UC Nursery and Floriculture Alliance
University of California
UC Nursery and Floriculture Alliance

Three retirements in nursery and floriculture programs

by Julie Newman

We bid farewell to three University of California Agriculture and Natural Resources (UC ANR) academic staff members who had focused programs in ornamental production — two farm advisors (Steven Tjosvold, James Bethke) and one extension specialist (Richard Evans). Their careers have advanced the commercial floriculture and nursery production industry with combined experience that stretched over 100 years!


Steven Tjosvold


Steven (Steve) Tjosvold concluded a 38-year career with UC ANR on June 28 as environmental horticulture farm advisor in Santa Cruz and Monterey counties. The emphasis of Tjosvold’s program was floriculture and nursery production, but he also worked with the turf and landscape industries and provided leadership for Santa Cruz County’s Master Gardner program. He is internationally respected in the scientific community and lauded by nursery growers for his years of research and extension activities contributing to the knowledge of the biology and management of Phytophthora ramorum (sudden oak death).

Tjosvold received an M.S. degree in environmental horticulture from UC Davis in 1980 and began his career with UC Cooperative Extension as a farm advisor intern in Alameda, Orange, and San Bernardino counties. Upon completion of his internship he joined the UC Cooperative Extension Santa Cruz County office in 1983 and developed a cross-county program with Monterey County.

Tjosvold’s early career focused on the management of nursery and landscape plant diseases (e.g., damping off, powdery mildew, Heterosporium leaf spot, rust, pitch canker, fusarium wilt) and insect problems (e.g., borers, thrips, blue gum psyllid, spider mites), as well as methods to improve water use and postharvest handling in nursery crops. In addition, Tjosvold helped to establish the use of scouting in ornamental production by working with other farm advisors to document effectiveness statewide. He was also one of the original founders of CORF, which eventually became UCNFA.

In the mid-1990s, many tanoaks and coast live oaks started dying in central and coastal California due to Phytophthora ramorum. Although this disease was previously only considered to be a problem in forests in North America, it began showing up in nurseries, including Santa Cruz County, where P. ramorum was officially detected on rhododendron plants in 2001. Quarantine regulations for this invasive species seriously impacted nursery growers. As a result, a critical focus of Tjosvold’s research and extension program was dedicated to understanding the biology of this pathogen and managing the spread of this disease, which helped to mitigate economic losses. Light brown apple moth — another invasive pest that economically impacted the nursery industry — also became an integral part of Tjosvold’s research and extension program. He was instrumental in developing monitoring methods, pheromone mating disruption, chemical control, as well as guidelines for managing this pest in nurseries.

During his career Tjosvold wrote or contributed to 94 scientific peer- reviewed publications and 234 industry publications. He served as editor/co-editor for UCNFA News; he also had a regular column (“Regional Report for Santa Cruz/Monterey Counties”) and contributed to numerous feature articles in UCNFA News and its predecessor, CORF News. He received many awards for his research and education efforts in Cooperative Extension, including the 2015 Western Extension Directors Association Award of Excellence for contributions to a team effort that addressed sudden oak death, 2012 California Association of Nurseries and Garden Center Award for Outstanding Research, 2008 Western Extension Directors’ Award of Excellence for contributions to a team effort of the Farm Water Quality Planning Project, UC ANR Distinguished Service Award for Outstanding Team Work (1997,2004, 2006), and the 2004 UC ANR Distinguished Service Award for Outstanding Extension.

As an emeritus, Tjosvold plans to launch a blog for UCNFA that will help to replace the loss of the newsletter due to retirements, and he will be available locally for focused educational projects and consultation. He is avid about fly fishing and hiking — he hopes to do lots more of it in the future.


James Bethke


James (Jim) Bethke retired last January, wrapping up a distinguished 37-year career with UC —  12+ years with UC ANR and 25 years with the Department of Entomology, UC Riverside. He is highly regarded for his expertise in the integrated pest management of pests of commercial floriculture and nursery crops.

Bethke grew up in Milwaukee, WI and showed an early interest in the insect world. His youth pastimes were turning over boards and rocks in yards and checking outdoor lights for new and interesting bugs. He collected jars full of insect specimens to study at home. 

Bethke received an M.S. degree in entomology in 1985 from UC Riverside. He worked as an undergraduate lab assistant and as a graduate research assistant for Dr. Michael Parrella on leafminer pests on ornamental crops. Upon graduation, he continued working in the Department of Entomology as a staff research associate in Dr. Richard Redak’s lab, focusing on research involving pest management of commercial floricultural and ornamental plants and supervising other lab staff.

