Committee Chair

Craddock, J. Hill

Committee Member

Gunasekera, Sumith; Barbosa, Jose

Department

Dept. of Biological and Environmental Sciences

College

College of Arts and Sciences

Publisher

University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)

Abstract

Phosphites, salts of phosphorous acid, are used to combat the devastating root-rot diseases of American chestnut (Castanea dentata) and other woody plants caused by the Oomycete Phytophthora cinnamomi. However, phosphite treatments may negatively affect the plant’s ability to form ectomycorrhizas, the mutualistic symbioses between tree roots and certain soil fungi, and the phosphites themselves may be phytotoxic at high doses. Container-grown chestnut seedlings were treated with six phosphite solutions ranging from 0.0g/l to 12g/l both with and without a spore inoculation of the ectomycorrhizal fungus Pisolithus tinctorius. Seedling survival, height, root collar diameter, and ectomycorrhizal colonization were measured during one growing season. Spore inoculation significantly improved seedling survival across all phosphite doses. Phosphite applications of 1.5 g/l (the lower boundary of the manufacturer’s recommendation) enhanced seedling growth and did not limit mycorrhiza formation significantly. Trees treated with highest doses of phosphite had lower survival, fewer mycorrhizas, and were significantly smaller.

Acknowledgments

I would like to thank Taylor Perkins, Jeff Briggs, Rick Fletcher, Joseph James, Steve Barilovitis, Adam Schwartz, David North, Jessica Dawes, Tim Barnhill, Chris Liveris, Elle Wood, and Kristen Stanfill for their help during this research. Without all of you this would have been more difficult. Thanks are extended to Cleary Chemical for donation of the phosphite. The undergraduate nursery assistants at the University of Tennessee at Chattanooga, the staff in the Department of Biological and Environmental Sciences at the University of Tennessee at Chattanooga were extremely helpful and deserve the best. Perhaps the most thanks is due to my major advisor, Dr. J. Hill Craddock and my committee members Dr. Jose Barbosa and Dr. Sumith Gunasekera. In closing, I would like to thank my grandmother, Dr. Ina Longway, my parents Ruth Longway and Richard Zachary, Jim and Sheila Jorgensen and their children, Dr. Woods and Judy Blake, my brother Joshua Jorgensen, my wife Mikayla Jorgensen and my children Vasher, Micah and Phoenix, for hanging in there with me through the good and the bad. My research was supported, in part, by the Summerfield Johnston Endowment for the Restoration of the American Chestnut, The American Chestnut Foundation, The Bettie J. Smith Family, and Dollywood.

Degree

M. S.; A thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Master of Science.

Date

12-2014

Subject

American chestnut

Keyword

American Chestnut; Pisolithus tinctorius; Ectomycorrhiza; Phosphite; Phytophthora cinnamomi;Castanea dentata

Document Type

Masters theses

DCMI Type

Text

Extent

xv, 67 leaves

Language

English

Rights

https://rightsstatements.org/page/InC/1.0/?language=en

License

http://creativecommons.org/licenses/by-nc-nd/3.0/

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