Strategies for Reduced Herbicide Input and Herbicide Resistant Weed Control in Soybean
Sustainable Production
AgricultureCrop protectionHerbicide
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Kurt Vollmer, University of Maryland
Co-Principal Investigators:
Kurt Vollmer, University of Maryland
Project Code:
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:

The objective of this research is to evaluate herbicide options for management of large common ragweed plants and investigate the value of delaying cereal rye termination in order to reduce herbicide inputs. It expands knowledge of non-chemical strategies to help control plants with fewer herbicide options. In no-till systems, multiple herbicide applications are needed to control weeds at planting and throughout the growing season. And, many problem weeds are resistant to key herbicides. Options for integrated control need to be explored. Accumulation of cover crop biomass is often the key to suppression of summer annual weeds like common ragweed and Palmer amaranth.

Key Benefactors:
farmers, agronomists, Extension agents

Information And Results
Final Project Results

Project complete

View uploaded report Word file

View uploaded report 2 Word file

In no-till soybeans, multiple herbicide applications are needed to control weeds throughout the growing season. The presence of weeds with resistance to multiple herbicides, such as common ragweed, continue to drive weed management programs. In Maryland, populations of common ragweed have become resistant to many of the herbicides upon which farmers have historically relied upon for postemergence control such as glyphosate, FirstRate, and Reflex. Alternative options are available, but tend to be less effective when applied to plants exceeding 3 inches in height. Furthermore, with the continued development of herbicide-resistant weeds, there is a need to integrate non-chemical tactics with existing herbicide programs. This project evaluated potential "rescue treatments" for larger common ragweed and cereal rye cover crop management in order to reduce herbicide inputs.

The first study evaluated single and sequential applications of Liberty, Enlist One, and Reflex applied alone or in tank-mixes when applied to common ragweed greater than 4 inches tall. This year's data showed that sequential applications containing Liberty or Enlist One were needed to achieve maximum control of larger common ragweed compared to single applications.

The second study evaluated the effects of delaying cereal rye termination in combination with one-, two-, and three-pass herbicide programs. Results from this year showed that the effects of cover crop management were independent of herbicide program. Winter annual weed and giant foxtail control was greater when cereal rye termination was delayed, regardless of herbicides used or herbicide application timing. Henbit and yellow woodsorrel control improved 59% and 70%, respectively, when termination was delayed until at least 2 weeks before planting. Delaying cereal rye termination until planting improved annual bluegrass control 44% compared to terminating cereal 2 weeks before planting, and 76% compared to terminating cereal rye 4 weeks before planting. Terminating cereal rye at planting improved giant foxtail control 10% compared to terminating cereal rye 2 weeks before planting, and 16% compared to terminating cereal rye 4 weeks before planting. Preplant herbicides followed by one or two additional applications controlled giant foxtail better than preplant herbicides alone, regardless of whether or not a residual herbicide was used.

This year's data illustrates the importance of making timely herbicide applications and the benefit of incorporating non-chemical tactics into a weed management program. However, additional research is needed to confirm these results and identify consistent treatments.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.