Proactive studies of herbicide resistance evolution and management

Most studies of herbicide resistance are reactive. A suspected case of resistance is reported froma commercial crop field where control has failed, seed is collected, resistance is confirmed by glasshouseor field-based dose response experiments, and in many cases biochemical and molecular assaysare designed to determine the mechanism of resistance. These studies are important as they enableconfirmation of resistance and emphasize the urgent need for alternative weed management strategies.Insights into the molecular mechanisms of resistance also inform patterns of multiple- and cross-resistance,contribute to a better basic understanding of rapid weed adaptation, and may provide novelleads for the discovery of the next generation of weed control tools. However, an important goal forherbicide resistance research must be to enable proactive as well as reactive management, studying‘evolution-in-action’ and enabling the evolution of resistance to be predicted, slowed and, if possible,even prevented. Studying the evolution of resistance in real-time presents several difficulties.Resistance evolves over many generations and in very large weed populations in farmers’ fields. Resistancemay first arise in a weed population because of gene flow from neighbouring or even distantpopulations. How can we design experiments that accounts for all these factors and that mimic whathappens in farmers’ fields so that we can understand the evolution of resistance before it becomes anagronomic or economic problem? My research with colleagues over the last ۲۰ years has attemptedto address those challenges using several different approaches. We have developed mathematicalmodels that simulate evolution of resistance, we have performed selection experiments with weedspecies in glasshouses, we have explored the use of model organisms with short generation times toexperimentally evolve herbicide resistance and most recently we have developed epidemiologicalapproaches that have potential to identify the evolution of resistance in field weed populations beforeresistance becomes widespread and problematic. In this presentation, I will share insights and resultsfrom these various approaches highlighting successes and failures, advantages and disadvantages ofvarious approaches to answer the question "how can we proactively manage the evolution of herbicideresistance"?