People

Affiliations:
Administrative Director, Wisconsin Seed Potato Certification Program

Education:
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.

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.

It is an honor to work on potato, one of the world’s most important food crops. I’m originally from Ethiopia. After graduating, I served for over 10 years as a researcher at the Amhara Agricultural Research Institute, where I was responsible for designing and conducting both lab and field-based potato research. In fall 2023, I joined the Department of Plant Pathology as a graduate research assistant. I am co-advised by Professor Amanda Gevens and Emeritus Professor Caitilyn Allen. My Ph.D. research focuses on developing and advancing methods for effective management of potato diseases.

Because potatoes are propagated clonally, they are prone to tuber-transmitted diseases that inflict major yield losses. My research project centered on two key potato pathosystems: silver scurf and bacterial wilt. Silver scurf, caused by the fungal pathogen Helminthosporium solani, is a growing concern for potato growers in Wisconsin and beyond, affecting tuber quality, marketability, and storability. Diploid potatoes offer a rapid and powerful approach to resistance breeding. In close collaboration with Dr Jeff Endelman’s potato breeding and genetics program, we have developed a breeding experiment to screen diploid potato germplasm for resistance to silver scurf. Until we have resistant potato varieties, fungicide will be an essential component of silver scurf disease management. However, fungicides put selective pressure on pathogens, leading to the emergence of chemical-resistant strains. Previous Ph.D. students in Gevens’ lab have collected H. solani strains from Wisconsin. Building on this work, I will use genetic and molecular tools to identify the mutant fungal gene(s) responsible for fungicide resistance. Bacterial wilt, caused by Ralstonia solanacearum, is one of the world’s most destructive potato diseases. In the Allen lab, I investigated how different Ralstonia strains colonize potato tubers and optimized a rapid field detection method to ensure the production of clean seed tubers. We also showed that the potato cv. Granola has useful tolerance to bacterial wilt. Overall, my Ph.D. work aims to increase the sustainability and profitability of the potato industry through advanced disease management.

Olee is a Ph.D. student at the Townsend Lab (co-supervised by Dr. Phil Townsend and Dr. Amanda Gevens) researching the capacities of imaging spectroscopy for early disease detection in potatoes. She is interested in applying remote sensing technologies in the agricultural and conservation domains, in particular data analysis and imaging techniques for site-specific monitoring and decision support systems. During her master’s in Germany, she developed an open-source workflow that involves object-based image analysis and deep learning techniques to detect invasive species in grassland using UAV RGB imagery. Before joining the lab, Olee worked as a research scientist at the Max Planck Institute for Biogeochemistry and developed an R package (rtry) to facilitate the pre-processing of plant trait data.

I’m a PhD student in the department of Plant Pathology, co-advised by Dr. Amanda Gevens and Dr. Russ Groves (Entomology). I completed a Biology B.S. at UW-Madison and then a Plant Pathology M.S. at the University of Minnesota. My current project is focused on evaluating the historical performance of potato disease models in Wisconsin and then attempting to improve spray recommendations to growers in order to reduce costs, environmental impact, and the risk of fungicide resistance.

Grazi is a first-year PhD student in the Plant Pathology department co-advised by Dr. Amanda Gevens and Dr. Peter Digennaro and is interested in plant-microbe interactions and disease management. She will be investigating the interaction between Pratylenchus and Verticilium in the Potato Early Dying disease complex.