How did you apply? For something fast growing / invasive like a Bradford pear, or a honeysuckle, you really need to get Glyphosate into the roots for it to die. I was taught this trick by an Arborist:
Cut the tree down and leave 4-6” above the ground. Take a small drill and put a 3/8” drill bit in it. Try to find the small hole in the very middle of the trunk and drill down into it. This is how the sap flows through the tree. Carefully spray 3-4 good sprays of Glyphosate into the hole with gloves and eye protection. The tree and gravity will take this down into the roots where they will die. The small amount of Glyophosate will stay in the roots for approximately eight years, and it won’t leak out into the soil as it’s held by them.
Cut the tree down and leave 4-6” above the ground. Take a small drill and put a 3/8” drill bit in it. Try to find the small hole in the very middle of the trunk and drill down into it. This is how the sap flows through the tree. Carefully spray 3-4 good sprays of Glyphosate into the hole with gloves and eye protection. The tree and gravity will take this down into the roots where they will die. The small amount of Glyophosate will stay in the roots for approximately eight years, and it won’t leak out into the soil as it’s held by them.