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 Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications
- Etiology and Biology of Tree Crop Diseases
- Rice Genetics
- Sustainable Floriculture
- Sustainable Viticulture

Title:   Author  item
                                            McElrone, Andrewitem
                                            GRANT, JOSEPH - University Of Californiaitem
                                            Kluepfel, Daniel
  Submitted to: Tree Physiology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 3/7/2010
                                    Publication  Date: 5/6/2010
                                    Citation: Mcelrone, A.J., Grant, J.A., Kluepfel, D.A. 2010. THE ROLE OF TYLOSES IN CROWN HYDRAULIC FAILURE OF MATURE WALNUT TREES AFFLICTED WITH APOPLEXY DISORDER. Tree Physiology. 30:761-772.Interpretive Summary:
                                Technical Abstract: In the Central Valley of California, mature walnut trees afflicted with apoplexy disorder exhibit rapid and complete canopy defoliation within a few weeks of symptom initiation.  Symptoms are typically found throughout the entire canopy and are initially expressed as wilting and chlorosis followed by scorching of leaves.  The cause of apoplexy disorder is unknown, so we set out to elucidate the water relations physiology underlying this condition.  Stem water potential ('s) of asymptomatic control trees remained high throughout the 2007 growing season while those of apoplexy afflicted trees decreased significantly with the onset of symptoms.  's’s were significantly reduced by at least 2.4 times in the lower, middle, and upper portions of the symptomatic canopies compared to those from asymptomatic, control trees.  Specific hydraulic conductivity (Ks) of symptomatic stems was dramatically lower than that of control branches, and no detectable Ks could be measured on several of the symptomatic stem samples. However, shallow root Ks did not significantly differ between symptomatic and asymptomatic trees suggesting hydraulic failure was isolated to the canopy of these grafted trees.  Heat pulse velocities measured in the main trunk at three radial depths consistently plummeted just prior to the onset of symptoms and eventually reached zero with complete canopy defoliation.  Light and scanning electron microscopy of stem and trunk sapwood revealed extensive tylose development in vessels throughout the canopy of symptomatic trees.  In 2008, the tylose development was linked to elevated ethylene production in the active sapwood of symptomatic trees. The cause of elevated ethylene that led to tylose production and subsequent apoplexy symptoms is yet to be determined.


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