Sudden Oak Life Announcement, Earth Day 2009

22 04 2009

Hope for California’s dying oaks

Findings reveal ‘fire mimicry’ practices improve oak health

Big Sur, Calif. – Despite being devastated by wildfires and ravaged by sudden oak death there is some hopeful news coming out of the oak forests of Big Sur. Results of a multi-year study show that the health of sick and diseased oaks is significantly improved with the use of mineral fertilizers and other fire mimicry practices.

According to case studies of 152 sick coast live oaks conducted by Dr Lee Klinger, an independent scientist and oak specialist living in Big Sur, improved canopy health was observed in 8 out of every 10 trees that were treated.

Oak trees

Hearst Castle oaks (photo by Lee Klinger)

Photo caption: Recovery of a treated coast live oak at Hearst Castle, California State Park. Photo on the left was taken January 4, 2006, photo on the right was taken January 2, 2008. (Photos by Lee Klinger)

The new results were published this month in the proceedings of an international conference of tree care professionals held in the UK in November 2008. The conference, organized by Treework Environmental Practice, brought together scientists from the US and Europe to discuss innovative and environmentally-friendly tree care practices.

Klinger’s work has been well received by tree care professionals in the UK where there is considerable interest in toxin-free alternatives. “We are encouraged by Dr Klinger’s results with the oaks in California, enough to want to explore his methods for improving the health and life expectancy of our mature and veteran trees currently showing signs of stress” says Neville Fay, Principal Consultant at Treework Environmental Practice.

Fay, a leader in conservation arboriculture in Europe, chaired the November 2008 conference Trees, Roots, Fungi, & Soils – Part 1 held at the National Museum in Cardiff, Wales where Klinger presented his paper. Klinger has accepted an invitation to present at Part 2 of this series, to be held this summer in London at the Linnean Society[1].

“Dr Klinger deserves to be acknowledged for presenting information that has widespread implications for all those involved in identifying tree stress and in improving tree health”, says Dr Olaf Ribeiro a noted forest pathologist in the US. He adds ”This well-researched and thought-provoking paper should be essential reading for arborists, foresters, ecologists and others who are involved in tree care”.

Ribiero is co-author of the book Phytophthora Diseases Worldwide.

Phytophthora diseases, like sudden oak death, are said by some to be the cause of the severe oak mortality seen in many parts of California. University of California scientists, however, have reported that the incidence of sudden oak death disease (Phytophthora ramorum) is “extremely rare” in forests that have burned in the past 50 years[2].

These findings back the theory held by Klinger and others that California’s oak forests are fire adapted and require periodic burning to stay healthy. Klinger states, “decades of fire suppression and hands-off management practices have led to overgrown and acidified conditions around the oaks” creating a ripe environment for pathogens and pests.

Klinger’s methods, then, are not directed at treating particular diseases or insect pests. Rather they are designed to improve the overall health of the forest by mimicking the effects of fire on soils and trees, but without all the smoke and flames.

To determine the efficacy of these methods, repeat photography of oak canopies was used to assess the leaf density changes for one, two, and three (or more) years of treatments. After three years, 81% of the oaks showed noticeable signs of improved canopy health.

Examples of the before-and-after photos of a treated oak are shown below, and others can be viewed at

Fire mimicry practices utilize natural products and treatment techniques designed to improve site conditions and soil fertility. These include clearing overgrowth, pruning dead branches, removing acid-producing organisms such as mosses and lichens, mineralizing the soils with AZOMITE®, applying lime wash to the trunks, and adding compost, compost tea, and mulch.

All of this is welcome news for property owners who are looking for greener alternatives to the spraying of fungicides or other toxic chemicals on their trees.

A copy of Dr Klinger’s recent paper can be found here.

For more information please email

[2] Moritz, M.A. & Odion, D.C. 2005. Examining the strength and possible causes of the relationship between fire history and sudden oak death. Oecologia, doi: 10.1007/s00442-005-0028-1.



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