If your dogwood has started bleeding orange, don't worry --- it's not sick or dying. Although the orange goo can look horrible, it is not due to anything inside the tree, but rather something feeding on the sap. Dogwoods can bleed after being pruned or injured. Although there is very little you can do once it occurs, you can take steps to prevent the bleeding in the future once you understand what caused it.
In actuality, your dogwood isn't bleeding orange sap. Its sap is being turned orange by yeast and fungi, such as Cryptococcus macerans, that store energy in carotene-filled sacs. Carotene is what gives carrots its orange color. The yeast feeds on the high sugar content of the sap. As the yeast spreads, it makes the sap look orange.
Why Dogwoods "Bleed"
Dogwoods are considered "bleeders." Bleeding occurs when a tree is injured or pruned in the late winter or early spring before it flowers. The dogwood mistakenly brings up sap to the injured area, thinking that it is needed to produce the flowers. It doesn't seem to understand that there is no place for the sap to go, and the sap ends up flowing out of the tree. Maples, butternuts, walnuts and birches are other bleeding trees.
Once a tree has been injured, there is nothing you can do but wait for it to heal itself. The bleeding itself does not do any major damage to the tree. Covering wounds with wound dressing will not stop a tree from bleeding and can do more harm to the tree by increasing moisture levels around the wound. If the sap bothers you, or if it is softening the bark, you can remove it with soap and water. Eventually, the tree will stop sending sap to the damaged area, usually in the early summer.
In the future, you can prevent your dogwood from bleeding by pruning it later, in the early summer when the leaves have formed on the tree. Dogwoods should not be trimmed in April or May because it makes them susceptible to borers. Making smaller cuts that are less than 3 inches in diameter also helps minimize bleeding.