Ancient Oak May Be Out on a Limb : Nature: The 1,000-year-old Encino landmark is threatened by disease and drought. Experts differ over what to do.

When the famed Lang oak tree of Encino was but a sapling, the Mayan Empire was crumbling and Vikings were sacking English sea towns.

In its 1,000 years of life, the tree has silently witnessed flood, fire and drought. But a Canoga Park arborist now fears that, thanks to the latest drought, the tree may not be around to witness modern history much longer.

Free-lance arborist Robert Wallace says the Lang oak, named after a rancher who once owned vast holdings in Encino, is suffering from slime flux, a tree ailment which can be deadly.

“It desperately needs special care,” Wallace said of the giant oak. “The tree just desperately needs it.”

But officials with the city’s street tree division, while agreeing the majestic oak is ill, said its condition is not grave and have ruled out treatments which Wallace says are needed to save the tree. Wallace says the city should chisel small holes in the bark to release toxic sap which is slowly killing the oak.

But Duane Gute Sr., speaking for city arborists, disagrees with the suggestion. “We feel you’re just adding more stress to the tree,” he said.

Gute, who is a superintendent in the street tree division, convened a team of arborists this month, at Wallace’s urging, to examine the oak and prescribe treatment. For the most part, the team decided to let the tree heal itself.

The tree, a California live oak, is south of Ventura Boulevard in the middle of Louise Avenue, which splits to accommodate the tree’s girth. With a trunk 24 feet in circumference and a thick canopy 150 feet across, the oak creates a woodsy atmosphere more resembling a whole forest than just a single tree.

“Normally, when you describe an old, old live oak, you’re talking about a 300-year-old tree,” Wallace said.

But the Lang oak’s longevity is extraordinary. “It’s just like standing next to a dinosaur,” Wallace said.

Not quite that old. But the tree was a mere centenarian when Pope Urban II proclaimed the First Crusade.

Donald Hanover, a professional arborist, said the tree’s great age has been estimated by comparing the number of rings in other large oaks felled over the years.

“It just has to be that old,” Hanover said of the 1,000-year estimate.

As far as local historians and tree aficionados can tell, the tree’s closest scrape with death came around 1958, when a developer planned to bulldoze the oak to make way for a road. Enraged citizens, led by a longtime resident named Vada Flowers, quickly formed a group called Encino Save the Oaks and persuaded city officials to intervene.

The developer eventually donated the tree to the city, which declared it a historic and cultural monument in 1963.

The tree’s current woes are being caused by bacteria that produce slime flux. A healthy tree can fight off the bacteria, but a tree weakened by drought or other conditions cannot, Wallace said.

The bacteria produce fermentation inside the tree and create gases which send toxic sap oozing through the bark. Dark patches on the Lang oak’s trunk, looking like burn marks, are signs of slime flux, Wallace said. That’s why he suggested boring small holes to release the sap and reduce the pressure on the tree’s system.

The condition is not always fatal, but “I’ve seen it kill a lot of trees,” he said.

But Gute said Wallace’s suggested cure would be worse than the disease. He added that city arborists noticed slime flux when they trimmed the tree in 1987. The disease is less active than four years ago, he said.

Hanover added that the oak is in better shape than many trees a fraction of its age. Nor is it surprising that the tree has at least a few ailments. “Anything that’s lived 1,000 years--if it doesn’t have a couple of warts, it’s a miracle,” he said.

Gute said city arborists, however, have decided to take some action to help the tree recover from the stress of the drought and fight off slime flux. In a few weeks city workers will install four-inch vertical pipes into the ground below the outer edges of the branches to give the roots more oxygen, Gute said.

As for the future, it’s impossible to predict how long the ancient oak will continue to bless a city street with shade and atmosphere, arborists said.

“Who really knows?” Hanover said. “It could go on forever.”

HOW SLIME FLUX KILLS

Slime flux is a debilitating and sometimes fatal condition that afflicts trees.

Treatment varies, depending on the overall health of the tree. Sometimes holes are bored into the trunk to release pressure. The tree may be sprayed with insecticide to kill boring beetles which, through their tunneling, spread the toxic sap through the tree’s system. Extra watering is sometimes recommended in times of drought to build up the tree’s strength.

* CAUSE AND EFFECTS

1. Bacteria that produce the slime flux enter through the tree’s roots.

2. Stressful conditions, such as drought, weaken the tree and allow the bacteria to grow and spread. The bacteria literally ferment inside the tree, creating pressure and a toxic sap that kills plant cells.

3. Over several years, the pressure continues to build, forcing sap to ooze through the bark. Eventually, the bacteria can weaken and kill the tree.