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Enough Already
by Bob Hartzler

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April 27, 2001 -   In a recent advertising campaign Monsanto has promoted the benefits of Transorb™ technology utilized in Roundup UltraMAX. The advertisements can be seen on television, in the farm press, on the internet ( http://roundupweedcam.monsanto.com/ ), and I assume heard on the radio.  Monsanto uses visual evidence from autoradiography and cryo-scanning electron microscopy to compare absorption and translocation of Roundup UltraMAX and Touchdown IQ.  They conclude that Transorb™ technology results in superior weed control with Roundup UltraMAX compared to Touchdown due to more rapid absorption of glyphosate with Roundup UltraMAX.

Specific methods used in the research are not provided, thus it is impossible to critique the methods and conclusions cited in the marketing campaign.   However,  the results presented by Monsanto differ considerably from research conducted by independent scientists and published in a scientific journal.   Researchers at the University of Illinois evaluated the absorption and translocation of two glyphosate formulations {Roundup Ultra and the original Touchdown 5} in both velvetleaf and giant foxtail (Satchivi, N. M., L. M. Wax, E. W. Stoller and D. P. Briskin.  2000.  Absorption and translocation of glyphosate isopropylamine and trimethylsulfonium salts in Abutilon theophrasti and Setaria faberi.   Weed Sci. 48:675-679).  The researchers reported no differences between the two products in absorption or translocation  (Figure 1 and Table 1).

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Table 1.  Distribution of foliar applied 14C-glyphosate in giant foxtail.

Hours after
treatment
Herbicide

Distribution of Radioactivity (% of applied)

    Treated leaf Above treated leaf Below treated leaf Root
1 Roundup Ultra 97.5 0.5 1.3 0.5
  Touchdown 97.6 0.5 1.1 0.5
3 Roundup Ultra 93.6 0.9 1.7 0.9
  Touchdown 93.4 0.9 1.9 1.0
24 Roundup Ultra 65.6 4.0 16.6 12.3
  Touchdown 64.8 4.1 16.0 12.0

Satchivi et al.  2000.  Weed Sci. 48:675-679

I recognize that Monsanto will state I am comparing apples to oranges since Syngenta recently changed Touchdown formulations from a trimethylsulfonium salt to a diammonium salt.  However, the authors' concluding statement in the Weed Science article addressed this issue:  'The absence of differences between these formulations may be because both formulations, upon ionization, yield the same active acid glyphosate'.  Any potential differences in absorption or translocation between glyphosate formulations is unlikely due to the particular salt formulation used in the product.  It is possible that differences in surfactants used in the formulations could alter product performance, but I have not seen any independent research showing a consistent advantage of one glyphosate product over another.  We believe that when glyphosate products are used at equivalent rates with appropriate additives that there should not be no consistent differences in performance.

Monsanto's marketing campaign recently won an award from the National Agri-Marketing Association in the national multimedia campaign category.  To the best of my knowledge, this is the first time that an ad has won both a marketing award and a place in the Hall of Shame.

Additional information on this topic (Click on title to go to article):
Absorption of foliar-applied herbicides
Which glyphosate product is best

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

For more information contact:
ISU Extension Agronomy
2104 Agronomy Hall
Ames, Iowa 50011-1010
Voice: (515) 294-1923
Fax: (515) 294-9985
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.