Historic orange tree threatened by disease in Riverside

RIVERSIDE, Calif. (KABC) -- An urgent effort is underway to save a single orange tree in Riverside. But this is not just any tree, it is literally the mother of navel orange trees, the parent of millions of others around the world.

Driving through one of the busier intersections in Riverside, Magnolia and Arlington avenues, most folks don't know much about the growing citrus tree or its place in history.

The reason it's labeled as California Historical Landmark No. 20 is that it's perhaps the oldest navel orange tree in existence, 143 years to be exact. But right now, it faces a big threat.

It's already protected by a stout fence, and there are smudge pots to prevent frost. But that won't help against the Asian citrus psyllid, a nasty pest that's threatening citrus trees all across Southern California.

This tree's most important protection comes from a lab at UC Riverside.

"The problem is that, unfortunately, we don't have a solution to the disease," Georgios Vidalakis of UC Riverside said.

That's why Vidalakis says they're constantly checking for it. They collect stems, peel back the bark, chop it up, extract the DNA, and then send it in for testing.

Right now, there's absolutely no indication that this tree is infected, but researchers know, that with each and every test they conduct comes the possibility of bad news.

But for a tree, that many agree is the parent of the economic boom of the citrus industry in Southern California, Vidalakis says it's the least they can do.