Waterhemp population exhibits resistance to dicamba

Waterhemp is one of the most troublesome agronomic weeds in the midwestern U.S., where it has rapidly evolved resistance to multiple herbicides.

One example: An Illinois waterhemp population has exhibited resistance to six herbicide groups, including 2,4-D, ALS inhibitors, PROTOX inhibitors, HPPD, PSII inhibitors and very long chain fatty acid synthesis inhibitors. Now the same population has shown signs of resistance to dicamba.

To learn more, researcher Patrick Tranel from the University of Illinois conducted multiple field and greenhouse experiments to confirm dicamba resistance, quantify the level of resistance and determine whether it is an inherited trait.

The results of his research, which are featured in the journal Weed Science, confirm what is believed to be one of the first instances of dicamba resistance in waterhemp. The herbicide controlled no more than 65 percent of the population under study, compared to at least 90 percent control by glyphosate and glufosinate. Greenhouse dose-response experiments indicated a 5- to 10-fold level of resistance to dicamba.

“Analysis shows dicamba resistance is moderately heritable within the population and is potentially caused by several genetically linked mutations,” Tranel said. “Further studies are expected to clarify the specific genes involved.”

To learn more, you are invited to read the article “Characterization and inheritance of dicamba resistance in a multiple-resistant waterhemp (Amaranthus tuberculatus) population from Illinois”