2018
Minimizing Carryover Herbicide Damage to NC Soybean Production
Category:
Sustainable Production
Keywords:
AgricultureCrop protectionHerbicide
Lead Principal Investigator:
Travis Gannon, North Carolina State University
Co-Principal Investigators:
Project Code:
17-033
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:

Herbicide carryover is its unintended persistence in the soil from one crop to the next and can occur in double-cropped or full-season system where soybeans follow wheat or corn. The goal of this project is to generate information on soybean sensitivity to metribuzin and on herbicide carryover in soybeans to address the current knowledge gap. This includes distinguishing Official Variety Trial soybean lines based on their response to metribuzin and other herbicide treatments and continuing studies to determine if different varieties have different physiological responses to residual herbicides. Results of this work will help growers make decisions about herbicide selection and application and soybean variety selection.

Key Benefactors:
farmers, agronomists, extension agents

Information And Results
Project Deliverables

Final Project Results

Soybean is grown in rotation with corn or winter wheat crops, which is an essential management practice to maintain soil health and maximize crop yields. Though herbicides are critical for weed management, there is potential for damage to soybean from carryover herbicide concentrations in the soil in a rotation system. Soybean is an important agricultural trade commodity and most of the 100 counties in North Carolina are involved in its production. Simultaneously, global climate forecast models predict drier summers and intensified drought conditions, which are factors that favor herbicide persistence and carryover. It is, therefore, critical to recognize problems that soybean production could encounter in the near future and find ways to minimize them.

Varying soil types were collected from the Mountain, Piedmont and Coastal regions of North Carolina and herbicide persistence experiments were conducted. As hypothesized, persistence was influenced by a combination of soil and herbicide physicochemical properties and this resulted in different carryover concentration estimates for each soil type. Environmental conditions such as soil temperature were shown to influence herbicide degradation and, consequently, carryover concentrations.

Differences in herbicide bioavailability among soil types may determine the potential of herbicide residue to damage sensitive crops in a carryover scenario. Therefore, dose-response studies are being conducted where a range of herbicide concentrations will be investigated to determine bioavailability across soils and the threshold for soybean damage in each soil to identify those of concern. It is important to examine the interrelationships that exist between herbicide degradation, soil adsorption and bioavailability since, collectively, these may influence the potential for carryover damage to crops.

North Carolina adapted soybean germplasm will be screened for variation in carryover herbicide sensitivity to provide recommendation to the growers. Growth, development, seed yield, biomass, leaf area and other physiological responses will be measured. It would also be imperative to study the influence of factors like water deficit or elevated temperatures on soybean response to carryover residues. Findings from these studies will be disseminated to NC soybean producers to help them optimize herbicide use programs, save on pesticide input costs and improve soybean yield.

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.