I've got a large (> 60 ft) evergreen tree in the back yard that is in distress. The foliage is turning brown, and the symptoms are progressing from the base upward. I don't know if there's a connection, but extensive excavation on the property next door about 2 1/2 years ago definitely impacted the roots. Any suggestions that might help save this tree would be greatly appreciated.
Looks like classic symptoms of cypress root rot (Phytophthora lateralis)—heavy cone crop, dull foliage colour, growth secession, premature foliage drop. This is a disease that attacks Port Orford cedar/Lawson cypress (Chamaecyparis lawsoniana), and has been working its way through the trees in the Vancouver area for a couple of decades. Infection, which happens below ground via ground water, is essentially a death sentence for the species. I'm afraid there isn't anything that can be done. While I was in England this year, I saw a number of Lawson cypress that looked suspiciously like they were infected by the disease, though I have to say knowledgeable people say P. lateralis is not yet present in Europe.
As I understand it various failed Chamaecyparis lawsoniana tested by Phytophthora expert (co-author of book on the genus) down here were found to have other pathogens present, including other species of Phytophthora as well as at least one other genus such as Pithium. When I was told about this point expressed was that local syndrome is not axiomatically produced by P. lateralis. So it seems occurrence of losses to water molds in Britain and belief that P. lateralis is not present there are not necessarily inconsistent. In another instance I heard root samples of declining Acer macrophyllum in Seattle arboretum also said to have produced growths of multiple species of pathogens when tested.
