Dogwood trees thrive in well-drained soils with a pH of 5.0 to 6.5. They are sensitive to high or rapidly changing soil temperatures. Keeping the tree healthy is the first line of defense against insects, disease and health problems. Dogwood trees are susceptible to the dogwood borer, twig borer and club gall insects, which cause rot and decay in the tree.
Transplant the tree to a more suitable location if it fails to thrive in its current home. Choose a location with well-drained soil, in partial shade. Avoid planting in heavy clay or very wet soil. Plant the tree as deep as the root ball, no deeper. Transplant only during the dormant season in late fall or very early spring. Apply a layer of mulch around the tree, scooping it away from the trunk to retain moisture in the soil and prevent weeds.
Water the tree generously for the first year to prevent drought. Continue to water the tree twice weekly throughout the first year.
Fertilize the tree with a slow-release fertilizer annually. Apply the fertilizer according to the package directions directly to the mulch surrounding the tree.
Inspect the tree often for signs of insects such as the dogwood borer, twig borer or club gall. The dogwood borer lays eggs on the trunk of the tree–where they hatch and enter the tree at a point of injury. Careful pruning will prevent these entrance sights. Look for twig borers along branches that have brown or yellowing ends. Inspect for club galls along branches and twigs. Look for swollen twigs. Prune the infected twigs or branches below the point of infection for each of these pests and apply an insecticide to the tree, following the label directions.
Examine the tree for illness or disease. Spot anthracnose, discula blight, cankers and root rot are common problems with the dogwood tree. Various forms of fungus cause these diseases, except for root rot. Spot anthracnose attacks the leaves, stems, flowers and buds of the dogwood. Discula blight attacks the twigs and branches. It leaves a purple spot on the leaves of the tree and they usually do not fall in the autumn. Prune affected branches from the tree and spray with a fungicide spray annually to treat both spot anthracnose and discula blight. Canker leaves blackened, water-soaked areas on the bark of the tree. These are not usually controlled once the tree is infested. Avoid injury to the tree during pruning and mowing to prevent cankers from forming and discard affected trees. Root rot is common among trees planted in an inadequate location. Transplant to a well-drained location in a raised bed if necessary.