New disease is destroying trees in Northwest

Christmas tree, timber industries threatened

October 01, 2002|By NEW YORK TIMES NEWS SERVICE

FAIRFAX, Calif. - Ascending the forested slopes of Mount Tamalpais, 15 miles north of San Francisco, Dr. Matteo Garbelotto and Dr. David Rizzo point out victim after victim of the fast-spreading new disease, sudden oak death syndrome.

But despite seeing dead, wilting and yellowing plants throughout these woods, it is hard for an observer to fathom the real power of this plague until the trail abruptly ends in a heap of ghostly white branches and trunks.

"We call this site mucho destructo," said Garbelotto, standing in the streaming sunlight next to a carpet of fallen trees where sudden oak death has brought down the forest canopy. Branches fall even as he speaks.

Such is the power of this plant pestilence that has infiltrated much of California and jumped to Oregon, killing tens of thousands of trees and spreading to 17 species - a list that now includes oaks, huckleberry, big leaf maples, rhododendrons and bay trees.

In September, scientists reported the disease was attacking redwood and Douglas fir, the mainstay of the Northwest's timber and Christmas tree industries, which together are worth billions of dollars.

"It would be a huge impact if the disease did spread," said Mike Moskovitz, a spokesman for the Weyerhaeuser Co., which owns or leases more than 2 1/2 million acres of timberland in Oregon and Washington, where Douglas firs account for 80 percent to 90 percent of harvests.

Moskovitz said the company was closely watching the infestation in southern Oregon, still limited to a small area where foresters are scouring for infected trees and burning any they find.

Even more significant than the number of trees the disease might kill are the restrictions it places on who will buy them.

California foresters and nursery owners are under increasing numbers of state, federal and international quarantines restricting the movement and sales of the many potentially infected plants from California.

Scientists, meanwhile, are rewriting the biology of this botanical scourge with each new finding. Many of the surprises have come from the laboratories of Garbelotto and Rizzo.

The teams together discovered the cause of the die-offs, a previously unknown pathogen species named Phytophthora ramorum. They have also pieced together much of the species' unusual and unusually damaging pattern of existence.

The researchers attribute their success in this scientific sleuthing to perseverance, ingenuity and a nearly complete lack of knowledge of what they should have expected from a Phytophthora pathogen.

"It's not like we were thinking outside the box," said Rizzo, noting that scientists better versed in Phytophthora biology would never have tried some of the experiments they tried. "We were never in the box."

The story of this disease begins, depending on whom you ask, somewhere from 1993 to 1995, some say in the forests near Santa Cruz or Big Sur, and according to much of the sudden oak death lore, in a back yard in these undulating foothills of Mount Tamalpais.

Standing on their wooded hillside property, considered by many to be the site of the first known case of the disease, Don and Connie Lewis recalled noticing that a tanoak had gone from perfectly healthy one week to brown and dying the next. They called in tree disease experts, who guessed that it might be drought stress or beetle attacks and advised the couple not to worry.

But and Lewis, master gardeners who had owned a hardwood tree farm in Pennsylvania, were not convinced that all was well in their neighborhood of multimillion-dollar homes.

"It was difficult to get anyone to listen," Lewis said. "Everyone just gave us these cockamamie explanations."

Reports of dying oak trees, often oozing a bloody red sap, continued to crop up. Some were large showcase trees worth tens of thousands of dollars to property owners.

Baltimore Sun Articles
|
|
|
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.