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Agency Biographies

Dr. Chavonda Jacobs-Young

Administrator, Agricultural Research Service

Dr. Chavonda Jacobs-Young is the Administrator for the Agricultural Research Service (ARS) and the Acting USDA Chief Scientist. Dr. Jacobs-Young recently served as the Acting Deputy Under Secretary of the REE mission area.  Previously, she served as ARS Associate Administrator for National Programs, where she led the Office of National Programs which manages the research objectives of the Agency. Dr. Jacobs-Young also led the Office of International Research Programs which is responsible for ARS' liaison with its international partners.

Prior to moving into her role at ARS, Dr. Jacobs-Young served as the Director of the Office of the Chief Scientist in the U.S. Department of Agriculture, where she was responsible for facilitating the coordination of scientific leadership across the Department to ensure that research supported by, and scientific advice provided to, the Department and external  stakeholders were held to the highest standards of intellectual rigor and scientific integrity. She also served as the Acting Director for USDA's National Institute of Food and Agriculture.

Dr. Jacobs-Young was a senior policy analyst for agriculture in the White House Office of Science and Technology Policy where she supported the President's science adviser and others within the Executive Office of the President on a variety of agricultural scientific activities and worked across the Federal Government to improve interagency cooperation and collaboration on high-priority scientific issues.

Dr. Jacobs-Young is a native of Georgia. She holds M.S. and Ph.D. degrees in Wood and Paper Science and a B.S. degree in Pulp and Paper Science and Technology from North Carolina State University. She also is a graduate of American University's Executive Leadership in Public Policy Implementation Program.

Dr. Chavonda Jacobs-Young

Hubert Hamer

Administrator, National Agricultural Statistics Service (NASS)

Hubert Hamer, serves as Administrator of the National Agricultural Statistics Service (NASS). Appointed in 2016, he brings extensive experience in all aspects of the agency’s work. Before becoming Administrator, he served as Director of the Statistics Division, which produces and releases more than 400 national statistical reports each year covering the agency’s crops, livestock, economic, demographic, environmental, and census programs. He also served as Executive Director of the NASS Agricultural Statistics Board (ASB) and Executive Director of the Advisory Committee on Agriculture Statistics.


From 2010 until he became head of the Statistics Division, Hubert was Chair of the Agricultural Statistics Board. As ASB Chair, he led the preparation and dissemination of market-sensitive ASB reports compiled and issued under special security conditions known as Lockup. He was also responsible for promotion and outreach of the NASS mission to all stakeholders. From May 2000 until April 2010, Hubert was NASS Associate Deputy Administrator for Field Operations, overseeing 24 state field offices as well as the Training and Career Development Office.


Since joining NASS, Hubert has served in many capacities both in Washington, D.C., and in the Louisiana, Illinois, and Missouri field offices. While directing the Missouri office, he completed USDA’s Senior Executive Candidate Development Program and was appointed to the Senior Executive Service in 2000. Hubert completed the program for Senior Managers in Government at Harvard University’s John F. Kennedy School of Government in 2004 and completed the Office of Personnel Management (OPM) Executive Potential Program in 1994. As part of the OPM program, he served as a fellow with the Senate Budget Committee and worked on the staff of the Secretary of Agriculture.


Hubert was born on a small livestock and row crop farm in Benton County, Mississippi, and later continued his development in Grand Junction, Tennessee. He is a graduate of Tennessee State University.

Hubert Hamer

Dr. Carrie Castille

Director, National Institute of Food and Agriculture (NIFA)

Dr. Carrie Castille was appointed to a six-year term as director of the U.S. Department of Agriculture’s National Institute of Food and Agriculture, which began on January 4, 2021. 

A Louisiana native, Dr. Castille has championed agriculture and rural issues for more than 20 years. She has spent her career working in the agriculture industry, education and policy, including serving as Natural Resource Leader and Assistant Professor at Louisiana State University (LSU) and Associate Commissioner and Science Advisor to the Commissioner for the Louisiana Department of Agriculture and Forestry.

