V.M. Badillo,^† Facultad de Agronomía, Universidad Central de Venezuela, Maracay, Aragua, Venezuela

Gracian T. Bara, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu‐Natal, Scottsville, Pietermaritzburg, South Africa

Homayoun Farahmand, Department of Horticultural Science, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran

Saichol Ketsa, Department of Horticulture, Faculty of Agriculture, Kasetsart University, Bangkok, and Thailand and Academy of Science, The Royal Society of Thailand, Dusit, Bangkok, Thailand

Mark D. Laing, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu‐Natal, Scottsville, Pietermaritzburg, South Africa

Freddy Leal, Facultad de Agronomía, Universidad Central de Venezuela, Maracay, Aragua, Venezuela.

Anish Malladi, Department of Horticulture, University of Georgia, Athens, GA, USA

Yossapol Palapol, Division of Agricultural Technology, Faculty of Science and Arts, Burapha University, Chanthaburi Campus, Thamai, Chanthaburi, Thailand

Robert E. Paull, Department of Tropical Plant and Soil Sciences, University of Hawaii at Manoa, HI, USA

Marc‐André Sparke, Department of Crop Science, Institute of Crop Physiology of Specialty Crops, University of Hohenheim, Stuttgart, Germany

Sven Verlinden, Department of Plant and Soil Sciences, West Virginia University, Morgantown, West Virginia, USA

Apinya Wisutiamonkul, Expert Centre of Innovative Agriculture, Thailand Institute of Scientific and Technological Research (TISTR), Khlong Luang, Pathum Thani, Thailand

Jens‐Norbert Wünsche, Department of Crop Science, Institute of Crop Physiology of Specialty Crops, University of Hohenheim, Stuttgart, Germany

Professor Theodore (Ted) DeJong has had a long and distinguished career in the broad area of whole tree physiology, with a particular emphasis on stone fruit species (peach, plum, and nectarine) that are relevant to California but widely grown in many areas of the world. This research has led to an enhanced understanding of tree growth and development, especially in areas relating to carbon balance in the tree, tree architecture, and the growth of the vegetative canopy, fruit, and roots. He has focused considerable effort on modeling these various processes. In addition, he has been a leader in an effective stone fruit breeding program.

Ted grew up in Ripon, CA and spent a good deal of time working on peach and almond farms in the area – he had loved farming ever since he was in grammar school. Ted attended Ripon Christian Schools and then Calvin College in Grand Rapids, Michigan. While in college he became interested in ecology and, because of his farming experience, was mainly interested in plant ecology. After college, in 1968, he married his wife Rose, and was scheduled to be drafted into the army and so he volunteered for admission to the Army Officer Candidate School. He graduated from OCS in late 1969, was commissioned, spent most of the next year in Fort Riley, Kansas, and went to Vietnam on September 11, 1970.

In September, 1971 he enrolled in an M.S. program at Fullerton State University in Plant Ecology. His mentor there was Dr Ted Haines and he was probably most influential in Ted subsequently choosing an academic career. In Jan, 1974 he enrolled in the Botany Ph.D. program at the University of California, Davis to continue studying Plant Ecology with Prof. Mike Barbour. His research was on the physiological ecology of Californian beach and dune species.

In January, 1978 he began a one‐year post‐doctoral fellowship at the Smithsonian Institution and did research on the physiological ecology of tidal marsh species. One year later, Ted returned to UC Davis on a Post‐Doctoral Fellowship in the Agronomy and Range Science Department with Prof. Don Phillips working on carbon and nitrogen assimilation interactions in legumes. At this time, he realized that he could have a rewarding career working in “applied environmental physiology of crop plants,” otherwise known as “crop physiology.”

He was appointed as a Lecturer/Pomologist/Co‐op Extension Specialist at the Kearney Agricultural Experiment Station and Extension Center (KAC) in the Pomology Department in April 1981. Thanks to good field staff support, he remained at Davis but conducted virtually all of his research and extension work at KAC for the first 25 years of his career. He was assigned to teach practical pomology courses at Davis and also co‐taught graduate level courses in plant/crop physiology. He enjoyed teaching and by the end of his career he was the main instructor for the pomology/tree crop physiology courses at UC Davis, even though he had never taken a formal pomology or horticulture course in his life.

His teaching had a lot of influence on his research because, early in his career, as he was teaching some of the pomological “dogma” to his students, he realized that some of it made little physiological/ecological sense. Furthermore, many of the current horticultural practices were often not backed up by sound scientific study, so some of these “dogmas” formed ideas for research. Such ideas led to investigating: the importance of leaf photosynthetic capacity in determining crop yield; fruit effects on photosynthesis; causes of the double sigmoid growth of stone fruit; carbohydrate and nitrogen allocation in fruit trees; carbohydrate storage in trees; causes of alternate bearing in fruit trees; physiological mechanisms involved in size‐controlling rootstocks; factors driving shoot growth in fruit trees; and interactions between fruit, shoot, and root growth in fruit trees.

