Abstract: An apparatus for applying herbicide to tall weeds which extend above a line formed by the upper reaches of desirable crops is disclosed. The apparatus includes a pair of hydraulic rams for elevating and lowering a rotatably mounted roller which has a covering of nap material such as nylon-dacron carpeting for facilitating the adherence of the herbicide thereto. A fluid pressure system or systems for controlling the flow rate of herbicide to the roller and for controlling the rotational speed of the roller is provided so that the herbicide application characteristics of the apparatus can be varied in accordance with the weed density and height conditions encountered. A wiper for spreading the herbicide and for foaming the herbicide prior to application to the weeds can also be included.