Published online by Cambridge University Press: 12 June 2017
The tolerance of four legume species to nitrofen (2,4-dichloro-phenyl-p-nitrophenyl ether), fluorodifen (p-nitrophenyl α,α,α-trifluoro-2-nitro-p-tolyl ether), and oxyfluorofen [2-chloro-1-(3-ethoxy-4-nitro-phenoxy)-4-(trifluoro-methyl)benzene] was investigated both pre- and postemergence in the greenhouse. Seedlings of species that emerged most rapidly seemed to be most tolerant to preemergence herbicide applications. There was no direct relationship between preemergence and postemergence tolerance. Oxyfluorfen was found to be at least 10 times as active as the other two herbicides both pre- and postemergence. Field experiments were conducted at two locations in Indiana to test the effect of method of application on the activity and selectivity of fluorodifen and oxyfluorfen on soybean [Glycine max (L.) Merr. ‘Wayne’] and greenbean (Phaseolus vulgaris L. ‘Spartan Arrow’). Crop injury and grass weed control were reduced by incorporation of the herbicides 8 cm deep in a silt loam. Method of application did not affect the activity of the herbicides on a sandy soil low in organic matter. Soybean was more tolerant than greenbean to both herbicides when applied preemergence but oxyfluorfen was far more active than fluorodifen on both crops.