Back in 2008 Kevin Feinstein over at FeralKevin blog interviewed me about Sudden Oak Death. I don’t know if he posted the interview, but reading over it I see that the information is still relevant. With permission from Kevin Feinstein, here is the transcript of that interview:
KF: Lots of people have heard about Sudden Oak Death. It’s been reported in the mainstream and alternative news. Could you first tell us what is this Sudden Oak Death, what type of trees does it affect, and is it in the East Bay?
LK: Sudden Oak Death is the popular name for Phytophthora ramorum, a stem canker disease that has infected thousands of tan oaks, coast live oaks, and black oaks around California. It is one of at least three Phytophthora stem canker diseases that, along with dozens of other diseases and insect pests, are contributing to the problem of oak mortality in this region. And, yes, this disease has been found in the east bay.
It is important, however, to make the distinction between the pathogen dubbed Sudden Oak Death and the greater problem of oak mortality in California. Many kinds of oaks, including the white oaks that do not even contract Sudden Oak Death, are dying. In fact, it’s not only the oaks that are affected. We also see madrones, bay laurels, sycamores, pines, Douglas fir, and redwoods dying as well. So the question arises, is Sudden Oak Death the “causal agent” of oak mortality or is it an opportunist taking advantage of already stressed and weakened trees. My view is that forest health and fire ecology are so closely coupled that the suppression, or rather cessation, of fire in the landscape has caused overgrown, acidified, and otherwise unsuitable conditions for the oaks and other fire-adapted trees.
KF: What’s the worst case scenario here? Many fear that we’ll lose ALL our live oak and tan oak forests to this disease, putting a final blow in the destruction of the California environment.
LK: I suppose the worst case scenario would be for the decline to reach a point where the large amount of dead wood combined with a few drought years and an errant spark leads to highly destructive wildfires. Rest assured, however, that we will not lose all our oaks. They will likely return after the fires.
KF: How does Sudden Oak Death compare to the Chestnut Blight that has all but eliminated the once dominant tree in Eastern North America?
LK: I haven’t done much work on chestnut blight, but I do know that the chestnuts, like the oaks in California, were prized for their edible nuts by the Native Americans, who used fire to keep the trees healthy. Thus, I believe that the demise of both the oaks and the chestnuts may be ultimately tied to the disappearance of the native people.
KF: What is currently being done to help with SOD?
LK: There are two fundamentally different approaches to solving the problem of Sudden Oak Death. The disease model approach focuses on understanding the biology and genetics of the Phytophthora ramorum pathogen in the eventual hope of developing a fungicide to cure the oaks. To date, no cure has been found, so the current focus of this approach is largely on controlling the spread of the pathogen. Details of the disease model approach can be found at:
Alternatively there is the ecological approach, which focuses on an ecosystem-level understanding of the problem in an attempt to bring the sick trees and infertile soils back to health. This approach does not involve treating a particular disease or pest. Rather, it uses nutrient amendments to help boost the natural defenses of the trees. Details of the ecological approach are provided at:
KF: One interesting point of your talk that I attended was the man who is charge of the World Phytophthora Collection says that the P. ramorum disease has been here a long time. Could you say a little more about this for our readers? Why is this never reported by news sources?
LK: In 2005 I collaborated with Dr. Michael Coffey, a professor of plant pathology at the University of California Riverside and curator of the World Phytophthora Collection, on a proposal to the US Forest Service to study the ecology of Phytophthora ramorum. Prof. Coffey has been quite skeptical of the view of certain Phytophthora experts that this pathogen was newly introduced, and so we had planned to examine the question of how exotic was this pathogen. Needless to say the proposal was not funded, which is one reason why folks have not heard about the disagreement of experts on this important point. I recommend you contact Prof. Coffey directly to find out his current views on the debate.
KF: One really potent aspect of your research is that you’re getting results. Could you tell us about some of the successes and failures you’ve had in treating the California oaks? What methods are you using?
LK: Indeed, the results I and others are getting are very encouraging. Before-and-after photos showing the recovery of many sick oaks and other trees can be found on my website noted above. We are using a range of techniques depending upon the situation. These methods, which are essentially ways to mimic the effects of fire, include amending soils with mineral-rich fertilizers, applications of limewash poultices, clearing of overgrown vegetation from the trunks and beneath the canopies of the trees, root crown excavations, additions of compost and mulch, pruning away dead branches, burning of slash, and more. It is important to recognize that there is no silver bullet here. Simply spreading some ashes around a sick tree will likely not solve the problem. Also, we are finding that most severely-diseased oaks are not able to recover even with intensive care. So it is important to treat the oaks before they reach the point of no return.
KF: Fire suppression seems to be playing a big part in the decline of our oak ecosystems. Why?
LK: It turns out that fires are quite beneficial for oaks and other kinds of trees. As ecosystems age they tend to acidify. Fire is nature’s way of bringing the pH of the forest system back into balance. The ash from the fires neutralizes acids that buildup in the soil. Fire also thins out overcrowded forests and removes shrubs that tend to be hosts for diseases such as Sudden Oak Death. The native people of California understood all this, which is why they burned regularly around the oaks. Now, with the suppression of fire, the oaks are becoming ill. Case in point, scientists studying the role of fire and disease have found that in oak forests that have burned in the past 50 years the incidence of Sudden Oak Death is “extremely rare”.
KF: There has been a lot of talk about the aerial spraying of pesticides in California for the Light Brown Apple Moth (LBAM). Apparently, most entomologists agree that the LBAM has been in California for 30 years. This seems very similar to the attack of Phytophthora ramorum as a recently introduced “invasive” pest when perhaps this is not true. Could you comment on this?
LK: I am not an expert on the Light Brown Apple Moth, but I am of the belief that the use of pesticides to control insect pests, or using fungicides to control diseases, is not a viable long-term solution for tree health. If the tree is having problems fighting off pests and/or diseases, then it is probably lacking certain nutrients, meaning there is a nutrient deficiency in the soils. A well-pruned, undamaged tree of any kind growing in fertile soils should have no problem coping with pests and disease.
KF: My research indicates that the term “Sudden Oak Death” only receives 47 searches per day on the internet. Considering how monumental a problem this is, do you have any thoughts as to why so few people are searching for it?
LK: I suppose this may reflect the fact that Sudden Oak Death has been in the public eye since 2001 and not much has changed in the past few years. In the arena of the disease model, there really hasn’t been much progress towards finding a solution. I think people are starting to look elsewhere for solutions, which may explain why I’m starting to get more and more calls lately for information on the fire mimicry treatments that I and others offer.
Thank you, Kevin, for giving me the opportunity to speak on this important issue.