College of Agriculture & Natural Resources
Plant Science & Landscape Architecture

University of Maryland Investigates Resistance to Glyphosate (Roundup) on Weeds in Major Crop Systems

This novel resistance to a mainstream herbicide has multi-billion dollar impact on food and feed production
Treated and untreated plants

College Park, MD -- Glyphosate, or “Roundup” as it is labeled commercially is used extensively to combat weeds in corn, soybean and cotton cropping systems. Widespread use has led to a growing number of glyphosate resistant weeds, which has a major impact on food and feed production, with estimates of yield losses at $13 billion per year in the United States. Burkhard Schulz, assistant professor in UMD’s Plant Science and Landscape Architecture department and his group have uncovered the mechanism and cause of glyphosate resistance in giant ragweed, one of the most detrimental weeds in the corn and soybean belt of the Midwest. Their findings describe a novel rapid response system that has not been found in any other plant species and has yet to be described in any other system.


The mechanism for glyphosate resistance in giant ragweed features a process that leads to detoxification of the herbicide which prompts re-growth of the weed and a subsequent crowding out of crop plants. Schulz’s analysis of physiological responses to glyphosate resistance extend far beyond a simple quantification of the weed’s resistance level, creating new models and pathways for future herbicide resistance research.


Schulz reports that without the efficacy of herbicides for food and feed production, losses could potentially slide to $45 billion per year. Additionally, the use of glyphosate in our food system has prompted several contentious issues, most notably concern over environmental and health burdens. These findings represent an important talking point in the discussion over effective use, safety of and possible reduction of chemical inputs in food production.


“This is the type of discovery that is highly applicable to a broad population because of the widespread use of roundup in agricultural production and as a tool to control weed growth in residential environments,” said Burkhard Schulz, Ph.D of UMD’s College of Agriculture and Natural Resources. “It’s a hot button issue, one that demands attention and focus to support growers with a simple weed control solution, and to reverse multi-billion dollar losses due to widespread herbicide resistance.”


Moving forward, Schulz aims to develop tactics to dis-arm the plant defense system that enables giant ragweed survival after toxic doses of glyphosate. Ultimately, his goal is to once again make the weed susceptible to glyphosate and to design strategies for identification and subsequent isolation of herbicide resistance genes from the resistant plants.


In collaboration with researchers from Colorado State University, USDA, Purdue University, Oregon State University, University of Guelph, Washington University and Monsanto, Schulz completed two manuscripts which were recently published in the journal Pest Management Science. The first is titled">http://onlinelibrary.wiley.com/doi/10.1002/ps.4567/full"> ">http://onlinelibrary.wiley.com/doi/10.1002/ps.4567/full">“Glyphosate resistance in Ambrosia">http://onlinelibrary.wiley.com/doi/10.1002/ps.4567/full">Ambrosia trifida:">http://onlinelibrary.wiley.com/doi/10.1002/ps.4567/full">: I. Novel rapid cell death response to glyphosate and the second “Glyphosate">http://onlinelibrary.wiley.com/doi/10.1002/ps.4569/full">Glyphosate resistance in Ambrosia">http://onlinelibrary.wiley.com/doi/10.1002/ps.4569/full">Ambrosia trifida:">http://onlinelibrary.wiley.com/doi/10.1002/ps.4569/full">: II. Rapid response physiology and non-target site resistance”.

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