Date of Graduation

5-2017

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor/Mentor

Norsworthy, Jason K.

Committee Member

Barber, L. Tom

Second Committee Member

Gbur, Edward E. Jr.

Third Committee Member

Roberts, Trenton L.

Keywords

Biological sciences; Health and environmental sciences; Cereal rye; Cotton; Cover crop

Abstract

Weed-resistance management has become a topic of concern for modern agriculture. Cost related to herbicide usage has increased greatly due to evolution and proliferation of resistant weeds. Therefore, experiments were conducted to investigate the potential for using cover crops to suppress problematic weeds in cotton as well as chemical options for cover crop dessication, and sensitivity of cover crops to residual herbicides were evaluated. No differences were observed for cereal rye biomass production and consequently weed suppression between broadcast and drilled planting methods. Total amount of cover crop biomass was vital to effectively suppress weeds. Hence, of the cover crops evaluated, cereal rye proved to be superior to others for weed suppression due to its ability to produce large amounts of biomass. Cereal rye biomass production increased as the seeding rate increased, which led to greater weed suppression at a seeding rate of 112 kg ha-1 and 168 kg ha-1 compared to 56 kg ha-1. Control of cover crops prior to row crop planting can be difficult depending upon the cover crop species. Paraquat plus metribuzin and glufosinate adequately controlled the legume cover crops hairy vetch (Vicia villosa Roth) and Austrian winterpea (Lathryrus hirsutus L). Cereal cover crops were completely controlled by glyphosate alone. Rapeseed was not effectively controlled by any of the termination options evaluated. Based on a herbicide carryover trial from corn, residual herbicides commonly applied in corn that will be rotated to a cover crop and eventually cotton have low risk to interfere with the cover crop establishment and development after corn harvest.

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