University of California
Walnut Scion & Rootstock Improvement


The Walnut Perspective

In 2014, US growers in the US produced 388,000 tons of walnuts on 290,000 acres with a value of $1.8 billion (USDA 2015). The US is the world's largest exporter of walnuts with over 50% sold on the export market.

Walnuts are a rich source of the omega-3 polyunsaturated fatty acid that protects the heart against cardiovascular disease and have been placed on the "super food" list by the FDA. In addition, walnut is an important hardwood with a timber value over $539 billion.

Successful walnut production today reflects research in orchard management and longterm breeding programs, focused on goals such as nut quality, tree health and yield. These efforts have been fruitful, supporting a successful industry for both the large-scale grower and the small orchardist. Ongoing research, using and developing new tools, will ensure high quality produce into the future.

The Working Group

The Walnut Scion & Rootstock Improvement Working Group is comprised of researchers from plant pathology, genetics, horticulture, pomology, plant breeding, germplasm, cooperative extension, and economics.

Within this working group are:

  • The research teams of Developing Disease Resistant Rootstock1/, a USDA-funded project
  • The Walnut Improvement Program, a walnut breeding program supported by the UC Davis Plant Sciences Department.
  • USDA scientists of the National Clonal Germplasm Repository.
  • The Walnut Genetics Implementation Group, a focus group of geneticists.

We are working to enhance longterm collaboration, communication, and exchange of information among the walnut research community and the tree crop industry.

1/Member of the working group were awarded a Specialty Crop Research Initiative (SCRI) grant by the USDA National Institute of Food and Agriculture in support of their work on disease-resistance in walnut rootstock. For details of this project see: Developing Disease Resistant Rootstock.

National Institute of Food & Agriculture
University of California Davis
California Walnut Board

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