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.


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

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What Should My Soybeans Look like when they are Ready to Harvest?

Prepared by Dennis Lange, MAFRI Farm Production Advisor (Altona)

For new growers knowing when soybeans are ready to harvest can be difficult.  Driving by the field, you may think that it is ready to harvest, but on closer inspection you may find plants that still look yellow to green instead of tan to brown. If your entire field has a greenish tinge or a majority of plants in the field once you walk in look green, your beans would not be ready to harvest.  If there is only a few plants that look like this, you may be ok or this might represent only a low spot or less advanced spot in the field. 

Note the green stem in the group of brown stems


This Field is 5 – 7 days away from harvest (credit: D.Lange, MAFRI)

The soybean plants and pods when mature, should be brown or tan in color and the seeds should rattle in the pod.  When the crop is mature and ready for harvest the seeds would be oval shape and firm.

Seeds on left are ripe and ready to harvest, seeds on right are green and not ready to harvest

Once the combine pulls into the field check the moisture which should be below 13%. The Canadian standard for safe storage is 14% moisture, however soybeans going into the USA require 13% moisture and since a large portion of the soybeans do go into the USA  it best to keep below that 13% level.

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Flea Beetles – Get Out Now and Look!

 Numerous calls have been coming in this week on flea beetles feeding and damaged canola.  If you have not yet, you should get out to your fields ASAP and see for yourself.

 As you are looking at your plants, run through this checklist

  1. When did you seed the field, has it been longer than 3 weeks (prior to May 22)?
  2. What is your plant population, is it less than 7 plants/ft2 (make a ‘L’ with your feet, how many plants are in the ‘L’)?
  3. What stage is your canola at – is less than 3 leaves?
  4. What % of the leaf has been bitten/injured – does it look like more than 25%?
  5. Are the flea beetles still seen and feeding on plants?

 If you have answered yes to all these question, you should consider an insecticide application to control the flea beetle population.

 The seed treatment has an expected lifespan of 3 to 4 weeks, so once seed is in the ground the clock is on and as you get closer to the end of the 3rd week, the flea beetles are becoming less and less controlled. Flea beetle feeding stresses the canola and with cool growing conditions, the canola is not growing as quickly as it could.

Many fields are in the not so ideal situation of slow growing canola, seed treatment insecticide component efficacy diminishing and high populations of flea beetles still in fields.  For more information see the June 12th Insect and Disease Update from MAFRI:  Manitoba Insect and Disease Update – June 12

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Submitted by Jeanette Gaultier, MAFRI Pesticide Specialist

We cautioned last week about herbicide application in cool temperatures. Since the 2013 growing season has not been setting records for heat, you may be stuck trying to balance optimal temperatures with recommended herbicide application timings. 

Crop injury in some situations may be unavoidable since both temperature and incorrect crop staging affect crop tolerance to herbicides.  The good news is that you may not need to be concerned if you see symptoms in your crop post application since not all injury contributes to yield loss.  

  • Growth Setback – Stunting of cereal crops treated with certain group 2 herbicides (e.g. Everest, Simplicity) or with Avenge is possible but generally will not affect yield.  Improper timing or cool temperatures during group 1 herbicide application can also cause setback.  Do not worry about yield penalties though, unless stunting is severe or other growth setbacks, such as reduced tillering or stem/head kinking, are present.
  • Chlorosis –Pale plants and chlorosis are indicators of reduced photosynthesis, a process necessary for crop growth.  However, slight chlorosis of leaves and growing points will not lead to decreased yields if plants are able to ‘grow out’ of the stress early in the season.  For example, beans treated with Basagran + group 1 herbicide may have both green and yellow leaves on the same plant without affecting growth.  Cool temperature application of group 2 herbicides and/or glyphosate may also cause slight chlorosis, that crops can grow out, depending on the severity.  Do not worry unless symptoms are severe; plants are more chlorotic than not or deformed growth tips, necrosis are also present.

The above are generalizations and yield penalties from herbicide injury in specific crop situations can vary depending on the severity of injury symptoms, crop growth stage as well as other factors that may be contributing to crop stress.

If you are concerned about your crop or want a second opinion, crop samples can be submitted to your local GO office or the Crop Diagnostic Centre.  MAFRI staff are able to provide visual assessment of crop injury only; you may be referred to a private lab for herbicide residue or nutrient testing if assessment of the symptoms is inconclusive. 





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What is the Extent of Crop Damage From the Heavy May Rains?

Compiled by the Staff at Crop Industry Branch, Manitoba Agriculture

Some areas of Manitoba received heavy rainfall during the May 2013 long weekend, resulting in the question “What is the extent of crop damage from the heavy rains?”

Field by field assessments over the coming days will give us a better idea of what impact the rains had.  The following though can provide you with an idea of what is potentially occurring and how to monitor fields to assess for damage and recovery.

