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143-year-old Washington navel mother tree gets special care

The mother of millions of navel orange trees around the world, a 143-year-old Washington navel orange tree in Riverside, is carefully protected by UC scientists and the Riverside parks department, reported Suzanne Hurt in the Riverside Press-Enterprise.

"We're not going to let this tree die," said Georgios Vidalakis, UC Cooperative Extension specialist in the Department of Plant Pathology at UC Riverside. Vidalakis is the director of the UC Citrus Clonal Protection Program.

Scientists protect the tree using special tools, insecticides and disease monitoring.

According to legend, the seedless and sweet Washington navel was an accidental mutant that appeared on the grounds of a Brazil monastery in the early 1800s. Tree clones were sent to USDA in Washington, D.C., and from there acquired by Eliza Tibbets, who tended the trees at her home in Riverside.

"Producing budding stock to make other saplings, Tibbets' trees birthed a citrus industry dubbed California's second gold rush," the Press-Enterprise story said.

John Bash, a UC Riverside staff researcher who worked with the Washington navel for 32 years, called the mother tree "one of the world's agricultural icons."

"There are literally millions and millions of trees that can trace their ancestry back to that single tree," Bash said.

Posted on Friday, August 29, 2014 at 9:17 AM


Hi Jeannette,  
There is actually a direct action that you all could take to help save the mother tree. Someone could bring an infected scion from Florida and graft it to a tree here in California without even understanding the danger. I believe that the introduction of greening to Florida was an accident and it could happen here in California. The number one search result if one googles "grafting citrus" is an article on This article is quite stale, from 1997 before greening was a threat. If you all could replace it with a new article with the same filename, but with an appropriate warning about citrus greening, and instructions on how to order clean budwood, it could help avoid the sort of accident here that wiped out Florida's citrus. I have written an article here about this problem:  
Please let me know if there is anything that I can do to help you. I love citrus and would like to help save the mother tree, too.  
Best regards,  
Dan Willey

Posted by Dan Willey on August 29, 2014 at 10:27 AM

Hi Dan,  
Your concerns are very valid and we appreciate you bringing to our attention the need to refresh a publication from 1997. We'll contact the author and get the ball rolling. You're correct - transferring budwood around the country, nation and state is of great concern right now and gardeners need to be aware of the serious problems diseased budwood can cause. The UC Master Gardener volunteers are actively working to raise awareness within the public in hopes that we will stop the progression of the disease. Unfortunately citrus greening, the disease huanglongbing, and the insect that vectors it, the Asian citrus psyllid, have already made their way to California. Fortunately, UC Cooperative Extension has been at the forefront of research and outreach/awareness efforts. Concerned individuals can contact their local UC Master Gardener program for more information on what to look for. Find your local UC Master Gardener program at If a gardener thinks they have the insect or disease, REPORT IT through USDA's Save Our Citrus campaign at

Posted by Missy Gable on August 29, 2014 at 11:18 AM

Thank you, Missy!  
As you all update the publication, I would suggest avoiding major changes so that you do not harm the document's google search ranking. Also, there are many hyperlinks to the document on the web already and this helps the google search ranking. So if you keep the same filename and location for the document, it will help it to maintain the good search ranking and thus help avoid the inadvertent grafting of greening-infected budwood not just in California, but also in Texas and Arizona.  
If I can be of help in this process, please let me know.  
Although a single tree in Los Angeles did test positive for citrus greening, the CDFA has fought it very hard within the quarantine zone. Lessons from Florida are being applied and there is great hope that spread of greening can be stopped. Education is the key and thank you for your efforts!  
Best regards,  
Dan Willey

Posted by Dan Willey on August 29, 2014 at 12:48 PM

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