When visiting customers and farms across the state this year, I walked through many clean fields, but there were also some fields with tough weeds competing with the wheat and barley. Chief among those driver weeds was kochia. In fact, in North Dakota, it’s difficult to find a grower, retailer or agronomist who wouldn’t include kochia at the top of their list of primary yield-robbing weeds.

Kochia is a summer annual weed that is particularly difficult to control. A single kochia plant can grow up to 7 feet tall and produce as many as 750,000 seeds. Additionally, those seeds can remain viable in the soil for five to seven years.

Why is kochia difficult to control?

As I drove across the state, I observed plenty of genetic diversity among kochia plants, even those within the same fields. In fact, it’s not uncommon to find red-, green- and purple-veined kochia plants next to each other in a single field. Kochia can also be tall and thin or shorter and bushy. Due to this extensive genetic diversity, kochia in this area is now resistant to multiple groups of herbicides:

• Group 2 – ALS
• Group 4 – 2,4-D, dicamba, fluroxypyr
• Group 9 – glyphosate

The Northern Plains are home to more than just wheat and barley, and controlling kochia across the state becomes even more difficult when taking crop rotation into consideration. Many growers in North Dakota plant several hundred acres of pulse crops such as garbanzo beans (chickpeas) and field peas (dry peas). These crops are not tolerant to many of the herbicides used to control kochia and other weeds. As a result, growers’ herbicide choices are often limited when it comes to controlling weeds in their cereal acres if they’re planning to follow that crop with a pulse crop.

Management tips
Kochia is a pervasive, tenacious weed, but there are tools available to manage it. I recommend choosing a herbicide with multiple, effective modes of action. Multiple effective modes of action help fight herbicide resistance and are key to one-pass weed control in wheat and barley. Effective weed control has the added benefit of reducing the weed seed bank, protecting the long-term viability and profitability of farms. In addition to multiple, effective modes of action, growers should also consider application flexibility, crop safety and rotation options when selecting a herbicide.

Popiel is the Syngenta agronomic service representative in North Dakota. For wheat agronomy tips, email [email protected].