Yes, pouring muriatic acid around the base of a tree can kill the tree. Muriatic acid is a highly corrosive hydrochloric acid that can cause severe damage to plant tissue. When applied to the base of a tree, the acid can penetrate the bark and into the tree's vascular system, where it can disrupt the movement of water and nutrients, and cause the tree to wilt and eventually die. Additionally, the acid can damage the tree's roots, which are responsible for absorbing water and nutrients from the soil and providing support for the tree. This can further weaken the tree and make it more susceptible to disease and insect infestation. Overall, pouring muriatic acid around the base of a tree is a harmful practice that can result in the death of the tree.