|I have noticed a blackish fungus slowly eating away at the base of my dogwood. I am aware of Anthracnose fungus, but have never seen it. Am I now looking at it on my Dogwood, or is this something else?|
|It could be. If you see signs elsewhere on the tree, then it may the Anthracnose. Once you see the characteristic circular, purple-brown leaf spots and lower branches dying back and cankerous growth on the branches, then you have about 2 to 3 years before the whole tree will die. If the water sprouts (lush new growth from the branches) are dying back from Anthracnose disease also, chances are the tree is almost gone.
However, you can prevent your tree from getting the disease and save a tree at theearly signs of the disease. Anthracnose fungal blight thrives in moist, cool conditions where the native dogwood commonly grows as an under story tree. If you give your tree 30% direct sun such as trees planted at the forest edge, mulch with 2 to 3 inches of bark, don't wet the leaves when watering and have good air circulation, your tree is less likely to get the disease. Trees planted on South or West facing, sunny slopes are less likely to get the disease. If you plant the tree in full sun, you won't get the disease, but dogwood borer will be more likely to infest your tree.
To save an infected tree, prune out cankerous branches as soon as they are noticed. To protect new growth and reduce the amount of leaf spot infection spray a fungicide such as copper sulfate three times in spring while the new growth is still succulent and most likely to get infected. Spray once at bug break and then twice again, at 10 day intervals, preferably after a rain.
If you need to replace your flowering dogwood, there are anthracnose resistant trees, but they are crosses between Cornus florida and Cornus kousa such as the Constellation series. However, unlike the Cornus florida, the the flowers open after the leaves come out and flower size and shapring dogwood trees, send a self-addressed stamped envelope to the U.S. Forest Service, Forest Health Protection, P.O. Box 2680, Asheville, NC 28802.