Canadian Journal of Plant Science (2017) 97, 891-901

M.G. Underwood, N. Soltani, D.C. Hooker, D.E. Robinson, J.P. Vink, C.J. Swanton and P.H. Sikkema (2017)
Benefit of tank mixing dicamba with glyphosate applied after emergence for weed control in dicamba- and glyphosate-resistant soybean
Canadian Journal of Plant Science 97 (5), 891-901
Abstract: Soybean resistant to both glyphosate and dicamba (Roundup Ready 2 Xtend™) has been developed by Monsanto Inc. and was commercially available for the first time in Canada in 2017. Six field trials were conducted over a 2-yr period (2014–2015) at three locations in southwestern Ontario to determine whether there is a benefit of including dicamba in a postemergence application of glyphosate at two application timings for the control of non-glyphosate-resistant weeds in Roundup Ready 2 Xtend™ soybean. Adding dicamba to glyphosate did not increase control of grass weed species. The tank mix of glyphosate and dicamba increased the control of redroot pigweed, common ragweed, common lambsquarters, and lady's thumb by as much as 14%, 3%, 7%, and 5%, respectively, at 8 weeks after the late-postemergence application. In general, broadleaf weed density and biomass collected 6 weeks after the late-postemergence application was reduced more with dicamba applied alone or together with glyphosate than when glyphosate was applied alone early postemergence. Due to the absence of a grass herbicide, weed interference with dicamba applied alone resulted in a yield loss of 30%–33% while treatments containing glyphosate resulted in a yield loss of only 3%–7%. The tank mix of glyphosate and dicamba improved broadleaf weed control, but it should not be applied alone due to poor control of grass weeds.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Clarence J. Swanton

Research topic(s) for pests/diseases/weeds:
pesticide resistance of pest
control - general

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Amaranthus retroflexus (weed)	Soybean (Glycine max)	Canada (east)
	Chenopodium album (weed)	Soybean (Glycine max)	Canada (east)
	Persicaria maculosa (weed)	Soybean (Glycine max)	Canada (east)
	Ambrosia artemisiifolia (weed)	Soybean (Glycine max)	Canada (east)