Project Profile: Soybean Planting Date and Seeding Rate with Residual Herbicides

About Ryan DeWerff


project_profile_ryan_300px

From an early age, I was involved in our family’s corn/soybean farm in central Illinois. My interest in farming led me to pursue a degree in Crop Science at the University of Illinois Urbana-Champaign. I developed an interest in crop protection as an undergraduate when I had the opportunity to intern at the University of Illinois Integrated Pest Management Farm. I decided to continue my education at the University of Wisconsin–Madison, where I am currently working on my M.S. in Weed Science.

Contact Information:
Email Address: dewerff@wisc.edu
LinkedIn Profile


Project Title: Preemergence Residual Herbicides in Early-Planted and Low Seeding Rate Soybean Production

Background

Profitable soybean production is dependent upon adequate weed control. The development of weed species resistant to multiple herbicide modes of action, especially glyphosate, has challenged future weed management strategies in soybean. Moreover, changes in soybean production practices may reduce early-season crop competitiveness with weeds.

Planting later in the season at higher crop densities are two cultural strategies often used to control or suppress weeds. However, improvements in soybean genetics and rising seed costs have made these practices both agronomically and economically disadvantaged. As soybean growers begin to plant earlier in the growing season at reduced seeding rates, weed management may be more dependent on preemergence residual herbicides for adequate early-season control.


Objectives

  1. Evaluate the difference in postemergence weed control timing opportunities based on residual herbicide use following different planting dates.
  2. Establish the effectiveness of weed suppression from increased soybean densities in relation to preemergence herbicide control.

Approach

Objective 1:

A small plot field study will be conducted for two years near Arlington, WI. Soybeans will be planted in 30 inch row widths at three distinct dates spread in the range of April 20th to June 1st. After each planting date, a PRE application of a residual herbicide will be made to half of the plots. Postemergence weed control will consist of one glyphosate application the V1, V2, V4, or R1 soybean growth stages. Weed competition will be estimated by recording weed heights and population densities prior to each POST application and prior to soybean harvest. The effects of these different management practices will be evaluated for the influence to soybean yield.

Objective 2:

A small plot field study will be conducted over two years near Arlington, WI. Soybeans will be planted in 15 inch row widths at five distinct seeding rates, ranging from 60,000 seeds per acre to 190,000 seeds per acre. A preemergence application of a residual herbicide will be made to half of the plots within three days after planting. Postemergence applications will be made at the V4 soybean growth stage and will consist of a glyphosate program or a conventional herbicide program. Weed density, heights, and biomass will be assessed prior to the V4 POST herbicide application to characterize the early-season competitive environment. The effects of these different management practices will be evaluated for the influence to soybean yield.


The results of these two experiments will allow us to better understand the need and value of using preemergence residual herbicides in soybean production given current production practices and economic realities.


Presentations

  • 2013 North Central Weed Science Society meeting paper, “Increased Soybean Seeding Rates Versus Preemergence Herbicide Use” [PDF]
  • 2013 North Central Weed Science Society meeting poster, “Optimum Glyphosate Application Timing in Soybean as Influenced by Preemergence Residual Emergence Use Following Different Planting Dates” [PDF]
  • 2012 North Central Weed Science Society meeting poster [PDF]
  • 2012 North Central Weed Science Society meeting abstract [PDF]
Updated December 17, 2013