Be sure and add in a surfactant when you mix it up. The surfactant will cause the herbicide to stick to the plant and cause it to be taken down to the roots. Most herbicides need this to work properly. I found this out the expensive way as I bought some stuff that was 100 bucks a gallon and didn't find out I needed the surfactant til I had sprayed it all. Needless to say, nothing died except my 100 bucks. The surfactant costs about 10 bucks and it doesn't take much. I found out about it when I called the chemical company and asked why my fields were still green and growing. They then went over the process and told me the short paragraph about the surfactant was in the middle of page 93 or 94, can't remember which. Good place to put pertinent info. Anyway, hope this may help someone.
Rob