I believe if it was just about any other plant you'd be fine. Definitely ideal conditions and enough time before rain, but Cogongrass is apparently a tough SOB.

Two years ago it showed up in a cornfield in the eastern part of VA. Since then we have received information to be on the lookout for it. From what I've read, the mixture you used is about the most effective control I've seen, but it's not uncommon for Cogongrass to regrow after one application. If you would, later on, post the outcome of your application. Hope it works, I've read where it's a very serious problem in the south, especially FL and AL.

Here's some info, but you might have already seen it.

http://www.cogongrass.org/control.cfm


http://www.threatsummary.forestthrea...fm?threatID=82