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The Root of the Problem
Forest ecologist Lee Klinger, Ph.D., stands just beyond the grape arbor at the Laguna de Santa Rosa Watershed Preserve in Sebastopol. It's early October, and he's about to lead a workshop. Participants will whitewash an oak tree with a blend of mineralized rock salt, hydrated lime, crushed oyster shells, and water, and spread trace minerals and oyster shells beneath the tree. This is the way American Indians and other indigenous peoples protected trees from pests and diseases, and Klinger is trying to revive it. "We can't just leave trees alone," he says. "They need to be tended, as the Indians tended them. We've got a lot of work to do, just to catch up."
Before putting the group to work, Klinger announces that he's on a mission to alert as many people as possible that Sudden Oak Death (SOD) is a sham. "Almost all the dying trees can be saved," he says. "Most of them don't even show evidence of disease. For the ones that do, the disease is secondary. They just need nutrition," in the form of minerals that are rich in calcium. This is holistic medicine for trees.
The prevailing view of Sudden Oak Death reflects the thinking of the pathologists that defined it: identify the cause of a disease and do whatever is necessary to control it. According to this view, the cause of SOD is a fungus called Phytophthora ramorum (P. ramorum). To prevent it from spreading, infected branches and entire trees are cut away. Nursery stock that is known to carry the fungus is strictly quarantined, and forest officials urge hikers to wash the soles of their shoes, bikers to wash their tires, and dog owners to wash their pets' paws when they leave an infected area. This is conventional medicine for trees.
Two different approaches to protecting California's trees, one holistic, the other conventional. Which approach is more likely to save our trees?
Most Californians would probably vote for the conventional approach, which has the decided advantage of being the only one they have ever heard of. It has the seal of approval of recognized authorities, including the California Oak Mortality Task Force (a coalition of public agencies, non-profit corporations and private interests), the University of California, the U.S. Department of Forestry, the U.S. Department of Agriculture and the mainstream media, as well as U.S. Congresswoman Lynne Woolsey, U.S. Congressman Sam Farr and U.S. Senator Barbara Boxer. With such weighty support behind it, small wonder that since 1999, the conventional "solution" for SOD has attracted $50 million and that most of the money has financed P. ramorum fungus research projects.
Recognized authorities notwithstanding, Michael Prudhomme of San Anselmo, who whitewashed his first tree at the Sebastopol EcoFest workshop, prefers Klinger's approach. "It makes total sense to me," he says. "I have lots of healthy oak trees and a few that appear to be sick. I'm very interested in learning ways to care for these trees."
Landscape gardener Scott Gough, who is caring for the trees on 1,000 acres of land in Lake County, also believes that Klinger is on the right track. "What he says makes much more sense to me than anything else I have heard," Gough says. "He has the comprehensive picture of the whole thing that's going on with Sudden Oak Death. That's a big deal."
It really is a big deal. Klinger has led research projects in forest ecology worldwide for 20 years, for the National Center for Atmospheric Research, the University of Oxford, the Chinese Academy of Sciences, and other prestigious institutions. Explaining what prompted him to settle in California in 2002, Klinger says, "A major driving force was the fact that Sudden Oak Death was here, and I knew I had a treatment and I knew it wasn't the fungus that was the primary cause."
Back then, Klinger had high hopes of collaborating with plant pathologist David Rizzo and forest pathologist Matteo Garbelotto, two respected University of California scientists who serve as science advisors to the California Oak Mortality Task Force. But they turned him down. Problem is, Klinger sees the fungus that Messrs. Rizzo and Garbelotto consider fatal as nothing more than an opportunistic species that takes advantage of trees that are already dying of other causes.
Explaining that P. ramorum kills a tree by growing a canker around the trunk, and that the canker "bleeds" black sap, Klinger says, "Most of the oaks that are dying do not have bleeding cankers. Given this, P. ramorum is not the best explanation for why the oaks are dying." A better explanation for the cause of tree death, he says, involves moss, soil acidification and tree roots.
Klinger's theory about tree death came together in 1985, when he was researching a massive decline of old-growth trees on Kruzof Island in southeastern Alaska. One day, he noticed that wherever trees were dying, thick growths of moss covered the ground and the trunks. On a hunch, he began digging and probing with his shovel, and discovered that there were no roots in the soil under moss mats. His data later confirmed that mosses are highly-acidic and that acid runoff from moss causes soil acidification. Acid rain, acid fog and other factors also contribute to soil acidity, which kills tree roots. And that, according to Klinger, is what's really killing most of the trees that are dying in California and other parts of the world.