What is the Extent of Crop Damage from the Heavy Rains – Updated May 2016

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Should I Still Be Concerned About a Spring Frost?

Spring frost is something that producers need to consider into late May and in some areas of Manitoba, there is an elevated risk of occurence into the month of June.

Average Date of last Spring Frost – is considered after May 19th.  In the  Portage la Prairie, Langruth, Pilot Mound, Morden and Altona regions there is less than a 50 percent chance that frost will occur after the 19th. In other areas, the last spring frost occurs, on average, after May 24. On higher elevations, central Interlake and the south-eastern regions of Manitoba can expect frost during the first week of June in one out of every two years.  Figure 1: Manitoba Average Last Spring Frost

1 in 4 year risk– that the last frost will occur about eight days later than average. This means a 25 % risk that the last spring frost will occur after May 24 in the Portage la Prairie and Altona regions. In most other regions of Manitoba, a 25% risk of a spring frost in the first week of June and in the Riding Mountain and Hodgson regions, that is will occur later than mid-June.  Figure 2: Manitoba Last Spring Frost (1 in 4 years)

1 in 10 year risk – a 10% risk that the last spring frost will occur later than June 3 for most regions.  A recent example of this is in 2009, when there was a wide spread frost through the agricultural growing region on June 6th.  Figure 3: Manitoba Last Spring Frost (1 in 10 years)

If a frost does occur, please refer to MAFRI`s Spring Frost Damage Bulletin to help assess the situation at

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Should I Be Cancelling My Soybean Seed?

Answer (provided by Dennis Lange, MAFRI Farm Production Advisor at Altona):

 Before you considering cancelling you soybean seed, here are a few things to consider:

  1. Variety Choice:  Is the variety suited for your growing region? If you chose a variety based on maturity ( found in Seed Manitoba 2013) and you are planting in May, you should reach  maturity  before reaching a killing frost, based on a normal growing season.
  2. Soil temperature: Soybeans like warm soils to germinate and grow. The warmer the soil, the quicker the beans come out of the ground.  For example, with soil temperatures at 10°C soybeans  take 14-17 days to emerge  vs. 7-10 days when soil temperatures are at 15°C.
  3. Seeding Date: Know the seeding deadlines in your growing region. If in Soybean Area 1, full coverage deadline is June 6. If in Soybean Areas 2, 3 or new crop insurance test area, your deadline is May 30. For further information contact MASC to determine which area you are in. Table 1: Soybean Yields by Seeding Date (2008-2012)

Using MASC seeding information from 2008-2012, yield potential differs depending on seeding date by Risk area.  

  • Risk Area 12 (includes Red River Valley) – highest yield potential was seeded during the 2nd week of May. 
  • In Western Manitoba:
  • Risk Area 1 – best yields when seeded in the 4th week of May, followed by week 3
  • Risk Area 2 – best yields in the 2nd week of May, with weeks 3 and 4 equal
  • Risk Area 3 – best yields in the 3rd week of May, followed by the 4th and 2nd weeks
  • Risk Area 4 – best yields in the 2nd week of May, with yields dropping in 4th week
  • Risk area 15 – similar to Risk Area 4 trends with best week the 2nd and yields dropping in the 4th week of May 

 In conclusion, if you are planting a variety that is suited for your growing region and planting in May, you should be confident that growing soybeans this year is still the right decision. Beans like warm soil so typically, planting in the 2nd or 3rd week of May when soil temperatures are warmer, allows the beans to get out of the ground quicker. But, waiting until June to plant, increases the risk of fall frost damage and yield reductions.

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Are Herbicides to Control Dandelions Still Effective After a Fall Frost?

Fall is a great time to work on controlling perennials such as Canada thistle and dandelions. As temperatures get cooler, the nutrients start moving down into the roots and if a herbicide can be taken up and translocated with those nutrients, it can equal better control.

A frost event though, can kill some weeds or can damage leaf tissue which will reduce herbicide uptake and therefore reduce the level of weed control. Within the next few days after the frost, you need to assess the target weeds in the areas that you want to obtain control – are the weeds still growing?  How much leaf tissue has been damaged?

If the plant leaves are still shiny green with minimal leaf tissue damage (i.e. not blackened/brown or brittle) there still may be the window to control the perennial, biennial and winter annual weeds with glyphosate.  If you do spray – spray in the afternoon when temperatures are warm and sunny, this will help with herbicide uptake.   Use rates appropriate to the stage and time of year – fall applications of glyphosate are recommended at a higher rate than when controlling pre-harvest.

One last thing – look at the forecast for the next week following the application.  If the temperatures look like they are going to continually be below freezing each night, it may be too late to make the application to get the economic control you are looking for.

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