2013/03/11 by Miki Okada, Bradley D. Hanson, Kurt J. Hembree +5 · 2 citations
Agricultural and Biological Sciences · Environmental Science · #Weed Control and Herbicide Applications #Turfgrass Adaptation and Management #Ecology and Vegetation Dynamics Studies
paper · pdf · doi:10.1111/eva.12061
openalex publication_date 2013/03/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/23
Abstract Recent increases in glyphosate use in perennial crops of C alifornia, USA , are hypothesized to have led to an increase in selection and evolution of resistance to the herbicide in C onyza canadensis populations. To gain insight into the evolutionary origins and spread of resistance and to inform glyphosate resistance management strategies, we investigated the geographical distribution of glyphosate resistance in C . canadensis across and surrounding the C entral V alley, its spatial relationship to groundwater protection areas ( GWPA ), and the genetic diversity and population structure and history using microsatellite markers. Frequencies of resistant individuals in 42 sampled populations were positively correlated with the size of GWPA within counties. Analyses of population genetic structure also supported spread of resistance in these areas. B ayesian clustering and approximate B ayesian computation ( ABC ) analyses revealed multiple independent origins of resistance within the C entral V alley. Based on parameter estimation in the ABC analyses, resistant genotypes underwent expansion after glyphosate use began in agriculture, but many years before it was detected. Thus, diversity in weed control practices prior to herbicide regulation in GWPA probably kept resistance frequencies low. Regionally coordinated efforts to reduce seed dispersal and selection pressure are needed to manage glyphosate resistance in C . canadensis .