As the end of September approaches, 2023 harvest is in the home stretch. Folks are now turning their attention to fall work and preparing for next year. With combined fields still fresh in their minds, post-harvest is an excellent time of year to take action on those weed-infested areas—specifically kochia!

There has been no lack of attention on kochia over the years, with confirmed resistance to multiple herbicide groups that we rely on in-crop (Group 2, 4, and 9). This is why we need to take full advantage of the long, open fall and attack those problem kochia areas with completely different modes of action.

These modes of action for fall include:

Group 3: Ethafluralin (Edge, Fortress)

No doubt the saying “What is old is new again” comes to mind when we think about these MicroActive Granule products. However, when it comes to kochia, these products offer a completely different group that can be very effective when applied properly. Specialized equipment (Valmar) is required to apply, as well as incorporation.

Group 14: Sulfentrazone, Flumioxazin (Authority, Valtera)

Products with these actives all offer a mode of action that needs to be moisture-activated (requires 1/2″ of moisture) for effective kochia control in the spring. Apply in the fall when soil temperatures are cooling to 10°C (> Oct. 5th). These actives offer very consistent control of kochia due to moisture from the snowmelt activating the herbicide and targeting early germinating kochia seedlings.

Group 15: Pyroxasulfone (Zidua, Focus)

As mentioned for the Group 14 products, they need to be applied in the fall when soil temperatures are cooling to 10°C. Group 15 products also require moisture in the spring for activation.

Group 19: Diflufenzopyr (Distinct)

This mode of action often gets overlooked! However, it does have very good activity on early germinating kochia seedlings. The window of application is prior to October 1st, and conditions must be warm (above 5°C for 3 consecutive days). Merge is a must at 1.25% v/v, even when mixed with glyphosate.

Other ways to reduce kochia populations, as taken from our ‘On the Horizon’ blog post from March 7th, 2023, include:

• Growing competitive crops on problem fields (e.g., winter cereals, annual or perennial forages, rye, or oats).

• Seeding a salt-tolerant forage blend in saline areas that are overgrown with kochia.

• Increasing your crop seeding rate and decreasing row spacing (if possible).

• Targeted tillage in problem areas.

As always, if you have any questions or concerns about the best fit for your farm, feel free to contact your local HFL sales agronomist.