Theses and Dissertations

Issuing Body

Mississippi State University


Reynolds, Daniel B.

Committee Member

Irby, J. Trenton

Committee Member

Eubank, Thomas W.

Committee Member

Dodds, Darrin M.

Date of Degree


Document Type

Graduate Thesis - Open Access


Weed Science

Degree Name

Master of Science (M.S.)


College of Agriculture and Life Sciences


Department of Plant and Soil Sciences


Auxin resistant cropping systems will provide producers with an alternative option for weed management, but with this new technology also comes the concern of off target movement of dicamba and/or 2,4-D to susceptible crops. Research was conducted over multiple site years in order to determine the effect of soybean response to different application timings and rates of 2,4-D and dicamba. 2,4-D was applied at 1X (0.56 kg ae/ha), 1/4X, 1/16X, 1/64X, and 1/256X rates, and dicamba was applied in a separate study at 1X (0.56 kg ae/ha), 1/4X, 1/16X, 1/64X, 1/256 and 1/1024X. All rates were applied at the V3 and R1 growth stages. Greatest yield losses occurred from dicamba applied at the R1 growth stage. Additional studies were conducted to determine at which growth stage soybeans are most sensitive to 2,4-D and dicamba. Greatest yield losses occurred at the late vegetative and early reproductive growth stages for both herbicides.