Date of Award


Document Type


Degree Name

Master of Science (MS)


Plant and Environmental Science

Committee Chair/Advisor

Dr. Guido Schnabel

Committee Member

Dr. Phillip M. Brannen

Committee Member

Dr. Hehe Wang


Monilinia fructicola (G. Winter) Honey is a fungal pathogen and is the causal agent of blossom blight, twig blight, green fruit rot, preharvest brown rot, and postharvest brown rot of peach (Prunus persica (L.) Batsch). Especially pre-and postharvest brown rot can have devastating economic impacts and negatively effects yield for peach growers throughout the southeastern United States. The most effective method for the control of pre- and postharvest brown rot is the application of synthetic fungicides during preharvest season. However, the consecutive use of fungicides with the same mode of action potentially give rise to resistance. This thesis focuses on the current resistance status of M. fructicola to methyl benzimidazole carbamate (MBC) and demethylation inhibitor (DMI) fungicides and the evaluation of polyoxin-D for brown rot control. Chapter 1 provides a snapshot of resistance to DMI fungicides for M. fructicola isolates collected between 2021 and 2022 from Alabama, Georgia, and South Carolina while also examining the mechanisms of resistance, namely the presence or absence of the genetic element Mona upstream MfCYP51. Chapter 2 examines the same set of M. fructicola isolates in Chapter 1 for resistance to MBC fungicides and describes nucleotide sequence analysis of the Tub2 gene in sensitive, low resistant and resistant isolates. Chapter 3 focuses on the preharvest application of polyoxin-D as a solo product or in combination with thyme oil or mineral oil for the control of brown rot.



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