The machine includes a frame adapted to move along spaced ridges planted with crop plants, frame support runners engaging the furrows between the ridges, a pair of transverse rows of weeding implements carried by the frame for movement along the ridges and furrows, the implements of one row disposed on one side of the plants and the implements of the other row disposed on the other side of the plants. Each row is transversely displaceable by a double acting hydraulic ram relative to the frame. The rams are controlled by an operator supported by the frame in a position to have a direct view of the weeding implements. Each implement is free to move up and down independently of the remaining implements in order to follow the ground contour. The implements of any one row can be raised together out of working position. These weeding implements can be earth working discs and/or thermal weeders. Each thermal weeder consists of an idle wheel having a rim formed by two spaced marginal portions rotating on the ridge on each side of the crop plants and of propane gas burner nozzles directed towards the ground on the outside of the marginal portions, the latter protecting the plants. The two marginal portions can be adjustably spaced in accordance with the size of the crop plants. For combustible black soil rich in organic matter, the wheel marginal portions have outwardly directed ground contacting cylindrical flanges interposed between the flame and the soil.