Insect-Borne Fungus Taking Its Toll of Famous Stands of Monterey Pines : Ecology: Scientists urge Californians not to plant the tree in hopes that a moratorium will help limit the affliction. Little else can be done about pitch canker until researchers develop a more resistant pine.

They first adorned California’s coastline and now grace its man-made landscapes. Monterey pines, blessed with quick growth and evergreen beauty, are among the most popular of trees.

But scientists now urge people not to plant the Monterey pine in California. They hope a moratorium will help limit an insect-borne fungus that afflicts the trees--and could threaten other valuable conifers.

Little more can be done about pitch canker fungus until researchers develop a more resistant strain of Monterey pine.

“It’s essentially not controllable at the moment,” said Andrew Storer, an entomologist at the University of California at Berkeley.

Storer and several other UC scientists have been studying the ailing trees, which are concentrated on or near the central coast, from Berkeley to the Monterey Peninsula. Smaller outbreaks range elsewhere along the coast, from Ukiah to San Diego.

Monterey pines become infected when beetles or other insects carrying pitch canker fungus burrow into the bark. The trees develop lesions that exude resin and start to die; needles fade, wilt and fall out.

The pines can die slowly from the fungus itself or from further infestation by insects taking advantage of the tree’s weakened state.

The disease can affect many different pines throughout the world. It is believed to be native to Mexico and is seen in the southeastern United States.

But it hadn’t been seen in Monterey pines anywhere until 1986. Since then, it has spread rapidly, with devastating results.

“In coastal Santa Cruz and Monterey counties it is affecting most of the trees, maybe 85%,” Storer said. Monterey pines outside California apparently remain unaffected, and nurserymen say the disease is not a serious problem in the state’s hot and dry inland areas.

The Monterey pine occurs naturally in three small stands on the central California coast, at Ano Nuevo Point, on the Monterey Peninsula and near San Luis Obispo.

But humans have made it the world’s most widely planted pine, Storer said. Its rapid, straight growth up to 100 feet make it prized for timber as well as for landscaping.

In California, it is one of the most popular of all nursery trees, a common sight in landscaping, along freeways and on golf courses. It is the predominant Christmas tree grown in the state.

Many of those trees are ailing or at risk because there’s no real way to control pitch canker, Storer said.

“Controls against insects won’t work--there are too many insects that do this. And they’re hard to get to because they hide under the bark,” he said. “And again, the fungus is in the bark.”

So Storer and other researchers recommend, in UC’s California Agriculture magazine, that no more Monterey pines be planted in California for the time being.

The scientists make an exception for Christmas tree farms, which depend heavily on Monterey pines. But they warn tree farmers in Southern California that they could lose a fifth of their crop this year.

Christmas trees, including Monterey pines, were a $21.8-million business in the state in 1992, the last year for which figures are available, according to the U.S. Department of Agriculture.

Most of those trees are Monterey pines--nearly 72% statewide in 1993 and 99.7% in Southern California--according to the California Christmas Tree Growers Assn.

The California Department of Transportation once planted thousands of Monterey pines along the state’s highways. But in the late 1980s it had to remove hundreds of infected trees and stopped planting the species, said Caltrans spokesman Jim Drago.

Scientists also warn landscapers to be cautious about planting other kinds of conifers. They’re concerned that pitch canker could spread to other species of pine and to the Douglas fir, an enormously important timber tree.

UC researchers are working on a guide for landscapers to help them decide which trees they can plant in which areas with minimal risk.

Storer and other UC plant and insect experts also want to develop a strain of Monterey pine resistant to the fungus. They’re hoping to get results from the remaining native stands--even though infection has spread to trees at Ano Nuevo and the Monterey Peninsula.

“Given enough time, I think it probably can be done” Storer said. “But it’s not something that’s going to be available for a number of years.”