Ariena H. C. van Bruggen obtained an M.Sc. degree in plant pathology from Wageningen University, the Netherlands, in 1976. She then joined the FAO in Ethiopia, where she set up a diagnostic clinic and did research on horticultural crops. She studied for a Ph.D. degree at Cornell University (1980–1985) under the guidance of P. A. Arneson. Her Ph.D. thesis was on the epidemiology of bean root rot caused by Rhizoctonia solani. van Bruggen was a post-doc for 1.5 years at the Boyce Thompson Institute in Ithaca, New York, where she worked on the effects of acid rain on fungicide wash-off and infection of potato by Alternaria solani and Phytophthora infestans. As an assistant professor in plant pathology at the University of California-Davis, she developed several innovative concepts and research approaches to solving disease problems in vegetable crops. First, she focused on lettuce corky root. She showed that corky root is caused by an oligotrophic, gram-negative bacterium named Rhizomonas suberifaciens. It was the first oligotrophic plant pathogen. Epidemiology and control of Rhizomonas were studied by Ph.D. student O’Brien. For her work on corky root, van Bruggen received the Jacob Eriksson Gold Medal and the Ciba Geigy Award from The American Phytopathological Society in 1993. In 1992, van Bruggen was promoted to associate professor in plant pathology at the University of California-Davis. The main emphasis of her research shifted to lettuce downy mildew. A forecasting system was developed with graduate students Scherm and Wu. The most important variables for infection were morning leaf wetness duration and afternoon humidity. Spore release and infection needed to occur on the same morning for infection to take place, a novel observation. The forecasting system was validated using GIS. Since 1990, van Bruggen’s research interests broadened to microbial ecology. Her program became more international, and in 1996, van Bruggen was promoted to full professor at the University of California-Davis. Ph.D. students Workneh and Grunwald et al. compared conventional and organic tomato production systems with respect to yield, nitrogen budget, soil characteristics, and tomato diseases. Severities of Phytophthora root rot and corky root on tomatoes were lower in organic than in conventional farms and the mechanisms for disease suppression were identified. They also studied microbial dynamics and organic matter decomposition after cover crop incorporation in relation to tomato damping-off. Fluctuations were noticed in soluble C and heterotrophic bacteria, which led to a new concept of soil health, reflected in the stability and resilience of microbial populations. As a result of her interest in sustainable agriculture, van Bruggen accepted a position as chair of the Biological Farming Systems Group at Wageningen University in 1999. The concept of soil health was further developed there. Bacterial populations were shown to oscillate along roots and over time after an impulse of organic material in soil. There was a succession of bacterial taxa within each wave rather than between waves. For the first time, it was shown that infections by root pathogens oscillated over time and in space! The oscillations were mimicked in simulation models by Ph.D. student Zelenev. Another new concept was developed about the cycling of microorganisms through ecosystems. van Bruggen and colleagues investigated the transitions of gfp-marked enteric pathogens and saprophytes through various ecological cycles.
Early on, van Bruggen realized that organic produce may be considered at risk of contamination because of the use of manure in organic farms. She launched a project in this area in 2003. The most notable result was that stability of E. coli O157:H7 populations around the decline curve and the predictability of the survival period were lower for conventional than for organic soils as shown by approximate entropy analysis by Ph.D. student Semenov. A simulation model for survival of E. coli O157:H7 in manure and soil mimicked observed oscillatory decline curves. Transmission of E. coli O157:H7 through the lettuce chain was modeled by Ph.D. student Franz, using probability distributions of pathogen prevalence and density in successive habitats. Physiological and molecular interactions between Salmonella and lettuce were investigated by Ph.D. student Klerks.
van Bruggen started her current position as professor in the Plant Pathology Department and Emerging Pathogens Institute in 2009. She continued her research on enteric pathogens, focusing on Salmonella. Together with two post-docs, she showed that Salmonella can enter tomato leaves and move to fruits through the phloem. She also followed her interest in the inverse relationship between biodiversity and invasibility of an ecosystem, in terms of survival of introduced enteric pathogens and spread of emerging plant diseases such as citrus black spot and huanglongbing.
van Bruggen has had an active international program. Many students from 12 developing countries carried out graduate research under her supervision. Most notable was that of Ph.D. student Mancini who investigated ecological, social, and economic impacts of IPM farmers’ field schools (FFS) in cotton production areas in India. As a consequence of this project, van Bruggen was asked to evaluate an IPM FFS project in South East Asia as a consultant for the FAO. She also evaluated an EU project on the implementation of quarantine regulations for the prevention of potato brown rot spread from Egypt, as a follow-up of Ph.D. research by Messiha. van Bruggen provided a range of service activities in plant pathology. Early on, she was a member of the Soilborne Pathogens and Epidemiology Committees of APS. She also served as a member of the Office of International Programs and became the liaison officer of APS to the International Society of Plant Pathology (ISPP). Within ISPP, she belonged to the Epidemiology Committee and served on the Jakob Eriksson Prize Fund Committee for many years. She organized a discussion session on International Research: Frontiers and Networking and a session on the New Threat of Late Blight at APS annual meetings. In 2008, she organized a symposium on Plant Disease Control in Organic Agriculture for the ICPP meeting. She was invited to give numerous oral presentations during meetings of various scientific societies worldwide. She was senior editor of APS PRESS and served on USDA grant panels and an NRC committee on the use of mycoherbicides to control illicit drugs.
