Laurence (Larry) V. Madden
Laurence (Larry) V. Madden was born in Ashland, Pennsylvania. He received his B.S. degree in 1975, M.S. degree in 1977, and Ph.D. degree in 1980, all from The Pennsylvania State University. He joined the Department of Plant Pathology at The Ohio State University (Wooster) in 1980 as a senior researcher. He became a faculty member in 1983 and was promoted to professor in 1990.
Dr. Madden is widely recognized as a leading international authority on botanical epidemiology who has made numerous seminal research contributions that have substantially increased our understanding of epidemics. He pioneered the use of many modeling approaches to analyze, compare, and understand the spatial and temporal components of plant disease epidemics. He has used knowledge gained from these advances to predict the risk of disease outbreaks and rates of disease increase based on population-dynamic principles and to develop efficient disease-management strategies. His research has directly affected individuals around the world who work to quantify and understand plant epidemics.
Of great significance in his early work are the development and interpretation of flexible differential-equation-based nonlinear models for describing disease development in plant populations and the evaluation of proper statistical methods for estimating and comparing model parameters. Continuing the research to this day, he recently developed with colleagues a coupled differentialequation model that directly links the population dynamics of insect vectors with the temporal progression of plant viral diseases. Because of the high complexity of plant virus systems, involving interactions of plants, insect vectors, and viruses, developing a strategic model previously was considered too difficult. In this landmark contribution, the basic reproductive number (R0) for predicting invasion and persistence of plant viruses was derived heuristically and mathematically. He showed that there are profound differences in disease development for the four transmission classes of viruses with insect vectors (nonpersistent, semipersistent, circulative, and propagative). He and Frank van den Bosch recently extended this research by developing a model for any plant pathogen infecting annual crops that explicitly accounts for disease development within seasons and pathogen survival between seasons. A new R0 was derived that can be used to predict disease invasion and persistence for introduced pathogens.
Through Madden’s research, our understanding of the spatial component of plant epidemics has been dramatically increased. He has demonstrated the dynamic and predictable change of disease aggregation over time in fields and was the first to characterize this dynamic process using spatiotemporal autoregressive moving-average (STARIMA) models. Madden’s recent research on the spatial heterogeneity of plant disease incidence has altered how plant pathologists assess aggregation of incidence. By focusing on the small-scale properties of pattern, he and Gareth Hughes developed the “binary power law” to characterize the spatial heterogeneity of disease incidence and showed that diseased plants follow a beta-binomial distribution as a consequence of the binary power law. The research has shown that much of the previously published work on distributions of plant disease incidence was either misleading or incorrect. This pioneering research has led to new concepts of the spatiotemporal processes inherent in botanical epidemics. The work has also led to the development of revised methods of sampling for disease incidence; determining the effects of experimental treatments on disease incidence, through the innovative use of generalized linear and generalized linear mixed models; and predicting disease dynamics at multiple scales in a spatial hierarchy (such as leaves and plants).
For more than 15 years, Madden has been conducting groundbreaking research on rain-splash dispersal of plant pathogens. He has characterized the physics of entrainment of spores into splash droplets and the relations between properties of impacting raindrops and resulting trajectories of splash droplets, showed the short trajectories of droplets, demonstrated the pronounced effect of surface topography and plant canopy structure on the biophysical aspects of dispersal, and demonstrated that rains of extremely short duration are sufficient for spore dispersal and plant infection. Of great significance is his work showing that rain intensity, the fundamental summary parameter for rain, affects spore dispersal in more complicated ways than considered previously. In a recent fundamental contribution to biomathematics, he and colleagues developed a model for spore transport across a surface in relation to rain intensity, topography, and other factors.
Dr. Madden has dramatically improved our understanding of the relationship between disease intensity and yield loss at the plant population level and has given a sound set of statistical protocols for analyzing and modeling crop losses. Most recently, he showed how to link disease progress and spatial heterogeneity models to models for yield as a function of “time of individual plant infection” and implemented new methodology for validating crop loss and other epidemiological models.
Madden has always been able to combine basic research on the mathematical and statistical aspects of botanical epidemics with more applied studies to solve practical problems. His early disease forecasting model for tomato early blight is the original basis for TOMCAST, a system for tomato disease management that has resulted in annual savings of millions of dollars. His recent work on rain splash has shown how the proper use of straw mulch (or other ground cover) can greatly decrease the incidence of diseases caused by splash-dispersed spores. He also has conducted field and laboratory studies to either develop forecasting systems or predict the risk of disease under various conditions.
Madden’s research has been extremely productive. He has authored or coauthored more than 150 refereed papers, 24 book chapters, and one book and is in great demand as a lecturer nationally and internationally. Recently, he has taken a leading role in addressing the threat of bioterrorism to U.S. crops and making proposals for better response plans to attack.
Dr. Madden has a long history of distinguished service to his profession. He served as editor-in-chief of Phytopathology from 1991 to 1993 and was president of APS from 1996 to 1997. He has received many honors in recognition of his accomplishments. He received the Ciba-Geigy Award from APS, the Distinguished Senior Research Award from Ohio State’s College of Agriculture, and The Ohio State University Distinguished Scholar Award. He is an elected Fellow of three scientific societies.
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