The mechanical action of a flexible weed harrow spring-tine during post-emergence selective treatment was evaluated in different soil textures and properties, and for different tine locations. The tine movements and forces acting on the tine were measured with strain gauges and analysed as mean tine torsion in the soil, the flexural variation of the tine top position and the properties of the vibration frequency during cultivation. In addition. a high-speed camera provided a visible description of the tine penetrating the soil. Experiments were conducted indoors in soil bins to reduce external influences. No plants were involved in the experiments in order to avoid biological variances.