I've tried orange oil and I've tried vinegar (straight) but not together, I'll be curious to hear how that works.
I posted in another thread that I spray poison oak. I HATE to use spray but we have really tried it all (pulling up, tilling where practical, mowing where practical, natural control like boiling water and above mentioned tries, and NOTHING has worked. The stuff is nuts. And I do have to re-spray in a lot of places still. I've read that the tiniest live root can spring a whole new plant. Spraying is my one big concession in life.... we're organic and sustainable for most everything else. It sucks, but it's reality.
I get such a bad reaction to it (have had to get a shot before! Which I hate MORE than spraying!) that while I hate to spray, I must. I haven't this spring (and my husband refuses to, he's the hold out) because I'm pregnant, which means next spring will be torturous! We have a couple acres and they are covered in it. I haven't even STARTED on any of that, I just try to control what is around our house.