Theses and Dissertations

ORCID

https://orcid.org/0009-0003-1055-5886

Advisor

Bond, Jason A.

Committee Member

Crow, Whitney

Committee Member

Allen, Thomas

Committee Member

Irby, Trent

Committee Member

Avila, Luis

Date of Degree

5-16-2025

Original embargo terms

Visible MSU Only 2 Years

Document Type

Dissertation - Campus Access Only

Major

Plant and Soil Science (Weed Science)

Degree Name

Doctor of Philosophy (Ph.D.)

College

College of Agriculture and Life Sciences

Department

Department of Plant and Soil Sciences

Abstract

Studies were conducted to evaluate the effectiveness of tiafenacil in controlling various sizes of Palmer amaranth, control of 7- and 25-cm Palmer amaranth with various herbicide formulations, Palmer amaranth control with tiafencail plus glyphosate with or without a prepackaged surfactant and different adjuvants, control of Palmer amaranth, barnyardgrass, and pitted morningglory with sequential applications of residual herbicides, different herbicides with or without sodium chlorate for preharvest desiccation of soybean, and different adjuvants mixed with paraquat, saflufenacil, and tiafenacil. Both rates of tiafenacil controlled 3- and10-cm Palmer amaranth >96% which was comparable to paraquat, but control declined following applications made to Palmer amaranth any larger. 2,4-D plus glufosinate, dicamba plus glyphosate and paraquat plus metribuzin provided >93% control of 7- and 25-cm Palmer amaranth. Tiafenacil’s ability to control Palmer amaranth decreased when applied without an adjuvant, even when applied with glyphosate containing a prepackaged surfactant. Paraquat plus metribuzin controlled Palmer amaranth >97% 7 DAT no matter the surfactant added. No difference in Palmer amaranth control was observed following two and three mode of action treatments. Dimethenamid-p provided comparable control to other preplant treatments when applied 14 DPP followed by an at planting application. No benefit in respect to soybean defoliation was observed from adding sodium chlorate to the mixture accept with the lower rate of saflufencil. Pooled across treatments NIP, NIS, and COC provided greatest soybean defoliation. These studies reiterated paraquat’s effectiveness in Mississippi row crop production. That said, these data show producers there are potentially other viable options for weed control and soybean desiccation in Mississippi should paraquat no longer be available.

Sponsorship (Optional)

Mississippi Soybean Promotion Board

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