Dinitroaniline Herbicide Persistence in Soil in Southwestern Ontario

Under southwestern Ontario climatic conditions ethalfluralin (1.0 kg/ha) (N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-trifluoromethylbenzenamine) and dinitramine (0.55 kg/ha) (N 4 ,N 4 -diethyl-a,a,a-trifluoro-3,5-dinitro-toluene-2,4 diamine) applied preplant incorporated to Brookston clay loam dissipated to less than 20% of the original rate within 70 days after application. Trifluralin (1.0 kg/ha, preplant incorporated) (a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) was more presistent with about 40% remaining in an extractable form after 110 days. In Fox sandy loam trifluralin (2.0 kg/ha, preplant incorporated) and oryzalin (2.0 kg/ha, preemergence) (3,5-dinitro-N 4 ,N 4 -dipropylsulfanilamide) appeared to have similar persistence with about 30% residue remaining after 80 days.