ABSTRACT
Urea ammonium nitrogen can be used as a carrier for herbicides to provide growers with an option for the control of broadleaf weeds and spraying nitrogen fertilizer in one pass in winter wheat. Field studies (six in total) were seeded in the autumn of 2005, 2006 and 2007 at Exeter and Ridgetown, Ontario, Canada to determine if UAN can be used as a carrier for bromoxynil/MCPA, dichlorprop/2,4-D, dicamba/MCPA/mecoprop, or thifensulfuron/tribenuron applied postemergence (POST) at three application timings (approximately April 20, May 1 and May 10) in winter wheat. Winter wheat injury was as much as 4%, 5%, 4% and 5% for bromoxynil/MCPA, dichloroprop/2,4-D, dicamba/MCPA/ mecoprop or thifensulfuron/tribenuron, respectively. There was minimal visible winter wheat injury with treatments evaluated at 4 and 9 week after treatment. There was no significant reduction in winter wheat height or yield with herbicides evaluated at various application timings except for dicamba/MCPA/mecoprop treatment which reduced height 3% and yield 25% at May 10 compared with April 20 application timing. Herbicides carrier had no effect on winter wheat height or yield with evaluated herbicides. Based on this research there is potential for co-application of UAN and bromoxynil/MCPA, dichlorprop/2,4-D, dicamba/MCPA/mecoprop, or thifensulfuron/tribenuron applied (POST) early in the spring in winter wheat.