Late winter kochia control in fields going to corn or grain sorghum

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Last week, we shared some general information about applying pre-emergence herbicides for kochia control. This week, we will focus on specific recommendations for fields going to corn or grain sorghum this growing season. Next week, we’ll discuss fields going to soybean, sunflower, and wheat.

Kochia control in fields going to corn

Kochia starts emerging from mid-February to early March and continues from spring into summer (Figure. 1). It is critical to start the growing season with clean fields. Therefore, any effective kochia control plan for fields going to corn should include early spring application of a burndown herbicide with an effective soil-residual herbicide for controlling early flushes. For example, an application of dicamba alone can control susceptible kochia; however, a combination of 1 to 2 pints of atrazine and 8 to 16 oz. dicamba will control existing broadleaf and grass weeds and provide extended residual activity, often into late spring. This combination will address dicamba-resistant biotypes, but other options are needed for triazine-resistant biotypes.

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Figure 1. A young kochia seedling in wheat residue. Photo by Sarah Lancaster, K-State Research and Extension.


A study published in 2019 by weed scientists from across the Great Plains reported excellent control (99%) of glyphosate-resistant kochia can be attained in corn by Degree Xtra followed by Impact, Verdict followed by Status, or Balance Flexx followed by Laudis + atrazine. These data support the recommendation to add atrazine to group 27 herbicides like Balance Flexx or Laudis and are likely the result of greater uptake of the group 27 herbicide. Data from Hays, KS, are shown in Figure 2. All treatments evaluated provided acceptable control, except for Acuron applied pre-emergence followed by Liberty + Status + Atrazine. Corn yields ranged from 88 to 111 bushels/acre, with the greatest yields obtained in Verdict + atrazine pre-emergence followed by Liberty + Atrazine, Roundup + Armezon Pro + atrazine, Liberty + Status + atrazine, or Roundup + Status + atrazine; Resicore + atrazine applied pre-emergence followed by Durango + atrazine; and Acuron applied pre-emergence followed by Roundup + atrazine. Pre-emergence programs based on Verdict plus atrazine could also be considered for fields going to grain sorghum. Regardless of the herbicide program, frequent scouting is essential to ensure postemergence herbicides are applied when kochia is small.  


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Figure 2. Kochia control in field studies conducted at Hays, KS. PRE, EPOST, and LPOST treatments were applied on April 23, June 11, and June 23, respectively. Similar letters indicate similar weed control.

Kochia control in fields going to sorghum

As sorghum planting in western Kansas generally begins in mid-May, conserving soil moisture by controlling kochia and other weeds before sorghum planting is of utmost importance. Like corn, kochia control in fields going to sorghum can be achieved with tank-mix application of dicamba (8 to 16 oz/a) with atrazine (1 to 2 pints/a) in early spring. If fields are infested with glyphosate-, triazine, and/or dicamba-resistant kochia, Sharpen (2 oz/a) or Gramoxone (2 to 4 pints/a) can also be used to control resistant kochia biotypes. An application of PRE herbicides such as DegreeXtra (64 to 96 oz/a), Lexar (96 oz/a), or Verdict (5 to 10 oz/a) at planting can help control kochia in sorghum.

Reference: Sbatella et al. 2019


Sarah Lancaster, Weed Management Specialist

Jeremie Kouame, Weed Scientist – Agricultural Research Center, Hays

Tags:  grain sorghum corn weed control kochia pre-plant herbicide