I have a ring of lily of the valley growing around a tree. After the plants...
I have a ring of lily of the valley growing around a tree. After the plants flower in May, the leaves on many of the plants are covered with a black blight. This problem has come back for the past three years. I had a landscaping company come out and they treated the soil, but it did not correct the problem. Help!
Montgomery County Maryland
Sounds like your lily of the valley has sooty mold. The most likely reason is the tree above the groundcover has some type of scale insect or aphids. These two insects produce a substance called honeydew which is dripping onto the lily of the valley. The sooty mold then grows on top of the honeydew. So do you happen to know what type of tree you have? For additional information go to the following link on the 'plant diagnostic' section of our website, http://plantdiagnostics.umd.edu/level3.cfm?causeID=389
If you do not think this is the problem please send us some digital photos.