2021
Late Season Planted Cover Crop Tolerance to Soybean Herbicide
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Contributor/Checkoff:
North Dakota Soybean Council
Category:
Sustainable Production
Keywords:
Field management Nutrient managementSoil healthTillageYield trials
Parent Project:
Fall-Seeded Cover Crop Tolerance to Herbicides
Lead Principal Investigator:
Greg Endres, North Dakota State University
Co-Principal Investigators:
Project Code:
QSSB
Contributing Organization (Checkoff):
North Dakota Soybean Council
$14,700
Institution Funded:
North Dakota State University, Carrington Research Extension Center
$14,700
Brief Project Summary:

Cover crop usage is expanding due to benefits including reduction in soil erosion, weed suppression, and long-term improvement in soil productivity. A risk often overlooked is herbicide residual that can greatly reduce cover crop stands. The project goal is to document the tolerance of late-summer planted, cool-season cover crops following the normally timed application of soybean pre- and post-applied herbicides that have soil residual. This research will provide information to help soybean farmers successfully establish cover crops during late summer following soybean production.

Key Benefactors:
farmers, agronomists, applicators, extension specialists

Information And Results
Project Deliverables

Field data of cover crop tolerance to soybean herbicides will be compiled across several site-years (Fargo, 2016 and 2018-20; and Carrington REC, 2018-20) to generate a reference table published in the 2021 ND Weed Control Guide (NDSU Extension circular W253).

Final Project Results

Update:

View uploaded report Word file

Late-season planted cover crop tolerance to soybean herbicides

Why the research is important to ND soybean farmers:
The goal of this project is to build a NDSU database on late-season planted cover crop tolerance to early season applied soybean herbicides that have soil residues. This database will aid farmers and crop advisers as plans are made for adding cover crops into their cropping system.

Research conducted:
• Study was conducted at Carrington and Fargo during 2018-20 and included nine soybean herbicides and eight cover crops. Soil and post-emergence herbicides were applied at labeled rates and timings to soybean. The crop was mowed during August (seed-fill stages) and cover crops direct planted into the soybean stubble generally late August to early September. Visual evaluation of injury (biomass and/or stand reduction) began generally in late September (3-4 months after application of herbicides).

Research findings:
• All herbicides, except Liberty 280, injured cover crops. Barley, winter rye and field pea had the greatest tolerance to herbicides. Radish, turnip and rapeseed/canola generally had the least tolerance to herbicides. These herbicides potentially have high risk of injury for cover crops: Spartan=radish; Valor=radish, turnip and rapeseed/canola; Pursuit=flax, radish and turnip; and Flexstar=radish.
Benefits/Recommendations to ND soybean farmers and industry:
Research reports for individual trials were written and published in ‘ND Weed Control Research’ (www.ag.ndsu.edu/weeds/nd-weed-control-research). After completion of the field study, a table was published in ‘2021 ND Weed Control Guide’ as a reference for farmers and crops advisers when selecting cover crops for fall establishment following soybean. This database will aid in successful establishment of fall cover crops, which will reduce soil erosion, help manage soil moisture, increase long-term productivity of soil, plus other benefits.

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.