The role of climate change and increasing atmospheric carbon dioxide on weed management: Herbicide efficacy

Rising concentrations of carbon dioxide [CO2] and a changing climate will almost certainly affect weed biology and demographics with consequences for crop productivity. The extent of such consequences could be minimal if weed management, particularly the widespread and effective use of herbicides, minimizes any future risk; but, such an outcome assumes that [CO2] or climate change will not affect herbicide efficacy per se. Is this a fair assumption? While additional data are greatly desired, there is sufficient information currently available to begin an initial assessment of both the physical and biological constraints likely to occur before, during and following herbicide application. The assessment provided here, while preliminary, reviews a number of physical and biological interactions that are likely, overall, to significantly reduce herbicide efficacy. These interactions can range from climatic extremes that influence spray coverage and field access to direct effects of [CO2] or temperature on plant biochemistry and morphology. Identification of these mechanisms will be essential to both understand and strengthen weed management strategies associated with rising levels of [CO2] in the context of an uncertain and rapidly changing climate. Published by Elsevier B.V.