When Should I Swath My Canola?

Staging canola for swathing or pre-harvest desiccation is critical to maintain high quality seed and maintain yield. Ideal swath timing is when 60% of seeds on the main stem have turned colour, meaning 60% of all the main stem seeds are showing some form of colour (yellow, brown, black) other than green.

For 60% seed colour change, the bottom third of the main stem of the plant will have totally brown/black to purplish seeds, the middle third will have turned, or be showing some spots of colour, and the top third are green. The green seeds must be firm and should roll between your fingers without squishing. At this stage, the average moisture content is about 30%.

Producers are reminded that more than one area in a field will need to be assessed for seed colour change. Relying on a visual assessment of canola pod colour alone will not provide an accurate estimate of crop stage. In many cases, the outside of the pod colour can turn brownish yellow but seeds inside may still be green.

Swathing

Delaying swathing of canola until the 60% seed colour change stage usually allows for:

  • Improved yield and quality through increased seed size
  • Reducing green seed
  • Higher oil content
  • Minimizing economic shattering losses

Earlier swathing tends to lock in green chlorophyll in underdeveloped seeds, reducing oil content and potentially causing marketing issues. Canola can be swathed in the 30-40% seed colour change stage to manage a large number of acres ripening at the same time, but producers should be aware that swathing at this stage can cause yield losses up to 8%.

Dry growing conditions and damaging weather have impacted canola development across Manitoba in 2018. Evaluating canola fields for evenness and uniformity is important to selecting the right time to swath or desiccate the crop. If growth conditions allowed large patches of delayed emergence, or hail set back crop development, estimating the patch size and managing the crop according to the largest percentage area is a good recommended practice.

Pre-Harvest Aid/Desiccation

Glyphosate, Heat and Diquat herbicides are all registered for use as either a pre-harvest aid or a desiccant on canola. Check the labels or the Guide to Crop Protection (https://www.gov.mb.ca/agriculture/crops/guides-and-publications/#gfcp) to know their specific use.

In general, a pre-harvest aid (glyphosate and Heat LQ) should be used to increase plant tissue drydown and kill green weeds. The correct stage is 60-75% seed colour change. Expect to harvest the crop 1-3 weeks after spraying, similar to the time expected between swathing and harvesting.

A desiccant with the active ingredient diquat works more quickly, forcing removal of crop moisture. A fast-acting product, expect to harvest 4-7 days after application. Target a minimum of 90% seed colour change, as diquat will lock in any remaining green chlorophyll in the seed.

Points to Consider

Caution is advised when swathing or desiccating a canola crop, since that is considered growth and development termination, according to pre-harvest interval (PHI) standards. Know the length in days PHI of the fungicide and/or insecticide used on the crop; swathing or desiccating should not take place before that PHI window closes.

More tips on canola harvest management can be found here: https://www.canolacouncil.org/media/530966/canola_swathing_guide.pdf

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Are the conditions right for sclerotinia in canola?

There are a few points to remember when considering a fungicide application for sclerotinia in canola this year:

  • In order for sclerotia to germinate and produce apothecia, they require at least 10 days of moist soil conditions (surface soil – as we aren’t concerned with sclerotia that are buried more than an inch or two below the surface).
  • Spores cannot infect leaves and stems directly – they grow on senescing tissue (i.e. canola petals) and then spread to the leaves and stems.
  • Dew/rainfall after petal drop is required for the pathogen to spread from the infected petals to the stem. Petals that dry up in leaf and branch axils without any moisture will not spread the infection.
  • The recommended timing for a fungicide application for sclerotinia management in canola is 20-50% bloom. This is because typically the canopy has filled in after 50% bloom. Petals can still be infected after 50% bloom, but when they fall, they tend to land on upper branch axils. Infection that only affects minor upper branches will not have a large impact on yield. If a crop is stagey or the canopy thin, infected petals may land on lower leaf and branch axils even after 50% bloom and infect the main stem. As long is there are petals present on the plants there is potential for infection to occur, the question is where will those petals land when they fall?
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Can Sidebanded Nitrogen Cause Injury in a Dry Year?

