The objective of our survey was to evaluate the main weed species and management strategies adopted in Wisconsin cropping systems, particularly in corn and soybeans. The survey was conducted this winter during the 2018 Wisconsin Agronomy Update Meetings, held across the state. A total of 286 respondents, representing 54 counties, completed the survey. Herein we present a summary of the main survey results with the hope these may help stakeholders with management decisions.
Primary role of survey respondents
- Agronomists and farmers were the main participants in our survey.
Crops managed by survey respondents
- Corn, soybeans, alfalfa and wheat, respectively, are the main crops managed by survey respondents.
Adoption of tillage
- Tillage is a common practice in Wisconsin cropping systems according to survey respondents.
Most troublesome weeds
- Waterhemp, giant ragweed, common lambsquarters, and common ragweed, respectively, are considered the most troublesome weed species in Wisconsin cropping systems according to survey respondents.
Perceived presence of glyphosate-resistant weeds
- Waterhemp, giant ragweed, and horseweed (aka marestail) are the main weed species that have evolved resistance to glyphosate in Wisconsin according to survey respondents.
Perceived presence of weed(s) resistant to a herbicide site-of-action (SOA) other than glyphosate
- Several survey respondents reported the occurrence of ALS-resistant waterhemp and giant ragweed in Wisconsin.
Adoption of 1- vs 2-pass herbicide program in corn and soybeans
- A 1-pass herbicide program is still pretty common in Wisconsin, particularly in corn.
Anticipated adoption of auxin-tolerant crops such as Xtend (dicamba-tolerant) and Enlist (2,4-D tolerant) soybeans
- The adoption of auxin-tolerant crops in Wisconsin will likely not be as high as in central and southern states.
Adoption of or interest in cover crops
- Several survey respondents reported the adoption or expressed interest in adopting cover crops in Wisconsin.
Lessons learned from the survey
Wisconsin cropping systems are very diversified in terms of crop rotation and tillage is a common strategy. The combination of crop rotation and tillage has likely helped postpone the selection for herbicide-resistant weeds (when comparing to the situation in neighboring states). Thus, Wisconsin farmers, continue to do what you have been doing, it’s working!
Despite the “delayed” arrival, herbicide-resistant weeds are here to stay, and perhaps more widespread than some of us may think (check this presentation: 2018 Update on Herbicide Resistant Weeds in Wisconsin). In order to manage herbicide-resistant weeds, besides continuing to deploy integrated weed management strategies (e.g., crop rotations, tillage, cover crops), farmers may have to consider adjusting their herbicide programs. A two pass program may be necessary to control the troublesome weed species with extended emergence window we are dealing with (e.g., waterhemp, giant ragweed, common lambsquarters). The addition of herbicides with soil residual activity in herbicide programs will enhance the control of these troublesome weeds and reduce the selection pressure on POST-emergence herbicides.
The lower interest in auxin-tolerant crops in Wisconsin is likely due to i) high diversity of sensitive crops in the landscape and concerns with off-target movement, ii) relative small fields, reducing the practically for the adoption of the technology due to buffer restrictions, and iii) lower incidence of herbicide-resistant weeds thus less need for the technology (as compared to neighboring states).
There seems to be high interest in incorporating cover crops in Wisconsin cropping systems. When deciding how best to use cover crops, it is important to consider the ultimate goal. Is it to increase soil organic matter, increase nutrient availability to subsequent crops, reduce soil compaction, supply forage for livestock, and/or suppress weeds? Answering these questions will help identify the cover crops strategies that offer the best chance of success for meeting the goal.
The WiscWeeds program will be investigating the several topics addressed in this survey: i) distribution and management of herbicide-resistant weeds, ii) the fit of auxin-tolerant crops in Wisconsin, and iii) cover crop management strategies. To stay tuned about our research updates and field days this summer, follow us on Twitter @WiscWeeds.
Thanks to the survey respondents for valuable feedback and to Maxwel Oliveira for compiling the results.