Riverside’s Parent Navel Orange Tree is Getting New Protection Against Citrus Greening Disease


(This article was written by Ryan Hagen of the Press Enterprise and published on June 11, 2019.)

The tree responsible for every Washington navel orange — including the ones that gave the Inland Empire its first prominence as a citrus center — is getting new, longer-lasting protection from the disease that’s devastated the orange industry elsewhere.

The cover over the parent navel orange tree at the corner of Arlington and Magnolia avenues in Riverside will hang over the steel structure that workers began installing in March, replacing a temporary cloth protection that officials admitted was “not beautiful.”

The new screen is a synthetic material made by the company Econet. The screen’s lifespan is five to eight years, but it will be inspected regularly before that, said Georgios Vidalakis, professor and director of the citrus protection program at UC Riverside.

“This one will buy us a few years so the city can design a more elegant structure like you see in arboretums — maybe a wood hexagonal pavilion that will be aesthetically more pleasant,” Vidalakis said. “Unless in the next few years we find a solution."

That’s the ultimate hope: That a cure for citrus greening disease can be found and the structure removed so crowds can better admire the historic parent navel orange.

But until then, he said, protection is vital.

Citrus greening disease — also known as huanglongbing or HLB — was found a few miles from the tree in 2017. Then it was rediscovered in May on the same property, near the 60/91/215 freeway interchange.

The disease, spread by the Asian citrus psyllid, leaves citrus trees with mottled leaves and fruit that is misshapen and fails to ripen, remaining green. The fruit also tastes bitter. There is no known treatment for the disease and trees usually die within three to five years.

Installation of the cover started Tuesday, June 11, and is expected to be done Thursday, said Adolfo Cruz, director of the Parks, Recreation and Community Services Department.

Other protective efforts have included inspections, insecticide applications and removing nearby trees without historic value.

Eliza Tibbets planted the tree in Riverside in 1873, using cuttings from a variety of orange grown in Brazil. When it proved well-suited for Riverside, she made a living by selling cuttings that spawned Southern California’s citrus empire.

Later, cuttings descended from Riverside’s navel orange were sent to replace Brazil’s Washington navel oranges, which had been wiped out by disease in the 1930s.