"human urine can kill a plant for sure"
Elaine, this gave me such a chuckle! Long, long ago, when my now-husband-of-24-years and I were first going together, I was living in a cabin that was really in the middle of nowhere -- he was a "city boy" and loved that he could go out at night to pee off the deck (this is definitely a "guy" thing)... I kept telling him he was going to kill all my grass, and yet it grew more rampantly there than anywhere!!
Back to the actual subject of this thread... Kyla, sometimes plants just "croak" -- it can be very frustrating when there is no apparent cause!