A holistic approach to mitigating pathogenic effects on trees

25 12 2009

For those of you who would like to read more about the details of the science and techniques involved in fire mimicry practices for oak restoration, here is a paper I wrote last year:

A holistic approach to mitigating pathogenic effects on trees

by Lee Klinger MA PhD

Presented at: Treework Environmental Practice Seminar XII
National Museum Cardiff, Cardiff, UK – 13th November 2008

Summary

The conventional ‘disease model’ approach to tree health focuses on identifying and controlling a specific pathogen (or pest) implicated as the causal agent of tree decline. Alternatively there are more holistic approaches in tree health that address a broader suite of processes occurring at the ecosystem level which may be predisposing the trees to infection by disease. Here I describe a holistic methodology that takes into account not only the proximal agents involved in tree decline, but also the age and structure of the forest, the abundance of cryptogams, the fire history, the acidity of the precipitation, the fertility of the soil, and the historical land care practices. This methodology is being implemented in the oak forests of coastal California which are experiencing high levels of mortality attributed, by most scientists, to the pathogen Phytophthora ramorum (aka sudden oak death). Evidence reported here of 1) acid rain, 2) acidifying effects of mosses and lichens, 3) the presence of acidic and nutrient deficient soils, and 4) a much lowered incidence of disease in recently burned areas, points to the likelihood that fire suppression has radically altered the structure and successional status of the forests, leading to enhanced competition and systemic acidification. Case study results of sick and diseased coast live oaks receiving holistic care, aimed not at treating P. ramorum but at reducing the environmental acidity, fertilizing the soils, and otherwise mimicking the effects of fire, show noticeable improvement in the health of the oaks after one year (78%, n=152), with further improvement in years two (84%, n=134) and three+ (81%, n=80). While the results do not indicate that the incidence of P. ramorum has changed significantly in the population of treated oaks, there is evidence that the sick, non-diseased trees are better able to resist infection.

Download the complete paper here.

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4 responses

27 12 2009
alberi

I read the entire paper- well done. I agree that there is ample evidence that soil acidification is predisposing trees to infection. Perhaps your new data should be added to the paper we presented at the COMTF meeting a few years ago and present this again?
What is also very interesting is that the calcium-mineral additions are not effective in reversing already P ramorum infected trees. Perhaps it would be wise to utilize the potassium phosphite (Agrifos) as part of an integrated pest management program ?

27 12 2009
Lee Klinger

Hi Ralph – Is there data showing that Agrifos is curing oaks infected with Phytophthora ramorum? I’m not aware of any such findings, but let me know if I’m wrong about this.

29 12 2009
alberi

You are correct, they only recommend using agrifos as a preventative. However, agrifos is labelled for the control of P ramorum on oaks, which means that it is proven effective. But as you know, every tree is different. Why not utilize an integrated program of cultural and nutritional strategies along with along with the agrifos?

29 12 2009
Lee Klinger

alberi – Because I haven’t seen results with Agrifos that come anywhere close to the results I’m getting with fire mimicry. If you know of such results please correct me.

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