Ted’s challenges to much of this “dogma” within the teaching framework have also been widely acknowledged internationally. New Zealand pomologist Dr Stuart Tustin states that “Ted’s incisive consideration of the science presented within the ISHS Fruit Section has always been highly valued by symposia participants, as has the friendly pugilism often arising in such discussions with Ted in such fora. He can always be relied upon to challenge concepts and interpretations and in such ways, contribute greatly to the scientific thinking and advances in fruit crop pomology and physiology.”

When he was a graduate student at UCD, he attended Prof. Robert Loomis’s crop ecology lectures for two years in a row and was fascinated with his crop modeling work. When Ted had his first sabbatical opportunity in 1987, he went to Wageningen University in the Netherlands to learn more about developments in that field of research. This was a watershed experience for his career. While there, he realized that plants can best be viewed as composite organisms made up of semi‐autonomous organs and the key to understanding/modeling whole plants was in understanding what drives the growth of those individual organs. This also led to development of a new model for explaining stone fruit growth patterns. After this sabbatical, much of his conceptually‐based research involved various aspects of crop modeling and the culmination of this work resulted in development of Functional–Structural Plant Models of peach and almond tree growth and physiology. The L‐Peach and L‐Almond models are still the most detailed and advanced virtual computer simulation models of fruit trees in existence today. They permitted the testing of, and/or demonstrated concepts behind, numerous fruit tree management practices that are commonly used in commercial fruit production.

Underpinning Ted’s work in crop modeling at the Department of Pomology (later Department of Plant Sciences) at UC Davis, was a range of research that focused on understanding tree physiological and orchard management factors that control the carbon balance/budgets of fruit and nut trees. His initial work focused on understanding the functioning and photosynthetic efficiencies of tree leaves and on understanding factors governing the horticultural efficiencies of orchard canopies. As he gained experience and understanding of factors controlling the “supply side” of the carbon balance equation, later studies focused on the “demand side” of the equation and the integration of both aspects into a functional understanding the how tree carbon budgets work. This “demand side” work focused on characterization and understanding factors governing flowering and fruit set, fruit growth, vegetative (leaf and shoot) growth, and root growth, and eventually involved numerous studies characterizing how rootstocks control shoot growth (see Horticultural Reviews 46:39–97 for this latter topic). Much of his intellectual stimulation for conducting the various aspects of this research came from an overall goal of developing an integrated understanding of fruit tree carbon budgets and growth through crop modeling. As indicated above, this led to the development of very sophisticated and complex functional–structural tree simulation models that are not only carbon budget models but also include integrated understanding of the architectural development of fruit trees.

French scientist, Dr Evelyn Costes, notes that: “with an an open‐minded vision Ted has combined skills in plant physiology, classical horticulture and fruit tree cultivation with new technologies involving computer programming and modelling. He thus has made an exceptional research contribution.”

Italian colleague, Dr Paolo Inglese, states that: “personally I gained a lot of inspiration from his papers on fruit growth and development and carbon partitioning in peach trees. I really learned a lot and, most interesting, it became easy to move from physiology to orchard management, understanding the basic factors of tree behavior. From this point of view, it is clear how strongly Ted DeJong influenced a large number of students, and younger scientists worldwide, with an impressive benefit for horticultural development, in terms of knowledge and, most importantly, field practices and orchard management. Indeed, it is worth noting that Ted’s research was always related to real problems experienced by stone fruit growers, particularly peach and almond growers. He is strongly dedicated to solving real problems through a clear scientific standpoint and this deserves our admiration. I have seen Ted giving lectures several times, but I have also seen him talking to growers in the field ready to learn and to share his knowledge as well as to understand the basic facts behind any particular horticultural technique.”

Pomology Farm Advisor, Rachel Elkins, summarizes Ted’s research achievements as follows: “Ted’s successful career reflects his thought process: creativity melded with logic and practicality. His upbringing on an almond farm in the Central Valley provided the necessary ‘grounding’ needed to ensure his research and extension contributions would impact commercial agriculture. His training in basic biology and ecology have provided the unique holistic perspective enabling him to think ‘out of the box’ about fundamental perennial crop physiology concepts. Those of us fortunate enough to take classes from him, study under him, and work with him have benefitted enormously. Indeed, the concept Ted has developed and demonstrated, that tree vigor and bearing at any given time of the year and life stage are fundamentally and primarily related to carbohydrate partitioning and balance has permanently influenced my own thought processes dealing with tree health issues in the field and in developing my own applied research. I am not alone; California tree crop advisors who have studied under, or worked with Ted, are well‐trained and confident in their understanding of fruit and nut crop physiology.”

In addition to this physiological research, he has also been the principle investigator on a prune breeding project since 1985. The Californian prune industry is currently dependent on a single cultivar. The goal of this project is the development of new prune/dried plum cultivars for the Californian industry that will increase orchard and processing efficiencies, spread the harvest season, and maintain or increase dried product quality. Ted holds 11 plant patents that cover the cultivars that have been developed in that program as well as collaborative development of size‐controlling rootstocks for peach and nectarine production.

