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Sudden Oak Death

Sudden Oak Death will affect virtually all gardeners in British Columbia, but is the cure worse than the ‘disease’?
by Art Drysdale
by Art Drysdale

email: art@artdrysdale.com

Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at http://www.artdrysdale.com


April 25, 2004

Since this article deals principally with Camellias, here is a shot from late March 2002 in Vancouver’s west end to give those of you who have never seen them, an idea of how glorious they are.
Author photo.

Though there has been little publicity about Sudden Oak Death (previously known as Sudden Oak Death Syndrome) in eastern Canada, it is indeed a major, major news story in British Columbia. It first came to light in Canada generally in March 2001, when the Canadian Food Inspection Agency (CFIA) placed interim regulations prohibiting entry of certain host plants from California and Oregon, as well as some European countries. I first wrote about it here on January 6, 2002.

Thought by most (but certainly not all) scientists to be caused by Phytophthora ramorum the ‘disease’ is not a fungus or a bacterium, but rather a member of a unique group of organisms called Oomycetes. Oomycetes share some characteristics of fungi but are biologically different.

Though there have been various (increasing and expanding) quarantines on nursery stock coming from California and Oregon (among other locations internationally), the nursery industry was able to live with them. Then came the announcement in September last year of much more strict regulations which led to the prohibition of all nursery stock from certain areas which meant the largest U.S. (California and Oregon) supplier of a wide range of nursery stock could not ship anything to Canada. Particularly affected by this was British Columbia, with its similar-to-Oregon climate and which depends heavily on shipments from companies such as Monrovia in Azusa California.

The announcement this week came from the CFIA, in conjunction with the B.C. Landscape and Nursery Association (BCLNA): there would be, immediately, a recall of all Camellia plants sold in the province since September 1 last year. The April 20 news release said, in part: The CFIA and BCLNA “are appealing to BC residents to assist in a recall of Camellia plants that were imported from Monrovia Nursery in Azusa, California. The recall is being conducted to remove any plants that may be infected with the plant disease Sudden Oak Death (SOD) from the environment. BCLNA [representatives] will be sent to the homes of people who own potentially infected Camellias, to remove them in a manner that will prevent spreading of the disease.

“Anyone who may have a Camellia from Monrovia is asked to: 1) Have ready the name of the garden centre where they purchased the Camellia and the approximate purchase date; 2) NOT to touch the plant. Leave it undisturbed in the garden. Suspect plants should be removed ONLY by qualified staff to prevent further spread of the disease; and 3) NOT to take the plant or its leaves to garden centres. (Plants can be tested only at an accredited laboratory.)

“An appreciation package, including a coupon that can be redeemed at a garden centre, will be given to each person that has a Camellia removed.

“The CFIA has been sampling plant material at Canadian nurseries and garden centres that received plants from California after being notified by US officials in March that CFIA has suspended entry into Canada of all plants from Monrovia Nursery and any SOD-susceptible plants from California, pending assurances by California that their exports are free of SOD. The CFIA is also continuing to survey, sample and test susceptible plant material previously received from California. It is anticipated that more premises may be found to be affected.”

So, now we can add SOD to the growing (pardon the pun) list ‘problems’ with which the CFIA are dealing, and in virtually all cases, dealing with them by removing, killing or culling thousands of trees, and now ornamental shrubs. In most recent history, first in 2000, it was the brown spruce longhorn beetle, the eradication (hopeful) of which lead to the destroying of tens of thousands of trees in, amongst other places, Point Pleasant Park in Halifax. Next, in 2002, came the Emerald ash borer, moving from Michigan into Essex County Ontario, and, beginning last year, the destruction there of tens of thousands of ash and other trees in a ring to try to confine the insect to one area. Then, in the Toronto/Vaughan area of Greater Toronto, beginning in September last year, we have the Asian longhorned beetle. Its control, buy quarantining a vast area and removing thousands of vulnerable trees, again supposedly to contain the spread of the beetle, is currently ongoing.

Finally, there is the destruction of currently in excess of 5,000 oak trees in Oakville Ontario, in order to try and “contain” the two-lined chestnut borer that is attacking stressed oaks (and other trees) there.

Let me return to SOD. One of the concerns is that not only oaks are affected. The ‘disease’ can be carried on and infect Rhododendron, Camellia, Viburnum, and Madrone (Arbutus), Douglas fir and many more trees and shrubs. Hence the removal order for the Camellias.

After reviewing a ton of printed material on this subject, it is quite apparent that not all scientists agree on what causes the ‘disease’ (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 Dr. Lee Klinger, who holds degrees (MAs and Ph.Ds) from the University of Colorado. He has been independently studying worldwide tree decline since the mid-80s. Lee Klinger 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 tree doesn’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.”, says Tara Treasurefield in a recent Sonoma Valley Voice. “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.

As reported by Annette Stark in the April 15 LA CityBeat, “Marin County [adjacent to San Francisco] botanist Ralph Zingaro has been treating trees, and reportedly curing them, by adjusting acidic soils with phosphates. He says the fungus is only opportunistic, and environmental causes are dominant.”

[As an aside, botanist Zingaro was recently served with a civil consumer protection lawsuit over his promotion and use of a fertilizer to combat SOD. He has been the subject of an ongoing inquiry by agriculture and district attorney officials who said arborists complained he had been touting the curative effects of a phosphite fertilizer product (formulated from neutralized phosphoric acid) before state regulators had approved a treatment for the disease. The case is to be heard May 5.]

Annette Stark in LA CityBeat also went further, quoting Don Dillon Jr., board chairman of the California Association of Nursery and Garden Centers, as “…urging scientists to recognize that California’s $3 billion wholesale nursery industry and 169,000 jobs are at stake. ‘Comments made by researchers--like when they found it on a wild rose in Sonoma [County], leading to the inference that all roses are at risk of spreading this disease--are ridiculous,’ he says. ‘It’s like saying all human beings have the potential of getting SARS; therefore all human beings should stop traveling.’

“The Sonoma rose findings involved a wood rose that was artificially inoculated with the fungus in a Berkeley lab. The announcement fuelled the controversy about what exactly causes SOD and how it can be controlled and cured.”

Still another aspect of SOD, is a controversy about whether or not the entire SOD programme is designed as a make work and “get grant money” boondoggle for academia, scientists and government (USDA) bureaucrats. Take for example, the statements of Bill Stringfellow, North American vice president for Agrichem, manufacturers of Agri-Fos a fungicide first reported by the University of California Berkeley as a ‘cure’, and later reduced in stature to a ‘“preventative’ for trees, which the pathogen has not yet reached. “The SOD effort is great big pork barrel project for the SOD task force and the USDA, which is getting huge government funds to cut down trees,” Bill Stringfellow argues. “So, this is job security, a retirement fund that’s worth millions of dollars.”

Similar sentiments have been expressed in Canada about the CFIA’s “fixes” for the earlier-named tree problems. Are all or some of these actions gigantic over-reactions? I guess it remains to be seen!

 

 


 

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