Live on Fox Island along the Missouri. Due to an abundance of cottonwood trees we are accustomed to a fair amount of sap during the summer. This summer has been the worst in over 24 years. A couple of neighbors are going to have their trees injected to attempt to control the tree aphids that apparently cause the honeydew. Just wondering if anyone has had any experience / success in treating trees to reduce the aphid infestation? Sounds like it runs about $100 / tree depending on size.