Toxic spills, chunks of concrete and discarded mattresses are among the things Caltrans workers keep a watchful eye on.

Now they have something else to add to their list of worries: rogue landscapers.

Over the past several months, rows of 15-foot trees that were to be used as noise barriers or screens near the 405 and 10 freeways have been cut down in an apparent bid to make nearby billboards - one of them illegal - more visible.

All of the ads were for Tropicana orange juice and all of them might have been put up by the same billboard company, World Wide Rush, which did not return phone calls. Tropicana also did not return calls.

It's not the first time trees near billboards have disappeared in Los Angeles. A

Some photos of the 21 heavily trimmed trees.
magnolia tree was hacked down in 2001 along the Sunset Strip and three palm trees were poisoned near Los Angeles International Airport a few years later.

But this is one of the first times Caltrans has had to deal with the problem. As for who the culprits could be, officials say they're stumped.

"It's really disturbing to me and disturbing to staff, because we have a lot of dead and dying landscape," said Daniel Freeman, Caltrans' deputy district director of maintenance. "And here someone comes along and cuts down healthy ones for no good reason."

City Attorney Rocky Delgadillo has filed charges against World Wide Rush, which put up the illegal billboard near the 10 Freeway and National Boulevard, and the owner of the

six-story building where it hangs.

A spokeswoman for the Sherman Oaks Galleria said World Wide Rush also operated the two billboards attached to the mall's parking structures, where other trees were cut down.

But the culprits - who probably used chain saws to take down a total of 17 Brisbane Box evergreens that can grow to 60 feet - have never been seen, or heard of, despite their noisy trade.

Their hasty landscaping jobs can be seen near the Sherman Oaks mall, where 12 trees were cut down, and at the 10 Freeway and National Boulevard offramp, where five other trees were felled. The trees cost at least $1,500 each, plus some $1,000 has spent to keep them up over the years.

"They did a terrible job cutting them down," Freeman said, describing the $42,500 in damage. "They weren't landscapers."

Given today's free-falling economy, it's unknown when the state agency can afford to replace the mutilated trees, Freeman said.

The trees are part of a massive landscaping investment the state agency makes to muffle clanky roadway noise and add easy-breathing aesthetics to its 45,000 miles of highway and freeway lanes.

Freeman said it looks like the trees were cut with chain saws, allowing the vandals to act quickly.

Vandals are believed to have worked in the dead of night, chopping each tree, leaving about half standing jagged in the ground and then hiding the debris behind other landscaping.

Caltrans was notified of its trashed trees near National Boulevard after receiving a phone call in late January from Delgadillo's office.

Delgadillo filed criminal charges on Jan. 30 against World Wide Rush and the building owner for illegally erecting the massive billboard without a permit and for installing a bright supergraphic sign after the city issued a moratorium on them.

The Federal Highway Administration is producing a study for Congress on supergraphic and digital signs to see if their razzle-dazzle displays distract drivers and endanger the highways. The report should be done this year.

When charges were filed, the supergraphic billboard in question advertised Tropicana orange juice. It has since been changed.

"It's still illegal. It doesn't matter what it says," said Asha Greenberg, assistant city attorney. "It's the fact that it's there."

Greenberg said charges for cutting down the trees are not included in the lawsuit, but that the office is interested in hearing from anybody who saw it happen.

Staff at the Sherman Oaks Galleria noticed a "severe pruning of the trees" next to the 405 Freeway and on five of their own trees in late December, said Katherine Defevere, general manager.

Weeks later two billboards for Tropicana orange juice were hung from the landmark mall's parking structure. Defevere said they are owned by World Wide Rush and that it's the first time the mega mall ever displayed billboards on its parking garage.

Defevere said the trees were too short to ever block the freeway view of the signs and believes that the hacked trees were a landscaping error.

"We don't know what happened," Defevere said. "We think someone did it by mistake." 818-713-3741