Effects of Weed Management Systems on Weed Species Communities in Glyphosate Resistant Crop Fields

A total of 156 agricultural fields across six U.S. states were studied to investigate the effect of weed managements systems of glyphosate resistant (GR) crops in weed community structure and composition. The fields were categorized into three weed management systems: a) a single continuous GR crop; b) a rotation of two GR crops; and c) a GR crop rotated with non-GR crop. The weed species population density, species richness and diversity were analyzed using mixed models to test the effect of year, geographic location, and weed management system.

The researchers identified a total of 329 weed species in all study sites during the whole duration of the study. Weed communities were found to be most strongly correlated with geographic location. Weed management system affected similarity among weed communities through an interaction with site location but this was not observed in all years of the experiment. The weed management systems of crop rotation and GR trait rotation generally reduced weed population density and species diversity, bu the effect of crop rotation were different based on geographic location.

Based on these findings, the researchers concluded that there is a need for locally adapted weed management systems to help GM crop trait to manage high weed diversity while decreasing crop-weed competition and maximizing yield.

The research article is available at http://onlinelibrary.wiley.com/doi/10.1111/avsc.12039/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false.