I did a quick search yesterday, to see if what I use has "Poast" in it.

Apparently, 'Poast' was a former name of the product I have in the cupboard.  My brand is called "Grass Getter".

Either way, you need to also purchase an oil surfactant to go with the concentrate, which helps the herbicide stay on the leaves of the plant you're treating.  (this would explain why it didn't work as well for me.)

I personally use "Grass-B-Gone" by Ortho (?), and it works REALLY well.  But it's also REALLY expensive!  Available at Hope Depot stores.

Use the above address to see one of the sites I found. You will have to scroll down the page about 2/3 the way in order to see what I found.  I think there is a cheaper source out there, but this site at least has a twin pack!

Adam~