Principal Investigator

Amanda Gevens

Department Chair, Professor, and Extension Specialist


689 Russell Labs
1630 Linden Dr
Madison, WI 53706


Ph.D. Plant Pathology – Michigan State University
M.S. Plant Pathology – Purdue University


Research Interests:

My research program investigates the ecology of fungus and fungus-like plant pathogens for enhanced and integrated disease management.  Specifically, we investigate Phytophthora species pathogenic on potato and vegetable crops in field and storage.  My program conducts research on P. infestans, P. capsici, and P. erythroseptica to determine pathogen genotypes/races/clonal lineages, mating types, host range, virulence, survivability, and resistance to commonly utilized fungicides.  Improved understanding of pathogen characters has promptly influenced statewide recommendations for Phytophthora disease management in Wisconsin production of potatoes and vegetables.


A second program emphasis is on species distribution and occurrence of pathogenic Alternaria affecting potato.  Preliminary studies confirmed the presence of A. alternata in late season epidemics of early blight in northern Wisconsin.  Speciation of Alternaria throughout the production season at several regions of concentrated potato production in Wisconsin is being undertaken to further characterize the pathogen profile.  Additionally, sub-populations of Alternaria spp. collected from potatoes were partially resistant to the commonly-used fungicide active ingredient, azoxystrobin.  Mechanisms of fungicide resistance can differ between species.  As such, species determination may aid in regional or field-level tailoring of fungicide programs for enhanced disease control.  Early blight, caused by A. solani, is present every year in Wisconsin and can, if unmanaged, cause significant yield loss and reduction in tuber quality.  The importance and incidence of brown spot, caused by A. alternata, is poorly understood in Wisconsin at this time.  Our research addresses efficacy of novel fungicides and fungicide programs for more immediate application and support of grower needs, as well exploring pathogen ecological factors which may influence longer term disease management solutions.


A final area of research emphasis is the investigation of component inputs and development of integrated disease management programming in potato systems to reduce reliance upon soil fumigation in managing key soilborne diseases.  Our research approaches have included evaluation of disease control with reduced rates, alternative formulations, and in-line versus broadcast applications of soil fumigants such as chloropicrin and metam sodium to reduce quantity of soil-applied chemical.  Preliminary work suggests similar efficacy of some in-line-applied fumigants compared to broad-cast fumigants, offering a reduction in chemical use, and off-target and negative environmental and human health effects.  At-plant applications of nematicidal and fungicidal materials, potato vine removal, crop rotations, and cover crops have also been investigated with some positive preliminary results.  Soilborne diseases of potato such as potato early dying and common scab are especially challenging to manage and our research in this area of fumigation alternatives has been of great interest in regional industry and in academic circles.


As the UW-Extension Potato and Vegetable Pathologist, my program supports vegetable growers by providing research-based recommendations for controlling diseases during production and in storage.  My research program directly feeds into my extension work.


Along with a team of UW vegetable production scientists across departments, I extend knowledge through grower educational meetings, through our UW Vegetable Crop Updates Newsletter distributed online and by email, through direct email or phone consultations, and through one-on-one visits and discussion.  The connections between researchers and growers are strong in WI, with growers providing extensive intellectual and farm resources in contribution to world-class applied and basic agricultural research.

Academic Staff

Monica Yu Chen

Assistant Researcher

As an assistant researcher in Gevens Vegetable Pathology lab, my work has been focusing on potato late blight, one of the most devastating plant diseases in the world. My recent research work is to collect and genotype Phytophthora infestans isolates, which is the pathogen causing late blight on potatoes and tomatoes. Different P.infestans isolates migrate globally through infected plants transportation. In addition, P. infestans evolves fast through sexual reproduction and natural or fungicide-driven mutations. My projects are to monitor the population dynamics of P. infestans in the field and characterize the pathogen in mating types, host range, virulence, survivability, and resistance to commonly utilized fungicides, so that we can provide research-based advice to growers on late blight management. My goal is to translate basic research in the lab into applicable practice in the field to improve disease management.


Ph.D. Plant Pathology – University of Wisconsin-Madison
M.S. Genetics – Northeast Normal University
B.S. Biological Education – Jilin Normal University

Stephen Jordan

Outreach Specialist and Coordinator of Field and Storage Trials


PhD – Purdue University
MS – Michigan State University
BS – Purdue University

Students and post-docs

John Hammel

M.S. Student

As a Research Intern in the Gevens lab, John is involved in a great variety of interesting research projects, both in the field and in the lab.  Across Wisconsin, at numerous Agricultural Research Stations (namely at Hancock, WI) and at private farms, John has undertaken a primary support role in various field trials investigating fungicide efficacy and host resistance research.  Such projects allow John to work with a wide array of potato diseases, including early blight, late blight, silver scurf, common scab, Rhizoctonia rots, and Dickeya rots.  He has worked on similar disease control projects for other crops as well including cucurbits, onion, bean, and carrot.  Back on campus, John offers direct support to graduate research projects and provides general assistance across the lab and in greenhouses.  John is especially interested in evaluating the underlying economics of disease management, and he loves to share the results of the lab’s research with Wisconsin’s potato and vegetable growers.


