There are several common dogwoods in the landscape, but the three most common species found in the PNW and B.C. are the Pacific (,C. nuttallii), the Eastern or flowering (C. florida), and the Kousa or Korean dogwood (C. kousa). All are spring flowering with white to pink blooms, and susceptible to varying degrees to several disease or insect pests.
Culture for Dogwood
Performs best with well drained, slightly acidic soils. All are considered part shade or understory trees, but Kousa dogwood can perform well in full sun. The white or pink showy dogwood flowers are actually modified leaf bracts.
Concerns about Dogwood
Dogwood anthracnose (Discula destructiva) is the most significant disease. Eastern dogwood is highly susceptible and may be killed by the fungus. Pacific dogwood is unlikely to be killed, but may be defoliated, while Kousa is mostly resistant. Spot anthracnose (Elsinoe corni) and powdery mildew are also foliar diseases of concern, and Kousa is again the most resistant. Deeply planted or drought/heat stressed trees may be attacked by the clearwing moth ‘dogwood borer’. Heavy damage from thrips has also been observed in northern California.
Management Practices for Dogwood
In areas with history of anthracnose disease, preventative fungicides should be applied in the spring. Mulch and fertilize according to soil nutrient analysis. Rake and remove all diseased foliage to reduce disease pressure the following season. Expose root collar if buried and apply preventative basal bark treatments for borers if trees are stressed.