Site-specific weed management based on species-specific weed densities

Blanket in-crop herbicide application over the entire field is, due to the
heterogeneous distribution of weeds, in most cases both environmentally unfavourable and
economically unprofitable. Novel technologies such as automatic weed recognition enable the
determination of weed distribution with high spatial resolution and form the necessary basis for
site-specific herbicide applications.
The present study proposes a weed management approach that aims to create spatially
explicit management plans based on decisions taken at the weed species level. To obtain sitespecific
information, species-specific weed distribution and density across the field must be
first determined. Weed distribution maps are subsequently generated with a geoinformation
system (GIS) for the weed species most commonly found on the field. Economic thresholds
indicate the weed density at which herbicide application is economically justified and therefore
provide valuable decision support for weed control decisions. In this study, existing thresholds
for prevalent weed species are used as a basis for developing management plans. A site-specific
herbicide application map is developed and used to determine the type of herbicide required to
control each species according to its economic threshold. Site-specific management plans based
on each species' economic threshold are a necessary step in reducing herbicide use and
increasing weed diversity on cropland.