Evans et al., 2015

Jeffrey A EvansPatrick J Tranel, Aaron G HagerBrian SchutteChenxi Wu,  Laura A Chatham, and Adam S Davis,  “Managing the evolution of herbicide resistance,” 2015, Pest Management Science, 72, DOI 10.1002/ps.4009.

BACKGROUND: Understanding and managing the evolutionary responses of pests and pathogens to control efforts is essential to human health and survival. Herbicide-resistant (HR) weeds undermine agricultural sustainability, productivity and profitability, yet the epidemiology of resistance evolution particularly at landscape scales is poorly understood. We studied glyphosate resistance in a major agricultural weed, Amaranthus tuberculatus (common waterhemp), using landscape, weed and management data from 105 central Illinois grain farms, including over 500 site-years of herbicide application records.

RESULTS: Glyphosate-resistant (GR) A. tuberculatus occurrence was greatest in fields with frequent glyphosate applications, high annual rates of herbicide mechanism of action (MOA) turnover and few MOAs/field/year. Combining herbicide MOAs at the time of application by herbicide mixing reduced the likelihood of GR A. tuberculatus.
CONCLUSIONS: These findings illustrate the importance of examining large-scale evolutionary processes at relevant spatial scales. Although measures such as herbicide mixing may delay GR or other HR weed traits, they are unlikely to prevent them. Long-term weed management will require truly diversified management practices that minimize selection for herbicide resistance traits.  FULL TEXT