Regular roundup weed killer has glyphosphate in it. Roundup Poison Ivy & Tough Brush killer (which really works on PI and Canadian Thistle, 2 weeds I can't control any other way) has both glyphosphate and triclopyr in it. You can also buy TRICLOPYR on its own and use it on poison ivy in the lawn, among annual and perennial plants, etc... it kills PI and brush (including brambles) without affecting the other ornamentals. I wouldn't use in in a food bed, and I'd test it on a little section before spraying my prize iris bed, but it's definitely worth a shot if you have poison ivy invading an area.
I learned that tip from our arborist, who also told me that fall was the best time to kill poison ivy with herbicides, as that's when the plants are drawing nutrients down to the roots for overwintering rather than putting out new growth. Best time doesn't mean only time, though... spray should work in any season to knock it back, and then you can spray any regrowth again in fall.
