Georgia: Dual Magnum vs. Outlook for Tropical Spiderwort Control

Tropical spiderwort. Photo: Mace Bauer, University of Florida

Tropical spiderwort. Photo: Mace Bauer, University of Florida

At the recent Decatur County Weed Meeting (January 7), I was asked by an attendee about the differences in the control of tropical spiderwort between Dual Magnum (S-metolachlor) and Outlook (dimethenamid-P).

Outlook is the activated isomer of the herbicide formerly sold as Frontier (dimethenamid).  If you are not very familiar with Outlook, it is in the same herbicide family as Dual Magnum (chloroacetamide), has the same mode of action (very long chain fatty acid synthesis inhibitor – WSSA#15), and this active ingredient has been around since the 1990’s. 

For whatever reason, Outlook never really received much attention during my career but recently BASF has dusted it off. 

My first response to the question was that I did not think that I had any data.  In my defense, you must remember that I have been in Georgia now for more than 20+ years and have conducted 50-70 field trials every year since then. 

So the immediate recall of historical data can be challenging, especially for a 56 year old guy who played 12 years of Pop Warner, high school, and D-3 college football long before concussion protocols were common.  However, after reviewing my old files, I discovered some data from 2002 that compared the performance of Outlook to Dual Magnum in a peanut trial conducted in Grady Co. 

The results of this trial are presented below (click on graph to download or view a higher quality graph):

It is obvious from this data that Outlook is not quite as effective for the control of tropical spiderwort as Dual Magnum.  However, it is only 1 year’s worth of data.  In 2020, I will be looking for a peanut field to conduct some additional spiderwort control research so please keep your eyes open.

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