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Soybean weed resistance management is spelled D-I-V-E-R-S-I-T-Y

June 24, 2016


While limited acres of Roundup Ready 2 Xtend soybeans have been planted this year, growers who want to plant this new technology in 2017 may be tempted to think this is the silver bullet for weed management. Though it will be another tool in the toolbox, growers have a lot to consider before making the switch.

To help navigate those decisions, Syngenta recently held a resistance roundtable discussion with industry experts.

Participating in the discussion were Stephen Powles, Ph.D., professor and director of the Australian Herbicide Resistance Initiative, University of Western Australia; Tim Hambrick, NC Cooperative Extension agent and 2014 Resistance Fighter of the Year; and Syngenta corn and soybean herbicide representatives.

Top of mind for all participants was the importance of diversity in managing resistant weeds. Out of roughly 170 million acres of glyphosate-tolerant farmland in the U.S., 84 million acres currently contain glyphosate-resistant weeds. The development and spread of glyphosate-resistant weeds is expected to continue for the foreseeable future. This spread has increased herbicide spending 2 to 3 times for soybean growers since Roundup Ready® technology was first introduced, said Powles. Growers are reminded that resistance management changes on a field-by-field basis, and a diverse herbicide program is the key to managing herbicide-resistant weeds and extending the life of herbicides that can be used with the new seed technologies, which are soon to be available.

Best management practices include:

  • Deliver full labeled rates and apply herbicides at the correct growth stage
  • Invest in full-season weed control methods to prevent the establishment of weeds
  • Vary weed control methods, technologies and planted crops
  • Evolve your weed control techniques before weeds evolve resistance to your herbicide
  • Restrict buildup of the weed seed bank as a key way to minimize resistance
  • Scout before and after herbicide spraying to know what weeds you’re up against in each field
  • Integrate both pre- and post-emergence herbicides into your management plan
  • Tank mix with different modes of action and rotate different herbicides
  • Yanking weeds should be a last resort

Growers have to think about managing weed resistance today to ensure we have multiple herbicide options for the future. Diversifying weed management strategies can help ensure current herbicide technologies remain effective until new ones become available. Two critical components of a herbicide program, regardless of the trait platform, include the use of a pre-emergence herbicide with effective modes of action on target weeds and the use of overlapping residuals.

View videos from the Resistance Roundtable discussion on YouTube or follow the conversation on Twitter® using #ResistanceRT.

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