A three-year experiment was conducted near Scottsbluff, NE, to evaluate the selectivity of POST-applied imazethapyr for weed control in alfalfa, birdsfoot trefoil, cicer milkvetch, red clover, sainfoin, and yellow sweetclover. Imazethapyr injured all legumes 15 DAT. Imazethapyr also reduced the height of birdsfoot trefoil, cicer milkvetch, red clover, and yellow sweeclover 28 DAT. Legume first cutting yields were not reduced by imazethapyr and with alfalfa, birdsfoot trefoil, cicer milkvetch, and sainfoin, first cutting yields were increased by imazethapyr. Imazethapyr reduced weed biomass in all legume seedings. Weed biomass in new seedings of alfalfa was reduced more than that of the other legumes.

Sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} and RO-13-8895 {acetone-O-[d-2-[p-[(α,α,α-trifluoro-p-tolyl)-oxy]phenoxy]propionyl]oxime} were evaluated for quackgrass [Agropyron repens (L.) Beauv. ♯ AGRRE] control in ‘Norcen’ birdsfoot trefoil [Lotus corniculatus (L.)], ‘Monarch’ cicer milkvetch [Astragalus cicer (L.) Hook.], and ‘Arlington’ red clover [Trifolium pratense (L.)]. None of the herbicide treatments applied to weed-free legumes 3, 15, and 30 cm tall reduced crop ground cover or seed yield. Postemergence treatments of sethoxydim and RO-13-8895 applied to quackgrass in the one- to four-leaf stage, at rates from 0.56 to 1.1 kg ai/ha, gave control of 57 to 91% in September of the seedling year. Legumes in all postemergence herbicide-treated plots produced more seed than legumes in untreated plots, regardless of time of application. Sequential applications of sethoxydim, RO-13-8895, or fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid} at 0.14 plus 0.14 kg ai/ha gave more effective quackgrass control and greater legume ground cover than single applications at 0.28 kg ai/ha.