Date of Graduation

5-2017

Document Type

Thesis

Degree Name

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

Degree Level

Graduate

Department

Food Science

Advisor/Mentor

Norsworthy, Jason K.

Committee Member

Norman, Richard J.

Second Committee Member

Hardke, Jarrod T.

Third Committee Member

Scott, Robert C.

Fourth Committee Member

Gbur, Edward E. Jr.

Keywords

Biological sciences; Benzobicyclon; Hydrolysate; Rice flatsedge; Rice herbicide; Rice tolerance; Weedy rice

Abstract

A new herbicide site of action (SOA) is needed by rice (Oryza sativa L.) producers in the Midsouth for the control of problematic and herbicide-resistant weeds. Currently, six problematic weeds are relevant to Midsouthern rice producers because of resistance to at least one SOA, if not more. Gowan Company is in the process of commercializing benzobicyclon for use in Midsouthern rice systems. Benzobicyclon, a Group 27 post-flood herbicide, controls a broad spectrum of aquatics, broadleaves, grasses, and sedges, including those currently resistant to Group 2 herbicides. This will be the first 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide commercially available in US rice production. Since, benzobicyclon is still under development, it is important to evaluate this herbicide in a drill-seeded rice production system. Therefore, experiments were conducted across Arkansas to determine rice cultivar tolerance, weed spectrum controlled, rate optimization, compatible tank-mix partners, and rotational crop safety. It is recommended to apply benzobicyclon into a continuous flood system. Japonica cultivars exhibited excellent crop safety to benzobicyclon, while indica cultivars showed high levels of sensitivity to the herbicide. Benzobicyclon effectively controlled Amazon sprangletop (Leptochloa panicoides J. Presl), ducksalad (Heteranthera limosa Sw.), California arrowhead (Sagittaria latifolia Willd.), indica rice, hemp sesbania (Sesbania herbacea Mill.), northern jointvetch (Aeschynomene virginica L.), red sprangletop (Leptochloa chinensis L.), rice flatsedge (Cyperus iria L.), and smallflower umbrella sedge (Cyperus difformis L.). The efficacy and spectrum of control of benzobicyclon is increased when applied with tank-mix partners such as bispyribac, cyhalofop, halosulfuron, imazamox, penoxsulam, and propanil. Cotton, grain sorghum, soybean, and sunflower can safely be planted in rotation with a drill-seeded rice crop that has been treated with benzobicyclon post-flood without concerns of crop yield loss. The findings of this research suggest that benzobicyclon has a strong fit in midsouthern rice systems.

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