Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Reynolds, Daniel B.

Committee Member

Tseng, Te-Ming (Paul)

Committee Member

Catchot, Angus L., Jr.

Committee Member

Byrd, John D.

Committee Member

McCurdy, James D.

Date of Degree

12-13-2019

Document Type

Dissertation - Open Access

Major

Plant and Soil Sciences (Weed Science)

Degree Name

Doctor of Philosophy (Ph.D)

College

College of Agriculture and Life Sciences

Department

Department of Plant and Soil Sciences

Abstract

Sprayer hygiene and concerns of off-target injury from auxin herbicides have increased in recent years. New auxin tolerant crops have broadened the use patterns of these herbicides. Therefore, experiments were conducted across two locations in Mississippi in 2016, 2017, and 2018 to evaluate sprayer cleanout procedures to aid in dicamba removal. Standard sprayer cleanout consisted of a triple rinse of 10% tank volume, with either a tank cleaner or ammonia added in the second rinse. Samples collected in each rinse step for all treatments were applied to actively growing soybean and dicamba concentration quantified with HPLC. Experiments were conducted to determine if various tank cleaners and ammonia produce visual injury when applied to actively growing soybean and cotton alone and in conjunction with glyphosate. No tank cleaner caused visual injury nor affected plant heights or yield. Furthermore, experiments were conducted to evaluate tank cleaner effectiveness to remove dicamba utilizing the standard cleanout procedure, with increased rinse volumes, sequence of water and tank cleaner rinses, and cleanout effectiveness following durations of idle time from application to cleanout. No tank cleaner provided greater dicamba removal, with all cleaners performing the same as cleanouts utilizing water alone. Increasing rinse volumes did not positively affect dicamba removal compared to 10% rinse volumes. Multiple rinse steps utilizing a tank cleaner or altering the standard cleanout procedure utilizing a water-tank cleaner-water rinse sequence did not result in greater dicamba removal from contaminated sprayer systems. Finally, increases in time between contamination with dicamba and cleanout did not negatively influence dicamba removal using the standard cleanout procedure.

URI

https://hdl.handle.net/11668/16476

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