OK, all you lawn and turf guys, need to ask a question. Recently (last week in Feb)

had my local "turf specialists" (MSU grad)to spray my yard. Not sure what he used but it killed the hell out of the weeds. I'm assuming it was atrazine but I'm not positive. Problem is, it's the second week in April and my grass isn't turning green yet. Most of the yard is St. Augustine and there are a couple of sections of zorro. You can tell where he didn't spray because that St. Augustine is green. The rest has yet to turn green or just barely turning green in some sections. The zorro is turning greener a lot faster than the St. Augustine. My question is, will the St. Augustine start greening or did the sob kill my yard?

Put some dales marinade on that augusta and it will rippen right up

Was your st Augustine already green when he sprayed? If so, there's not a whole lot of chemicals you can apply to st Augustine that won't either damage it or kill it.

has a slightly yellow hue to it.

I have always heard you can't put ANY chemicals on St. Augustine. Sounds like you're finding out the hard way.