Real‐time variable‐rate herbicide application for weed control in carrots

A camera sensor for precision weed control in arable fields has been developed at the Leibniz Institute for Agricultural Engineering. For herbicide spraying in carrots, the sensor was positioned at the front three‐point linkage of a tractor and was operated between carrot rows. In field trials in 2 years, real‐time (online) technology in which sensing and spraying were performed in one step was evaluated in comparison with a conventional uniform spraying application. The spray volume was linearly adjusted to the camera‐detected weed coverage level from a minimum of 200 L ha^?1 if no weeds were present to a maximum of 400 L ha^?1. The herbicide savings were 30% in 2007 and 34%, 43% and 36% for each of three applications in 2010. There were no significant differences between the camera‐based and conventional spraying approaches with regard to yield parameters, total carrot weight and weight of marketable carrots. Regarding the weed control efficiency of the camera‐based spraying procedure in the 2010 experiment, no trend was observed between the weed coverage and the application rate of the previous spraying.