In addition to causing tree roots to die, says Klinger, "Left unchecked, mosses degrade bark and create spaces where fungi and beetles can get in. The moss will very slowly bring a tree down. People must tend trees, and keep moss off them with whitewash. Bark is like skin, and whitewash decreases acidity. But calcium is just a start. Trees need trace minerals, too." Klinger's work on mosses has since been confirmed, peer-reviewed, and published in several scientific papers.
Klinger's research on peatlands, which he has shown are the climax species of forest ecosystems, has also been confirmed. "There are lots of ancient peat bogs on Kruzof Island, many older than 8,000 years," he says. "I excavated the bogs. Buried beneath them, I found large stumps and other remnants of the old-growth forest, a younger stage in the development of the ecosystem." Intact stumps of oak forests have also been found beneath peat bogs in the British Isles. Klinger believes that in 1000-2000 years, peatlands -- bogs, fens, and swamps -- will replace many of the old-growth forests of today. "They'll remain peatlands until they're destroyed by fire, glaciers, floods or a rise in the sea level," he says.
Klinger's findings baffle plant pathologist Ted Swiecki of Phytosphere Research, a plant science consulting and research firm in Vacaville. "Trees have had mosses growing on them for centuries," he says. "Trees are capable of sustaining moss on their bark. Lichens grow on trees; they're happy. It grows on healthy trees and diseased trees and has no effect. Anything that grows equally commonly on trees has no effect."
But consulting arborist Ralph Zingaro of BioPest in Petaluma also believes that acidity is a problem, and he wants to make sure that California's forests don't evolve into peatlands during his lifetime. "It's up to the people of California," he says. "Do they want a bunch of dead trees, or do they want a bunch of live trees? The trees need a good dose of calcium. Otherwise, we'll just let nature take its course and we've got a bunch of dead trees. There's nothing wrong with that. Let nature take its course. Some people will say, 'Great! I need the firewood.'"
No Magic Bullet
Pat Robards, forest ranger at China Camp in Marin County, is a great fan of the California Oak Morality Task Force. "The Task Force is just incredible," he says. "A completely unknown disease was addressed so quickly and thoroughly by scientists. This was like being able to watch the Black Plague and identify the cause of it and prevent its spread." He hastens to add, though, that it's not over, not by a long stretch. "What we're looking at now is an unknown wave coming at us," says Robards. "For example, some large, very beautiful huge trees were still producing green leaves with P. ramorum all over the trunk. They're dead now. In China Camp, if they were anywhere near a targeted area, we felled the tree. Early last summer we took about 170 trees out, and 99% were coast live oaks and black oaks. The trees we didn't cut down are still falling."
Trees will soon be falling in Humboldt County, too. "We're not going to eliminate [Sudden Oak Death]," says U.C. plant pathologist David Rizzo. "[But] in Humboldt County, where it's just getting started, we can target it and really slow down the spread of it. We can manage it aggressively by removing branches and some trees that are showing infection." To that end, forest monitors in Humboldt County are on the lookout for black spots on the leaves of bay laurels and tanoaks. "[The black spots] are dead tissue and P. ramorum hides inside them," says Rizzo. "During rainstorms, P. ramorum comes out and can affect new leaves."
Rizzo and Garbelotto also recommend the one brand of phosphite (a chemical compound) that the Department of Pesticide Regulation has approved to protect oaks and tanoaks from P. ramorum. Arborists have used potassium phosphite fertilizer for many years, and in 1998, Zingaro discovered its effectiveness with oaks that are showing signs of stress.
In 2002, after Zingaro persuaded him to conduct some experiments with phosphite, Garbelotto was suitably impressed with the results. Last year, he developed a new way to apply the approved brand. "The reason trees are not treated in general is because though you may have a product that works well, there is no way to make it go where it's supposed to," he says. After considerable research, he found a way to deliver phosphite directly to the P. ramorum fungus on tree trunks and make it stick. "You just spray the compound on the bark," he says. "Many scientists around the world are trying it and having positive results."
