Field experiments were conducted in 1996 and 1997 at five locations in southwestern Ontario to develop dose-response curves for SAN 1269H (SAN 835H plus dicamba) for weed control and crop tolerance in corn. SAN 1269H controlled wild buckwheat (Polygonum convolvulus L.), common ragweed (Ambrosia artemisiifolia L.), common lambsquarters (Chenopodium album L.), pigweeds (Amaranthus retroflexus L. and A. powellii S. Wats.), barnyardgrass [Echinochloa crus-galli (L.) Beauv.], and yellow foxtail [Setaria glauca (L.) Beauv.]. Biologically effective doses of SAN 1269H (BAS 662H) were 440, 430, 180, and 40 g/ha for yellow foxtail, barnyard grass, wild buckwheat, and common ragweed, respectively. The biologically effective dose (that which provides 90% reduction in weed dry matter) for common lambsquarters was 560 g/ha when SAN 1269H was applied preemergence (PRE) and 110 g/ha when applied postemergence (POST). When applied PRE at a rate of 420 g/ha, pigweed was controlled, whereas only 85 g/ha was required when applied POST. Grain yield increased with dose of SAN 1269H and did not differ with time of application. Temporary crop injury was observed when SAN 1269H was applied at the four- to six-leaf growth stage. Optimum corn yields were achieved with doses of 100 to 250 g/ha.

Field experiments were conducted in 1997 and 1998 near Rossville in northeast Kansas to evaluate control of imazethapyr-resistant common sunflower with selected herbicides in corn and soybean. In soybean, common sunflower control was unacceptable with imazethapyr, chlorimuron, CGA-277476, and cloransulam applied alone. Lactofen or acifluorfen applied with these herbicides slightly improved control, whereas glyphosate applied with them controlled more than 97% of common sunflower. All herbicides reduced common sunflower populations in the corn. The greatest reductions occurred when atrazine was applied with dicamba, 2,4-D, RPA 201772, or CGA-152005 plus primisulfuron. These herbicide combinations also stunted common sunflower that survived treatment. Several herbicide alternatives are available to control imazethapyr-resistant common sunflower in corn. However, glyphosate was the only herbicide that gave adequate control in soybean.