an apparatus for controlling weeds and for treating crops planted in rows has a horizontal frame connected to a transverse , horizontal tool bar of a propelling vehicle by a parallelogram linkage which is maintained in gauged vertical relation to a crop row shoulder surface by a pair of gauge wheels affixed to the frame and rolling along the shoulder surface . a pair of disc blades which may be rotatable if desired are adjustably carried along either side of the crop row shoulder by shafts mounted in the clamps on the frame , the clamps permitting vertical , lateral , and angular positioning of the shafts and disc blades . a pair of spray nozzles may be carried from the rear end of the frame for positioning on either side of the crop row for application of herbicides and other chemicals .