Bests & Worsts Reviews from Amazon

I am convinced that the formula has changed in the last year or two. Previously the weeds became limp within 24hrs and eventually died. The new formula does not kill weeds! I have sprayed Round up on a warm 75 degree day, and the weeds still survived. Monsanto tell us if the formula has changed and do you have a weed killer? I have used Round Up for about 35 years and have never had a problem!