Q: There is a hackberry tree in my neighbor’s yard, ten feet away, and its
branches hang over our deck. The falling leaves deposit what looks like dirt
and a sticky residue on our deck and plants. Is this from bugs or some other
sickness on the tree?

A: The tree is infested with hackberry aphids. But here is some good news: if
the tree is only ten feet away, there will inevitably be lots of underground
roots on your property. You can use a systemic insecticide that contains
imidacloprid to control the aphids from your side of the fence. The chemical
will be absorbed by the roots and go up to the leaves and kill insects that suck
sap. If you are tired of the mess, this is a way to fix it.