But impressive as the short-term results of phosphite may be, it wouldn't be accurate to describe it as a magic bullet. Though the brand approved for use against P. ramorum is classified as a fungicide, it doesn't kill the fungus. "It doesn't directly affect P. ramorum. It simply enhances the defense mechanism of the plant," says Garbelotto. In addition, the manufacturer cautions that its product may lose disease resistance with repeated use at high rates. Accordingly, Garbelotto says, "We don't want to overuse the product because the pathogen [fungus] will develop resistance. Use it where it's going to make sense -- if the tree is not infected yet, but is at high risk; on trees that are in the early stages of infection; on trees that are closest to the infection site."
As David Rizzo and Matteo Garbelotto continue to focus on P. ramorum, other researchers are finding evidence of acidification in California soils. Under a grant from the California Department of Food and Agriculture, Robert O. Miller, an affiliate professor of soils and crop sciences at Colorado State University, tested the acidity of 50,000 samples of California soils, most from agricultural land, some from forested areas. "Statewide, we found that 22% of the soils were moderately or strongly acidic and 4% were very strongly acidic," he says. "I'd expect the agricultural market to be putting a lot of lime on their soils." Over the past two years, Klinger and Zingaro have collected 130 soil samples from forested areas infected with P. ramorum. After comparing Miller's data with the samples he and Zingaro have collected, Klinger says, "The Sudden Oak Death soils are much more acidic than what Miller is finding."
Arborist Craig Peterson, who owns Arborworks in Marin County, is also testing soils for acidity. In addition, he says, "I'm handing out free pH test kits to any other arborist that wants them. We've always been told that the coastal soils here are rich in calcium and that they're always neutral or alkaline. I have not gotten one alkaline reading. All the trees are suffering from a lack of calcium."
But what strikes other researchers as "too acidic" is normal to Rizzo, Swiecki, and consulting urban forester Ray Moritz, who serves on the Task Force's Executive Committee. Moritz says that during all 27 years that he has been testing Marin County soils, they have been slightly acidic. "The neutral or alkaline soils are the exception, not the rule."
Moritz also disputes claims that acid rain affects Marin County soils. "Sudden Oak Death made its first recognized infestation in Marin County, where 85% of the time the winds are out of the west-northwest off the ocean. There is virtually no industry in Marin County, and the first infestations and the first huge dieoffs of tanoak were west of the freeway. Where would that acid rain come from?"
How about from the ocean?
"The ocean off the California coast is not producing as much acidity as further north," says Klinger. "But it is a significant amount. The closer you get to the coast, the more acidic is the rainfall and the more acidic is the soil. The lower the calcium in the soil, the closer you get to the coast."
Still, Sudden Oak Death researchers see no evidence that soil acidity and acid rain are harming California's oak trees and no evidence that calcium would help them. "I have yet to see any sound data that any of our forest trees are calcium deficient," says Ted Swiecki. "Calcium deficiency has various symptoms, and they don't show up on our trees. If a tree is in a more stressful situation or it's declining, it tends to be at much lower risk of developing the disease. We don't know exactly what controls it, but relatively vigorous trees are the ones that are [getting P. ramorum]."
That's reason enough to avoid calcium, says Garbelotto. "One of the main concerns that I have regarding the use of calcium is that it appears that plants that are very healthy become more susceptible to the disease. P. ramorum likes plants that grow very well because they produce a lot of sugar. To use anything that would potentially improve the general health of the tree may not necessarily mean that it's going to be protected from Sudden Oak Death." Cornell University forest ecologist Tim Fahey, Ph.D., couldn't disagree more.
"It would be highly unlikely that making trees more healthy would make them more vulnerable to disease infections," says Fahey, who witnessed a striking regeneration of sugar maple seedlings after calcium was applied to a forest damaged by acid rain. Scott Gough is also getting encouraging results with calcium. Last spring, he began treating the stressed trees under his care with whitewash, crushed oyster shells, and trace minerals. "I have been watching these trees for five years," he says. "The ones we treated in the spring showed signs within a month or two of clearly different, new, vigorous growth patterns. It's obvious that they are getting better."
In January, Klinger will make formal presentations on two papers at the Second Sudden Oak Death Science Symposium in Monterey. One of the papers is about acid rain and soil acidity. The other is about the treatment that native peoples used to protect the trees they relied on for food, shelter and fuel. Though he's grateful for this opportunity, Klinger wishes he could reach more Californians. "If they could just know that there's a simple, non-toxic treatment that has been used for thousands of years, and that all this talk about the fungus killing the trees is driven by the disease model, and the disease model isn't working in human health and it doesn't work in tree health either.
"If they could just know that the ways that indigenous peoples cared for trees is tree care at its finest."
North Bay Bohemian
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