Agronomy •  2022-02-14

The tools you need to manage herbicide-resistant waterhemp

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soybean growth

Herbicide-resistant waterhemp is a rapidly growing problem for Canadian soybean growers. Once established, waterhemp can be tough to manage because, biologically speaking, it has a lot of tools in its arsenal that help it adapt and thrive, no matter what you throw at it.

There are three tools in particular that make waterhemp such a formidable foe and the king of herbicide resistance: abundant seed production, genetic diversity and a highly competitive growth habit.

More specifically, one waterhemp plant can produce somewhere around 250,000 seeds when growing in a competitive crop environment, and as many as a million seeds or more when not challenged by other plants.

As well, those seeds are genetically diverse from one another; a result of the fact that waterhemp does not self-pollinate and requires both male and female plants to reproduce.

And finally, waterhemp is an incredible field competitor – seeds germinate all season long and grow incredibly fast (2.5 cm to 3 cm per day) – making it a difficult target for herbicides.

Ultimately, herbicide resistance is a numbers game – the more seeds a plant can produce and the greater their capacity for survival, the greater the chance that herbicide resistance will develop. That’s waterhemp in a nutshell. Its ability to survive and adapt is why most waterhemp populations in Canada carry resistance to two or more herbicide groups, including:

  • Group 2, atrazine
  • Group 9, glyphosate
  • Group 5, metribuzine
  • Group 14, PPO inhibitors
  • Group 27, mesotrione (first detected in 2020)


The Enlist weed control system tackles waterhemp

The Enlist™ weed control system, with Brevant® seeds Enlist E3™ soybeans, can be a powerful tool when it comes to effectively managing waterhemp because it brings two new herbicide options to the table. You can choose:

  • Enlist Duo™ a proprietary blend of 2,4-D choline (Group 4 and 9) and glyphosate for control of resistant waterhemp populations and non-glyphosate resistant weeds or
  • Enlist 1 a stand-alone 2,4-D choline formulation (Group 4) that can be tank-mixed with Liberty 200 SN (Group 10) for two modes of action that all waterhemp populations are currently susceptible to.

Both herbicides can be applied from pre-plant up to the R2 stage, so you have the flexibility to go after late flushes of waterhemp. They also contain Colex-D technology for near-zero volatility and low drift – they stay where they’re sprayed.

Brevant seeds Enlist E3 soybeans complete the picture. An advanced seed with high yield potential and robust herbicide tolerance to 2,4-D, glyphosate and glufosinate, Brevant seeds Enlist E3 soybeans are a powerful match against resistant waterhemp. 

Brevant seeds Enlist E3 soybeans paired with Enlist herbicides are powerful tools for soybean growers looking for an answer to resistant waterhemp. This weed is a proven competitor – but that doesn’t mean it gets to win.