Canadian Journal of Plant Science (2007) 87, 175-182

J.D. Vyn, C.J. Swanton, S.E. Weaver and P.H. Sikkema (2007)
Control of herbicide-resistant common waterhemp (Amaranthus tuberculatus var. rudis) with pre- and post-emergence herbicides in soybean
Canadian Journal of Plant Science 87 (1), 175-182
Abstract: Common waterhemp was first identified in Ontario in 2002. Eight trials were conducted over a 3-yr period (2003-2005) at Cottam and Petrolia, Ontario to determine the efficacy of various preemergence and postemergence herbicides for the control of herbicide-resistant waterhemp in soybean [Glycine max (L.) Merr.]. Waterhemp was resistant to the acetolactate synthase-inhibiting herbicides at both locations and to the photosystem II-inhibiting herbicides at Petrolia; therefore, results varied by location. Results at Petrolia also varied across years. Waterhemp interference resulted in soybean yield losses of up to 73% in weedy versus weed-free checks. Preemergence-applied metolachlor, dimethenamid, and linuron provided greater than 80% control and metolachlor plus metribuzin 94% or greater control of waterhemp 70 d after emergence at both locations. Acifluorfen, fomesafen, imazamox plus fomesafen, and glyphosate applied postemergence resulted in 87% or greater waterhemp control 70 d after application at Cottam in 2003 and 2004 and at Petrolia in 2004; however, waterhemp control with these herbicides was only 60 to 66% at Petrolia in 2005 due to prolonged weed emergence. Multiple herbicide applications per season may be required for effective waterhemp control in soybean.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Full text of article
Database assignments for author(s): Clarence J. Swanton

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

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Amaranthus tuberculatus (weed)	Soybean (Glycine max)	Canada (east)