I like esshup's advice above.
I continue to be impressed by the performance of "selective" herbicides on our property. "Use as directed", and it almost always kills what it is supposed to kill and does not harm what it is supposed to spare.
Unless I have an emergency need, I ALWAYS spot treat first on some test areas. I keep a supply of those cheap, wire survey flags in my truck. If spraying in thicker cover, I mark out a test area first and then perform a treatment. Very easy to monitor results then.
You can also observe how many days it takes to see plant damages. If it takes 10 days for obvious results, I usually spray a full tank and then come back after at least 10 days and do my adjacent treatment. That way I never overspray, or miss areas of coverage.
