Ten herbicides were applied preemergence to proso millet (Panicum miliaceum), three Amaranthus species, and Chenopodium album L. The herbicides were either incorporated or left on the soil surface and plots were either sprinkler or furrow irrigated. The phytotoxicity of some herbicides was increased by soil incorporation and/or sprinkler irrigation. Some were unaffected by method of irrigation, and others were not affected by incorporation. Grass and broadleaf weed control were affected differently by incorporation and irrigation. When incorporated with furrow irrigation, five herbicides developed weed control patterns indicating a movement similar to salt movement. A more complex pattern occurred with non-incorporated herbicides.