Why is my linden tree dropping little drops of sap? It gets on my car and windows and smears when I try to wipe if off.

Question

The tree appears to be healthy. We have had a lot of moisture in Iowa this year.

Answer 1

What is dropping from the trees is digested sap - your tree most likely has aphids. You can wash them out of the tree with a high powered spray, but you should also treat the tree with neem oil or insecticidal soap. Here's an article that explains the problem and how to fix it: https://www.gardeningknowhow.com/plant-problems/pests/insects/aphids-tree-disease.htm