Summary of Preemergence 2017/2018 Weed Control Trials

By Brent Bean, Ph.D., Sorghum Checkoff Agronomist

In 2017 and 2018 the United Sorghum Checkoff Program sponsored preplant and PRE weed control trials in the High Plains of Texas and Kansas and a PRE trial in Georgia. A presentation summarizing these trials has been complied for your reference. Most of the results presented are from trials conducted by Wayne Keeling, Ph.D., at Texas A&M University research facility in Lubbock, Texas, and Randall Currie, Ph.D., at Kansas State University in Garden City, Kansas.

Key takeaways from the trials:

  1. Premixes of Bicep formulations and Degree Xtra or Fultime NXT gave better weed control than atrazine alone.
  2. Degree Xtra and Fultime NXT are premixes of atrazine + acetochlor (Warrant) and had a tendency to give better control of pigweed and other broadleaf weeds than Bicep formulations.
  3. Lumax EZ (Callisto + atrazine + S-metolachlor) consistently gave the best season-long control of broadleaf weeds. Callisto applied alone did not give season-long control. Callisto + atrazine gave good control, but not as good as the three way mix.  Keep in mind Lumax EZ cannot be used on sandy soils.
  4. Preplant applications of any of the above mentioned premixes applied 14 days prior to planting resulted in season-long control as good as the same treatments applied PRE.
  5. Verdict + Outlook was somewhat inconsistent in controlling pigweed in these trials. However, it was one of the better treatments for kochia and Russian thistle control in Kansas.
  6. Dual Magnum and Warrant only provided short-term control and did not provide season-long control of pigweed or other broadleaf weeds in Texas or Kansas.
  7. S-metolachlor provided as much as 30 percent better control than metolachlor. This could likely be offset by increasing the metolachlor rate.
  8. Valor applied 14 days preplant provided good initial control but began to fail after 30 days. Some minor crop injury was observed, especially with the higher 2 oz rate.   Valor label requires treatment be applied 30 days prior to planting sorghum.
  9. In Georgia in sandy soils, crop injury was high with any Callisto containing treatments. Dual Magnum provided season-long control of weeds and annual grasses.

If you would like complete reports of any of the 2017 or 2018 trials, please email Brent Bean, Ph.D., at

Another article of interest, Preemergence Weed Control, can found on on the Agronomy Insights page.

Always refer to the product label for more information concerning soil type and crop rotation restrictions, as well as rates and other information.