Vintage oak trees are dramatic and beautiful complements to many Marin County homes. Millions of these trees, plus California bay, Douglas fir, and redwoods are under attack and have been killed by Sudden Oak Death (SOD).
I found in the the Marin Independent Journal (Saving oak trees from SOD) a hopeful cure and preventative for your trees. The method, proposed by William Binzen of Woodacre, is simple, inexpensive, and non-toxic. There are two steps:
- Spray the bottom 6 feet of the tree with a phosphate fertilizer. This is a standard part of all garden fertilizers.
- Apply calcium, lime, ground oyster shells, etc to the soil around the tree to lower the pH of the soil.
Carry out this procedure twice a year for compromised trees or once a year to protect healthy trees. For a longer discussion of why and hoe, see this article from the Marin IJ: Saving oak trees from SOD.