I live in the mid Atlantic and I have been sawing down these things along my fence line for the last week. I started off just sawing to open up a view, now I am in this area I don't really care so I have been sawing the tree into a third or so circumference and spraying it with 41% glyphosate in the crack I made with the saw.

Think that will be enough to kill it? These are huge ones at least 28 years old. I just want to see if it's enough to see them die and come back in a year or two and maybe clear them.

This guy is doing a hack and spray. I assume my method would be better since I am cutting like a third of the tree right?