Studies showed that johnsongrass from fields in Lauderdale and Fayette counties survive glyphosate 2-3 times the labeled rate, says University of Tennessee Institute of Agriculture.

The wet season has delayed crop development and post-emergence herbicide applications in many soybean fields, and there are some large giant ragweed waiting to be treated.

A news release from the Weed Science Society of America last week covered the results of a study in Arkansas cotton fields to determine the effect over time of releasing 20,000 glyphosate-resistant Palmer amaranth seeds in a patch, within a 1-square-mile area.

What are some good options to control ryegrass with a short turnaround to plant back to corn? When addressing this question we have to realize that some of this ryegrass is likely glyphosate-resistant (GR). Though we do not have it officially confirmed at this point, I am confident from the last couple years' field observations that Tennessee does have a few fields with glyphosate-resistant ryegrass.

Research over the last couple of years has shown that two shot burndown programs which include either 2 shots in the spring or fall plus spring burndown treatments are needed in areas with a history of poor marestail control due to glyphosate and ALS herbicide resistance.