Glyphosate Resistance in Soybeans

This article was written by Mark Rosenberg, former SDSU Extension Agronomy - Weeds Field Specialist.

Many weeds have developed glyphosate resistance in the past few years. Many producers who use Roundup Ready soybeans have a temptation to rely on glyphosate products to control post-emergent weeds, causing them to potentially become resistant to the chemical. If producers are unable to gain control over the weed, then weed competition will cause a significant yield loss.

There are four weed species confirmed to be glyphosate resistant in South Dakota: kochia, waterhemp, horseweed (marestail), and common ragweed. Glyphosate-resistant waterhemp is one of biggest concerns for soybean producers in the state. However, this list may continue to grow and could include giant ragweed and common ragweed in the future.

For growers who are struggling with glyphosate resistant species, early control is critical. The reason producers are seeing more weed species becoming glyphosate resistant is because of less crop rotation. If a producer always uses Roundup Ready soybeans and treats the weed species with glyphosate, then he should consider changing the variety and using a different herbicide, like switching to Liberty Link and using Ignite herbicide.

SDSU Extension Weed Project encourages producers to use a pre-emergent herbicide as a proactive management strategy when growing soybeans. This cannot be stressed enough. Pre-emergent herbicides are a valuable management strategy for producers because their use helps provide adequate control before the weed species is out-of-control.

SD Pest Management Guide: Soybeans

The South Dakota Pest Management Guide Soybeans is SDSU Extension’s source of information. It helps select effective weed herbicide programs for soybeans within the crop rotation sequence, rotating between sites of action to reduce the chance for herbicide-resistant weed development.

  • The guides will be available through the iGrow Store or the Extension Weed Program at SDSU in Brookings.
  • The staff may be reached at 605.688.4591 or 605.626.2870.

Related Topics

Soybean Weeds, Growing Soybeans

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