Agronomy •  2022-12-19

Controlling kochia with a program approach

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Kochia is a scourge for western soybean growers. With the widespread resistance to Group 2 herbicides, increasing amounts of Group 9 resistance, and some Group 4 resistance in Western Canada. kochia is a difficult weed to control in many crops, including soybeans. If there is one weed out there that requires strict attention to a multi-mode-of-action (MMOA) approach to herbicide selection, kochia is it.

For those growing Enlist E3 soybeans, a program approach to kochia management is essential. This is a two-pass system that begins with the application of residual herbicides that have modes-of-action kochia is still susceptible to, followed by a post-emergence application of Enlist 1 herbicide tank-mixed with a Group 10 herbicide.

The problem: Kochia is a prolific seed producer, typically generating about 15,000 seeds per plant.  Seeds are dispersed through combines at harvest or, when left undisturbed, a mature kochia plant will snap off at the soil surface and become a tumbleweed, dropping seeds as it rolls. It’s also drought-tolerant and an early-germinator, so controlling it early is key. Kochia will also germinate throughout the growing season, which makes a one-pass weed control system less effective.

The main challenge is overcoming kochia’s widespread resistance to important broad-spectrum herbicides. A 2017 study led by researchers at Agriculture and Agri-Food Canada in southern Alberta found that all kochia populations are resistant to Group 2 herbicides, 50 per cent are resistant to Group 9 (glyphosate), 18 per cent are resistant to Group 4 (dicamba), and 10 per cent had three-way resistance.1

Controlling kochia with the Enlist™ weed control system: Because kochia is an early-germinating weed, early weed removal is a key strategy for good control. It is important to take an MMOA approach to herbicide selection in order to protect herbicide tools that are still effective against this weed.

Not allowing kochia to set seed is also a valuable control strategy. Mow, till or spray out kochia patches in fields, roadsides and around sloughs and on headlands. Kochia seeds do not survive long in the soil, so getting on top of seed production can help reduce kochia populations going forward.

The Enlist weed control system offered with Enlist E3 soybean varieties with tolerance to 2,4-D (Group 4) and glufosinate (Group 10), includes two herbicide options:

  • Enlist Duo™ herbicide a convenient proprietary blend of 2,4-D choline (Group 4) and glyphosate.
  • Enlist™ 1 herbicide a stand-alone 2,4-D choline formulation that can be tank-mixed with Liberty® 200 SN (Group 10) or glyphosate.

Both herbicides come with Colex-D technology for near-zero volatility and low drift so it stays where it’s sprayed.

The program approach to control kochia: This two-pass system uses multiple modes-of-action to effectively control resistant and non-resistant kochia in Enlist E3 soybeans.

  1. Start with a residual herbicide at pre-emergence. Apply Authority® 480 herbicide (Group 14 sulfentrazone) or Valtera herbicide (Group 14 flumioxazin). Kochia is susceptible to this mode of action so early weed removal can be achieved, while residual activity helps keep weed competition at bay through critical early growth stages.
  2. Apply Enlist 1 herbicide with Liberty 200 SN at post-emergence. Because Liberty 200 SN is a Group 10 herbicide, it will control all resistant biotypes of kochia that may have survived the pre-emergence application, or those that simply germinated afterward.

This two-pass, MMOA weed management approach provides three effective modes of action against resistant and non-resistant kochia.

Key takeaways: In some crops – flax and Clearfield® canola to name two – there are extremely limited in-crop herbicide solutions for kochia. Enlist E3 soybeans and the Enlist Weed Control System provide an opportunity for in-crop kochia control that can help you get on top of the problem.

Kochia is a highly genetically diverse plant, meaning it can develop resistance to herbicides fairly quickly. It’s critical to pay attention to the modes of action you use, to rotate them, to use multiple modes whenever possible and include them in an integrated weed management program. It is the only way to preserve herbicide efficacy for as long as possible.


1Canadian Journal of Plant Science, Vol. 99, No. 2, April 2019: Triple resistant kochia [Kochia scoparia (L.) Schrad.] in Alberta.