Niklaus J. Grünwald was born and raised in Caracas, Venezuela. He entered the field of plant pathology after working as a grower and farm manager in Switzerland. He earned his B.S. degree in plant science from the University of California at Davis (UC Davis) in 1991, after transferring from the University of Zurich, and his Ph.D. degree under the supervision of Ariena H. C. van Bruggen from UC Davis in 1997. He pursued postdoctoral research with William E. Fry at Cornell University, joined the USDA Agricultural Research Service in Prosser, WA, as a research plant pathologist in 2001, and moved to his current position with the USDA ARS in Corvallis, OR, in 2004. He also holds a courtesy appointment in the Department of Botany and Plant Pathology, The Center for Genome Research and Bioinformatics, and the Molecular and Cellular Biology Research Programs at Oregon State University.
Grünwald’s current research program is focused on the biology and management of oomycete plant pathogens, with an emphasis on the sudden oak death pathogen Phytophthora ramorum. Throughout his career, he has maintained a multidisciplinary, comprehensive research approach in both basic and applied plant pathology that has resulted in more than 40 journal articles, reviews, and book chapters.
Grünwald is probably best known for several significant contributions that provided multiple novel insights into the biology of clade 1c Phytophthora species at their center of evolution. He conducted this work as a postdoctoral researcher under the supervision of Fry in Toluca, Mexico. As is typical for his work, he conducted research on several interrelated aspects using interdisciplinary approaches to describe the natural history, genetics, evolution, and management of this host–pathogen system. Grünwald described the population structure of Phytophthora infestans, the cause of potato late blight, at its center of coevolution with wild Solanum species, and developed disease management strategies adapted to the highland tropics. During this work, he also codiscovered Phytophthora ipomoeae Flier & Grünwald, a new species belonging to clade 1c, the clade that also includes P. infestans, P. phaseoli affecting lima bean, and P. mirabilis infecting Mirabilis jalapa. The host specificity and phylogenetic work provide further evidence that clade 1c Phytophthora species were derived from one common ancestor and evolved through a process of sympatric speciation in the central highlands of Mexico. This constitutes a textbook example of sympatric speciation of a plant pathogen. He also demonstrated that oospores survive the dry Toluca winter and can serve as a source of primary inoculum for initiation of epidemics. His efforts showed that the number of fungicide sprays applied in central Mexico for control of potato late blight could be significantly reduced from the current grower practice of 16–24 applications to only 4–8 applications. Grünwald led an effort to characterize resistance in Mexican potato germplasm. This work clearly indicates that rate-reducing resistance to potato late blight is durable and can have a significant impact on disease management. More recently, he evaluated the hypothesis that exposure to several oomycete fungicides would lead to selection and lower genotypic diversity of the population. This is the first body of work testing selection within a growing season on a sexual plant pathogen at its center of origin and demonstrating that directional selection toward resistance combined with a reduction in genetic diversity of the P. infestans population was observed for the fungicide metalaxyl. These results also emphasize the need for a continuing vigilance regarding further introductions of exotic strains of P. infestans into the United States.
Grünwald also has made significant contributions toward understanding the population genetics of plant pathogens in general. He improved the use of indices of diversity and outlined a theoretical framework for the scaling of genotypic diversity indices that corrects previous inadequate applications. He also demonstrated that the oomycete Aphanomyces euteiches is much more diverse genetically than was thought previously. He showed that genotypic diversity exists within a soil sample and that populations are significantly differentiated at the field and regional scales. More recently, he contributed to the discovery that Sclerotinia sclerotiorum shows high genetic diversity and significantly less clonality in the western United States, which is consistent either with genetic exchange and recombination or with large population size and high genetic variation, particularly compared with the clonality observed in the northeastern United States.
In addition to his impressive research accomplishments, Grünwald has been actively involved in service to APS and other agencies. He served or currently serves as a senior editor for Phytopathology, editor for Plant Pathology, senior editor for the APSnet Education Center, chair of the APS Epidemiology and Genetics Committees, and board member of the APS Office of International Programs (OIP) and the APS Office of Electronic Communication (OEC). He has been instrumental in initiating the translation of many plant disease lessons into Spanish, Portuguese, and more recently, Chinese. He also has organized two workshops on Analysis of Population Genetic Data. He has served as a panel member or reviewer for several national and international grant programs. Grünwald’s outstanding and innovative research contributions, which have improved our understanding of the population biology, evolution, and management of oomycete plant pathogens, and in particular, of Phytophthora infestans at its center of origin, make him a worthy recipient of this year’s Syngenta Award.