Submitted by: John Heard, Manitoba Agriculture, Soil Fertility Specialist

With a lack of seedbed moisture, there are justified concerns about seedplaced fertilizer injury to canola and other crops.  How safe is sidebanded nitrogen? Research studies by  Dr. Cindy Grant documented considerable canola stand thinning when high rates of sidebanded urea or UAN solution were applied.  Agrotain (AT) served to reduce stand injury, but is no longer supported for this use by the manufacturer. 

Points:
  • Stands were thinned at even modest N rates, on a clay loam soil.  At high rates stands were reduced to 50%
  • Crop growth compensated for reduced stands and generally produced as good a yield as the Agrotain protected stands, except at the highest rate.
For more detailed analysis and discussion on the issue see the full .pdf
More topics on soil fertility can be found on Manitoba Agriculture’s Soil Fertility webpages.
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Seed Placed Fertilizer Cautions for Canola

Submitted by: John Heard, Manitoba Agriculture, Soil Fertility Specialist

Spring 2018 has brought many questions about seedplaced fertilizer rates for canola.  Several factors are causing concern:

  • Drier soils – which increase the risk of seed toxicity
  • Desire to apply sufficient P to meet crop removal – since many fields have seen decreasing P levels due to high yield.  P removal is about 1 lb P2O5/bu, so high yield potential fields are looking at high P replacement rates.
  • Increased use in low disturbance, low seedbed utilization (SBU) drills.  Many new openers are arriving on the scene, which are “close-to-seed” sidebanding for which one may need to consider as seedplaced.
  • Desire by growers to reduce seeding rates for cost savings.  Most research studies investigating seedplaced fertilizer injury were seeded at some 150 seed/m2, about double what some farmers are now targeting.
For more detailed analysis on the issue, see the full text in .pdf format 
 
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Blackleg in Canola – to spray or not to spray?

Things to consider:

  1. Crop rotation – the tighter the rotation the higher the risk of blackleg
  2. Historic levels of blackleg in that field – have you experienced yield loss from blackleg?
  3. Weather forecast – infection requires free moisture (light-moderate rainfall, not soil saturation)
  4. Presence of inoculum –can you see leaf lesions on first true leaves? or pseudothecia present on canola stubble?
  5. Yield potential – what is your target yield, return on investment expected?

If you have made the decision to spray, what else do you need to know?

  1. Application timing – apply at the 2 to 4 leaf stage, later applications are not as effective at reducing disease.
  2. Fungicide type – strobilurin fungicides (Group 11) are more effective at reducing disease than triazoles (Group 3). For more information on what products are registered for blackleg management, see the MB Guide to Field Crop Protection http://www.gov.mb.ca/agriculture/crops/guides-and-publications/pubs/crop-protection-guide-disease.pdf.
  3. Yield increase….not guaranteed – while strobilurin fungicides applied at the 2 to 4 leaf stage did significantly reduce the severity of the disease, yield bumps were only observed when a susceptible cultivar was grown.

 

 

 

Reference: Liu, C. 2014. Evaluation of fungicides for management of blackleg disease on canola and QoI-fungicide resistance in Leptosphaeria maculans in Western Canada. Master of Science Thesis. University of Manitoba. 172 pp.

 

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Manitoba Insect & Disease Update – Issue 10: July 20, 2016

The Manitoba Insect and Disease Update is now posted at: http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/insect-report-2016-07-20.html

Some highlights from the update:

Insects:

  • Pea aphid levels are still a concern in some pea fields, although many fields will be getting to the stage where management would no longer be economical.
  • Aphid levels have dropped in many cereal fields where previously levels had been increasing. High levels of natural enemies have been noted in some of these fields, and some intense rains may have also contributed.
  • In some areas of Central and Southwest Manitoba, greater than 90% of the wheat midge are expected to have emerged. In many areas of Manitoba about 50 to 90% of wheat midge are expected to have emerged. A reminder that wheat that has already produced anthers is no longer susceptible to feeding by wheat midge. Even if adults are still active in these more advanced fields, the larvae will not feed on the grain.
  • Egg masses of European corn corer are starting to be noted in some fields of corn. So far there are no reports of high levels, but now is the time to be checking fields for the egg masses.
european-corn-borer-egg-masses

Figure 1. Egg masses of European corn borer.

Plant Pathogens:

  • Some infections of blackleg in canola and fusarium head blight in cereals have been reported.
  • A few cases of loose smut in barley were also reported.
  • Two positive identifications of Goss’s Wilt in corn were made. The positive identifications were made based on immunostrips and/or polymerase chain reaction (PCR) assays.