B.S. Plant Pathology – University of Wisconsin-Madison, 2016

Shane Hansen

PhD student

I feel fortunate to have found the field of plant pathology. For me, it is a perfect blend of my love for plants, developed while growing up on a small potato farm, and an affinity for conducting research, discovered during my undergraduate studies at Brigham Young University-Idaho. Since graduating with my undergraduate degree in biology, I have worked for a plant pathologist conducting private agricultural research. I am thrilled that instead of an office and a cubicle I am able to spend my day in the field and in the lab. I enjoy interfacing with growers. I have deep respect for the challenge they face: finding the line between economic feasibility year-to-year and environmental sustainability over the decades. I am excited for the opportunity to study the pathogens that present a significant challenge to both of these goals.

Afona Irabor

PhD Student

I am from Benin City, Edo State in Southern Nigeria. I received a Bachelor of Agriculture degree in Crop Science from the University of Benin, Benin City. My interest in plant pathology started when I took a crop protection class in the third year of my undergraduate studies. In my final year, I conducted a research project focused on evaluating the fungicidal properties of crude extracts of Ocimum gratissimum L. against pathogens associated with eggplant (Solanum melongena L.). The knowledge and research experience gained during my undergraduate studies made me appreciate the need for more effective, sustainable and environmentally sound disease management strategies, and fueled my desire to pursue graduate studies and research in plant pathology.

I proceeded to earn a Master of Science degree in Agricultural Science with a concentration in Plant Science from Tennessee State University, Nashville, Tennessee. My master’s thesis research was focused on the biological control of Phytophthora blight of bell pepper and southern blight of tomato using selected bacterial endophytes.

I am thrilled to start my Ph.D. in Plant Pathology at the University of Wisconsin, and I look forward to being a part of the city of Madison. At UW-Madison, I hope to deepen my knowledge of the biology of plant pathogens, ecology and epidemiology of plant diseases, molecular plant-microbe interactions, plant disease resistance, and plant disease management, while enhancing my research, leadership and professional skills.

I enjoy reading, working out, watching movies and listening to music.

Olee Lam

PhD Student

Eric Larson

PhD student

Eric is a Ph.D candidate in the Department of Plant Pathology. His research focuses on exploring the relationship between Phytohpthora infestan’s gene expression and virulence on a potato host. Preliminary work has been done to quantify the loss of virulence on a potato host after continued maintenance of P. infestans cultures in an artificial media system. He will continue with RNAseq studies to explore whole transcriptome changes in P. infestans after it is continually challenged on a partially resistant potato host.

B.S. Botany – Oregon State University, 2014

Sofía Macchiavelli Girón

PhD student

I’m investigating pathogen detection, character, and host resistance for improved management of potato silver scurf caused by the fungus Helminthosporium solani. Silver scurf is a tuber blemish disease of great and increasing concern to the fresh and processing markets of the U. S. potato industry in the last decade. While blemish diseases affect the tuber periderm, the symptoms result in reduced appearance and quality impacting the marketability and processing of the crop.  Further, the disease can predispose tubers to heightened water loss and secondary pathogen infection in storage.  I’m also interested in improving our understanding of the relationship between H. solani and another economically important blemish disease, potato black dot caused by the fungus Colletotrichum coccodes. My research will generate basic and practical information, which will lend to the development of changes in industry practice to reduce these diseases.


B.S. Biology – University of Puerto Rico, Mayagüez, 2015

Tina Wu

PhD student

Tina is a PhD student in the Plant Pathology program and is co-advised by Dr. Erin Silva. Her project seeks to improve the management of tomato light blight under an organic system. Specifically, Tina is evaluating contemporary predominant clonal lineages of P. infestans for sensitivity to copper fungicides as compared to biopesticides. Her work also investigates the efficacy, mode of action, and implementation of biological products within a sustainable management program.


B.S. Microbiology and Genetics – Iowa State University

Lab Alumni

Sidrat Abdullah


Dr. Abdullah was a Post-Doc with a primary focus on the project titled ‘Late Blight Resistant Potato Germplasm for US Breeding Programs’ in collaboration with Dennis Halterman, Vegetable Crops Research Unit USDA, ARS. His work emphasizes the interaction between the RB gene and the corresponding IPI-O effector and understanding the molecular interactions between host R gene products and pathogen effectors. His research also focuses on testing the durability of known R genes by repeated passage of P. infestans through resistant hosts and diploid potato breeding to introduce new sources of resistance into late blight resistant germplasm.



