New Chairs for Plant Pathology and Land, Air and Water Resources Departments

Professors Johan Leveau and Jorge Mazza Rodrigues will take over as chairs of the Department of Plant Pathology and Department of Land, Air and Water Resources, respectively, Dean Ashley M. Stokes from the College of Agricultural and Environmental Sciences announced. 

The appointments took effect July 1, 2026.

Plant Pathology

Leveau, who is a microbial ecologist and professor, has served as interim chair since January, replacing Dave Rizzo. 

“I’m quite honored to be in this position,” Leveau said. “It’s really a role of service in support of faculty development, especially junior faculty, and to promote the success of our postdocs and our students.”

The department of Plant Pathology turns 100 in 2027 and Leveau said he hopes to build on that history and continue to attract top quality faculty, enhance student programming and ensure long-term growth.

Stokes said Leveau has had a significant impact on the department and college. 

“His internationally recognized work in microbial phytobiomes, bioreporters and single-cell microbial ecology is complemented by his outstanding contributions to instruction, student mentorship, university service and professional leadership,” Stokes said.

The department has 19 faculty members, 50 project scientists and postdocs, 250 undergraduates, 28 graduate students and four affiliated U.S. Department of Agriculture researchers. 

The plant pathology graduate program and global disease biology undergraduate program train students in disease and health of plants and in the context of their interconnectedness with humans, animals, and the environment. 

“Our students come out of these programs with a sense of urgency and a training that really is ready to go,” he said. “The world needs global disease biology and plant pathology students now more than ever.”

Leveau joined UC Davis in 2008 and leads a research program that operates at the intersection between microbial ecology and plant pathology with an interest in plant microbiomes and biostimulants, which are akin to probiotics for plants. He has served as the lead faculty advisor for global disease biology since 2015 and a mentor for plant pathology, microbiology and ecology Ph.D. students. 

He teaches courses on disease and society and the microbiome of people, animals and plants.

Leveau earned his bachelor’s and master’s degree in biology from Wageningen Agricultural University in The Netherlands and a Ph.D. in microbiology from the Swiss Federal Institute of Technology in Switzerland. He completed a postdoc in plant microbiology at UC Berkeley and worked as a senior scientist at the Netherlands Institute of Ecology.

Land, Air and Water Resources 

The Department of Land, Air and Water Resources, or LAWR, is home to faculty, students and researchers working to advance sustainable solutions in atmospheric science, soil, water, agriculture and environmental science.

Mazza Rodrigues, who joined the faculty in 2014, specializes in soil microbiology. Originally from Brazil, Mazza Rodrigues earned bachelor's and master's degrees from the University of São Paulo and a Ph.D. from Michigan State University.

Stokes said he’s a distinguished faculty member whose work on soil microbes and microbial communities is internationally recognized. “Jorge is exceptionally well qualified to serve as department chair, with an impressive record of research, teaching, mentoring and service,” she said. 

Mazza Rodrigues succeeds Distinguished Professor William Horwath, who is the James G. Boswell Endowed Chair in Soil Science.

As chair, Mazza Rodrigues said he wants to build on the department’s strengths by encouraging more interdisciplinary collaboration across research areas, bringing in new faculty and continuing to support students at all levels.

“Our college has the highest percentage of first-generation students. We need students to know there are resources that are going to make it easier for them,” he explained. “Also, experiential learning is such a great opportunity for you to learn from your mistakes. I truly believe that we should take advantage of that.”

The department supports four undergraduate majors and three graduate groups. Mazza Rodrigues said he looks forward to working across these programs to bring people together to address urgent issues in California such as water management, air pollution and the shift toward more sustainable and organic farming practices, with the goal of making a broader impact across the state.

“Leadership takes time. You need patience to change things,” he said. “We have had awesome leadership in the past and it will be hard to fill those shoes, but I'm ready.”