Worse I have ever seen was hot and humid July a neighbor got it under his armpits his bush and around his eyes. He was so miserable he wanted to die. Sweat and oozing sores. This was 35 years ago and treatment has come a long way. Burning is a no no for sure.
Seems to work better if you spray it down the stem to mainline it. You are right about spraying the foliage with round up. Just make sure you don't have it on your shoes and walk around on an customers expensive lawn if you are a landscaper.
