Submitted to: Weed Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/4/2011
Publication Date: 7/1/2011
Citation: Williams, M., Boydston, R.A., Peachey, R.E., Robinson, D. 2011. Significance of atrazine as a tank-mix partner with tembotrione. Weed Technology. 25(3):299-302. Interpretive Summary: Atrazine has been used to control weeds in corn production for over fifty years in the U.S. Most of the other herbicides used in corn are mixed with atrazine to improve their performance, but this may change in the event of future restrictions of atrazine. We asked the question: How much does atrazine improve performance of tembotrione, one of the newest herbicides registered in corn? We answered this question by analyzing a dataset with sweet corn and weed responses to tembotrione applied with, and without, atrazine in field studies conducted across North America. We found addition of atrazine not only improved weed control and crop yield, but also reduced variation in responses. As a result, lower risk of weed control failure and crop losses occured when atrazine was applied with tembotrione. In considering the low cost of atrazine, our work shows why it remains a popular herbicide among corn growers. The impact of this work is that economically viable alternatives need immediate development, particularly if atrazine is deemed inapproppriate for continued use.
Technical Abstract: Manufacturers of several postemergence corn herbicides recommend tank-mixing the herbicide with atrazine to improve performance; however, regulatory changes in atrazine use are possible. The objective of this work was to quantify the effect of postemergence atrazine on effectiveness of tembotrione in corn. Using sweet corn, a corn type highly reliant on atrazine, field studies were conducted two years each in Illinois, Oregon, Washington, and Ontario, Canada. Tembotrione at 31 g/ha was applied alone and with atrazine at 370 g/ha postemergence at the four- to five-collar stage of corn. Predominant weed species observed in the experiment were common to corn production, including large crabgrass, wild-proso millet, common lambsquarters, and velvetleaf. For nearly every weed species and species group, addition of atrazine improved performance of tembotrione by providing 3 to 45% higher mean levels of control at two weeks after treatment. Atrazine also reduced variation (i.e. standard deviation) in control of the weed community by 45%. Sweet corn yields were 9 to 13% higher and less variable when atrazine was applied with tembotrione, compared to tembotrione alone. Future additional restrictions, or complete loss of atrazine, will precipitate the need for major change in weed management systems for corn, particularly in the production of specialty types of corn.