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

Research Objectives & Teams


Objective 1
Identify and characterize Juglans germplasm resistant to key soil-borne pathogens.

Objective 2
Genetic, physical, and functional mapping of disease resistance genes and deployment of molecular markers for rapid screening of resistance.

Objective 3
Quantify economic impact of disease-resistant rootstocks on the U.S. walnut industry.

Objective 4
Conduct extension efforts that: 1) deliver disease-resistant rootstocks to stakeholders and 2) assess emerging threats to walnut rootstocks.

field work

Project Research Teams

Germplasm Assembly Team

  • We will generate, propagate, and curate open-pollinated and hybrid seedlings and clones, and coordinate with genomics and mapping team members.

Disease Resistance Team

We will evaluate walnut rootstock germplasm for resistance, with a focus on each of the following major diseases of walnut:

  • Crown gall disease
  • Phytophthora root and crown rot
  • Lesion nematode
  • Armillaria root disease

Genomics & Mapping Team

  • We will make genetic gains in disease resistance breeding.
  • We will identify the genetic loci which mediate disease resistance.

Economic Analysis Team

  • We will assemble and analyze cost and income data from industry, nurserymen, growers and collaborating scientists.

Outreach & Education Team

  • We will disseminate new rootstock information and conduct new rootstock orchard demonstration trials.

Emerging Diseases Team

  • We will assess the incidence and severity of TCD and LPC in walnut.
  • We will roaden awareness of Juglans genotypes resistant / tolerant to TCD.
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