What is the green in color liquid weed killer that contractors use and won't kill ornamental shrubs?

I've seen contract landscape companies spraying medians, desert landscape, sidewalk cracks, etc. When they spray it is a green colored liquid that is left on the ground but eventually disappears. I would ask the guys doing it...but they don't speak english :( It doesn't harm any of the ornamental shrubs or trees either. I asked soemone at home depot once and they steered me in the wrong direction.What is the green in color liquid weed killer that contractors use and won't kill ornamental shrubs?
The color is just dye...kind of like food coloring. It proves that you were there and did the job to whoever is paying you. It also helps to keep track of where you have sprayed. That is all it is.What is the green in color liquid weed killer that contractors use and won't kill ornamental shrubs?
There is a product called ';Over the top'; that works. I think it is made by Gordon's or Bayer.
another thing it helps with is to determine drift from the wind while spraying the link is to a commercial product used..


http://209.85.207.104/search?q=cache:LY2鈥?/a>