Field experiments were conducted to determine effects of adding 2.8 kg/ha (NH4)2SO4 and/or substituting BCH 81508 S for crop oil with sethoxydim applied to large crabgrass, corn, johnsongrass, and common bermudagrass. Adding (NH4)2SO4 did not affect control of johnsongrass or common bermudagrass but did increase control of large crabgrass and corn by 6 and 15%, respectively. Cora control was enhanced more by (NH4)2SO4 at lower sethoxydim rates. Substituting BCH 81508 S for crop oil increased seedling johnsongrass, large crabgrass, common bermudagrass, rhizome johnsongrass, and corn control by 7, 9, 9, 10, and 15%, respectively. A sethoxydim rate by spray adjuvant interaction was observed with seedling johnsongrass, common bermudagrass, and corn where response to BCH 81508 S decreased as sethoxydim rates increased. The effects of substituting BCH 81508 S for crop oil and adding (NH4)2SO4 were independent.

The effect of ammonium sulfate on absorption of 14C-sethoxydim applied alone and with bentazon was studied in large crabgrass. Adding ammonium sulfate to 14C-sethoxydim increased 14C absorption 6-fold at 0.5 h after application but did not affect the amount of 14C absorbed 1 or 4 h after application. Applying bentazon with 14C-sethoxydim reduced 14C absorption 26%. When 14C-sethoxydim was applied with bentazon and ammonium sulfate, 14C absorption and translocation were similar to those with 14C-sethoxydim alone.