Call it the “Barney Fife rule of weed control.”

When it comes to summer annual weeds, especially kochia, “You got to nip it! Nip it in the bud!”

Kochia, that annual bane of Kansas farmers, is particularly problematic to control. When it matures, it turns into a tumbleweed, spreading its seed across fallow fields in the late fall and winter. In some fields in western Kansas, for example, you can visually track the path of the kochia tumbleweed in the field as plants emerge and mature.

Sarah Lancaster, K-State Research and Extension Weed Management specialist, warns growers that now is the time to finalize plans farmers may have for kochia control before planting.

“In western Kansas, kochia is among the first summer annual weeds to emerge in the spring,” she writes in the Feb. 15 Agronomy eUpdate. Weed scientists at the Southwest Research and Extension Center in Garden City, Kan., reported kochia emerging in fallow plots as early as the first week of February.

It’s important to control those kochia seedlings when they’re small because herbicides are more effective at that stage. Remember, there is glyphosate-resistant kochia prevalent all over western Kansas, and the earlier farmers can nip kochia, the better chance they have to stay ahead of exacerbating resistance.

Early control also limits the damage those first flushes of seedlings can do to the field. K-State weed scientist Jeremie Kouame explained in a release that a combination of preemergence pesticides can restrict early kochia growth. A tank-mix of dicamba and atrazine is one recommended treatment.

Scouting early and often is key to keeping on top of kochia, Lancaster advises.

“One of the best weed management tools we have are our footprints in the field,” she says.

The later in the season you go, the tougher it can be to stop kochia and the narrower your chemistry options become, Lancaster says.

“If folks missed the window for preemergence applications this spring, I think one thing to remember as kochia gets larger is that there is known resistance to atrazine, ALS-inhibiting [Group 2] herbicides, glyphosate, dicamba and fluroxypyr [Starane] in Kansas,” Lancaster says.

“So, knowing the resistance profile of each field is important. Effective herbicides that contain saflufenacil [Sharpen] can provide effective control prior to corn or grain sorghum. However, it’s important to note that widespread resistance to saflufenacil and other PPO-inhibiting [Group 14] has been reported in North Dakota.”

She advises growers to continue to be on the lookout for resistance in their fields and share those reports with Extension.

Kouame and Lancaster reported that recent research shows some successful kochia control herbicide programs for both corn and sorghum. In corn, an herbicide program that uses either Degree Xtra followed by Impact; Verdict followed by Status; or Balance Flexx followed by Laudis plus AAtrex seems to work, Kouame says. These herbicides, he says, synergize when they’re mixed, and their efficacy increases.

In sorghum, Lancaster says Verdict, a combination of dimethenamid-p and saflufenacil, can not only burndown kochia and pigweed, but also offer some residual activity.

If you’ve got questions about how you can nip kochia in the bud, email Lancaster at [email protected].