In addition to his extensive research activities, Prof. DeJong also held a number of administrative positions at UC Davis, several of which coincided with challenging financial times and consequent organizational restructuring. He served on the College Research Committee and later the College Executive Committee, being the Chair during a College reorganization. In that role he also served on the Campus Senate Executive Council and on the Committee on Academic Planning and Budget Review for eight years, during several budget crises and strategic planning projects. From these experiences, he gained an understanding of the politics involved in campus and university decision making and became somewhat disillusioned in the process given the continuing decline in academic values and principles.

He was chair of the Pomology Department for eight years and was also a Vice‐Chair in the Plant Sciences Department for three years. He additionally chaired numerous other committees including the Pomology/Plant Sciences Department’s Field Facilities Committee for nearly 30 years, the College Air Shuttle Committee for 15 years and the Foundation Plant Services (FPS) Strawberry Advisory Committee for 15 years. He also served as a Senate representative on the Athletics Administrative Advisory Committee for more than six years as well as the Administrative Committee for the Transition of UC Davis athletics from Division II to Division I. He regards his main accomplishment in this latter service was to try to maintain the UC Davis vision of “student‐athlete” as the university moved to higher levels of competition.

Prof. DeJong’s scientific output has been prodigious over the past four decades. He has published over 200 manuscripts in refereed scientific journals. In addition, he has presented numerous talks at grower meetings and scientific conferences. He has also maintained a regular teaching program and mentored more than 50 Masters, Ph.D., and post‐doctoral students from the US and several foreign countries.

Fellow Pomologist, Prof. Greg Reighard, Clemson University, states: “His publication record is unmatched by his peers, while his research has been productive, relevant, well received and widely implemented by his clientele. In my opinion, he is the foremost authority on stone fruit whole tree physiology in the world. His advice is frequently solicited by his peers for his insight into problems related with fruit production. His prolific publication record and esteemed standing with research journals and professional societies are a testament to his abilities as a scholar and mentor.”

Prof. DeJong has been an active member of professional horticultural science societies for many years, contributing widely and consistently to their scientific programs during that time. In particular, he has supported many ISHS symposia and has, consequently, published in a number of Acta Horticulturae volumes (70 manuscripts in 23 Acta Horticulturae volumes). He has also been the convener of two ISHS symposia and is currently (2014–22) the Chair of the Section Pome and Stone Fruits.

His achievements have been recognized by a number of honors and awards, including: Smithsonian Post‐doctoral Fellow, 1979; Netherlands International Agriculture Center Fellowship, January–July, 1987; NATO Senior Guest Fellowship to Italy, July–August 1987; Fellow, American Society for Horticultural Science, Class of 2002; The National Peach Council Outstanding Peach Researcher Award, 2002; UC Davis Distinguished Professor, 2013; ISHS Lifetime Achievement Award for Outstanding Contributions to Research and Education in Fruit Crop Physiology, 2014; and ISHS Fellow, 2018.

Prof. DeJong observes that he was extremely fortunate to have had his career in a time that he and many of his colleagues, who were in the Pomology Department during this period, call the “golden age of pomology.” It was a time when there was ample financial and personnel support for research. He started with a department‐paid career staff research associate (SRA) and enough San Joaquin Valley/industry support to support another young SRA to plant and maintain tree crop research plots and to conduct numerous “exploratory” research projects to gain new perspectives on how fruit trees work. In addition, the university believed in, and supported, field research. Research was valued for the help that it provided growers rather than just how much funding it brought into the university. He observes that too often research is increasingly valued now more for the funding that it generates than the actual societal benefits derived from it. Field stations are run now more as “profit centers” than as research support enterprises.

He is deeply concerned that future pomology researchers will not be as successful as he was able to be, not because (he claims) he was especially talented, but because it will be impossible to access the practical, integrated experience that he was able to gain because of the support systems that were in place when he began his career. Because of early experiences, he was able to sustain funding mechanisms with long term horizons. It will be nearly impossible for young researchers to do the same now, when they are obligated to continually develop new projects and garner new funding for projects lasting only two to three years when working on complex, perennial crops.

Prof. DeJong and his wife have a family of three sons and ten grandchildren. Their eldest, Jason, is Professor of Geotechnical Engineering at UCD and the youngest, Matthew, is Professor of Structural Engineering at UC Berkeley. Their middle son, Michael, is a Fire‐fighter/Paramedic, also based in California. Although formally retired, Ted continues to do research and to contribute to the programs at UCD.

“I would like to close on a personal note and state that no one currently working in the field of stone fruit pomology is at Ted’s level as to what he has accomplished. There are some outstanding pomologists working throughout the world on stone fruit physiology, but I think Ted stands as tall or taller (no pun intended) than all of them at this stage of his career” – Dr Greg Reighard.