any pictures? Dogwoods can get several foliar diseases, but much fewer foliar insect problems. At this point in the season, I wouldn't do anything with fall approaching. As the leaves fall in the fall (autumn) clean them up and burn them or bag them. Next year, look for the problems early.

Don't they have pretty bad anthracnose up north?

I'm new here, but would like to share my experience with dogwood.

Dogwood anthracnose is quite a problem in my region of the northeast, so many people are turning to cornus kousa instead, as it seems to be resistant. I prefer our native cornus florida, however, and the two in my yard are doing fairly well, despite an annual bout with anthracnose, especially considering they're over 30 years old (all the authorities seem to feel that's about the max lifespan for a dogwood). They were here and over 10' tall when we moved in in '77, so precise age is unknown. They're growing as undestory trees, in the dappled shade of very tall, limbed-up oaks; I water regularly and feed lightly in spring and late fall. Some years the symptoms were worse than others, but now that I've identified the problem and have been giving the trees a little TLC, there seems to be gradual improvement - each year the symptoms appear later and are less severe. FYI, we live in an area with a very sandy soil, so it's drier and poorer than these trees would generally like.

Is there an agricultural extension office nearby where you could take a sample of the affected leaves? They could probably ID the problem for you, as well as give you treatment recommendations ... all for no fee (it's through your state university).

Good luck with your dogwood. They are lovely native trees and worth the effort.

You're correct about Discula. I usually forget about that one since we don't find it very often down here, and if we do it's in the form of leaf spots. We're too hot for it usually.

Thanks for all the replies... It is most definitely anthracnose....Is there anyhting I can do NOW to halt the progress of the disease ? Any suggestions would help..I am not really in favor of using systemics or the like, but would do so to save my tree....
Thanks,
Joyce

From Rutgers Publication E160 (from results in link below):

Dogwood anthracnose or decline caused by the fungus Discula, is primarily a disease of flowering dogwood (Cornus florida). Tan colored leaf spots with purple margins form on developing leaves and flower bracts. These spots grow together, forming large blotches on leaf blades and along leaf margins. Infected leaves eventually die. The fungus may continue to grow down into the petioles and branches, resulting in the death of twigs and branches. Brown, elliptical cankers may form at the base of dead branches. Drought, winter injury, and environmental stress predispose dogwood to anthracnose. Kousa dogwood (Cornus kousa) is resistant to this disease.

Proper Management
Improve plant vigor, avoid moisture stress, avoid wounding,
and prune affected branches 6 to 8 inches below diseased tissue during dry weather with sterilized pruning tools. Avoid planting dogwoods in shady or crowded areas.

Chemical Control
Chlorothalonil provides fair control of the leaf spot phase
of this disease only. Apply the fungicide according to label
recommendations.

I expect you'd find similar information on the Cornell extension website.

The Rutgers report on Trees and Shrubs from the 2008 Spring Flower Fair mentions two cornus florida varieties with anthracnose resistance: 'Appalachian Spring' and 'Cherokee Chief'. I hope it won't be necessary, but if you wind up having to replace the tree, maybe consider those cultivars.

Here is a link that might be useful: Rutgers Search Results

I have a Kousa Dogwood that is about five years old and this year the leaves have turned brown and the bark is peeling. No other trees or plants in the vicinity are having problems. I have left it alone since I planted it and it has done fine until this year. What could be happening and what could be done? Again, the key is that no one has ever given special treatment to this tree and it has always looked fine AND everything else around it is doing fine currently except the Kousa Dogwood.