Submitted by: John Gavloski, Entomologist & Pratisara Bajracharya, Field Crop Pathologist, Manitoba Agriculture

Manitoba Agriculture website: www.manitoba.ca/agriculture
Manitoba Agriculture on Twitter: @MBGovAg
Manitoba Agriculture on YouTube: www.youtube.com/ManitobaAgriculture

 

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HOW DO I CONTROL VOLUNTEER CANOLA IN MY SOYBEAN?

First ask yourself if you need to control the volunteer canola in your crop.  Research by Dr. Rob Gulden and graduate student Paul Gregoire at the University of Manitoba (U of M) showed that volunteer canola had little impact on soybean yield when there are less than:

  • 3 plants/m2 in solid seeded or narrow row soybean, or
  • 1.5 plants/m2 in wide row soybean.

Although economic thresholds (ET) such as these don’t consider seed return, this is generally not a concern for canola given it’s prevalence in our crop rotations.

If your volunteer canola populations exceed the ET, the U of M researchers also assessed the effectiveness of various post-emergent herbicides (Table 1).  Control of volunteer canola by the herbicides listed in table 1 are based on comparisons of treated research plots.  It’s unlikely that any of these options will provide full control of bolting or flowering volunteer canola.

Table 1: Ranking and application timing of volunteer canola herbicides in soybean

Vol Canola Control in Soybeans

*Will not control CLEARFIELD canola volunteers

**Registered in the Red River Valley only

Another consideration: use of these herbicides on larger volunteer canola may only set plants back, resulting in later flowering canola that may cause issues during soybean harvest.

Previous research by Dr. Gulden has shown that one of the best ways to manage volunteer canola is by limiting weed seedbank additions from canola harvest losses. Slower combine speeds while harvesting this year’s canola is a good way to reduce volunteer canola populations in future soybean stands.

IMG_20160712_070736

Submitted by Dr. Jeanette Gaultier, Weed Specialist, Manitoba Agriculture

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Spring Frost or Late Snow and Emerged Canola – Time to Re-Seed?

Temperature is the instigator for causing frost, but damage inflicted and need to re-seed canola is highly influenced on these other factors:

  1. Duration
    • Short but LIGHT frost = < 2 hours,  may not cause much damage if frost is light (above -1 to -2°C), crop type and staging is tolerant, conditions wet and crop has become acclimatized.
    • Short and HARD frost = < 2 hours, but hard frost (lower than -2°C), crops like canola are more sensitive to longer frost vs. cereals, damage can be variable in field and across area.
    • Long frost = > 2 hours, whether light or hard the longer the negative temperatures the more time for damage to happen.  Tolerance by crop type varies.
  2. Other Environmental Conditions
    • Cloudy and wet – prior to a frost, cool temperatures slow plant growth and ‘hardens’ plants off, which will help them tolerate a frost.  Also wet soil helps buffer the cold air effects on the plants, as wet soils change temperature slower than dry soils.
    • Sunny and dry – The combination of a  dramatic drop in air temperatures when plants are actively growing then a brilliant sunny day after the frost event is where we have seen the most damage.  Scouting after the frost (24 and 48 hours) is very important though to assess extent and percentage of field injury.
    • Field trash cover – increased trash in fields was seen to increase frost damage on very susceptible crops in the 2009 June and May 30, 2015 frost
  3. Crop Type
    • Spring Cereals – more tolerant than other crops types, can tolerant to temperatures as low as -6°C as growing point below ground until the 5 leaf stage.
    • Winter Wheat – can withstand very low temperatures for a short period of time (-11°C for less than 2 hours) up until the tillering stage.
    • Corn – smaller then V5, will recover from light frost as growing point below ground. Leaves probably will be killed, but plants will recover if the growing point ok.
    • Oilseeds – environmental conditions impact frost severity on susceptible canola and flax cotyledons. Resiliency increases at the 3-4 leaf stage (canola) or 2nd whorl (flax).  Sunflowers are fairly tolerant  up to the V4 stage.
    • Pulses – peas are most tolerant, then soybean, edibles bean are very susceptible even before emergence.   Field pea crops are rarely lost to frost. Soybean are more sensitive, but the smaller the soybean plant the more tolerant they are  – from emergence to cotyledon can withstand short light frosts.

