ARS | Publication request: Performance consistency of reduced Atrazine use in sweet corn

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 29, 2010
Publication Date: January 1, 2011
Citation: Williams, M.M. II, Boydston, R.A., Peachey, R.E., Robinson, D. 2011. Performance consistency of reduced Atrazine use in sweet corn. Field Crops Research. 121:96-104.

Interpretive Summary: Currently, most sweet corn fields suffer yield losses due to weed interference, and growers may be losing their most widely used weed control tactic - atrazine herbicide. We conducted studies throughout the major processing sweet corn growing areas in North America to determine the impact of using less atrazine on sweet corn production. We were particularly interested in testing the idea that weed control and crop losses from reduced atrazine use were less severe in a vigorous growing crop hybrid, compared to a weakly growing crop hybrid. In a total of eight environments, we found that atrazine's contribution to weed control and yield protection were greatest when other aspects of weed management resulted in poor weed control. Sweet corn production did not benefit from atrazine in every environment, but most. Indeed, the vigorous growing crop hybrid provided weed suppression as atrazine use was reduced, that was not observed in the weakly growing crop hybrid. A complexity of multiple and variable weed control tactics is believed to be more robust over time than weed management systems dominated by a single tactic, and the impact of this work is showing that loss of atrazine use will necessitate migration towards those more complex weed management systems.

Technical Abstract: Atrazine is the most widely used herbicide in North American corn production; however, additional restrictions on its use in the near future are conceivable. Currently, a majority of commercial sweet corn fields suffer losses due to weeds, despite widespread use of atrazine. Field experiments were conducted in the primary North American production areas of sweet corn grown for processing to determine the implications of further reductions in atrazine use on weed control and crop yield. A range of atrazine doses (0 to 1,120 g/ha) applied postemergence with tembotrione (31 g/ha) were tested in two hybrids differing in canopy architecture and competitive ability with weeds. Atrazine applied postemergence reduced risk (i.e. more variable outcomes) of poor herbicide performance. Atrazine doses up to 1,120 g/ha with tembotrione improved grass control and broadleaf control in five of eight and seven of eight environments, respectively. Of the three environments which had particularly low broadleaf weed control (<50%) with tembotrione alone, sweet corn yield was improved with atrazine, too. Hybrid 'Code128' produced a taller, denser canopy which was more efficient at capturing light and competing with weeds than 'Quickie'. As a result, greater crop competitiveness decreased risk of incomplete weed control as atrazine dose was reduced. Atrazine’s contribution to weed control and yield protection was greatest when other aspects of weed management resulted in poor weed control. Should atrazine use be further restricted or banned altogether, this research shows the importance of improving other aspects of weed management systems, both herbicidal and non-chemical tactics.