In 2017, Dr. Castille joined USDA as state director for Louisiana Rural Development. In 2019, she was named the mid-south coordinator for USDA’s Farm Production and Conservation mission area serving Louisiana, Mississippi, Arkansas, Tennessee and Missouri.

Prior to joining USDA, she was appointed by USDA Secretary Tom Vilsack to the National Agriculture Research, Extension, Education, and Economics (NAREEE) advisory board from 2010 – 2017. During her term, she served as Chair of the NAREEE board, and contributed to many organizations, including the Association of Public and Land-grant Universities’ Council on Agriculture Research, Extension, and Teaching. In 2014, Dr. Castille was appointed to the National Council for Environmental Policy and Technology by EPA Administrator Gina McCarthy.

From 2010-2015, Dr. Castille was a member of the National Food Animal Veterinary Institute Board of Directors. She is also a past chair of the Southern U.S. Trade Association Operations Committee and a Fellow of the Food Systems Leadership Institute.

During her career, Dr. Castille received the Secretary’s Award of Excellence in 2003 from Secretary of Agriculture Ann Veneman for development of the Louisiana Master Farmer Program and the Secretary’s Award for Excellence in Rural Development in 2018 from Secretary Sonny Perdue. In 2017, she was the first female inducted into the University of Louisiana Lafayette College of Engineering Hall of Distinction. She also will be the first female to serve as NIFA director in a non-acting capacity.

Dr. Castille holds a Ph.D. in Renewable Natural Resources (with emphasis on environmental and public policy) from Louisiana State University, an M.S. degree in Environmental Studies from Louisiana State University, and a B.S. degree in Industrial Engineering from the University of Louisiana at Lafayette. 

Dr. Carrie Castille, Director, National Institute of Food and Agriculture

Dr. Spiro Stefanou

Administrator, Economic Research Service

Spiro Stefanou is the Administrator of the Economic Research Service. He provides leadership and guidance for the agency research, analytical, and technical operations. Since 2015, Dr. Stefanou was a Professor of Economics in the Food and Resource Economics Department at the University of Florida.

Prior to his time at the University of Florida, Dr. Stefanou was Professor of Agricultural Economics at Penn State University since 1983. 

He is a Distinguished Fellow of the Agricultural and Applied Economics Association and was a Marie Curie Senior Fellow at the University of Crete (Rethymnon, Greece), Mansholt Senior Fellow at Wageningen University (Netherlands), and Jean Monnet Fellow at the European University Institute (Florence, Italy).  He has been a visiting professor at the Institute for Advanced Studies (Vienna, Austria), and the Mediterranean Agronomic Institute (at Chania).  Dr. Stefanou has served on the editorial boards of six national and international journals. 

Dr. Stefanou received his Ph.D. in Agricultural Economics from the University of California, Davis, his M.S. in Agricultural and Resource Economics from the University of Maryland and a Bachelor of Arts in Anthropology from George Washington University.

Dr. Spiro Stefanou, Administrator, ERS

Dr. Dionne Toombs

Director for the Office of the Chief Scientist

Dr. Dionne Toombs is the Director for the Office of the Chief Scientist (OCS). In this role, she provides leadership on a wide range of issues affecting science programs and science policy in agricultural research, education, and economics. She comes to OCS from the National Institute of Food and Agriculture (NIFA) where she was Director of the Division of Nutrition, leading a collaboration of nutrition science leaders across the Department. Under her leadership, the Division provided direction in science policy and program development to ensure the safety of America’s food supply and the availability of healthy food to its citizens.

She served as National Program Leader for NIFA’s Agriculture Food and Research Initiative (AFRI), leading large competitive grant programs to fund research into nutrition, food science and technology, and food safety.

Dr. Toombs received her Ph.D. in Nutritional Sciences from Howard University. She earned her Master of Science degree from Alabama A & M University and her Bachelor of Science degree in Biology from Bethune-Cookman University.

Dr. Dionne Toombs