Three UC Cooperative Extension weed science academics retire

Jun 24, 2020

Extracted from the UC ANR News & Events blog (


UC Cooperative Extension weed science advisor Kurt Hembree retires on July 1

Retiring UC Cooperative Extension weed science advisor Kurt Hembree credits his mentor and predecessor, Bill Fischer, for his successful 26-year career conducting a weed research and extension program for farmers in Fresno County.

"He instilled in me a real appreciation for both the art and science behind weed management," Hembree said.

Hembree started working as Fischer's agricultural assistant when he was a plant science student at Fresno State. After graduation in 1986, Hembree was promoted to staff research associate, a position he held for eight years.

Recognizing the opportunity to succeed Fischer in his academic role, Hembree returned to Fresno State to complete a master's degree. Fischer retired in 1994 and Hembree was named UCCE weed science advisor later the same year.

Hembree said he was privileged to work with a tight-knit group of academic and non-academic staff, growers, consultants and the allied industries.

"Everybody knew everybody. I developed strong friendships over my career," he said. "I cherish that."

An early research success set a course for the future.

The weed nightshade posed a significant problem in seeded fields of processing tomatoes, a plant in the same family. Hembree conducted trials on a new product that selectively removed the nightshade.

"That was a major breakthrough," Hembree said. "We were able to get the product labeled for tomatoes and it made a huge impact right away."

That was just the beginning.

"When I came on board, there weren't many products registered for weed control in orchards, vineyards and agronomic crops," Hembree said. "We worked closely with the industry and there were lots of opportunities to look at new products. These new tools were economically sound and reduced the hard labor of hand weeding."

In retirement, Hembree plans to move with his wife to northern Mississippi to be closer to family. - Jeannette Warnert


UCCE weed advisor John Roncoroni retires July 1

After 38 years of service, John Roncoroni, UC Cooperative Extension advisor specializing in vineyard weed management in Napa County, plans to retire July 1.

Over the years, Roncoroni has become a trusted resource for weed management research and extension, not only in the North Coast, but throughout California. He is known for his research on conventional and organic herbicides, hedgerows in vineyards, irrigation pond weed control, and sheep for grazing weeds in commercial trees and vines.

"Over the years working with John Roncoroni, I experienced firsthand his dedication, passion and knowledge to educate farmers and agricultural workers – both in English and Spanish – about best management practices to control and eradicate invasive weeds and weeds of concerns for the agricultural industry. John will be missed greatly," said Jose Chang, Monterey County assistant agricultural commissioner and former deputy agricultural commissioner in Napa County.

After earning a bachelor's degree in environmental policy analysis and planning at UC Davis, Roncoroni began his career as a UC Davis postgraduate researcher in 1983, then became a staff research associate working with other weed scientists in crops, forest and rangelands. He earned a master's degree in horticulture at UC Davis in 1999.

In 2007, when Roncoroni became a UC Cooperative Extension advisor in Napa County, most conventional grape growers used glyphosate, or Roundup, for the weed control.

"In fact, Roundup only was considered the most sustainable weed management method," Roncoroni said. "This over-reliance on glyphosate resulted in biological resistance by weeds."

He taught growers about alternative herbicides and non-chemical weed control methods and how to make these methods more effective. Little did he know that this research would become even more valuable when some consumers began to object to glyphosate use.

Because he has studied weed management in a broad array of environments, Roncoroni is often asked by UCCE colleagues to give weed control tips to different audiences ranging from golf course turf managers to small-scale Mien strawberry farmers.

"Over the years I have had the opportunity to work on weed control in forestry, rangeland, row crops, alfalfa, fruit and nut trees, but it was my early training in weed management in turf and ornamentals, mulches and alternative weed control that added to my effectiveness in teaching weed control to urban audiences and to training UC Master Gardeners," said Roncoroni, who has trained more than 1,700 UC Master Gardener volunteers in weed identification, biology and management.

Roncoroni's expertise has been recognized by the California Sustainable Winegrowing Alliance, which asked him to assist in writing their standards for sustainable winegrowing, and the California Department of Pesticide Regulation, which asked him to serve on its Pest Management Advisory Committee. In 2018, the California Weed Science Society named Roncoroni an Honorary member, its highest honor. - Pam Kan-Rice


UCCE integrated pest management expert Cheryl Wilen retires after 25-year career

UC Cooperative Extension integrated pest management advisor Cheryl Wilen retired in April after serving UC Agriculture and Natural Resources in a wide variety of leadership and academic capacities during her 25-year career. To help with transitions in the San Diego County UCCE office, Wilen accepted a six-month assignment in May to continue serving as interim director.

Wilen earned a bachelor's degree in horticulture at the University of Maryland, a master's degree in horticulture at University of Arizona and a doctoral degree at UC Riverside. Following graduation, Wilen worked a year at UC Riverside as a post-doctoral fellow.

In 1995, Wilen was hired by UC ANR to conduct applied research in the turf, ornamental horticulture and nursery industries to develop and promote the use of integrated pest management in San Diego, Los Angeles and Orange counties. She shared her results and information generated by scientists across the university with growers and pest control advisers to reduce the use of toxic pesticides, cut the cost of pest control and use environmentally sound methods in production.

Over the years, Wilen was frequently tapped to take on leadership roles while maintaining her academic program. She served as acting and interim director of the Statewide UC IPM Program, program leader of UCCE's Endemic and Invasive Pests and Diseases Strategic Initiative, and as county director in San Diego County. Wilen also had opportunities to take sabbatical and study leaves to improve her Spanish-speaking skills, learn about international participatory extension methodology and receive training on research methods to study snails and slugs.

"I love working with UC Agriculture and Natural Resources," Wilen said. "The positions I held matched well with my professional and personal style. I always felt that I was responsible for choosing my destination and the journey to get there, whether that was my career or my research and extension programs."

Wilen said she also valued the relationships she developed over the years in her job.

"I met and became friends with people in UC that I would never have been so lucky to know without the opportunities afforded me by serving on diverse committees," Wilen said.

Wilen has been awarded the honor of emeritus status, which will continue her academic relationship with UCCE even after her stint in the director post is complete.

"I have a couple of grants I'm continuing to work on," she said.

She also has plans to do things that she didn't have time for while working full time.

"Plans for my free time include entering sweepstakes, organizing electronics cables, continuing to paddle with my outrigger canoe club, exploring the outdoors, travel, volunteering and enjoying time with my partner and the rest of my family," she said. - Jeannette Warnert

Original source


By Jeannette E. Warnert
Author - Communications Specialist
By Pamela Kan-Rice
Author - Assistant Director, News and Information Outreach
By Gale Perez
Posted by - Program Representative