Activated carbon, applied over the seeded row in a band 2.5 cm wide, protected grasses from herbicides applied preemergence. The carbon rate required to protect the grasses varied with the grass species, the herbicide, and the rate of herbicide application. Most of the herbicides controlled weeds effectively between the rows. The herbicides usually controlled weeds less effectively within the carbon bands. Diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] was inactivated most readily by the carbon and showed the greatest safety margin on the crop species. Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], simazine [2-chloro-4,6-bis(ethylamino)-s-triazine], and terbacil (3-tert-butyl-5-chloro-6-methyluracil) required higher carbon rates for crop protection than diuron and showed a much narrower safety margin on crops. Use of this technique made possible the effective control of weeds during establishment and, subsequently, the production of high quality seed in the first seed crop.