Expert: Mick Bridge - 9/25/2008

Question
why is my  Kousa dogwood losing big patches of bark from the trunk to thelateral branches ? iI live in Rockville , MD. and this tree has never had any problems before now. There are nonsigns of insects on the trunk                          or on the leaves.

Answer
It is very difficult to diagnose problems without seeing the tree, but
http://www.hgic.umd.edu/_media/documents/hg12_001.pdf
suggests some possible answers.
C kousa is resistant to anthracnose, see
http://vvv.caes.state.ct.us/FactSheetFiles/PlantPathology/fspp086f.htm
but this sounds the most likely problem. Kousa can still suffer if there is high disease pressure. Are there other dogwoods, particularly C. florida around you? If they are also suffering then this disease may be the cause.
Are there any borer holes visible?

If this is the cause, the Connecticut website suggest some possible treatments.