In Memoriam: Milton Schroth

October 31, 2023
A photo illustration of Milton Schroth

Milton Schroth

Milton Neil Schroth, a world-renowned plant pathologist and professor emeritus with more than three decades of service to UC Berkeley, died on October 11. He was 90. 

Schroth was born on June 25, 1933, and grew up in Southern California. While earning his BA in Botany from Pomona College, he also played football and was twice named to the All-Pacific Coast football team and later inducted into the Pomona-Pitzer Athletics Hall of Fame. Schroth continued his education at Berkeley, earning his PhD in 1961. He subsequently joined the College of Agriculture as a professor and Plant Pathologist with the Agricultural Experiment Station (AES).

During his tenure at Berkeley, Schroth made major contributions to research on bacterial diseases, systematics, and biocontrol. He published over 300 articles—half in major peer-reviewed journals including Nature, Phytopathology, and the Journal of Bacteriology—and found a way to cure crown galls, the tumor-like growths that certain bacterial pathogens cause on many trees, without harming healthy plant tissue. He also discovered the causes of several unknown diseases that affected papaya, sugar beets, and oak trees, and showed that E. coli could multiply rapidly in vegetables like lettuce in moist, warm conditions.

He is best known for defining a type of soil bacteria that colonize root systems and enhance plant growth, spearheading worldwide research into so-called “plant growth promoting rhizobacteria.” Schroth also identified a separate soil-born bacterium capable of producing an antibiotic that plant roots could absorb as a result of that work. Further inquiries into soil bacteria discovered that certain strains of internal bacteria within plants could aggravate or reduce the extent of a disease.

Schroth’s research often questioned concepts that were popular and widely accepted among academics. A paper he co-authored with graduate student David C. Sands ended the debate on whether there is a genetic difference between the typical soil bacterium Pseudomonas spp. and plant pathogenic pseudomonads. With the help of a medical microbiologist, Schroth reported that Pseudomonas aeruginosa—a drug-resistant bacterial pathogen associated with serious illnesses—could colonize both flowering plants and humans. 

During his career, Schroth served as chair of the Department of Plant Pathology, associate dean of the College of Natural Resources, assistant director of the AES, and assistant to the vice president for the University of California’s Division of Agriculture and Natural Resources. A lifelong advocate for democratizing scientific knowledge, Schroth took a groundbreaking step in curating a comprehensive repository of images and data of the world's most critical bacterial plant disease, which remains freely accessible to all at

To many of his students, Schroth is remembered as a dedicated educator and mentor. He established the "Graduate Excellence Award Fund" to support graduate students, the "Endowment for Early Career Professionals," and a student travel fund in the American Phytopathological Society (APS). He and his wife Nancy also established the "Schroth Faces of the Future Symposium," highlighting research from the best and brightest early career professionals in plant pathology.

“Milt Schroth was a true leader in the field of plant bacteriology,” said Steven Lindow, a professor emeritus in the Department of Plant and Microbial Biology. “ He made many seminal contributions in plant disease diagnosis and control through his work, which often challenged the common dogma in the field.” 

In addition to his impactful research in the field of plant pathology, Schroth made significant contributions to the College,” said David Ackerly, dean of Rausser College of Natural Resources. “We are thankful for his years of service through leadership in the College and in the UC Division of Agriculture and Natural Resources.”

Schroth was named a Fellow of the American Phytopathological Society in 1975 and received the Berkeley Citation in 1996 for his service and contributions to the University. 

He is survived by his wife of 64 years, Nancy; his two sons, Eric and Steven; his daughter Holly; and 5 grandchildren.