Date of Award

1989

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Plant, Enviromental and Soil Sciences

First Advisor

James F. Fontenot

Abstract

Fourteen experiments, conducted at varying times during an 8-year period from 1981 through 1988, were designed to investigate plant growth regulators (PGRs) for their potential benefits in the production and maintenance of warm season turfgrasses. Turfgrass species evaluated over the eight year period, but not necessarily every year, included: common bermudagrass (Cynodon dactylon L.), bahiagrass (Paspalum notatum Flugge), carpetgrass (Axonopus affinis Chase.), centipedegrass (Eremochloa ophiuroides (Munro) Hack.), St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze), and zoysiagrass (Zoysia japonica Steud.). The chemicals evaluated included: N-2,4-dimethyl-5-(trifluormethyl)-sulfonyl-aminophenylacetamide (mefluidide); a-(1-methylethyl)-a- (4-(trifluoromethoxy)-phenyl) -5-pyrimidenemethanol (flurprimidol); N- ((acetylamino)methyl) -2-chloro-N-(2,6-diethylphenyl)acetamide (amidochlor); N-(phosphonomethyl)glycine (glyphosate); 3-7-dichloro-8-quinoline-carboxylic acid (quinclorac); 2- (1-(ethotymine)-butyl) -5- (2-(ethylthio)-propyl) -3-hydroty-2-cyclohexene-1-one (sethoxydim); 2- ( ( ( ((4,6-dimethyl-2-pyrimidinyl)amino) carbonyl) amino) sulfonyl) benzoic acid (sulfometuron); b-(Cyclohexylmethylene)-a-(1,1-dimethylethyl)-1H-1,2,4-triazole(C.A.) (BAY RSW 0411); and (2- (4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl) -3-pyridinecarboxylic acid (imazapyr). Data collected included: turf injury, color, leaf growth reduction, leaf density reduction, and seedhead inhibition. This research has shown that most of the PGRs tested are effective in regulating the growth of one or more warm season turfgrass species. Sethoxydim and sulfometuron have shown species selectivity to centipedegrass. Bahiagrass seedheads were effectively suppressed with sequential applications of glyphosate and sethoxydim controlled seedheads in carpetgrass. Mefluidide privded the most consistent PGR effects with the species used. More research is needed to determine optimum rates and application timing for each turf species. Tank-mix combinations also need to be explored for improved efficacy.

Pages

79

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