Six Ways to Manage HPPD Resistance
HPPD inhibitors are powerful additions to the weed-control toolbox, but there are no bulletproof answers in the fight against herbicide resistance.
To date, HPPD inhibitors have suffered multiple confirmed cases of resistance involving Palmer amaranth and waterhemp. Resistant weeds have been found in Kansas, Nebraska, Wisconsin, Illinois and Iowa in cases stretching back to 2009.
The consequences of HPPD-resistant weeds can be severe. Research from the University of Illinois, for example, indicates waterhemp can slice off 40% to 70% of corn and soybean yields.
Despite the current challenges, proper stewardship of HPPD herbicides is possible. The following are six ways farmers can manage weed resistance and promote sustainability of existing chemistries.
- Continually monitor fields for any tough-to-manage or resistant weeds.
- Adopt azero-tolerance approachto keep seeds from entering the soil seedbank.
- Always tankmix herbicides that have at least two modes and sites of action.
- Follow integrated pest management practices;a comprehensive approach is outlinedhere.
- Follow HPPD stewardship guidelines as outlined by theHerbicide Resistance Action Committee.
- Attack weeds when they are small.
A 2015 study from the University of Illinois showed that regardless of application rate, HPPD herbicides controlled less than 40% of resistant waterhemp. Even so, application timing made a difference, according to associate professor Aaron Hager.
“We saw the best results when we treated plants only two to five centimeters tall,” he says.
This strategy also keeps weeds from proliferating and spreading. Waterhemp and pigweed, in particular, are notorious for being able to produce hundreds of thousands of seeds from a single mature plant. These seeds can stay viable for several years.
When dialing up an herbicide management program, learn the full scope of resistance for target weeds. It may be helpful to consult the International Survey of Herbicide Resistant Weeds before finalizing the tankmix.
Photo Credit: © 2012 AgStock Images / Bill Barksdale