Studies were conducted in 2009 and 2010 under field and growth room conditions to determine a) cultivar tolerance of soybean to preemergence (PRE) applications of saflufenacil and b) the biologically effective rate of saflufenacil/dimethenamid-p for control of annual weeds applied PRE alone and prior to an in-crop application of glyphosate. Environmental conditions following application influenced the amount of soybean injury caused by saflufenacil, as well as the rate of saflufenacil/dimethenamid-p required for the control of annual weeds. Increased soybean injury from saflufenacil was observed when soybean emergence was delayed due to cool, wet conditions following planting. Injury decreased with time; however, sensitive soybean cultivars were unable to fully recover from early season injury under adverse environmental conditions. OAC Hanover was the most sensitive cultivar in both field and hydroponic testing. With adequate moisture and above average temperatures in 2010, between 224 and 374 g a.i. ha-1 of saflufenacil/dimethenamid-p was required for 80% control of common ragweed, common lambsquarters, and green foxtail 4 weeks after treatment (WAT). In contrast, with below average temperatures and excessive moisture in 2009, between 528 and 613 g a.i. ha-1 of saflufenacil/dimethenamid-p was necessary for the same level of weed control. Pigweed species were least affected by environmental conditions after application with only 245 g a.i. ha-1 required for 80% control 4 WAT in both years. Excellent full season control of all weed species was achieved with saflufenacil/dimethenamid-p applied PRE followed by glyphosate postemergence (POST). However, there was no difference in yield when saflufenacil/dimethenamid-p was followed by glyphosate POST compared to a single glyphosate POST application. / BASF Canada