Scouting After a Frost (or Snow event)

Scouting should start 24 – 48 hours after the frost and continue for the 5 days following the frost event.  Look for leaves wilting, looking “water-soaked” or see “frost banding”.  Watch for new growth in the plant.  You do not want to see plants wilted and not perking back up or pinching off on the stem near the growing point (canola, flax, soybeans).  Also assess the area affected by frost, small areas or a few plants damaged are ok, as other plants emerged (or just emerging) will fill in those spaces.  Large dead areas may need to be re-seeded.

If in doubt of what look for, call your local agronomists, local FPE Specialist with Manitoba Agriculture or the Crop Industry Branch.

For more specific details on what actually occurs to plants with a frost and crop specific details and symptoms to look for (and how long after a frost to do assessment) see Manitoba Agriculture’s Spring Frost Damage Bulletin.

NEW RE-SEED Calculator developed by Manitoba Agriculture using historic data from MASC is another tool to help determine if re-seeding is finanacially the right decision, depending on plant stands and time of year see calculator at: https://www.gov.mb.ca/agriculture/business-and-economics/financial-management/pubs/calculator_canolareseed.xls

Submitted by Anastasia Kubinec, Manitoba Agriculture, Oilseeds Crop Specialist

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QU: Should I Be Worried About Stored Canola and Flax Spoiling on a 31C Day in May

Excellent question that we usually do not have to think about in early May!

As most grain is still cold in the bin and with the rapid increase in outside temperature, the potential for spoilage could still occur in stored canola and flax still in the bin from 2015 harvest.

If you think this might be an issues, check what is the seed moisture and the temperature is again. The 5C, 8.5% moisture canola in March had no risk of spoilage, but a 35C, 8.5% moisture canola does.  Flax is susceptible to spoilage as well, if the grain gets very warm in the bin and the moisture is over 8%.   If things are all good today, check in a couple of days again if the May heat wave continues and consider turning on the aeration fan and open up the bin hatch at the top of the bin to let humidity escape.

This question came in as a concern over the potential of condensation to form on the bin walls from the hot outside air hitting the cold grain in the bin.  Aeration could be used as a tool with the hot, but very dry air to warm the grain slowly and move some of the potential humidity out through the top vent or hatch.  Monitoring though is key and should continue until the grain is delivered to catch spoilage issues. A great resource on more about aeration and grain in storage can be found on the PAMI (Prairie Agricultural Machinery Institute) website www.pami.ca/crops/storage and at the Canadian Grains Commission https://www.grainscanada.gc.ca/storage-entrepose/ssg-de-eng.htm

Safe storage chart for canola and flax

Submitted by Anastasia Kubinec, Oilseed Crop Specialist, Manitoba Agriculture

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Historically, what has been seeding progress prior to May 1st?

Some producers have started their 2016 seeding operations, with spring wheat being seeded and from what I’ve heard a few acres of corn as well.  With some seeding done, I’ve been asked the question: “What has been seeding progress prior to May 1st in Manitoba in recent years?”.

Producers who participate in AgriInsurance provides seeding date information to Manitoba Agricultural Services Corporation (MASC).  This dataset provides us a historical perspective of when seeding has taken place in the past.

In Table 1, cumulative seeding progress prior to May 1st for six crop types is provided.  A five year (2010-2014) average cumulative seeding progress is noted, along with what was seeded prior to May 1st in 2015. Please note that data is for final insured crop in the ground.

Table 1:  Seeding progress in Manitoba prior to May 1st.

Historical Planting Progress prior to May 1st

Data Source:  Manitoba Agricultural Services Corporation (MASC)

What the table doesn’t show is the wide range of seeding progress prior to May 1st over the past few years.  If we look at seeding progress for red spring wheat in Manitoba, we’ve seen less than 1% of acres seeded prior to May 1st (2009, 2011, 2013 and 2014) but as many as 65% of acres (2010) planted in April.

Look for future updates to historical seeding progress as we enter May!

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture

Follow Manitoba Agriculture on Twitter (@MBGovAg) to receive updates on seeding progress through the weekly Manitoba Crop Report.
The weekly crop report is also available at Manitoba Crop Report.

 

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