how to kill adult trees using muriatic acid muriatic acid is a harsh chemical sometimes referred to as hydrochloric acid pool supply stores sell the product because it's designed to stabilize the pH balance and swimming pools even when used around the house you mix the acid water first which dilutes the harshness of the chemical muriatic acid burns through nearly anything it touches making it a suitable killer for weeds and adult trees around your home it's best to use muriatic acid with caution as it can kill other plants in the surrounding areas things you'll need rubber gloves goggles metal bucket shovel hacksaw combined the muriatic acid with water in a metal bucket according to the manufacturer recommended ratio on the back of the bottle wear rubber gloves and goggles to protect your hands and eyes from the acid as it's extremely harsh and dangerous dig around the base of the adult tree making a trench deep enough to expose the roots pour the muriatic acid directly onto the roots of the tree cut the tree down to just a stump removing the upper branches and portions of the tree pour more of the acid mixture on the top of the stump forcing the tree to absorb the acid in multiple ways tips warnings it typically takes several treatments before an adult tree completely dies add more of the acid mixture to the roots and stump of the tree every few days you