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Document Type

Campus-Only Access for Five (5) Years

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Plant Biology

Year Degree Awarded

2017

Month Degree Awarded

May

First Advisor

Geunhwa Jung

Second Advisor

Daniel Manter

Third Advisor

Dong Wang

Fourth Advisor

Robert Wick

Subject Categories

Agronomy and Crop Sciences

Abstract

Golf courses comprise 50 million acres in the United States of highly managed turf susceptible to abiotic and biotic stressors. A growing area of interest is utilizing microbes to improve plant growth, increase disease and stress tolerance, and reduce pathogens. In order to develop these new practices, we must gain an understanding of turfgrass microbial communities and how they are affected by management practices. We characterized bacteria, fungi, and nematodes on three golf courses: one organic, one with reduced inputs, and one conventional. We took samples from three management areas on each course representing different management intensities (roughs, fairways, and putting greens). This is the first study to our knowledge to use metagenomics to describe bacteria and fungi on all three management areas of golf courses. The conventional and hybrid putting green were most similar to one another in nematode and microbe community composition than to the roughs and fairways of their respective courses or of the organic putting green. The organic putting green differed markedly in the high number of beneficial bacterivore nematodes and low number of herbivore nematodes compared to the conventional and hybrid putting greens. Management intensity affected fungal but not bacterial abundance, diversity, and richness. Canonical correspondence analysis and multiple stepwise regression analyses revealed pH, phosphorous, and organic matter were positively related to increased herbivore nematodes and negatively related to increased bacterivore nematodes, however there was no separation of fungal or bacterial communities based on soil properties. Lastly, we investigated the abundance of bacteria, fungi, and specifically the turf pathogen Sclerotinia homoeocarpa in the soil and thatch of the three golf courses on the three management areas and determined that fungal abundance is always greater in the thatch. S. homoeocarpa abundance did not vary among management areas on the soil or thatch, suggesting the fungal inoculum is unaffected by different management intensities. The results of our study provide baseline data on the nematode, bacterial, and fungal communities on golf courses under different management intensities. The results will help in developing future research studies to examine how cultural practices can be used to increase turf health and decrease disease severity, optimizing biocontrol organism activity, and decreasing herbivore nematode populations while increasing beneficial bacterivores.

Available for download on Saturday, May 12, 2018

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