Abstract: A plurality of spray chambers are mounted on a boom secured to a three-point trailer hitch of a tractor. Controlled herbicide spraying of the unwanted growth which occurs in the furrows between dikes in fields of strawberries, lettuce, corn, tomatoes, onions, and other crops is achieved. Each spray chamber includes two overlapping sections which are movable towards and away from each other against the bias of springs so that varying widths of furrows between adjacent dikes are accommodated. In addition, an entire spray chamber is laterally adjustable to accommodate varying distances between adjacent furrows as is encountered due to "blow outs" of dikes due to over-watering or storm conditions to cause partial collapse of a dike.