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Theo Newbold

Understanding Drivers of Fungal Endophyte Community Composition and Diversity  



I am a plant pathologist interested in the biotic and abiotic factors that drive endophyte communities of agricultural systems. This means that I study fungi that live inside plant tissue, but who don't always cause disease. These exciting organisms play diverse roles within their hosts; from helping plants cope with environmental stress to helping them fight off herbivores and pathogens. These fungi may serve different roles in their hosts over time, including as saprobes, and pathogens. I want to know how factors, like management style and disease status, drive these fungal communities. 

Foundation for Food and Agriculture Fellow
2023 - 2026

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Photo by Becky Kirkland 2023

Equity and Justice

I am dedicated to making science more equitable, accessible and inclusive. As a transgender, blind, fat, and first generation college student my expeicn To help create new systems of support and implement structural change I have served on many academic and professional DEI committees,  authored educational resources, engaged in open discussion, and sought to be an advocate for my future, current, and past colleagues. 


I currently sit as a member of the Pennsylvania State University Department of Plant Pathology and Environmental Microbiology DEI Committee focused in internal department affairs (2023-2024). This past year I served as the chair for the American Phytopathological Society Committee for Diversity, Equity, and Inclusion (APS CDEI) as well as president for the Plant Pathology Association at the Pennsylvania State University (2022 - 2023). I have also previously served as the APS CDEI Vice Chair, sat on Oregon State University (OSU) Botany and Plant Pathology Departmental DEI committee and the OSU College of Agriculture' Climate, Inclusion, and Diversity Taskforce (2018 - 2022). 

Follow the links below to learn about initiatives I am involved in and how APS CDEI is working to change the faces of plant pathology. 


I am fascinated by endophytic fungi and drivers of their community composition and diversity. Fungal endophytes are fungi that grow asymptomatically inside plant tissues, and can include latent pathogens, commensalists, mutualists, and/or opportunistic saprobes (among others). I want to understand what factors, such an environment, host age and management style, drive community composition and diversity, especially as this relates to known pathogens.


Academic Experience

2021 - Present

The Pennsylvania State University 

PhD, Plant Pathology

Advised by: Kuldau, G.A. and Crandall, S.G.

I want to understand what factors drive fungal endophyte community composition and diversity in leaves of row crops, especially fungal pathogens.


Oregon State University 

M.S. Plant Pathology

Advised by: Mahaffee, W.

I sought to understand fitness costs associated with QoI/Strobilurin fungicide resistance in Erysiphe necator, causal agent of grapevine powdery mildew disease in Vitis spp. 

2017 - 2018

C.S.U. Monterey Bay

B.S. Ecological, Organismal, and  Evolutionary Biology

Advised by: Miles. T. 

I compared molecular detection tools for the root rot pathogen, Phytophthora cinnamomi in blueberry and avocado. 

Design Book


Newbold, C. L. (2021). Is Resistance Futile: Examining Fitness Costs Associated with QoI Resistance in E. necator. (Master's Thesis)

Stergiopoulos, I., Aoun, N., van Huynh, Q., Neill, T., Lowder, S.R., Newbold, C., Cooper, M.L., Ding, S., Moyer, M.M., Miles, T.D. and Oliver, C.L. (2022). Identification of Putative SDHI Target Site Mutations in the SDHB, SDHC, and SDHD Subunits of the Grape Powdery Mildew Pathogen Erysiphe necator. Plant Disease, 106(9), pp.2310-2320.

Featured In...

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Plant Health and Healthy Humans

September 21, 2020

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The Sting of Sizeism in the Scientific Workplace

Author: Carrie Arnold

June 6, 2022

Women in Ag Science

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