Project Details:

Best Management Practices in Soybeans for Managing Herbicide-Resistant Weeds in Western Kansas

Parent Project: This is the first year of this project.
Checkoff Organization:Kansas Soybean Commission
Categories:Weed control
Organization Project Code:1996
Project Year:2019
Lead Principal Investigator:Andrew Tucker (Fort Hays State University)
Co-Principal Investigators:
Vipan Kumar (Kansas State University)

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

Controlling herbicide-resistant (HR) Palmer amaranth and Kochia has historically been challenging for soybean producers. There are concerns with new herbicide-tolerant soybeans that although initially they may provide better control of these resistant weed species, however, long term we may put additional selection pressure on these weed species, which may allow for more resistant populations in the future. Other weed control strategies, that are not solely reliant on chemical weed control, need to be evaluated to develop integrated weed management programs. One of the most effective methods of weed control is the use of cultural control practices. This study will focus on the use of cultural control practices that would be easy to implement for soybean production.

It is well documented in research literature that if you increase plant-to-plant within crop competition there will be a reduction in undesirable weeds. To increase plant-to-plant competition in soybean, a producer can either increase seeding rates to increase competition in row or to decrease row spacing so that you have increased competition across the row. These types of studies have been done in traditional soybean production areas; however, they have not been done in western Kansas (west of Salina), under dryland environments.

Another weed control strategy is altering planting dates to give the crop a competitive advantage over weeds. Traditionally, soybeans are planted in May while double crop soybeans are planted in June. Delaying planting so that an extra flush of weeds can be controlled prior to planting soybean could help give soybeans a competitive advantage over those weed species. Research on evaluating soybean planting timing in western Kansas is lacking under dryland environments.

Historically, western Kansas has not been planted with near the acres of soybeans compared to the rest of the state, but there have been more acres planted in recent years. With better advancements in improved soybean genetics, we fully expect soybean production to increase in this region. Therefore, research-based information is needed on evaluating seeding rates, row spacing, and planting dates as components of integrated weed management (IWM) for the future success of those producers.

Project Objectives

1. Quantify the impact of row-spacing, time of planting, and seeding rates on glyphosate-resistant kochia and Palmer amaranth interference in soybean.
2. Determine the ultimate impact of those agronomic practices on soybean grain yields and quality in western Kansas.

Project Deliverables

This study falls under 1.A., as outlined by the Kansas Soybean Commission priority list. It also helps address some of the items listed in bold underneath item 1 (Breeding/Production/Environmental Programs), specifically regarding herbicide-­resistant weeds.

Progress of Work

Updated August 23, 2019:

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Updated September 17, 2019:

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Updated December 12, 2019:

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Final Project Results

Updated April 14, 2020:

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Benefit to Soybean Farmers

Results obtained through this research will help in developing integrated weed management systems for management of glyphosate-resistant kochia and Palmer amaranth in western Kansas. Information gained through this project will be shared with growers at field days and through extension publications. The overall goal of this research is to enhance Kansas soybean production by developing sustainable, environmental friendly, and economical weed control methods for herbicide-resistant weed populations.

Performance Metrics

Project Years