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Protecting crop health during herbicide applications
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Protecting crop health during herbicide applications

Oct 09, 2019

Not only does this approach lead to higher yields in a particular growing season, it will help ensure the viability of your operation (and your neighbour’s) for years to come.

Open field of Canola

Control and safety = Higher yield potential

Recent field trials examined the potential crop injury from spraying off-label on Roundup Ready® canola. The research confirmed that spraying canola above the recommended rates or outside the application window was costing farmers three bushels per acre or more in yield*.

More specifically, spraying off-label can result in the following yield-reducing crop conditions:

Chlorosis / yellowing

  • Earlier on in the crop cycle, you might notice chlorosis or yellowing of the crop. Although chlorosis might not appear uniformly across the field, there may be spots where it’s apparent and indicates damage.

Growth reduction

  • It’s tough to notice growth reduction if a check strip isn’t left to compare plant height, but often crop growth may be stunted as a result of off-label spraying.

Flower bleaching

  • As canola enters into the flowering stage, flowers may seem bleached and won’t have the rich, distinct yellow of canola. Similar to growth reduction, this may be hard to identify unless there is a check strip. If the colour of the flower looks less bright than some of your other fields, this is most likely due to spraying off-label.

It can sometimes be difficult to determine the exact cause of some of these crop conditions, which is why it’s a good idea to involve a trusted agronomist or farm advisor if you’re ever in doubt.

Best practices in applying glyphosate herbicide

While following the label’s application rates is the ideal way to keep your crop healthy, there are a few other best practices to get the most (and safest outcome) out of glyphosate.

  • Weeds should be actively growing. Plant growth stops below 5°C. Delay applications for at least 24 hours, preferably 48 hours, after temperatures near 0°C to allow plants to recover and begin growing again.
  • Use water volumes of five to 10 gallons/acre when water quality is good. Water volumes at the lower end of the range are recommended with hard water. Add ammonium sulphate to the water at 1% of total spray volume to reduce hard water antagonism. Find another water source for spraying glyphosate if hardness exceeds 40 grains/US gallon total hardness (700 ppm CaCO3 equivalent).
  • Attack weeds early. Smaller weeds are easier to control. Make every effort to control species at the one to three-leaf stage.
  • Sunny, warm and humid are optimum conditions for top performance. This includes warm temperatures through the night.
  • Avoid travel speeds during spraying that create large amounts of dust. Clark Brenzil, provincial specialist in weed management with Saskatchewan Ministry of Agriculture, recommends that if dusty conditions can’t be avoided, spray from downwind to upwind to minimize the dust deposition on unsprayed leaves.

The next generation of canola

When developing TruFlex™ canola with Roundup Ready® Technology, the first new canola system in over 20 years, crop safety was a top priority. TruFlex combines new genetics with advances in trait technology for better weed control and crop safety compared to Roundup Ready canola.

TruFlex canola gives farmers the option to apply Roundup WeatherMAX® herbicide in-crop at 0.67 L/ac. for two applications or 1.33 L/ac. for a single application. That means you can choose the ideal rate for the unique weed issues on your farm and have the flexibility to deal with any weather or equipment challenges that arise.

By removing weeds early, you’ll give your TruFlex canola crop the best opportunity to reach its maximum yield potential and help ensure the overall health and safety of the field. And with the TruFlex system, you’ll be able to control a broader spectrum of weeds than was possible with Roundup Ready canola – further enhancing your operation’s weed management plan.


To learn more about canola’s next generation, visit




Monsanto Technology Development Trials – 2009-2012