As far as spraying the pine trees for pine straw raking I'm assuming you mean the understory. Correct?
There are a number of chemicals that you can use to manage woody and herbaceous growth in a pine stand. Those include Arsenal (Imazapyr), Escort (Metsulfuron methyl), Velpar (Hexazinone), and Oust (Sulfometuron methyl) all of which can be applied by broadcast. If you have longleaf pine, the best herbicide I can recommend is Velpar due to its ability to manage hardwood competition. Applications vary based upon age of stand as well as stage of comepeting growth. I recommend going to google and typing in "Forest Herbicide" and you'll get plenty of info. I do recommend UGA Publications over others but I'm partial! Haha!!