Ph.D. Plant Science – South Dakota State University, Brookings SD, 2017
M.S. Plant Biotechnology (Molecular breeding and plant pathology) – Wageningen University, Wageningen, The Netherlands, 2012

Mary Appleman

PhD Student

Mary is an agronomist by training with experience in commercial potato production and research in central Wisconsin. Her current interest is understanding the ways in which data management and evolving disease detection tools can aid commercial growers in detecting, diagnosing, and managing disease in potato cropping systems. She pursued a PhD in Plant Pathology, co-advised by Dr. Russ Groves and Dr. Amanda Gevens, but left the program early to take a job in industry in the Netherlands.



B.S. Agronomy, University of Wisconsin

Julia Crane

Julia’s research focus is on applied microbial ecology and the management of fungal plant pathogens.  Julia worked in the Gevens lab as a postdoctoral research associate, where she focused on improving management of the potato blemish diseases silver scurf and black dot. Her research projects included developing pathogen detection methods, evaluating pathogen infection dynamics in the field and post-harvest, and investigating the genetic basis of varietal resistance to silver scurf.  While in the Gevens lab, Julia participated in extension activities such as by presenting at growers meetings. Julia also worked collaborated on research trials with members of the Wisconsin potato industry.

Julia currently works in the fungicide discovery group at Valent BioSciences LLC, where she coordinates greenhouse and field testing of early-stage biofungicide candidates.

Postdoc Plant Pathology – University of Wisconsin-Madison, 2014-15
Ph.D. Plant Pathology – Cornell University, 2013
B.S. Environmental Science & Policy, B.A. Anthropology – University of Maryland, College Park, 2007

Shunping Ding

PhD student

Shunping was a PhD student in the lab and her work focuses on the potato early blight complex (EBC) with the goal of mitigating loss in potato production by helping the potato industry to manage the disease in an economical and environmentally responsible manner. EBC is the combined diseases of early blight caused by Alternaria solani and brown spot caused by A. alternata, and Shunping’s research includes studying the pathogenicity of A. alternata, pathogen assemblage and epidemiology of the disease complex, interaction between the two pathogens, dispersal of the pathogens, and the detection of fungicide resistance in the pathogens.


Shunping is now a faculty member at Cal Poly San Louis Obispo and her web page can be viewed here:



Ph.D. in Plant Pathology, Department of Plant Pathology, University of Wisconsin Madison
M.Phil Microbiology – The University of Hong Kong, 2013
B.S. Biology – Henan University, 2010

Kenneth Frost

Ken’s research in the lab was focused on learning how the environment (e.g., temperature, humidity, or wind) influenced the occurrence and progression of several key foliar disease of carrot and onion. The goal of his work was to reduce disease impacts by using disease forecast models to inform the timing of fungicide applications.

Ph.D. Plant Pathology – University of Wisconsin-Madison, 2012
M.S. Plant Pathology – University of Wisconsin-Madison, 2004
B.S. Biochemistry – University of Wisconsin-Madison, 2000

Michelle Marks

PhD student

Michelle was a Ph.D. student in the Plant Pathology program.  Her work focuses on gaining a better understanding of the pathogen Pseudoperonospora humuli, causing hop downy mildew, as it exists in Wisconsin.  Some of Michelle’s objectives include testing WI pathogen populations for resistance to mefenoxam and using temperature data to predict the emergence of this systemic pathogen in the spring.  Overall, Michelle’s goal is to improve downy mildew disease management in Wisconsin hops.  Prior to joining the lab, Michelle spent a little over a year with the New York State Integrated Pest Management program working primarily with tree fruit IPM.  In her free time Michelle enjoys skiing, cross-stitch, and perusing antique stores.


B.S. Biology – State University of New York at Geneseo, 2011

Katie Morey Gold

PhD student

Katie was a PhD student in the Department of Plant Pathology and an MS student in the Biometry program in the Department of Statistics. Her research combines precision agriculture, remote sensing, and old school plant pathology to develop disease management tools. Katie’s work is the development of hyperspectral reflectance and imaging systems for use in potato as real time, aerial based, early disease detection systems, and the investigation of how these tools can be used to further understanding of metabolic changes that occur due to late blight infection before visual symptoms appear. Additionally, Katie uses spatio-temporal modeling to understand regional late blight disease dynamics and spore dispersal.


Ph.D. Plant Pathology – University of Wisconsin-Madison, ongoing
M.S. Biometry – University of Wisconsin-Madison, ongoing
B.S. Plant Science and Agricultural Science – Rutgers University, 2014