We know, kochia sucks!
It’s easily becoming one of the most troublesome weeds in Western Canada, and the available herbicide options to control it are decreasing. Kochia populations are becoming resistant to multiple herbicide groups (including Group 2-, 4-, and 9-). What’s even scarier is that about 45 percent of the population has stacked resistance to all three herbicide groups.
Kochia is one heck of a weed. There are a number of characteristics that make kochia quick to adapt and tough to manage for farmers.
- A single plant can produce up to 25,000 seeds – In addition to producing a ton of seed, kochia also cross-pollinates. So a plant can be pollinated by one with different genetics in it, and pass along herbicide resistance.
- Efficient seed spreader – Kochia is a tumbleweed so its seeds are distributed as plants tumble through fields. According to Saskatchewan Pulse Growers the germination rate of kochia seeds can be up to 60 – 70 percent when temperatures reach 25°C.
- Short seedbank longevity – This makes it better for kochia populations to develop herbicide resistance because a plant sets all its seed in one year. If that plant had resistance all that seed will germinate next year and there will be minimal susceptible kochia left. This means kochia populations can shift from susceptible to resistant very quickly.
Over the years, kochia has been able to thrive and spread because of these characteristics. Nowadays, herbicide resistance is not the only major threat when it comes to kochia.
KOchia continues to migrate
Due to a number of factors, from its ability to travel and spread seeds to increasingly drier and hotter conditions, kochia is now taking root in more areas of the prairies than ever before. In a Grainews’ update on weed pressures prior to the 2024 growing season, professionals across the prairies identified kochia as a significant threat for farmers. In Alberta and Saskatchewan kochia populations are migrating further and further north, while drier conditions in Manitoba have helped their most serious weed problem get worse.
Managing Kochia resistance
Kochia knows how to get around herbicides, so it takes a multi-pronged approach to effectively manage it. Here are some tips:
- Layer it on – Controlling kochia with one herbicide application is next to impossible so plan a strategy that includes herbicide layering. Start with a soil active pre-emergent herbicide like Valtera™ EZ or Fierce® EZ in the fall or spring for up to eight weeks of extended control to manage flushing weeds. Follow up with in-crop and post-harvest herbicides that also control kochia.
- Spray it right – When spraying for kochia, be sure your water quality is good, by checking that the pH is in line so glyphosate and other herbicides added will work effectively. Sprayer speed and coverage are also important – keep speed under 14 mph and make sure the auto boom is calculated to the proper height.
- Multiple modes of action – Choosing herbicides with more than one active ingredient that kochia has not developed resistance to is another way to slow it down. Valtera EZ contains the active ingredient, flumioxazin (Group 14), and Fierce EZ has both flumioxazin and pyroxasulfone (Group 15). These products offer up to eight weeks of soil active control of problem weeds like kochia in pulses, wheat and soybeans. Tank-mix these products with other herbicides like glyphosate, BlackHawk® or GoldWing® to manage emerged kochia and other weeds.
Take control
Scouting, crop rotation, mixing up herbicide use and timing along with keeping records are all recommended for managing weed resistance. Weeds, especially kochia, are smart and adaptable. It’s important to be aware of what’s happening in every field. Be proactive, and plan ahead with a solid strategy for the growing season.
Kill weeds before they take hold with two windows of opportunity – Valtera EZ and Fierce EZ can be applied in the fall or the spring with excellent re-cropping flexibility to help manage kochia, and other tough weeds.
The image above shows an example Valtera herbicide activity on a very heavy population of kochia plants. The escapes can be managed with an in-crop herbicide (photo credit: Jason Lindgren).
To learn more, contact us at 1.800.868.5444 or your local Nufarm Territory Manager.
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