Impact of atrazine prohibition on the sustainability of weed management in Wisconsin maize production

BACKGROUND Controversy has surrounded atrazine owing to its susceptibility to leaching and run‐off, with regular calls for a ban or restrictions on its use. In the context of a decreasing trend in the percentage of US maize using no‐till since 2008, coinciding with the trend of glyphosate‐resistant weeds becoming problematic in the Midwestern United States, we empirically examine how atrazine use restrictions have impacted the diversity of weed management practices used by Wisconsin maize farmers. RESULTS Using survey data from farms inside and outside atrazine prohibition areas, we found that prohibiting atrazine did not directly impact tillage practices, but rather it increased the adoption of herbicide‐resistant seed, which then increased adoption of conservation tillage systems. We also found that prohibiting atrazine and using herbicide‐resistant seed reduced the number of herbicide sites of action used. CONCLUSIONS The results indicate that prohibiting atrazine reduced the diversity of weed management practices, which increased the risk of herbicide resistance. Our concern is that a regulatory policy to address one issue (atrazine in groundwater) has induced farmer responses that increase problems with another issue (herbicide‐resistant weeds) that longer term will contribute to water quality problems from increased soil erosion and offset the initial benefits. © 2016 Society of Chemical Industry