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Sudden Oak Death Roars Back

Richard Halstead
Marin IJ link to article
December 11, 2007

DONNA SHOEMAKER of Larkspur has raised more than $1,100 to cover the cost of special treatments for an ailing coast live oak tree that is believed to be infected with the sudden oak death pathogen - even though scientists studying the disease expect the treatments will prove futile.

"I've kind of adopted this tree," said Shoemaker, who looked on as the tree was doctored Friday in the King Mountain Open Space Preserve, adjacent to Larkspur.

Shoemaker's desperation illustrates the frustration many Marin residents are feeling now as the number of trees dying because of sudden oak death has spiked, say officials studying the disease.

"In the absence of a resoundingly effective treatment for trees that are already infected, I think she is not alone in grasping at straws," said Steven Swain, horticultural adviser with the University of California Cooperative Extension in Marin.

Scientists studying the disease say the upsurge in tree deaths comes after a lull of several years. They say the trees that are dying now were infected after warm spring rains in 2005 and 2006. Research has shown that production of the spores that cause sudden oak death spike during warm, wet weather. Despite its name, sudden oak death can take a year or more to kill a tree.

"Throughout the county, there is a whole other wave of coast live oak mortality, and it's just showing up right now," said Mike Swezy, natural resource specialist for the Marin Municipal Water District.

Since it emerged in Mill Valley in 1995, sudden oak death has killed tens of thousands of oaks and spread to at least 14 counties in California and Oregon. There is no known cure.

Swain said the new wave of tree deaths has yet to crest.

The majority of the trees that have died so far have been tan oaks, Swain said. Coast live oaks can take up to three years before they begin exhibiting symptoms, he said.

"We haven't really seen the beginning of the true coast live oak mortality as a result of the rains of 2005 and 2006," Swain said.

"My guess is we're going to see just as much next year with trees that took two years to die after the 2006 episode," said Rizzo, who along with a UC Berkeley scientist identified the fungus-like organism that causes sudden oak death.

County officials are scrambling to figure out how to pay for the removal of dead trees from along roadways, in parks and areas designated as fire breaks. Marin County Supervisor Judy Arnold said she submitted a plea to state Sen. Carole Migden, D-San Francisco, and Assemblyman Mark Leno, D-San Francisco, for $750,000 in state aid. She is still waiting for a definitive response.

"Sudden oak is worse this year almost than it has ever been," Arnold said. "The thing we're up against is the state budget and the lack of funding. Leno says it is just bleak up there because they're looking at a $9 billion deficit next year."

In 2001, the state allocated about $1.3 million to Marin and nine other counties affected by sudden oak death. Marin received $350,000 for hazardous tree removal. The state and federal government also provided $900,000 in 2003 to operate two collection yards where dead trees could be safely stored before being disposed of. One of the yards was in San Rafael. But the yards closed after their two years of funding ran out.

During the lull, officials scaled back funding to battle sudden oak death. Rizzo said last year was the first since the epidemic started that the U.S. Forest Service provided no new money for basic research. Funding for monitoring the disease was cut by more than 50 percent last year, he said.

Arnold said the Marin Municipal Water District has estimated it may have to spend another $50,000 to $100,000 a year to remove dead trees on its lands, in addition to the $100,000 a year it has been spending annually since 2001.

"The disease has completely covered our lands," Swezy said. Prior to the recent wave, there had been areas of the watershed's 21,000 acres that had remained unscathed. "That is not the case anymore," Swezy said.

Even trees at higher elevations have proved vulnerable.

"There was a thought that maybe there was an elevational limit to it," Swezy said. "Now we have tan oaks and live oaks at 2,000 feet that are showing up dead in large numbers. So much for that theory."

Swezy estimates the disease may have killed more than 100,000 trees on water district land alone.


Rizzo said sudden oak disease has become much worse in the Point Reyes area, and Ellie Rilla, director of the UC Cooperative Extension in Marin, said the disease has spread for the first time to the ranches of West Marin.
"We've been to groves on some ranches where the trees are all infected," Rilla said. "They're all bleeding, and chances are they're all going to die."

One of those ranches belongs to Mike and Sally Gale. Sally's mother's family, the Dolcinis, has owned the 600-acre ranch since 1862. Gale said she has identified one grove of about 50 trees where all the coast live oaks appear to be infected, and she suspects the disease is widespread on the ranch.

"Probably all of my oak groves have been hit," Gale said.

In addition to the effect on the local ecosystem, Gale is concerned that the loss of trees will accelerate erosion on the ranch. She has appealed to the Marin Resource Conservation District for funding to replace the dead trees. But Gale is in a quandary as to whether she should replant native coast live oaks or some other variety of oak that might be more resistant to sudden oak death.

"Different experts, if you ask them, will give you different opinions," Gale said.

A phosphate product, developed by the Australian company Agrichem, has proved effective in protecting uninfected trees from sudden oak death. It is much less effective, however, in helping trees fight off the disease.

Shoemaker said that is one of the reasons she hired Dr. Lee Klinger of Big Sur to treat the sick oak tree, even though his theories on sudden oak death fall outside the scientific mainstream. Shoemaker said she was looking for something that offered hope. Open Space officials gave approval for the treatment.

Klinger, who has a doctorate in forest ecology from the University of Colorado, maintains that an increase in the acid content of the soil - because of a proliferation of moss caused by prolonged fire suppression - has fatally weakened the trees. His treatments consist largely of adding alkaline-rich minerals to the soil around the roots of sick trees and applying lime to the trunks of the trees.

Rizzo said he and other researchers have looked at Klinger's theory and rejected it because of lack of credible evidence. Rizzo said trees in the eastern United States that have been subjected to acid rain have not shown any unusual susceptibility to disease. Also, Rizzo said Klinger has contended that the sick trees have weakened roots while, in fact, trees that die of sudden oak death die from the top down. The roots of the trees are typically the last part of the tree to die, Rizzo said.