Project Details:

Title:
Soybean tolerance to preplant-applied dicamba

Parent Project: This is the first year of this project.
Checkoff Organization:North Dakota Soybean Council
Categories:Agronomy, Crop management systems
Organization Project Code:NDSC 2023 Agr 12
Project Year:2023
Lead Principal Investigator:Greg Endres (North Dakota State University)
Co-Principal Investigators:
Keywords:

Information and Results

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Project Summary

There are a limited number of preplant (PP) burndown herbicides, available for soybean and other broadleaf row crops, that are effective on herbicide-resistant broadleaf weeds, provide initial soil residual, and are low cost. Low rates of dicamba fit this description but waiting periods between dicamba application and row crop planting generally restrict use of the herbicide, due to potential crop injury. Data from this study, which is within the scope of ND Soybean Council research priorities – Herbicide Resistance, will be shared with ND farmers and crop advisers to allow them to make decisions with this herbicide use strategy.

Project Objectives

1. Build a ND database that provides a reference for soybean growers to make decisions on use of pre-plant low-dose dicamba for burndown weed control while minimizing potential crop injury.
2. The database may also be used to potentially revise dicamba labels to allow use of this strategy in the future.

Project Deliverables

ND data will provide guidance on soybean tolerance when planted at short intervals following pre-plant applied dicamba at low rates.

Progress of Work

Updated November 30, 2022:
See attached file.

View uploaded report Word file

Final Project Results

Updated June 26, 2023:
Background and Objectives:

There are a limited number of preplant (PP) burndown herbicides, available for soybean, that are effective on herbicide-resistant broadleaf weeds, provide initial soil residual, and are low cost. Low rates of dicamba fit this description but waiting periods between dicamba application and soybean planting generally restrict use of the herbicide, due to potential crop injury. Questions regarding this strategy have been received by NDSU Extension crop specialists and researchers but NDSU data has not been available to provide recommendations.

Study objectives are to evaluate soybean plant growth and seed yield response based on timing of planting following application of preplant, low-dose soil rate of dicamba with or without water activation.

Outcome:
The two-year was conducted at three NDSU research sites: Carrington (irrigated); and Minot and Prosper (dryland). Four targeted treatments: 1) untreated and 2) treated (Clarity or generic dicamba preplant applied 4 fl oz product/A mid-May); non-Xtend tolerant soybean planted 3) <14 days after dicamba application and before rain or irrigation, and 4) >14 days after dicamba application and rain or irrigation >1”. Field data generated included soybean plant development (emergence, flower and maturity) dates, plant density and canopy, injury ratings 1-2, 3-4 and 6-8 weeks after plant emergence, and crop height 3-4 and 6-8 weeks after emergence, and seed yield.
Averaged across five site-years, soybean plant injury with the first planting date (2-7 days and <0.10” rain after dicamba application) ranged from 43-87%. Plant injury with the second planting date (16-20 days and 0.6-3.0” water following dicamba application) was 4-53%. Averaged across four site-years, plant density with dicamba treatments vs. untreated checks was reduced 0-68% with the first planting date and 0-27% with the second planting date. Averaged across two site-years, soybean seed yield from dicamba-treated soil was statistically similar to the untreated checks, but tended to decline with dicamba-treated soil.
In summary, non-Xtend tolerant soybean plant injury and reduction generally were not acceptable with the prior low-dose PP application of dicamba with limited waiting period for planting, especially with limited water before planting. Also, potential for loss of seed yield exists.
Benefits to ND soybean farmers:
This North Dakota study provides data for guidance to farmers and crop advisers on non-Xtend tolerant soybean tolerance when planted at short intervals following PP-applied dicamba at low rates.

Why the Research is Important to ND Soybean Farmers:

There are a limited number of preplant (PP) burndown herbicides, available for soybean, that are effective on herbicide-resistant broadleaf weeds, provide initial soil residual, and are low cost. Low rates of dicamba fit this description but waiting periods between dicamba application and soybean planting generally restrict use of the herbicide, due to potential crop injury. Study objectives are to evaluate soybean plant growth and seed yield response based on timing of planting following application of preplant, low-dose soil rate of dicamba with or without water activation.
Research Conducted:
The two-year was conducted at three NDSU research sites: Carrington (irrigated); and Minot and Prosper (dryland). Four targeted treatments:
1) untreated and 2) treated (Clarity or generic dicamba preplant applied 4 fl oz product/A mid-May); non-Xtend tolerant soybean planted 3) <14 days after dicamba application and before rain or irrigation, and 4) >14 days after dicamba application and rain or irrigation >1”.
Field data included soybean plant development (emergence, flower and maturity) dates, plant density and canopy, injury ratings 1-2, 3-4 and 6-8 weeks after plant emergence, and crop height 3-4 and 6-8 weeks after emergence, and seed yield.
Research Findings:
Averaged across five site-years, soybean plant injury with the first planting date (2-7 days and <0.10” rain after dicamba application) ranged from 43-87%. Plant injury with the second planting date (16-20 days and 0.6-3.0” water following dicamba application) was 4-53%. Averaged across four site-years, plant density with dicamba treatments vs. untreated checks was reduced 0-68% with the first planting date and 0-27% with the second planting date. Averaged across two site-years, soybean seed yield from dicamba-treated soil was statistically similar to the untreated checks, but tended to decline with dicamba-treated soil.
In summary, non-Xtend tolerant soybean plant injury and reduction generally were not acceptable with the prior low-dose PP application of dicamba with limited waiting period for planting, especially with limited water before planting. Also, potential for loss of seed yield exists.
Benefits/Recommendations:
This North Dakota study provides data for guidance to farmers and crop advisers on non-Xtend tolerant soybean tolerance when planted at short intervals following PP-applied dicamba at low rates.

Benefit to Soybean Farmers

If soybean will tolerate a low-dose pre-plant application of dicamba with limited waiting period for planting or after a significant rainfall, farmers will have another herbicide option to control herbicide-resistant broadleaf weeds including horseweed (marestail), kochia, pigweed species, and wild buckwheat.

Performance Metrics

Project Years

YearProject Title (each year)
2023Soybean tolerance to preplant-applied dicamba