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Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article discusses results of a study that examines the ammonium sulfate (AMS) and water hardness effect on glyphosate and glufosinate activity in corn in fields near Harrow and Ridgetown, Ontario. The study showed that water hardness has no effect on control of velvetleaf, common lambsquarters, redroot pigweed and annual grasses green foxtail and barnyardgrass. It concludes that AMS and water hardness have little benefit on glyphosate efficacy in corn.

Abstract: Five field trials were conducted over a three-year period (2006–2008) at two locations in southwestern Ontario to determine the length of time herbicides can remain in the spray tank prior to application in the field without impacting efficacy. Four pre-emergence and five post-emergence herbicides were mixed at their labelled rates and then applied in maize. Herbicides were either applied immediately after mixing in water, or after being held in solution for 1, 3 or 7 days. The most common weed species in the trials were Abutilon theophrasti, Amaranthus retroflexus, Ambrosia artemisiifolia, and Chenopodium album. Holding the herbicides in spray solution for up to 7 days did not affect the efficacy of the post-emergence herbicides in this study. Similarly, control of A. retroflexus and C. album with the pre-emergence herbicides was not affected holding the herbicides in spray solution for up to 7 days. However, control of A. theophrasti was decreased when isoxaflutole plus atrazine, dimethenamid plus dicamba/atrazine, or rimsulfuron plus S-metolachlor plus dicamba was in spray solution for more than 1 day. Nonetheless, there were no decreases in yield for any of the treatments evaluated. These data provide valuable information which growers can use to make informed decisions on whether to apply herbicides in non-ideal weather or to postpone application. The results of this study suggest that for the herbicides and weed species tested it is better to postpone application rather than make applications under non-ideal conditions. [Copyright &y& Elsevier]