U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Crops Pathology and Genetics Research: Davis, CA
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    Outreach Events
                        UC Davis Picnic Day
                                    Kinders go to College
                                    STEM Girls
                                    Future Scientist Program
                                    Agriculture Future of America
                                    Wallace-Carver Fellowship
                                    Young Scholars Program
                                    Annual Awards Banquet
                    About Us
                        About Us
                                    Our Mission
                                    Principal InvestigatorsSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Pacific West Area Davis, California Crops Pathology and Genetics Research Research





- Browne, Greg
- Plant Diseases (303)

Research Project: **Location:
                            Crops Pathology and Genetics Research** Project Number: 2032-22000-017-051-R
                        
                        Project Type: Reimbursable Cooperative Agreement Start Date: Jun 1, 2023
                        
                        End Date: May 31, 2024 **Objective:**
                        
                        Objective 1. In vitro and traditional walnut rootstock propagation that supports continuing selection and trialing of elite walnut rootstocks.
Objective 2. Intensive rootstock trialing that tests putative superiority of new elite rootstocks for commercial walnut production. 
Objective 3. Publication and extension outreach that scientifically summarizes confirmed advantages and potential limitations of new walnut rootstocks. **Approach:**
                        
                        Objective 1. Micropropagation methods will be used to preserve and multiply elite walnut rootstock genotypes. Two key sources of elites will include: 1) a "pool" of J. microcarpa x J. regia 'Serr' clones selected for putative CG, NEM, or PHY resistance (or resistance to two or three of the pathogens) from trials with replicated clonal plants (the clones were from '31 .01' and '31.09' J microcarpa mother trees pollinated by 'Serr'); and 2) a pool of elite J microcarpa x J regia seedlings (initially one plant per genotype) selected for putative CG, PHY, or NEM resistance (the seedlings were from
'29.1 l ', '31.0 l ', '31.03', '31.09' and '3 l.12' mother trees of J microcarpa open pollinated with J. regia). Elites from the former and latter sources will be micropropagated: 1) for short-term assessment of resistance phenotypes in all three pathosystems (CG, PHY, NEM; done in a Davis greenhouse for CG and PHY and in KARE field plots for NEM) and 2) for long-term orchard assessments of walnut tree performance on the experimental rootstocks (done in commercial and experiment station orchards). Short-term confirmations of CG and PHY resistance will use ungrafted rootstocks (for pot trials in greenhouse, for field planting at KARE), whereas long-term trials in orchards will use grafted trees finished by a commercial nursery. Each batch of the experimental elite clones rooted for the additional CG, NEM, and PHY testing, whether destined for short­ term or long-term evaluations, will be produced along with clonal Vlach, VX211, and RX1 rootstocks, which will serve as resistance standards for comparisons with the experimentals.
Objective 2.  Short-term trials will be conducted to confirm putatively high resistance to CG, PHY, and NEM and complete PRP data sets. These trials are considered necessary because putatively high levels of resistance were, for some clones, based on data sets with limited replication, and resistance phenotyping has, for some clones, been completed only for one or two of the three pathogen systems. The confirmatory and PRP trials will be conducted in a greenhouse at Davis (for CG and PHY) and in field plots (for NEM).
Objective 3. Data obtained from trials conducted under objective 2 will be summarized and provide the basis for extension outreach. The outreach will occur through presentations at UCCE-and industry­ sponsored meetings, industry reports and trade publications, and peer-reviewed journal submissions. Although field meetings are not planned for each 2016 trial location in 2023, it is anticipated that some UC Advisors in counties hosting the walnut rootstock trials will offer field days or informal tours featuring them.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov