Ryan Flaming: Palmer amaranth control in sorghum

Ryan Flaming
A study conducted in 2019 near Hays evaluated the effectiveness of POST-applied herbicides for Palmer amaranth control in grain sorghum.

A study sponsored by the United Sorghum Checkoff Program was conducted in 2019 at K-State Ag Research Center near Hays to evaluate the effectiveness of POST-applied herbicides for Palmer amaranth control in grain sorghum.

The study site had a natural infestation of Palmer amaranth and grain sorghum was planted on June 13, 2019. The test plots were sprayed with AAtrex (atrazine) applied PRE at 32 oz/a rate. The tested POST programs included AAtrex, Clarity, Huskie, AAtrex + Clarity, Huskie + Clarity, Huskie + AAtrex (see Table 1). All POST programs were applied on July 10, 2019 (grain sorghum was 8 to 10 inches tall and Palmer amaranth was 6 to 8 inches tall).

Results indicated that AAtrex + Huskie applied POST had up to 95% control of Palmer amaranth at 49 DAT, whereas control ranged from 82 to 89% with POST applied AAtrex, Clarity, Huskie alone or tank-mixture of AAtrex + Clarity and Huskie + Clarity. However, it is important to note that 5 to 17% crop injury was also observed with all Clarity based programs.

— Ryan Flaming is a Kansas State Research and Extension Agent for Harvey County. Agriculture is his specialty. He can be reached at 316-284-6930.

Flaming