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Supporting an alternate approach to Sudden Oak Death!

April 28, 2008  By Art Drysdale

Last year in our August/September issue I wrote in detail about Sudden
Oak Death (SOD). Amongst other ideas, I said that the Canadian Nursery
Landscape Association was attempting “to develop and implement a
Canadian Nursery Certification Program for exporting nurseries. The
USDA is apparently considering implementing a similar program to
complement trade with Canada. Only the Netherlands has such a
certification programme for growing nurseries in place at this time.”

Last year in our August/September issue I wrote in detail about Sudden Oak Death (SOD). Amongst other ideas, I said that the Canadian Nursery Landscape Association was attempting “to develop and implement a Canadian Nursery Certification Program for exporting nurseries. The USDA is apparently considering implementing a similar program to complement trade with Canada. Only the Netherlands has such a certification programme for growing nurseries in place at this time.”

I also cited the work of Lee Klinger who has degrees (MAs and PhDs) from the University of Colorado. He has been independently studying worldwide tree decline since the mid-80s. He has researched ecology and complexity for more than 14 years at the National Center for Atmospheric Research in Boulder, Colorado, leading and conducting studies to characterize all the major ecosystems, from arctic Alaska to central Africa. Recognized as one of the world’s leading scholars in this area, Lee Klinger has presented novel works about the fate of old-growth forests, origins of the peat lands and how they all relate to ice age initiation. His achievements include the discovery of the primary cause of forest decline.


In the August issue, I wrote: “It is quite apparent that not all scientists agree on what causes SOD (whether it is Phytophthora ramorum alone, with other factors, or at all). For example, disputing the idea that P. ramorum is the primary cause of SOD, some scientists are dubious. “Even if you take the strictest definition of SOD – the Phytophthora pathogen – there are still problems, the most serious one being that the mosses were not controlled (or accounted for) in their test,” says Lee Klinger, who built his career on studying mosses and first published about their effect on tree roots in 1991. He maintains that mosses might be killing the oaks.

Additionally, Lee Klinger believes that only trees with SOD are being studied. “If the trees don’t have SOD, they’re not studying them.” And, he says, “Most of the trees that are dying have no sign of Phytophthora.”

In 1985, when he was researching tree death and forest decline on Kruzof Island off the coast of Alaska, Lee Klinger “noticed that dying trees and the ground around them were covered with moss.” His 20 years of research data support his contention that moss runoff, which is highly acidic, increases the acid content of the soil and contributes to yellow cedar decline in Alaska, sudden oak death in California and Europe, and similar epidemics of dying trees and forests. The simple, non-toxic, and universal solution to tree death and forest decline, says Dr. Klinger, is to reduce soil acidity.

“There are many ways to reduce soil acidity. Scientists at Hubbard Brook Research Foundation in New Hampshire, and at Cornell University in New York, are doing it by treating declining forests with calcium and other minerals. In the 1980s, German scientists reversed the decline of the Black Forest by using lime to reduce the acidic content of the soil. And long ago, Native Americans revitalized dying forests with fire, which also decreases the acidic content of the soil.”

Additional information is now available. For example, here is a quote from a draft of a paper (by Lee F. Klinger, Ralph Zingaro and Michael Coffey) in preparation for the Journal of Forest Ecology and Management. “Data on pH from 34,700 soil samples taken from a wide range of agricultural and forest soils in California indicate that between 14 and 21 per cent of the soils are acidic (pH < 6.0) and three to four per cent are strongly acidic (pH < 5.0). However, a subset of samples taken from SOD-affected sites indicates that 72 per cent of these soils are acidic and 4 per cent are strongly acidic. The soils from these sites were also found to be consistently low in calcium and very high in soluble aluminum and iron. These results lend further support to the theory that systemic acidification is adversely affecting the health of the trees and soils in SOD-affected forests. The situation described here in California is not unlike that in other regions of the world where aging forests are experiencing decline. From this and other work (e.g., studies at Hubbard Brook), we strongly believe that the cause (and the definition) of SOD is still an open question, and that the scope of SOD research should be expanded to include studies of acidification by cryptogams in the context of forest and soil ecology.”

Ralph Zingaro, whom I also mentioned extensively in last year’s item on this subject, was this year invited to the Acid Rain 2005 conference in Prague, the Czech Republic, to deliver the paper from which the foregoing quotes are taken. There he also met with Paul G. Schaberg of the USDA Forest Service Northeastern Research Station in Vermont. The latter is heavily involved in work on calcium depletion and how it has predisposed trees to forest infections.

In a recent Oecologia (a peer-reviewed journal from Springer – Verlag) a lengthy paper by Max A. Moritz and Dennis C. Odion, discusses “Examining the strength and possible causes of the relationship between fire history and Sudden Oak Death.” Amongst many findings and conclusions they found “that wherever a fire has occurred within the past 50 years there is no SOD.”

