gm-soy/report-4

Root colonization of glyphosate-resistant soybeans by pathogenic Fusarium fungi increased with glyphosate application.

Manipulated Organism: Soybean (Glycine max).

Inserted Transgenes: CP4 EPSPS gene cloned from Agrobacterium, which produces an herbicide-resistant version of the enzyme targeted by the herbicide glyphosate (Roundup).

Goal of This Study: Previous research had demonstrated that when weeds are sprayed with glyphosate, elevated levels of pathogenic Fusarium fungi are associated with their roots. This study was designed to investigate the phenomenon using glyphosate-resistant (GR) soybeans.

Results of This Study: Fusarium colonization of the GR soybeans was twofold higher as a result of the glyphosate treatment over a wide range of soil moisture conditions.

Additional Comments: "The combined effects of glyphosate with optimum to high soil moisture that led to increased Fusarium populations (root colonization) in this study may help explain the Fusarium disease epidemics documented in GR soybean fields during wet growing seasons, notably in 1997" (p. 1718).

Source: Means, N. E. and R. J. Kremer (2007). "Influence of Soil Moisture on Root Colonization of Glyphosate-treated Soybean by Fusarium Species," Communications in Soil Science and Plant Analysis vol. 38, pp. 1713-20.

Author Affiliations: University of Missouri, Columbia, Missouri; USDA Agricultural Research Service, Columbia, Missouri.

Funding: USDA and Ag Spectrum Company, Dewitt, Iowa.

Product Status: GR soybeans have been grown commercially in the US since 1996 and currently constitute over 90% of the US soybean crop.

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Seth JordanAugust 26, 2020