Home Indiana Agriculture News Growers Have Hard Choices on Controlling Resistant Weeds

Growers Have Hard Choices on Controlling Resistant Weeds


Four major weeds in Indiana are resistant to most weed control products; that leaves soybean growers with some difficult choices. Bill Johnson, Extension Weed Specialist, says waterhemp and Palmer amaranth are going to be the hardest to deal with.

“All of the waterhemp and Palmer amaranth in Indiana is glyphosate and ALS resistant. A lot of the waterhemp is also PPO resistant. The only thing you can do is spray a PPO and just hope it is not resistant. There is really nothing else you can do.”

Johnson says controlling marestail also has few good options.

“What we are recommending is to use the highest rate of glyphosate you legally can and add a half rate of Classic and half rate of Firstrate, and just hope for the best,” he states.

Giant ragweed is another weed that will be hard to control this year.

“Again, most in the state is glyphosate and ALS resistant but not PPO resistant. Thus, growers can use Flexstar and Cobra,” says Johnson.

For more recommendations, contact your local extension office.