Neighbor has a tree that shits leaves and gunk all over our back patio and the roots are coming under our fence and fucking up our concrete. I want to start spraying the limbs hanging over our fence with salt water and pour buckets of the stuff down on the roots if necessary. Approx how much salt am I going to need and how long do I need to keep dousing it to see this tree dead? Tree is approx. 20 foot tall and 10 years old.