Collaborative kochia management with metribuzin and mowing

Kochia is the exact opposite of pulses, particularly lentils, making it the perfect growth competitor. It’s tolerant of environmnetal stress conditions, will quickly evolve and has prolific seed production and dispersal.

“Kochia is now recognized as one of the most serious weed challenges facing growers across the Western Prairies, particularly in pulse systems,” Racquelle Peters, research officer with the agronomic crop imaging lab at the University of Saskatchewan, said during the Saskatchewan Pulse Growers research webinar.

Peters is leading the Framework for a Collaborative Kochia Management Program in Pulses alongside Steve Shirtliffe, professor and researcher in the U of S’s department of plant sciences. Multiple research projects create an integrated management framework of chemical tools to work alongside cultural and mechanical methods to reduce herbicide pressures.

The program is running for six years, with some of the projects beginning last fall.

There are three management programs within the framework: saline landscape management, mechanical seed bank and chemical technologies.

Saline landscapes

“The goal here is to evaluate how different weed control systems affect kochia populations across a naturally occurring saline gradient,” Peters said.

To measure salinity, they used electromagnetic conductivity and were able to identify the variation of salt in the areas of the field.

Last fall, they applied residual treatments and seeded lentils this spring. The aim is to link herbicide performance and cultural practices to salinity levels to improved integrated weed management.

The treatment to the soil will be adjusted based on other framework results as the project progresses.

The second saline project is to test effects of soil applied herbicide layering in saline versus non-saline areas when dealing with herbicide resistant kochia. This one is taking place at Scott, Sask.

They’re comparing the layering of Edge (ethalfluralin) with Fierce EZ or Valtera EZ versus Treflan (trifluralin) with Fierce or Valtera with fall applications. Application was fall 2025 and will be seeding to lentils in spring 2026, followed by barley in 2027.

“This work will help identify herbicide combinations that work under saline conditions and guide more site specific management recommendations,” said Peters.

Mechanical management

There are two mechanical method trials, both to do with kochia mowing.

The first is a four to five year field scale project to determine if mowing effectively reduces kochia populations and seed banks over time. They’re tracking the results with monitoring tools such as satellite imagery.

The second is an analysis of the necessary timing and frequency of mowing to have an effect on seed production.

The trial has used four mowings between June and September, in different combinations, to find the most effective combination.

“We don’t want to jump to too many conclusions yet, but what we did see is that multiple mowing timings, especially in late July and August, were more effective … while mowing too early, say in June, or too late, in September, can stimulate kochia growth,” Peters said.

The data is quite new, and additional seed production data is still being determined. However, Peters and the team are happy with what’s been seen so far.

Chemical treatments

On the chemical side of the trial, three projects are underway.

Field studies are taking place in Saskatoon, Scott and Lethbridge with metribuzin dose trials, building off the greenhouse dose response trials performed by Shaun Sharpe.

Sharpe’s experiment applied metribuzin to three kochia populations with varying degrees of herbicide resistance, including just Group two resistant, Group two and glyphosate resistance, and combined resistance to groups two, fourand nine.

He trialled multiple dose rates but found that kochia was most responsive to the full rate label,ed for chickpeas of 509 grams per acre.

On a similar note, the researchers will also try to determine if metribuzin-resistant kochia is occurring on the Prairies.

To do that, Charles Geddes will be performing herbicide resistance surveys across Saskatchewan, Manitoba and Alberta. The goal is to test about 800 kochia samples.

Geddes had sampled 278 kochia plants from 204 surveyed fields in Saskatchewan in 2024, and so far, no resistance to metribuzin has been found.

“This is the first broad look at Group five resistance in Western Canada,” Peters said.

“And this will directly support the metribuzin control studies we are doing as well as supporting better herbicide planning going forward.”

The other chemical project is comparing metribuzin co-packs efficacy on kochia to find new herbicide options.

Peters presented the results at the Crop Production Show in January 2026, which found the best control was from fall-applied, high-rate residuals such as Fierce MTZ, Sencor and Bifecta EZ. However, the herbicides alone gave a “strong foundation” but were not enough control.