- Created: Friday, 05 May 2017 09:16
North Dakota State University
The following information was provided by Lee Van Wychen, Director of Science Policy for Weed Science Society of America. Last year, the National and Regional Weed Science Societies conducted a survey of the most common and troublesome weeds in 26 different cropping systems and natural areas across the U.S. and Canada. Common weeds refer to are those weeds that are found to be most frequent, while troublesome weeds were those that were classified as most difficult to control (but may not be widespread). There were nearly 700 responses from weed science society members from 49 states, Puerto Rico, and eight Canadian provinces. The entire data set for 2015 is available for download at: http://wssa.net/wp-content/uploads/2015-Weed-Survey_final.xlsx
The lists below are based on an aggregation of their responses. Seven weeds appeared on both the “most troublesome” and “most common” lists in the United States, including common lambsquarters, waterhemp spp., foxtail spp., horseweed, kochia, morningglory spp, and Palmer amaranth. More than 650 weeds were mentioned at least once by survey respondents.
For Canada, the weed species in the Alberta, Saskatchewan, and Manitoba prairies tended to dominate the survey. The most troublesome weed species were from the genus Galium which includes cleavers (a.k.a. catchweed bedstraw) and false cleavers. The most common weed in Canada was wild buckwheat, which appeared on both the “common” and “troublesome” lists along with wild oat.
Amaranthus or pigweed species ranked high on the United States list. These were grouped into three main categories: Palmer amaranth, waterhemp, and redroot pigweed. However for Canada, there was no survey response that listed amaranth or waterhemp. Only redroot & smooth pigweed were listed by Canadian survey respondents.
Not surprisingly, almost every weed species listed above has confirmed resistance to at least one herbicide mechanism of action. Twelve representative crop/ecosystem categories (chart shown below) and listed the most troublesome weed and the most common weed for each, based on the number of times that species was listed by survey respondents for that crop/ecosystem category across both the U.S. and Canada.