The single-minded focus of California (and other) scientists on a fungus is difficult for Lee Klinger to understand, particularly since he sees the same fungus as 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, Lee 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, according to him, is a bit more complex, involving mosses, soil acidification and tree roots.

Professor Klinger adds, “I have not seen any peer-reviewed published papers on soil chemistry or root analyses related to SOD,” he says. “Mosses, which are clearly implicated in soil acidification and the mortality of fine roots, and are abundant in all areas of SOD, have not been carefully investigated or controlled in any of the research or experiments on SOD. These analyses are basic science that should be done in any forest decline situation. Until they are done, the cause of SOD cannot be determined.”

The discovery of a red oak tree in New York State infected with SOD could force changes in a nationwide quarantine of California nurseries as scientists re-evaluate the spread of the mysterious microbe.

In response to Ralph Zingaro’s discovery of P. ramorum in New York State, the local USDA people located an infected tree in the same location in July last year. He also found oak trees infected with SOD in Pennsylvania and New Hampshire. The New York State find was in the Tiffany Creek Preserve, a 77 hectare (192-acre) nature park in Nassau County, nowhere near any nurseries that might have received diseased flora from California.

Forestry experts are at a loss to explain how the pathogen got to the preserve or how long it has been there. The fungus-like organism has, until now, never been found in the wild, outside of the coastal regions of northern California and southern Oregon.

“The finding in New York raises more questions about the distribution of P. ramorum throughout the United States,” said Don Dillon Jr., chairman of the board of the California Association of Nurseries and Garden Centers. “If it has been there for some time, it raises questions about the whole nature of the pathogen. It may be naturally occurring in other places. It could have come from back east and spread here.”

The New York oak tree’s lack of any apparent connection to California is particularly troubling to regulators and puzzling to scientists. It could mean that Phytophthora ramorum is a naturally occurring pathogen that already exists throughout the country and, possibly, throughout the world. If that is the case, then there is no reason for California nurseries (or others elsewhere) to face restrictions. In fact, the tack taken by the Canadian Nursery Landscape Association, which is bound to be costly, may be fruitless. It might well be better if they were to help fund an independent research project such as that I’ll mention at the end of this article.

Lee Klinger believes sick oak trees just need a healthy dose of vitamins. Now he just needs to convince a skeptical science community that he has an easy cure to Sudden Oak Death.

He tried to do just that January 18-21 this year during the Sudden Oak Death Science Symposium at the Marriott Hotel in Monterey, California where hundreds of scientists converged to share their findings about the disease that has killed thousands of trees since the mid-1990s.

Much of the talk centred on where the infections have occurred, possible ways the disease is spread and what type of trees are affected. Research on treatment is still preliminary and will take years to sort out, scientists say.

But Lee Klinger says he can help save many of the sick trees if he can just get researchers to listen to him. But so far researchers in California are not convinced. He said scientists are going down the wrong path by looking at pesticides and fungicides as possible cures. Ralph Zingaro said much of the work being done by sudden oak disease researchers is a waste of taxpayer money.

“We need more common sense injected into the discussion,” Ralph said.

There is at present an application by Lee Klinger and others for a relatively small and economical research project (US$49,000) that will prove, once and for all, that P. ramorum has been in forests all along. That remains the critical unresolved question in this scientific debate. The abundant production of certain spores by P. ramorum and the general properties of such to survive in soil provide an opportunity. Though their survival in soil may be measured in years, these thick-walled structures are likely to persist intact, especially in peat soils. If P. ramorum were to be shown to occur in soils and/or sediments older than 50 years, then the debate might be settled.

Therefore, they propose to investigate carefully, buried soils at three sites in northern California. At two sites the soils have been buried (due to landslides, which will be confirmed using aerial photographs), or in peat bogs, which can be dated using radiocarbon analysis. Soils in all three areas are near present rampant infections of P. ramorum and have been totally undisturbed for 50 or more years. This will determine whether or not the preserved materials contain evidence of P. ramorum, especially the spores. If they do reveal spores, then that evidence should surely get the research onto the proper track. And, calcium may become a valuable commodity for garden centres. If you wish to know more about the $49,000 research project, contact Ralph Zingaro at

Another valuable resource on this topic is a new non-profit organization, the Sudden Oak Life Task Force. It was created this year to investigate, educate, and implement solutions to Sudden Oak Death and other tree diseases. The Task Force is open to anyone interested in healing the ancient trees. You may check it out on the Web at

Art Drysdale, who broadcasts on gardening daily to one of the largest radio gardening audiences in Canada on Ontario’s AM740, as well as on Easy 101 covering most of southwestern Ontario, also hosts two new TV gardening vignettes weekly on Shaw Cable’s Vancouver Island network and may be reached by e-mail at, or check his website at:

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