In recent years a whole lot of attention has been paid to Sudden Oak Death, a stem canker disease (Phytophthora ramorum) that has sickened countless oaks in California. I, too, believe that Sudden Oak Death is a particularly aggressive pathogen that requires our careful observation and study. To be sure, I often inspect the sick coast live oaks and tan oaks here in Big Sur and at least half have bleeding stem cankers.
Still, there are many other problems I am seeing in these forests that cannot be attributed to Sudden Oak Death. Pines are becoming infected with pitch pine canker, sycamores are sick with anthracnose, bays are toppling from a root collar fungus, and redwoods are losing their tops. It seems that something larger is going on . . .
I believe that the real problem is not pathological, it is ecological. This is a fire-adapted forest that is now deteriorating from years of fire suppression and neglect. The forest ecosystem is becoming overgrown and the soil is losing fertility. Add to that the occurrence of acid rain.
Hence, the use of ‘fire mimicry’ techniques to improve the health of the ecosystem, aka Sudden Oak Life. By clearing the woody understory and fertilizing the soils we are attempting to resuscitate fire-adapted trees and forests.
Although we have had many successes with this approach (see Case Studies) there are situations where the trees are so sick and stressed that, despite all our efforts, they cannot be saved.
Consider case study no. 20041129.6 in Fairfax, CA where a bleeding coast live oak was treated in November of 2004. Leith Carstarphen of Ecologic Landscaping and Daniel Brooke of Arboright collaborated in the work on this tree (see North Bay for results of other oaks treated here). The photos below depict the sequence of changes in the tree’s canopy over the past four years. Initially, the infected tree seemed to be showing some improvement, as is indicated by the two-year photo below. But by year three an unexpected complication arose with construction of a new garage at the base of the tree. At this point the tree had begun to show some early signs of deterioration. By year four the tree appears to be all but dead.
Photo caption: Coast live oak in Fairfax, CA, 2-yr results. Photo on the left was taken November 29, 2004, photo on the right was taken November 14, 2006 (Photos by Lee Klinger)
Photo caption: Same tree as above, 3-yr results. Photo on the left was taken November 29, 2004, photo on the right was taken November 29, 2007. (Photos by Lee Klinger)
Photo caption: Same tree as above, 4-yr results. Photo on the left was taken November 29, 2004, photo on the right was taken November 29, 2008. (Photos by Lee Klinger)
While the shock of construction probably hurt this tree, I have seen healthier oaks fare just fine under similar impacts of construction. I suspect that both the disease (Sudden Oak Death) and the construction were the proximal causes in the demise of this tree.
I take this oak as a reminder that many trees are simply too sick to be saved by fire mimicry or any other known treatment regimes. The obvious way to effectively deal with Sudden Oak Death is to intervene before the oaks become too ill.