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.