only the seed. A screen works. Another method is to put the collected sample in the bottom of a deep five-gallon (20-litre) pail and stick a blower or old hairdryer into the pail. Chaff and straw will blow out and leave the seed behind.

    How to calculate loss per acre

    1. Measure the seed in the pan. The CCC grain loss kit includes a small scale that can measure in increments of 0.1 of a gram, which you need for taking canola weights. You can also use volume or make a visual estimate. For more on these options, click here for a link to the Combine Seed Loss Guide.
    2. Calculate based on one square foot. The pan in the CCC grain loss kit is one square foot, which makes the calculation easy. If your pan is two square feet, for example, divide the weight by 2 to get the total for one square foot.
    3. Determine the concentration factor for your combine. This is a ratio of swather or straight cut header width and combine discharge width. For example, if the header is 30 feet and the discharge width is five feet, then the CF is “6.” See the table below to calculate your CF.
    4. Plug these numbers into the Weighing Method table below to get losses in terms of pounds per acre. For example, if the cleaned sample amounts to 6.2 grams per square foot and the combine CF is 6, this converts to a loss of 100 pounds per acre — or two bushels per acre.
    5. Take another sample before moving on to steps 2.

    Visual assessment:
    While not as accurate, a visual assessment can provide a quick verification of combine loss.

    Step 2. Determine whether those losses are acceptable

    Combines running efficiently will lose some grain. If your target is zero losses, you’ll probably end up running too slow to get the job done in a timely fashion, risking  natural losses and cost increases that will outweigh any reduction in grain loss.

    With canola, a 3 to 5 bushel/acre loss is common. This represents a significant loss in production across the Prairies, not to mention a large number of volunteer plants to deal with. On a 40 bushel/acre canola crop, a 3 to 5 bushel loss represents 7.5% to 12.5% of the potential yield. Reducing those losses can provide a significant boost in profit.

    An acceptable loss rate strikes a balance between productivity, saving grain, and a clean sample. For some, 1% is worth striving for. For others, 3% might be best if the harvest season is tight and it means they can keep the feed rate up and harvest an extra quarter section per week per machine.

    Making proper adjustments

    The general tip if losses are too high is to check the combine operators’ manual and look at the range of settings for canola. Are you within those ranges? If not, try that first. Try one variable at a time and check losses between each adjustment. It is also worth checking that the automatic settings on newer combines are calibrated. For example, if the chaffer setting on the monitor says 18mm, take a ruler and check that the chaffer spacing is in fact 18mm.

    When considering adjustments, here are a few specific situations and possible solutions:

    • If you find unthreshed pods in the chaff, the combine is underthreshing. Increase cylinder or rotor speed, narrow the concave setting, add concave blanks, or slow down.
    • Losses can also result from underthreshing, or going too slow. If straw is getting pulverized into small pieces that drop down to the sieves, thus reducing air flow and separation, this is usually a result of overthreshing. Cracked seed is another sign of overthreshing. Consider lowering the cylinder speed or widening the concave setting. This adjustment may also make it possible to drive faster and keep losses constant.


    [1]  Watson, P, Brandt, S., Clayton, G., Harker, N. 2008.  Canola Harvest Management Study. CARP, Canola Council of Canada.

    [2] Gan, Y., Malhi, S. S., Brandt, S. A. and McDonald, C. L. 2008. Assessment of seed shattering resistance and yield loss in five oilseed crops. Can. J. Plant Sci. 88: 267_270.

    [3]  Irvine, B. and Lafond, G. P. 2010. Pushing canola instead of windrowing can be a viable alternative. Can. J. Plant Sci. 90:145_152.

    [4]  Canola Production Centre, 2001. 2002 Summary.

    [5]  Gan, Y., Malhi, S. S., Brandt, S. A. and McDonald, C. L. 2008. Assessment of seed shattering resistance and yield loss in five oilseed crops. Can. J. Plant Sci. 88: 267_270.

    [6]  McGREGOR, D.J. 1992. Swathing canola stops seed filling. Research Letter. Agric. Can. Res. Sta., Saskatoon, Saskatchewan.

    [7]  Vera, C. L., Downey, R. K., Woods, S. M., Raney, J. P., McGregor, D. I., Elliott, R. H. and Johnson, E. N. 2007. Yield and quality of canola seed as affected by stage of maturity at swathing. Can. J. Plant Sci. 87: 13–26.

    [8]  Cenkowski, S., S. Sokhansanj, and F.W. Sosulski. 1989a. Effect of harvest date and swathing on moisture content and chlorophyll content of canola seed. Can. J. Plant Sci. 69: 925-928.

    [9] Sokhansanj, and F.W. Sosulski. 1989b. The effect of drying temperature and chlorophyll content of canola seed. Can. Inst. Food Sci. Technol. J. 22: 383-386.

    [10] McGregor, D.I. 1994. Relationship between chlorophyll clearing and moisture loss. p. 26. In An Overview of Canola Agronomic and Varietal Research 1990-1993. Canola Council of Canada, Winnipeg, Manitoba.

    [11]  Wright, E.B. 1994. The influence of an artificially induced fall frost on the seed quality of Westar canola. p. 19. In An Overview of Canola Agronomic and Varietal Research 1990-1993. Canola Council of Canada, Winnipeg, Manitoba.

    [12]  S.V. Angadi of AAFC Swift Current CROP SCIENCE, VOL. 43, JULY– AUGUST 2003

    [13]  Darwent, A. L., Kirkland, K. J., Townley-Smith, L., Harker, K. N. and Cessna, A. J. 2000. Effect of preharvest applications of glyphosate on the drying, yield and quality of canola. Can. J. Plant Sci. 80: 433–439.

    [14]  Reglone label

    [15]  Roundup Transorb label

    [16]  Holzapfel, C., 2010.  Evaluating the effectiveness of pod-sealants for reducing shattering losses in several cultivars of direct-combined canola. CARP-SCDC 2009-10

    [17] Burton L. Johnson, Kent R. McKay, Robert A. Henson, Eric D. Eriksmoen, and Lee Novak. 2005. Comparing Straight Harvest with an Anti-shattering Agent to Swathed Harvest of Canola and the Evaluation of Field Scale Straight Combining Compared to Swathed Canola

    [18]  Canola@Fact; Understanding the maturing canola seed and the impact of frost. Aug 2006. Condensed article by Murray Hartman, ARD

    [19]  Green, B.R., Singh, S., Babic, I., Bladen, C. and Johnson-Flanagan, A.M. 1998. Relationship of chlorophyll, seed moisture and ABA levels in the maturing Brassica napus seed and effect of a mild freezing stress. Physiologia Plantarum 104:125-133.

    [20]  Johnson-Flanagan, A.M., Maret, L.L.D. and Pomeroy, M.K. 1994. Humidification of green canola seeds leads to pigment degradation in the absence of germination. Crop Sci. 34:1618-1623.