By Garance Burke
Special to The Washington Post
Monday, January 19, 2004; Page A08

MARIN, Calif. -- For eight years, a mysterious pathogen called sudden
oak death has eluded researchers as it has killed off thousands of oak
trees along the California coastline. The highly contagious disease,
which causes trees to develop blood-colored oozing cankers before they
dry up entirely, has spread through state parks and private ranches
alike, and it now covers one-fifth of the California landscape.

Last fall, when scientists released a pesticide that can inoculate the
trees against the infection, authorities hailed it as an important
victory for western forests. But the discovery of a second strain of the
disease on a potted plant in a Portland, Ore., nursery has sparked fears
that the blight may prove to be resistant to the treatment, posing an
even greater scientific challenge.

"What happens when something of this size hits in the public health
field? You get an international outcry about SARS," said Matteo
Garbelotto, the University of California at Berkeley plant pathologist
who first identified sudden oak death in 1995. "But when an
environmental crisis of this scope hits, no one pays any attention -- it
flies under the radar. Something similar to this happened with Dutch elm
disease, and the one that really wiped out all the elms was the second
wave."

Garbelotto, who developed the phosphate-based pesticide, has been
training California tree experts how to combat the disease with plastic
syringes and power drills. Straun Edwards was one of 60 arborists who
gathered recently on a dry hill north of San Francisco to learn how to
vaccinate trees against the funguslike pathogen.

"People just don't know what to do when they see a 200-year-old tree
wither up and die in a period of a few weeks," said Edwards as he strode
along a dirt path that revealed vistas of the oak woodlands below.
"Sudden oak death was starting to affect business, because my customers
would be, like, 'I don't care what it costs; just save my tree,' and I
would have to be, like, 'I'm sorry; I can't.' Now at least there's
something I can do."

Plant pathologists first discovered the organism in an oak grove in the
Marin hills, just a few miles from the site of the workshop. After
mapping its DNA, they named it Phytopthera ramorum and concluded it was
a relative of Ireland's potato blight. With sudden oak death -- as it is
commonly known -- now turning up in forests in British Columbia and the
Netherlands, scientists are increasingly concerned about the long-term
effects the disease may have on forest ecosystems.

Sudden oak death spreads through airborne spores, which typically form
on bay leaves and then disperse onto oaks, redwoods, firs, madrones,
evergreens and other species. Once infected, the trees develop the
telltale oozing cankers, and their canopies quickly turn from green to
brown. After that, hordes of bark beetles attack the trees and weaken
their vascular systems so significantly that the trees can topple in
strong winds.

The devastation is clearest in the area around majestic Big Sur State
Park, just south of Monterey Bay. Long renowned for its granite cliffs
and 1,000-year-old redwood trees, Big Sur closed several of its canyon
trails last year when park officials realized campers could be hit by
falling timber. Several paths are lined with groves of gray, dying tan
oaks, and rangers have put up signs warning park visitors to wash their
boots and tires with Lysol to keep from bringing the spores with them.

In infested areas such as Marin, authorities are also concerned that
Phytopthera ramorum is increasing the amount of dry fuel on the forest
floor, said Steve Jones, California's deputy chief for forest pest
management, who helped fight last year's San Diego area wildfires.

"Sudden oak death is not . . . like an insect, where you can track it,"
Jones said. "It's this invisible thing that's causing infections, and
we're going to have to live with it. Ultimately, what we'll be doing is
managing the forests for the disease to minimize the impacts."

Yet for arborists such as Edwards, who tends infected trees along
California's central coast, the advent of the pesticide was a milestone.
Until last October, the state had refused to certify a dozen suspect
cures that were being marketed to desperate homeowners.

"You notice I'm hugging this tree?" Doug Schmidt, a UC-Berkeley
researcher, asked as he measured the circumference of one giant oak by
wrapping his arms around its trunk. "First thing you want to know is how
much pesticide you're going to inject into the bark after you've drilled
your hole. Then you take your syringe out."

The state-certified phosphate-based treatment works by penetrating the
cambium, the layer between the bark and the wood core that is most
affected by the disease, Schmidt told the arborists. Once the liquid
moves past the inner bark layer, the oak tree starts releasing chemicals
to fight off the infection, much the way a vaccine engenders immunity in
the human body. Tree experts can encourage the tree's resistance by
spraying it with a topical application of the pesticide and by following
up with seasonal "booster shots."

But the Australian-manufactured treatment has limitations: Costs prevent
it from being used to treat whole forests, and the chemicals cannot
counter sudden oak death's ability to lie dormant in hosts as different
as potted rhododendrons and giant redwoods.

"This is a big step forward for saving individual oak trees and all oaks
that act as hosts. But beyond that, it's not clear how much of it is
inherited in the seedlings," Garbelotto said. "All this does is mask the
symptoms, but they can still move around."

In an attempt to halt the spread, federal and state authorities have
sunk more than $20 million into research and regulatory oversight of
hazardous materials in the past four years. Because Garbelotto's lab
confirmed that 37 different plant species can act as hosts for the
disease, the U.S. Department of Agriculture's Forest Service has been
investigating whether the pathogen (in either of its mating forms) could
attack eastern black oaks and pin oaks.

Last summer, the Forest Service conducted a survey in Virginia and six
other eastern states to determine local species' vulnerability to the
blight. It took several months for the insect and disease specialists to
sample enough ornamental shrubs and mountain laurels to come to a
judgment, but in October they determined that no symptoms of sudden oak
death have been detected on the East Coast or in the Appalachians.

"In all fairness, we don't really know what we would do if it were
introduced into the East," said Steve Oak, the Forest Service
pathologist who coordinated the survey. "It's not a foregone conclusion
that it would be an apocalypse, but this is really not something we want
to learn about as a consequence of it showing up."