Comparing threshold concepts for weed control

Abstract: Using economic thresholds in weed control decisions can reduce herbicide inputs
without the risk of significant yield losses. Different approaches exist for translating weed
occurrences in an arable field into weed control concepts. In the 1980s, the first economic
thresholds were developed in which weed species were divided into monocotyledonous and
dicotyledonous weeds, with a specific control threshold set at a maximum density for each group. Control of the weeds is consequently recommended if the number of individual weed plants in one group exceeds the defined threshold. In recent years, additional economic threshold concepts have evolved, which no longer refer to groups of weeds but to individual weed species. These economic threshold concepts allow for control decisions based on the lowest possible economic risk but neglect the ecological impact of controlling ecologically relevant weed species. Advanced weed control approaches might, therefore, consider specific functional traits of weed species connected to service (e. g., provision of ecosystem services) and disservice (e. g., competitive ability) provision and adjust control decisions based on the occurrence of these traits. This study compares three threshold concepts for weed control based on the required data input, processing, and the generated output. We discuss the technological demand and applicability of these different weed control threshold concepts.