Potential geographic distribution of Palmer amaranth under current and future climates

Authors: Kistner-Thomas, Erica; Hatfield, Jerry

Submitted to: Agricultural and Environmental Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2018
Publication Date: 4/12/2018
Citation: Kistner-Thomas, E.J., Hatfield, J.L. 2018. Potential geographic distribution of Palmer amaranth under current and future climates. Agricultural and Environmental Letters. 3:170044. https://doi.org/10.2134/ael2017.12.0044.
DOI: https://doi.org/10.2134/ael2017.12.0044

Interpretive Summary: Palmer amaranth is a widespread economically damaging weed of corn, soy, and cotton in the United States. Originally from the arid Southwestern US, this highly competitive weed has spread across the country due to human-assisted dispersal of its seeds. It has also invaded portions of Africa, Europe, and South America. Palmer amaranth is very difficult and expensive to control due in part to its ability to develop herbicide resistance, including resistance to glyphosate. Climate change will add further complications to managing this species. To assess the impacts of climate change on Palmer amaranth, we modeled its potential global distribution under both current and future climate scenarios. Model projections indicated that key row-crop production regions in Africa and Australia are most at risk in terms of both current and future climate scenarios. In the Northern Hemisphere, projected increases in temperature will likely enable Palmer amaranth to expand its range northward into Canada and northern Europe. The results of this study show that the likely range expansion of this weed under future climate change should be considered in its biosecurity planning and weed management programs. Results from this study will impact biosecurity agencies' decisions about managing the invasion risks posed by this weed in light of climate change.

Technical Abstract: Herbicide resistant weeds are increasingly becoming a major challenge for agricultural production worldwide. Palmer amaranth is an invasive annual forb that has recently emerged as one of the most widespread and severe agronomic weeds in the US, due in part to its facility for evolving herbicide resistance. It has also invaded several parts of the world, including key agricultural production regions in South America. Climate change will likely exacerbate the challenges of managing this species. In this study, we developed a process-oriented bioclimatic niche model of Palmer amaranth to examine its potential global distribution under current and future climate scenarios. The model agreed well with all credible distribution data. Under future climate scenarios, projected increases in temperatures will expand potential Palmer amaranth range poleward and lengthen its growing season. Model projections under current and future climates highlight several agricultural production regions of increasing and emerging risk from this weed.