Iowa State University Extension Weed Science

Is there such a thing as a Superweed?
by Bob Hartzler and Mike Owen

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August 23, 2014 -  During the heyday of the Roundup Ready era Dr. Owen and I debated the finding of glyphosate resistant waterhemp (http://www.weeds.iastate.edu/mgmt/2003/pointcount.shtml).  Our current disagreement is whether or not the term “superweed” frequently used by the press and others is appropriate. Dr. Owen will support the position that use of “superweed” is not appropriate whereas I will defend the use of the term.


Mike:  While I admit that using the term “superweed” to describe glyphosate-resistant weeds has resulted in greater attention to the increasing problem of evolved herbicide resistance in many crop systems, it is a cheap journalistic term that sensationalizes a normal biological characteristic of adaptation to selective factors, in this case, herbicides.  Groups that are against GMOs, herbicide use, and modern farming practices likely coined the term to draw negative attention in the non-farming public.  The term was even used by then House of Representative Dennis Kucinich who chaired a House Oversight Hearing to determine if the USDA policy on GMOs were creating superweeds (http://oversight.house.gov/hearing/are-superweeds-an-outgrowth-of-usda-biotech-policy-part-i/).  Weeds that have evolved resistance to one or more herbicides behave no differently than susceptible populations when the herbicide(s) is not used.  Growth rate, seed production and importantly, competitive ability are all the same.  There is not ecological, biological or physiological advantage other than the resistant populations do not respond to a herbicide.  Herbicide-resistant weeds cannot leap tall buildings with single bound and thus should not be characterized as super.

Bob:  But these weeds are ‘faster than the silver bullet glyphosate’; that makes them pretty super in my book.  But in all seriousness, my basis for not being disturbed by the term superweed is that the majority of the definitions used for weeds are based on man’s perspective rather than the biological/ecological traits of the plant (e.g. ‘a plant out of place’, ‘a plant whose virtues have not been discovered’, ‘a plant that interferes with the activities of man’, etc.).  The plants that have earned the title superweed are herbicide resistant biotypes selected in the agriculture systems that dominate industrialized nations.  Conventional agriculture is almost completely reliant on herbicides to manage weeds.  Thus, these weeds have the potential of forcing dramatic changes in agricultural production – I would call that pretty super.  If the definition for a weed that I use in my weed science class was adopted universally – a plant adapted to colonization of disturbed habitats – I might be bothered more by the term superweed.

Mike:   A couple of belated points to consider; the first is that there is an “official” definition of superweed: 
World English Dictionary: superweed — n. a hybrid plant that contains genes for herbicide resistance: produced by accidental crossing of genetically engineered crop plants with wild plants 

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009


Please note that the World English Dictionary specifically stresses that a superweed is a hybrid between GE crops and wild plants.  As a general statement, there is only one example where the hybridization occurs and that is in canola and some of the weed Brassicas.  Thus the term is applicable to only one plant family and does not apply to the Amaranthus species, Conyza, or any other weeds that have evolved herbicide resistance because of the selection pressures imposed by the use of herbicides. 
Second, I will begrudgingly accept the term “superweed” as it has brought considerable attention to the need for more effective and diverse management of the most important pest complex.  Federal funding for weed management research has increased, commodity group support has increased, and the consistency of articles in the popular ag-press has resulted in a slow improvement in weed management tactics in some crop systems.
In conclusion, while the term is meaningless in ecological discussions, the notoriety of “superweeds” has resulted in more attention to weed management, albeit belated recognition.  Even the advocacy groups who mistakenly attribute superweeds as a direct result of GE genes moving around still has the positive result of increasing the discussion about weed management.  Thus, I surrender to you, Dr. Hartzler, and declare you the winner of this debate.

Bob:  Dictionary?  Haven’t they gone the way of slide rules and landline telephones?  While I agree the ‘official’ definition is ridiculous, I am comfortable in stating that greater than 90% of people (including the media) using the term ‘superweed’ are not aware of how the folks at the World English Dictionary have defined the term.  Wikipedia states that ‘superweed’ is used to describe a weed that is resistant to glyphosate.  I suspect this is much closer to how most people would define superweed.
As long as we have a production system that is nearly completely reliant on herbicides for weed management, herbicide resistant weeds will remain a serious threat to agriculture.  Simply look at the number of individuals and organizations that have encouraged the EPA and USDA to hasten the approval of the new herbicide resistant traits to help battle the current resistant weed problems.  I can’t remember this type of support for any other pending weed management tool.  This suggests our current weed problem is different than problems faced in the past – how much more ‘super’ than that can you get?

Mike – Bob, as previously stated, I am running up the white flag and surrender.  While I still disagree with your interpretation, I willingly concede that most people, whether in the agricultural sector or the general public (which represents more than 95% of the population) agree with your definition.  You win!

Resurrection of a superweed, or just bad application timing?

 Prepared by Bob Hartzler, extension weed management specialist, Department of Agronomy, Iowa State University

For more information contact:
1126C Agronomy Hall
Ames, Iowa 50011-1010
Voice: (515) 294-1164

http://www.weeds.iastate.edu

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Common chemical and trade names are used in this publication. The use of trade names is for clarity by the reader. Inclusion of a trade name does not imply endorsement of that particular brand of herbicide and exclusion does not imply nonapproval.