In field studies conducted in 1971 through 1977 weed yields were higher in EPTC (S-ethyl dipropylthiocarbamate) and alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide]-treated areas as compared to handweeded plots. Weeds present in EPTC-and alachlortreated areas did not result in a significant field bean (Phaseolus vulgaris L. ‘Great Northern 59’) yield reduction as compared to hand-weeded plots. For every 1000 kg of dry weeds present in field beans there was a corresponding decrease in field bean yields of 208 kg/ha. Weed yields produced in plots treated with alachlor, dinitramine (N
4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine), EPTC, metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), and profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine] were significantly less when herbicides were incorporated with the rotary tiller as compared to incorporation with the spike-tooth harrow. Incorporation method was not as critical with butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine], with spike-tooth harrow incorporation of herbicides providing similar weed control to that obtained with the rotary tiller. Weed densities and yields were higher in plots seeded with field bean determinate variety ‘Great Northern 1140’ than in plots seeded with indeterminate variety ‘Tara’, when either EPTC or alachlor were applied preplant and incorporated. Neither field bean variety competed well with weeds when no herbicide was used.