Date of Graduation

12-2019

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor/Mentor

Jason K. Norsworthy

Committee Member

Lon T. Barber

Second Committee Member

Trenton L. Roberts

Third Committee Member

Edward E. Gbur

Fourth Committee Member

Michael J. Walsh

Keywords

herbicide resistance, weed management, narrow-windrow burning

Abstract

Today, most growers use chemical weed management programs; however, a sole reliance on herbicides will place more resistance selection pressure on the weeds to which the herbicide is being applied. As herbicide resistance continues to grow and rob growers of yield, alternative weed control options are being sought to create complex integrated weed management programs to prolong the use of effective herbicides. Harvest weed seed control (HWSC) is a non-chemical practice that has been widely adopted in Australia due to herbicide resistance problems. In most cases, herbicide-resistant weeds that survive applications of herbicides produce viable seed that pass through the combine during crop harvest. HWSC focuses on lowering the soil seedbank by targeting weed seeds that pass through a combine at harvest. Experiments were conducted at the University of Arkansas in 2014 and 2015 to test the efficacy of HWSC on weeds in a soybean production system. Palmer amaranth, which has been deemed the most troublesome weed in the U.S., retains better than 97% of its seed at crop maturity, making it a viable option for seed capture and destruction during harvest. The efficacy of narrow-windrow burning was tested on two small- and large-seeded grass and broadleaf weeds (Palmer amaranth, barnyardgrass, johnsongrass, and pitted morningglory). All seed exposed to narrow-windrow burning treatments were killed. These data suggest that integration of HWSC into current weed management programs in soybean will be a valuable asset to lowering the soil seedbank and ultimately lowering the resistance selection pressure that is placed on herbicides due to lower weed densities.

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