Theses and Dissertations

ORCID

0000-0001-9935-3938

Issuing Body

Mississippi State University

Advisor

McCurdy, James D.

Committee Member

Tseng, Te-Ming P.

Committee Member

Stewart, Barry R.

Committee Member

Ferguson, Jason C.

Date of Degree

12-9-2022

Document Type

Graduate Thesis - Open Access

Major

Plant and Soil Science with Weed Science concentration

Degree Name

Master of Science (M.S.)

College

College of Agriculture and Life Sciences

Department

Department of Plant and Soil Sciences

Abstract

Annual bluegrass (Poa annua L.) is a problematic weed in turfgrass that has evolved resistance to twelve different herbicide sites of action. The mitotic-inhibiting herbicide pronamide has both pre- and post-emergence activity on susceptible annual bluegrass populations. Still, post-emergence activity may be compromised in some resistant populations due to the lack of root uptake or an unknown foliar resistance mechanism. Spray droplet size may affect foliar and soil deposition of pronamide, thus potentially explaining variation in population control or differential foliar and root uptake. Pronamide, flazasulfuron, and pronamide + flazasulfuron deposition were quantified on annual bluegrass as affected by spray-droplet size. The efficacy of these herbicide treatments in resistant (R) and susceptible (S) annual bluegrass populations was then evaluated with two droplet sizes (400 and 1000 μm). Absorption and translocation of pronamide were investigated in R and S populations following foliar-only and soil-only pronamide applications.

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