Project Director

Craddock, J. Hill

Department Examiner

Boyd, Jennifer; Klug, Hope


Dept. of Biological and Environmental Sciences


University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)


Cryphonectria parasitica is the ascomycete fungus species that causes chestnut blight disease. Symptoms of chestnut blight include bark cankers and eventually the death of American chestnut, Castanea dentata. However, not all Castanea species are equally affected by the disease, and some Asian species appear highly resistant. The OALDS and SSA in this study aim to assist in screening for resistance to C. parasitica within a year. We investigated the effect of C. parasitica on three North American species, one European species, four East Asian species of Castanea, and nine full-sib families of TACF backcross hybrids. Our study used both a small stem assay to measure canker lengths and an excised leaf disc assay to measure variation in tolerance to oxalic acid between the different Castanea species and hybrids. We inoculated 967 container-grown seedlings with C. parasitica strain EP155 and allowed cankers to develop for 12 weeks. Two measurements were recorded for each canker: orange zone and full length of necrosis, following the method of Cipollini et al. 2021. Excised leaf discs were soaked in a 50 mM solution of OA for 8 hours and then digitally imaged for measurement of browning with Image J, following the method of Harden 2023. Results show differences that vary by Castanea species in resistance to C. parasitica, as measured by orange zone in the SSA was significant between species. OA degradation (browning) did not have any statistically significant results. While the initial results seemed promising, the statistical analysis did not show any significance. These methods may continue to be practiced but should not fully replace the traditional method for C. parasitica resistance screening.


Thank you to Dr. Hill Craddock for guidance throughout the thesis process. Thank you to Dr. Jennifer Boyd and Dr. Hope Klug for agreeing to be on my examination committee. Thank you to the Fortwood Greenhouse crew, especially Dr. Paola Zannini. Thank you to Dr. Jared Westbrook and my friend Mert Sekmen for helping me with R. Thank you to the Tucker Foundation for supporting me through scholarships for the last year. Thank you to my friends Ronan Lanam, Joanna Maldanado, Sarah Singleton, Haleigh Sturman, and Rue Wooten for assisting me with hole punching leaves and emotional support throughout this project.


B. S.; An honors thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Bachelor of Science.




American chestnut--Disease and pest resistance--Genetic aspects; Chestnut blight; Cryphonectriaceae; Selection (Plant breeding)


chestnut; C. parasitica; C. dentata; blight; chestnut blight


Environmental Health and Protection

Document Type



vii, 38 leaves