Using a diverse mix of herbicides is an important strategy for maintaining effective weed control in corn and soybeans. In a Roundup Ready® system, this means integrating preemergence herbicides, sequential treatments and/or tank mix partners in the weed management program. Each year, the University of Minnesota Applied Weed Research team evaluates corn and soybean herbicide strategies for weed control, yield and returns. Results from the 2010 evaluations and diversification strategies can be accessed from the links to the right. These links will be updated with 2011 evaluations as soon as they are available.
While integrating a variety of herbicides is essential for maintaining effective weed control in the long run, many labels have application restrictions or groundwater advisories based on conditions that are common in Dakota County. University of Minnesota Extension-Dakota County, Dakota County Water Resources Department and Office of GIS collaborated to develop an interactive map that quickly identifies these sensitive areas of coarse-textured soils and shallow groundwater throughout rural Dakota County where restrictions or advisories may apply (shown in pink).
The on-line mapping tool shows groundwater sensitive areas (pink) based on coarse textured soil (sandy loams or loamy sands) and shallow groundwater (<30 feet) in Dakota County. Click on the map picture (below) to launch the interactive groundwater sensitivity map.
Herbicide groundwater application restriction and advisory reference
The tables (attached below) include herbicides from the 2010 and 2011 University of Minnesota corn and soybean weed control evaluations (see attachment below) that contain restrictions or advisories for groundwater (surface water not included).
Read the herbicide label, as it is the final authority.
Table 1 focuses on application
restrictions where herbicides
cannot be applied if certain conditions exist. Please note that restrictions based on “sand” don’t apply in Dakota County, since the County doesn’t have any soils that are classified strictly as “sand.” Groundwater advisories, however, would apply for all of these herbicides in Table 1. The application
restrictions that do apply in Dakota County include herbicides that contain alachlor (Micro-Tech and IntRRo) or acetochlor (Harness/Surpass & others, Surestart, Warrant).
Groundwater advisories generally state that the herbicide has properties that make it susceptible to leaching, particularly on coarse-textured or permeable soils where groundwater is shallow. Judicious use of these herbicides is strongly encouraged. Table 2 includes herbicides from the 2010 and 2011 weed control evaluations and Diversification Options that contain a groundwater advisory.
Even though it appears that every herbicide from the evaluations falls into one of these two lists, Table 3 is a summary of preemergence and postemergence corn and soybean herbicides that contain neither a groundwater restriction nor an advisory.
New chemistry for 2012 New herbicide chemistry is expected to be released in the US in 2012. The herbicide, pyroxasulfone, is expected to be sold under the trade names of Anthem, Fierce and Zidua. As of this writing, information on any groundwater restrictions or advisories is not available. This site will be updated as soon as the information is released.
For questions or comments about the interactive groundwater sensitivity map, please contact Phyllis Bongard at University of Minnesota Extension-Dakota County at 651-480-7757 or by e-mail at bonga028@umn.edu.
The information provided in this application is intended for educational purposes only and is not guaranteed in any way. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the University of Minnesota or Dakota County is implied. Information provided is not intended to replace actual local groundwater knowledge.
Soil texture classifications are derived from Soil Survey of Dakota County, 1983.
The depth to groundwater classification is based on a statistical analysis of well construction records and Department of Natural Resources observation data. It represents a 97.5% confidence level that the average water table has not been less than 30 feet deep during the period of record.