On returning to South Africa in 1984 she accepted a post as research officer in the Department of Biochemistry at the University of Cape Town. In this position, her primary objective was to establish a laboratory to study the molecular biology of histone proteins in sea urchins. In 1986 she moved to the University of Stellenbosch in the position of Research Officer and commenced research on wine killer yeasts. This study was completed at the end of 1988 when she moved to a position as lecturer and researcher in the Department of Microbiology and Biochemistry at the University of the Orange Free State, Bloemfontein.
During the following 10 years at the University of the Orange Free State, Wingfield developed a research program on the molecular taxonomy of fungi that cause diseases of forest plantation trees and directed the Forest Molecular Biology Co-operative Program. She is currently a Professor in the Department of Genetics at the University of Pretoria. She served the Faculty of Natural and Agricultural Science as deputy Dean and Acting Dean before her recent appointment as a Research Chair in Fungal Genomics, a prestigious appointment fully funded by the South African Department of Science and Technology (DST) and managed by the National Research Foundation (NRF).
The success of Wingfield’s research program has largely been as the result of working at the intersection of two research areas, namely molecular genetics and mycology. Her research group is often the first to apply new (particularly DNA based) techniques to answer questions regarding forest pathogens. These DNA based studies have proved to be more powerful at distinguishing between species than the traditional morphological methods. She and colleagues frequently, therefore, find that a particular pathogen under investigation has not previously been described. Her work has contributed strongly to a dramatic re-formulation of fungal taxonomic method (the New Code), which will substantially facilitate diagnostics of fungal plant pathogens.
Wingfield and her collaborators have produced molecular based phylogenies for many of the important tree pathogens. This has allowed her to analyse the species diversity of these fungi and has resulted in the description of novel fungal taxa including globally important tree pathogens. Her continuously expanding phylogenetic analyses allow her and her collaborators to interrogate questions regarding the evolution and spread of these fungi. These studies have served to highlight the fact that fungi have probably spread around the world more than might have been anticipated and despite significant geographical barriers.
Her research concerning the phylogenetic relationships between fungal pathogens of trees has promoted an increasing focus on the population genetics of tree pathogens. She has pursued questions relating to the centers of origin and diversity of many different tree pathogens. In many cases the results have been surprising and intriguing. Her research is sometimes frustrated by the fact that it is difficult (or impossible) to obtain appropriate isolates, but the global reach of her research group, and collaborations with large numbers of scientists in other parts of the world have allowed her and her students some unique research opportunities. There are incidences where results have been surprising and unexpected. In many cases, this is because there have not been previous studies on similar fungi. Overall, these population studies have added substantial depth to already interesting phylogenetic studies.
Wingfield's career includes very significant service as a mentor and teacher of young scientists. She has advised 45 honors students, 50 M.S. students, 54 Ph.D. students, and 19 post-doctoral scholars. She has taught numerous courses, eight of which have been at the University of Pretoria, and has continued to mentor students after she assumed her considerable administrative responsibilities as a Dean. She is an ad hoc or appointed editor for numerous scientific journals, and has served as an external examiner for theses in South Africa, Hong Kong, Australia and Namibia.
Wingfield is the past chair of the National Science and Technology Forum, the current Secretary General of the International Society of Plant Pathology, project leader in the DST, NRF Centre of Excellence in Tree Health Biotechnology, and serves as vice President of the Academy of Science of South Africa. She is an active member of numerous professional societies, task forces and working groups, and has played a key role in developing the molecular capabilities and expertise of the Forestry and Agricultural Biotechnology Institute and the Department of Genetics at the University of Pretoria. She is a Fellow of the Royal Society of South Africa, the Third World Academy of Science, and the African Academy of Science. She has received numerous other awards including the University of Pretoria Chancellors Award for Research, the Department of Science and Technology Distinguished Women in Science Award, the African Union Awards for Women in Science and the Christiaan Hendrik Persoon Medal which is the highest recognition awarded by the Southern African Society of Plant Pathology.