Date of Award

May 2020

Document Type


Degree Name

Doctor of Philosophy (PhD)


Division of Agriculture (SAFES)

Committee Member

Lambert B. McCarty

Committee Member

Virgil L. Quisenberry

Committee Member

William C. Bridges

Committee Member

Lewis R. Hubbard


Thatch is a layer of living and dead plant material (stems and roots) between turfgrass leaf tissue and the soil surface and if excessive, it can decrease playability of turf surfaces, increase mower scalping and disease pressure, reduce pesticide efficacy and water infiltration, plus harbor insects. In golf greens, mechanical, thus, disruptive practices such as vertical mowing, core cultivation, grooming, and topdressing are traditional agronomic methods for managing thatch/organic matter. Greenhouse and field experiments were conducted for two years to evaluate two commercial biostimulant products, Worm Power and Earth MAX, and their impact on thatch and rooting depth. Earth MAX had two rates, and was named Earth MAX (1) and Earth MAX (2). In addition to the biostimulants, two industry standards were included: blackstrap molasses and sand topdressing. Greenhouse studies yielded results showing Earth MAX (1), and sand topdressing provided an average of 16% greater root length than untreated control in year 1. However, in year 2, Worm Power provided 16% greater root length than untreated control. Earth MAX (1) provided 117% greater root mass than untreated control in year 2. No treatments provided greater root mass in Year 1. For both years, blackstrap molasses, Earth MAX (1), and Earth MAX (2) reduced thatch thickness by 30%, 24%, and 18% respectively, versus the untreated; however, no decrease in thatch weight by treatments was observed. Whereas, results from the two-year field trials, showed that all treatments, with the exception of blackstrap molasses, provided an average of 18% greater root length than untreated control. However, blackstrap molasses provided 146% greater root mass, and 9% less thatch weight over the two-year study when compared to the untreated control. For both years, blackstrap molasses, Earth MAX (1), and Earth MAX (2), and Worm Power reduced thatch thickness an average of 26% versus the untreated.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.