Walnut Scion & Rootstock Improvement
Walnut Scion & Rootstock Improvement
Walnut Scion & Rootstock Improvement
University of California
Walnut Scion & Rootstock Improvement

Addressing Stakeholder Needs

Message from Walnut Nurseries

Commercial nursery.
Commercial nursery.
There is a crucial need for new improved rootstocks that address the mounting challenges of growing walnuts commercially in the U.S. The list of present and looming disease, soil, and water issues is extensive.

When one considers virtually all walnuts planted in California in the future will be either planted in replanted orchard soils or in areas with poor soil or water conditions, one can understand why the rootstocks that started the industry as we planted into virgin, ideal soil conditions will not sustain the walnut industry going forward.

Loss of Soil Fumigants

Cultivation of walnut in the U.S. is challenged by soilborne diseases that, for decades, have been controlled primarily by soil fumigants, especially methyl bromide which is now only available through critical use exemptions. Alternative fumigants are now subject to increasing regulatory restrictions. To remain competitive and sustainable, the U.S. walnut industry must reduce or eliminate dependence on soil fumigation. 

Our Vision

This project addresses these needs through identification of Juglans germplasm with resistance to the targeted pathogens, development of genomic tools for rapid identification of resistant progeny from directed crosses, and deployment of resistant rootstocks in long-term field trials.

Webmaster Email: fruitsandnuts@ucdavis.edu