I have been treating crabgrass with Drive for the last few weeks. Usually the crabgrass is toast, but sometimes I get little or no control. Since I know I will get asked, I am using it at the correct rate of .367 oz/1k and using a label approved surfactant. A close look at the label turned up this phrase which I found odd: "Biotypes of large and smooth crabgrass in California have shown varied response to Drive 75 DF herbicide. If control failure occurs following the application of a full or split application rates do not reapply Drive 75 DF herbicide, and change to a herbicide with a different mode of action." Here is the label I found that on, you can find it on page 7 footnote 4. http://www.lesco.com/Label.aspx?label=063899.pdf Now I don't know there are any types of crabgrass that are found exclusively in California, but could it be that there are some forms of common crabgrass that Drive won't control well? Is anyone else getting a "varied response" with Drive?