The herbicide-fertilizer combos are supposed to be disallowed.
http://www.hc-sc.gc.ca/cps-spc/pubs/.../index-eng.php
I keep seeing the bottles of Killex and Roundup on the shelves at Canadian Tire and Walmart, so there's that. You can always spot spray weeds and fertilize separately.
I sprayed my dandelions with Killex (I used to pull them but spent an entire afternoon yanking them only to notice that it looked like I hadn't pulled a single one) and yet the fataing things still popped seed heads this week - they look like hell but I'm amazed. Maybe they need more spray? Luckily I'm renting and will be moving to a fresh property soon. Thank goodness.