QuestionI have an oak tree that is around 10 years old and I have noticed a blackish coating on the leaves. I am not sure if this harms the tree, but late last year is when I noticed this isuse. I figured with winter come and the lossing of the leaves this might cure it, but this year I notice the blackish color back. When the leaves first came out the leaves were a pretty green but now they are getting the sticky black coating back. I have also notice the tree is also putting out more sap then normal. Does any one know what this is and how to treat it...
AnswerThis is caused by an insect called aphid or possibly scales. These are insects that suck the plant juices from the tree and secrete a sticky substance called honeydew/ Honeydew is high in sugar content and a black sooty mold will grow on the honeydew. The sap dropping is the honeydew. Treat the aphids and scales and you will get rid of the black and sap. Small tree can be sprayed with an insecticide but the folage is hard to cove. There is anew systemic insecticide called Bayer Advanced that is applied to the soil and the tree roots take the insecticide up to the leaves and branches where the insect sucks in the insecticide killing the insec. I would check with your loacl nursery fro a systemic insecticide that is applied to the soil.
