Answer: It may be that the tree isn't dropping sap, but that aphids or other sap-sucking insects infest the tree, and their waste, called honeydew, is what falls from the tree. It's not practical to spray a large tree in an attempt to eliminate insects, because you'd need to spray frequently -- it would likely be cheaper to build a garage and a gazebo! To verify the source of the problem, contact a local arborist -- they may have another solution to offer you. Best of luck!
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