Hello Bryan, I don't have the answer you're looking for quite yet but will ask a couple more questions. In general, tell us about the tree and where it is. Things like size, how long its been in the ground, how much sun does it get, any new paving work nearby, has it been a wet or dry, warm or cool spring and early summer? I'm rather new myself so I'll take a guess and see if the more experienced folks here agree.
Hi Mark The tree is located in White Rock , B. C. Canada 40+' tall Years & years ( mature tree ) Good sun exposure No new paving near by , but the house that was built by it is fairly new , 4 years old . Wet , wet ,& more wet Cool , and more cool I did more research last night to see if I could nail it down and the only thing that really jumps out is , Dogwood Anthracnose . It is my neighbours tree and they are not gardeners so I was trying to help them out . They have had the problem for a couple of years now at least .
Bryan, you might want to use the Search option in the above title bar for "Dogwood anthracnose". Quite a bit of discussion that may help.
Leaf wetness is the primary issue, and many species of Cornus, Acer, Platanus are known to be very susceptible to Anthracnose in the region.
We have this problem with our Dogwood too and have recieved conflicting advice on the prognosis. We've been told the fungus will eventually kill the tree, but we've also seen that in a dry year it seems to clear up and looks fine. We already have a dying cherry tree and would rather not lose two big trees on our property!
