Theses and Dissertations

Advisor

Byrd, John D.

Committee Member

Rushing, Jason B.

Committee Member

Russell, David P.

Committee Member

Ervin, Gary N.

Committee Member

Tseng, Te-Ming (Paul)

Date of Degree

12-12-2025

Original embargo terms

Immediate Worldwide Access

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

Studies were conducted in Oktibbeha and Clay Counties in Mississippi to determine the response of green antelopehorn milkweed and hemp dogbane to triclopyr and other auxin herbicides in non-cropland areas. These studies were conducted at four locations with well established populations for each species throughout 2020 to 2023, with applications repeated at each location the following year if populations persisted. Treatments included a high and low rate of each herbicide studied, with all four triclopyr formulations included for both species. Injury response data were collected two and four weeks after treatment and population density data were evaluated using individual stem counts within two 1-meter squares. For both species, all triclopyr treatments provided adequate control to manage the species as well as MezaVue. However, both species were not adequately controlled with the DuraCor treatments, and hemp dogbane was not controlled with the Method treatments. A third study was conducted both in the field and in the greenhouse in Oktibbeha County Mississippi to determine the effects that clipping of green antelopehorn milkweed at different growth stages has on its ability to regrow in that growing season. Milkweed establishment was not accomplished in the greenhouse and unable to be evaluated. In the field, stems were cut with scissors at each growth stage, vegetative, bud, bloom, and early pod, at either soil level or just below reproductive structure, depending on study. Those cut during pod stage, either soil level or below reproductive, were less likely to regrow than any other stage. This suggests that mowing applications made right after formation of pods may help to limit the size of green antelopehorn milkweed populations, while earlier cutting could prevent loss of milkweed populations in pollinator habitats. More work in the future could help integrate non-chemical forms of milkweed management.

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