People all over the eastern United States are familiar with dogwood trees. A true southern staple, the flowering dogwood can be found anywhere from public parks, to forests, to your neighbor’s back yard. However, there is a serious threat to the flowering dogwood population that you should keep watch for. “Destructive dogwood anthracnose” is a fungal disease that has a mortality rate up to 95 percent in effected populations. First documented in the states in the late 1970’s, destructive dogwood anthracnose worked its way through the eastern U.S. from New York, down the Appalachian Mountains and into Georgia by the early 1990’s. In its southern reaches, this disease tends to be localized in areas of high elevation. Though destructive dogwood anthracnose has not, at this time, been reported in Florida, the disease may still move into our area. Watch for these symptoms to see if a dogwood has become infected with destructive dogwood anthracnose:
Leaves on lower branches will develop irregularly shaped, light brown spots with ruddy brown edges. These type of spots indicate conditions in the environment that are less friendly to the fungus, but they will still lead to defoliation and likely plant death.
Water-soaked, black spots that extend from the tip of the leaf, through the veins and into the stem. These type spots indicate conditions in the environment that are favorable for the fungus and will lead to defoliation and likely plant death.
Tan, slimy fungal spores that ooze from the spots during spring time may distinguish destructive dogwood anthracnose from other, nonfatal diseases.
Destructive dogwood anthracnose will typically lead to death in smaller trees within three years due to repeated defoliation. Larger trees generally live longer while infected than smaller trees, but they will still die from the disease. These larger trees will slowly lose their lower branches as the infection moves from the leaves, into the twigs and eventually kills the branches before the tree itself dies. For this reason, larger trees with destructive dogwood anthracnose will develop a dome-like appearance as they loose their lower branches. The disease then moves from the branches into the bole of the dogwood, killing it from the base.
If you are familiar with dogwood trees, you many know that they tend to be prone to root problems and other diseases due to their intolerance of very wet or very dry weather. Therefore, if your dogwoods develop spotting or other cosmetic problems, it is likely not destructive dogwood anthracnose. The best way to protect your trees from disease is not to wait until they are already sick. Be sure to plant your dogwoods properly and in an area that is well suited to their moisture sensitivity. Unfortunately, little can be done to treat a tree that is already infected. Instead, care for your healthy trees by keeping them properly ventilated and by avoiding over watering.