What do the monitoring networks tell us about how weeds respond to changes in agricultural practices?

The weed flora found in arable fields has been profoundly altered by changes in agricultural practices over recent decades. Alongside an overall decline in the number of species and individuals per plot, new species have emerged, some of which have become new problems. Whilst such observations are within the remit of expert opinion, networks of observation stations prove to be an unrivalled source of information for quantifying these changes in greater detail and linking them to farming practices. Developments are currently underway aimed at enabling the network to support modelling that will allow a more direct link to be established between plant health risks and crop management decisions. Following on from the article by Fried et al. (2008) in this same journal, this article reviews the knowledge gained through the Biovigilance-Flore network between 2002 and 2010 across 1,440 plots and 722 municipalities in mainland France. It also presents recent developments.