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Title: ACCUMULATION OF SHIKIMATE IN CORN AND SOYBEAN EXPOSED TO VARIOUS RATES OF GLYPHOSATE

Author
item Henry, William
item Koger Iii, Clifford
item Shaner, Dale

Submitted to: Crop Management at www.cropmanagement.org
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2005
Publication Date: 11/23/2005
Citation: Henry, W.B., Koger III, C.H., Shaner, D.L. 2005. Accumulation of shikimate in corn and soybean exposed to various rates of glyphosate. Online. Crop Management doi:1094/CM-2005-1123-01-RS.

Interpretive Summary: In this manuscript we describe the various effects of herbicide application on two crops, soybean and corn. Roundup is one of the most commonly used herbicides throughout the world. Because it is so widely used under so many different environmental conditions, this herbicide could be misapplied or drift onto neighboring crops like soybean or corn. Because organic producers are wary of any herbicide exposure on their crops and conventional producers with non-roundup ready crops could be subject to herbicide injury from roundup drift, it would be good to be able to identify crops that had been exposed to roundup. The objective of our research was to examine a test that is useful for identifying crops that have been sprayed with roundup. We found that we could identify a peak in plant response to roundup application between 4 and 7 days following herbicide exposure. In summary, further refinement of this procedure may lead to an assay that can detect roundup drift or roundup resistant weeds.

Technical Abstract: Glyphosate is used extensively throughout the world as a burndown and in-crop herbicide. Because organic producers are wary of any herbicide exposure to their products, and producer’s non-roundup ready crops would be susceptible to glyphosate drift injury, it would be beneficial to have a way to determine if a crop had been exposed to glyphosate. The objective of our research was to evaluate a spectrophotometric assay as an inexpensive and rapid procedure to measure shikimate accumulation in conventional corn and soybean following glyphosate application. Shikimate levels peaked between 4 and 7 days after application in both corn and soybean. It is useful to understand the behavior of shikimate in plants so that management decisions can be made regarding conventional crops’ exposure to glyphosate. In summary, further refinement of this assay may lead to an assay that can be used to monitor glyphosate drift or detect glyphosate resistant weeds.