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

Abstract: 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.