Cercospora and septoria leaf spots are very similar in size and appearance. Spots caused by Cercospora species have tan-brown areas with diffuse borders. Septoria leaf spots are a dark brown purple in color, later developing light brown or gray centers with dark borders. Although insects often damage dogwood trees, the damage is usually minor. If the tree is planted in full sun with limited water or under other stress, the damage can be serious.
Most insect damage occurs on the trunk and branches of dogwoods.
The female moth lays eggs on the bark. The borers can become established only if they locate a wound or opening in the bark. Inside the tree, they feed on the cambium, which is where water and food-carrying structures of the tree are produced. If the cambium is destroyed, branches or the entire tree will die. Leaves of dogwoods infested with the dogwood borer will often turn red and drop early.