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Here we go again
by Bob Hartzler

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February 7, 2001 -  Last year it was Monsanto and Zeneca going after each other's glyphosate product, this year Dow AgroSciences is attacking BASF and dicamba.  The new ad from Dow AgroSciences apparently is trying to scare farmers away from using products containing dicamba.

hornet.jpg (68012 bytes)Most everyone involved in corn production understands that growth regulator herbicides (2,4-D; dicamba; etc.) can induce stalk brittleness in corn.   Growers have learned to minimize this risk by avoiding sensitive hybrids and making timely applications of growth regulator herbicides.  In the research reported in the ad, experiments were set up to maximize the potential for crop injury.  There is nothing wrong with this approach as long as this is made clear in the presentation of the results.  To increase the likelihood of injury, corn was planted in June to ensure it would be growing rapidly when the herbicides were applied, and at least one of the hybrids used in the study was rated as sensitive to growth regulator herbicides.  But most importantly, the ad does not provide any details on what a simulated wind gust entails.   Wind was simulated by mounting a metal bar 4-6 inches above the ground and driving through the field at 5-7 MPH approximately one week after application when the corn was at the V6 stage.  Studies have shown that strong winds play an important role in the occurence of greensnap.  There is no simple way to simulate this event, and the methods used here probably are as good as any.   However, I feel the methods should be made clear whenever presenting these data.   Dow AgroSciences put together a nice factsheet in 1999 that described the methods used in the experiments in detail. 

The results of these experiments support Dow AgroSciences' claim that clopyralid (the growth regulator herbicide in Hornet) is less likely to induce greensnap than dicamba.  However, the advertisement greatly exaggerates the potential for this response since it does not put the data into context.  Thus, this ad makes the Hall of Shame for its blatant attempt to mislead farmers on the safety of competing products.  In my view, they should have never pulled this piece out of the waste basket.









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
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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.