The biggest problem with dogwood trees today is anthracnose disease. The fungus that does it is called Discula destructiva. This killer has wiped out huge stands in the Northeast. It hits wild trees the hardest. Even your yard tree can fall to it without good care. The fight starts the day you plant.
When I hiked a stretch of the Blue Ridge last fall, I found grim proof of the spread. Most mature wild dogwoods stood dead or barely hanging on. Only the small resistant cultivars in nearby yards looked healthy. That walk taught me how serious this problem with dogwood trees has become in the East.
USDA FEIS reports anthracnose has hit large numbers of trees from New England to Virginia. Some experts say there is little hope of saving flowering dogwood in the wild. The disease starts on the leaves with tan spots ringed in purple. It moves into the twigs by year two. By year three, you see major dieback in the canopy.
Powdery mildew is the next big issue for your tree. The fungus Erysiphe pulchra coats leaves in a white powder by August. The leaves curl and drop early. Trees lose growth and bloom less the next spring. Mildew alone will not kill your tree. Stacked on top of other stress, it can push your tree over the edge fast.
Dogwood borer, or Synanthedon scitula, is the bug that does the most damage. The larvae chew tunnels under the bark. You will see small holes and sawdust at the base of your trunk. A heavy borer load can kill a tree in two years. Borers love wounds. Any nick from a mower or trimmer opens the door wide.
Surface roots add to the long list of dogwood tree issues in your yard. USDA FEIS shows roots stay less than 3 ft (0.9 m) deep. Drought hits your tree fast and hard. A two-week dry stretch in July can wilt leaves in a single day. Deep weekly watering for the first three years saves more trees than any other one step.
Thin bark is one more weak point you should know. USDA FEIS calls dogwood bark among the thinnest of any eastern tree. A bump from your string trimmer rips open a wound that may never close. Sunscald on the south side can crack the bark in winter. Wrap young trunks with white tree wrap for the first three winters.
If you ask what kills dogwood trees in the long run, the answer is a stack of stresses. One stress alone rarely does it. A drought year plus a borer hit plus anthracnose can take down a 20-year tree in one season. Each stress on its own would have been fine. Together they crush even a strong tree.
Most dogwood tree care problems come from poor site choice on day one. A full-sun lawn site dooms your tree. Heavy clay drowns the roots. Turfgrass right up to the trunk steals water. A mower swinging by each week wounds the bark. Fix the site first and most other problems go away on their own over time.
To beat all these threats at once, plant a resistant cultivar like 'Appalachian Spring' or a Stellar series hybrid. Pick a spot with morning sun and afternoon shade. Water deep in dry weeks. Mulch in a wide 8 to 10 ft (2.4 to 3 m) ring. Never let mowers or trimmers near your trunk. Follow these five steps and your tree should live for 50 years or more.
Read the full article: Dogwood Tree: Complete Guide for Home Gardens
