Year of Publication

2015

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Agriculture, Food and Environment

Department

Plant and Soil Sciences

First Advisor

Dr. David W. Williams

Abstract

Over the past couple of decades, there has been an increased interest in evaluating the environmental impacts of some turfgrass management practices. Two independent studies were conducted to examine different questions of turfgrass management impacts and sustainability. The first study examined the inputs and outputs of four different turfgrass home lawn systems. Two of these systems were designated as high maintenance and were composed of either a pure stand of Kentucky bluegrass (Poa pratensis L.) or tall fescue (Festuca arundinacea Schreb.). The other two systems were designated as low maintenance and were composed of either a pure stand of zoyisagrass (Zoysia japonica Steud.) or a mixed species endemic polystand. Soil samples were taken yearly from each plot and analyzed to determine total carbon content. Results from this study indicated carbon and nitrogen pools were not significantly different between the four systems but depth of sampling was significant.

For the second study, various formulated surfactants were examined to determine if they could enhance the fungicidal activity of a protein washed and concentrated from tobacco leaves (Nicotiana tabacum L.) that has been shown to be effective in combating foliar-infecting turfgrass diseases in previous studies. Since previous studies indicated the protein was most effective at high concentrations when applied every seven days, it was hypothesized a surfactant may allow the protein to perform as well for a longer period of time or at lower concentrations. The efficacy of the protein against a root infecting pathogen (Ophiosphaerella korrae) was also examined. Results from this study indicated a water based surfactant may allow solutions of the protein applied every 14 days to perform similarly to solutions of the protein alone applied every 7 days without a surfactant against Sclerotinia homoeocarpa F. T. Bennett. Also, the protein did appear to be somewhat effective in combating the root infecting pathogen tested in this study when applied on a schedule similar to current commercial fungicide recommendations.

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