In July 2005, Bethke joined the UC Cooperative Extension San Diego County office as the floriculture and nursery farm advisor, initially as a split appointment with the entomology department at UC Riverside. His extension program in both San Diego and Riverside counties continued to emphasize the integrated pest management of major pests of floriculture and nursery production. Bethke was highly active in helping the ornamental production industry address the serious impacts of invasive pests through research and extension, as well as collaboration with regulators, growers, and other scientists on advisory committees that set policy on invasive pests (e.g., Diaprepes root weevil, European pepper moth, goldspotted oak borer, light brown apple moth, polyphagous shot hole borer, Q-biotype whitefly). In addition, Bethke took the reins as UC Cooperative Extension, San Diego county director in 2012.

During his career, Bethke has written or contributed to over 800 publications which include 62 peer-reviewed publications (39 in scholarly journal articles, 16 of which were senior author publications). He was a regular contributor to UCNFA News with two columns: “Insect Hot Topics” (which focused on new and invasive pests) and “Regional Report for San Diego/Riverside Counties,” along with writing feature articles and contributing to the “CDFA Nursery Advisory Report.” He has been a frequently invited speaker had has given over 600 presentations. His research and education efforts in Cooperative Extension have been recognized by UC ANR and the nursery and agricultural industries with significant awards, including the 2014 California Association of Nurseries and Garden Centers Outstanding Research Award, 2013 California Association of Pest Control Advisers Outstanding Contribution to Agriculture, 2013 San Diego County Flower and Plant Association Outstanding Person of the Year Award, 2011 San Diego County Agricultural Commission Certificate of Excellence, and the 2011 UC ANR Outstanding New Academic Distinguished Service Award.

Bethke is a member of the Entomological Society of America (ESA), Entomological Association of Southern California, Pesticide Applicators Professional Association (PAPA), American Society of Horticultural Science (ASHS), and an affiliate member of the San Diego County Flower and Plant Association and the California Association of Pest Control Advisers (CAPCA). He is also the Science Advisor to the Center for Applied Horticulture Research and for the California Citrus Nursery Board.

Bethke plans to spend considerable time outdoors during his retirement fishing, camping, hiking and collecting more specimens for his vast collection of insects and other arthropods.


Richard Evans


Richard Evans retired June 30 after 32 years of service as Cooperative Extension specialist in nursery crop production at UC Davis.  He received his PhD in Plant Physiology at UC Davis and shortly thereafter joined the department of Environmental Horticulture (which is now part of the department of Plant Sciences) in 1986. In addition to his responsibilities as extension specialist, Evans also regularly taught two undergraduate courses (“Management of Container Media,” “Principles and Practices of Plant Propagation”) and one graduate course (“Principles of Horticulture and Agronomy”), along with supervising many graduate students over the years.

Evans’s research has focused primarily on identifying nutrient and water requirements of greenhouse and nursery crops. His research group determined the nitrogen, phosphorus, potassium, and water uptake of nearly 100 ornamental crops, with the goal of providing commercial growers with information needed to use fertilizer and water more efficiently. Among the significant findings arising from that work was a description of the spatial and temporal separation of nitrogen assimilation in greenhouse rose crops. Evans’s work with students led to the discovery that rose nitrogen uptake is highest when shoot growth rate is lowest; they quantified the redistribution of stored nutrients in rose plants in response to management practices. These and related studies formed the foundation of an Extension program aimed at improving fertilizer and water management in ornamental crop production.

Throughout his career Evans has been a strong advocate for programs aimed at field workers rather than farm owners alone. He was instrumental in developing hands-on irrigation training in Spanish and English for greenhouse and field irrigators, and he participated in award-winning Extension programs that helped California crop producers meet Federal water quality standards.

During his career, Evans contributed to over 70 peer-reviewed publications. He had a regular column in UCNFA News (“Science to the Grower”) in which he presented grower-friendly literature reviews of topics related to the ornamental production industry that showcased his characteristic dry humor and wit. He received several significant awards for his research and extension efforts, including a Western Extension Directors’ Award of Excellence, a UC ANR Distinguished Service Award, an Allan Armitage Leadership Award from the Association of Specialty Cut Flower Growers, and an American Society for Horticultural Science Outstanding Publication award in Floriculture and Nursery Production.

As an emeritus, Evans will continue as the major professor for a graduate student and as faculty advisor for the Horticulture and Agronomy Graduate Group, along with working to complete some ongoing research projects. His retirement plans include providing daycare for his 3-year-old grandson and 7-year-old granddaughter and partnering with his wife in her food safety consulting business. He also plans to spend lots of time playing guitar and accordion.




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