Abstract: An apparatus (mulcher) for keeping down groundcover between parallel rows of plants, especially rows of wine grape or fruit plants, with two chopping blade rotors rotating in one and the same plane, each around an axis perpendicular to the ground. The distance between the rotational axes is adjustable in a direction perpendicular to the plant rows even though the rotational areas of the chopping blade rotors may overlap. A separate electric motor is assigned to each of the chopping blade rotors, and devices are provided to control the electric motor so that that collisions between the chopping blade rotors are avoided.