Not true, unfortunately. Roundup will not kill Nutsedge...........it'll kill the aboveground part, but not the nut below ground, so it'll come back very quickly.............
I also cannot get roundup to kill Snow on a Mountain.
When using RoundUp, it is important that the target plant is dry. No watering, no dew, no rain, for a couple of days after treatment.
The goal is to get the plant to drink the RoundUp like water or dew.
Timing and preparation is very important.
I have never met anything that RoundUp will not kill. Just lucky I guess.
Another method of killing plants more naturally is to buy some chem fertilizer as strong as you can find like 20-20-20.
Just dump it on what ever you want to kill. I mean dump it! Pile it on. Very effective. I’ve killed full grown trees like this.
Just my stupid opinion...good luck guys