Giant Problem of Giant Ragweed

Chris Evans, Illinois Wildlife Action Plan, - See more at:

Giant ragweed (Chris Evans, Illinois Wildlife Action Plan,

by Andrew Haun, Agribusiness and Applied Economics major

After spending considerable time in research and presentations on giant ragweed (Ambrosia trifida), I’ve only scratched the surface to the problem this weed presents to farmers (conventional and organic alike).  A prolific weed that not only halts half million dollar equipment during harvest, but has been a golden goose for pharmaceutical companies in the allergy medication market (giant ragweed is the leading cause of allergies in the U.S.).

Giant ragweed is one of the more hardy weed species common in Midwest farms. The seed is proficient at overwintering and the plant itself is an aggressive competitor for sun, water, and nutrients.  Stands of giant ragweed can reach an excess of 10ft in height if left untreated.

Organic farmers who face perennial bouts with giant ragweed understand this problem and often times, are left at its mercy.  Non-chemical weed management practices tend to be far less effective at giant ragweed control.

As time passes, conventional farmers must now look at other chemical options to increase the effectiveness of their management program. The plant has been exposed to herbicides such as glyphosate and ALS (acetolactate synthase) inhibitor herbicides and the once small number of  herbicide-resistant populations now flourish.

As giant ragweed continues to evolve, our ability and willingness to adapt must follow suit.  Research abounds from many of the U.S.’s top agricultural institutions with efforts to educate not only farmers but the general public about the proliferation of tolerant giant ragweed, and give farmers new management options to improve the performance of their crops.

For more information:

University of Tennessee Extension. Giant Ragweed (pdf)

M.S. Thesis, The Ohio State University. Evaluation of glyphosate resistant giant ragweed (Ambrosia trifida) in Ohio soybean (Glycine max) fields by James D. Bethel > Ohiolink

Purdue University. Biology and Management of Giant Ragweed (pdf)

This blog post was an assignment for  Societal Issues: Pesticides, Alternatives and the Environment (PLNTPTH 4597). The views expressed are those of the author and do not necessarily reflect the views of the class, Department of Plant Pathology or the instructor.

Chris Evans, Illinois Wildlife Action Plan, – See more at:

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