Volunteer castorbean (Ricinus communis L.) was most effectively controlled by preemergence application of 2-chloro-4,6-bis(isopropylamino)-s-triazine (propazine) at 1.1 to 2.2 kg/ha in grain sorghum (Sorghum bicolor (Moench) L.) and by 1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea (fluometuron) at 1.7 to 2.2 kg/ha in cotton (Gossypium hirsutum L.). Preplant applications of propazine were not as effective as preemergence treatments. Efficacy of soil-applied herbicides was greatest when 1 to 2 cm of rain occurred within 7 to 10 days after application. Effective postemergence treatments on castorbean seedlings with two to eight true leaves were 2-chloro-4(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) at 1.1 to 1.7 kg/ha, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) at 0.9 kg/ha, or 2,4-bis(isopropylamino)-6-(methylthio)-s-triazine (prometryne) at 0.9 kg/ha.