This publication is intended to serve as a practical reference and educational tool to be used in scouting corn and soybean fields for the presence of weeds, identifying whether a rescue treatment is necessary, and determining crop response to herbicide activity. This publication consists of two main sections. The first section includes information on weed identification, scouting and mapping procedures, and a discussion of economic thresholds for weeds. An identification key and color photographs of weeds common to Missouri are also included. The second section includes information on diagnosing herbicide injury. It discusses the various causes and conditions contributing to herbicide injury. It also includes a key to help determine which ...