I had a problem with raspberries growing semi-wild in my yard.

To kill the plants I would cut off a tip of a stem and put a length of the cut stem into a bottle of 5% acetic acid solution.

Within a few days the entire plant would die; however, I noticed that on a couple plants the cut area would wither but the plant itself shows signs of not having been affected at all!!!

Am wondering why the apparent ineffectiveness of the solution shows up on a couple plants and not others. Could it be the weather condition? The temperatures have dropped somewhat.