Weed Control Challenges with Delayed Grain Sorghum Planting
Recently, concerns have been raised about grain sorghum that was planted relatively late in the season. As mentioned in a previous eUpdate (https://www.agronomy.k-state.edu/eupdates/2026/issue-1102-may-7/preplant-herbicides-grain-sorghum-2026.html), postemergence herbicide options in grain sorghum are limited, so planting into a weed-free seedbed and using strong residual herbicides are key in each situation.
Delayed planting can create two different situations:
The residual herbicide applied at burndown has run out before planting.
The answer to this situation depends on which herbicides were used in the spring. When choosing herbicides for the second burndown application, be sure to consider the maximum annual application rate for each active ingredient (not the herbicide product) and the preplant intervals for the herbicides being applied. Saflufenacil (Sharpen, others) and tiafenacil (Reviton) are two herbicides with short preplant interval that may be used ahead of planting sorghum. Grain sorghum may be planted any time after application of saflufenacil up to 4 oz (0.088 lb ai/a), but has a 3-month plant-back restriction when 5 oz or more have been applied. With tiafenacil (Reviton), the sorghum plantback intervals are 0, 7, and 14 days with 1.0, 2.0, or 3.0 oz (0.023, 0.046, or 0.067 lb ai/a), respectively. Be sure to include residual herbicides, including the full rate of a group 15 herbicide like S-metolachlor (Dual, others) or dimethenamid (Outlook), as well as atrazine and mesotrione, if the maximum annual application rate has not been exceeded and soil texture allows.
The sprayer didn’t get to the field before emergence.
Once grain sorghum has emerged, few weed control options will work without causing crop injury. Including a group 15 herbicide plus atrazine will still be important for residual weed control in this situation. Atrazine can only be applied up to 12” grain sorghum. For general broadleaf weed control, products such as bromoxynil (Buctril, others) plus atrazine, Kochiavore (fluroxypyr + bromoxynil + 2,4-D), Huskie (pyrasulfotole + bromoxynil), or Starane NXT (fluroxypyr r+ bromoxynil) may be broadcast applied. One possible scenario to minimize crop injury is to make a targeted herbicide application. Control of emerged grasses will generally be poor unless a herbicide-tolerant sorghum is planted. These include Double Team sorghum (FirstAct herbicide), igrowth sorghum (Imiflex herbicide) or Inzen sorghum (Zest herbicide).
As planting and application delays continue, producers should evaluate each field individually and adjust herbicide programs accordingly. Always consult current herbicide labels and the 2026 Chemical Weed Control for Field Crops, Pastures, Rangeland, and Noncropland guide before making application decisions (https://www.bookstore.ksre.ksu.edu/pubs/CHEMWEEDGUIDE.pdf )
The use of trade names is for clarity to readers and does not imply endorsement of a particular product, nor does exclusion imply non-approval. Always consult the herbicide label for the most current use requirements. Users should read and follow all label directions.
Sarah Ganske, Extension Weed Science Specialist
slancaster@ksu.edu
Patrick Geier, Weed Scientist - Southwest Research & Extension Center, Garden City
pgeier@ksu.edu
Jeremie Kouame, Weed Scientist – Agricultural Research Center, Hays
jkouame@ksu.edu