@sozobe,
Not to be too nit-picky, but I think posion ivy propagates through creeping vines or roots - NOT berries!
You need Round-up or something similar and spray the leaves (light infestation); however, it's been my experience that real problem infestations may mean digging up the roots (spreading wider than you might think) and efficient eradication entails some REAL grunt work.
http://landscaping.about.com/cs/weedsdiseases/a/poison_ivy_3.htm
" ... consider various methods to get rid of poison ivy itself, where it grows in your yard. The first question to ask is how to how to get rid of poison ivy safely.
Indeed, a word caution is in order, before discussing any actions to be taken to get rid of poison ivy on the landscape. When approaching poison ivy to engage it in battle, try to have as little of your skin exposed as possible, since it is through physical contact with poison ivy (all parts of it, including the roots) that the rash is contracted. At the very least, this means wearing gloves, long-sleeved shirt and full-length pants. Secondly, understand that any of the methods discussed below to get rid of poison ivy may have to be implemented more than once to achieve complete success.
One organic method used to get rid of poison ivy is to pull it out by the roots. The roots must be disposed of; do not burn! Inhaling fumes from burning poison ivy causes far greater health problems than just the rash caused by skin contact. Another natural method is to get rid of poison ivy by smothering it. Smothering entails cutting it back close to the ground, then placing newspapers, cardboard, old carpeting, tarps, mulch or some other covering on top of it. However, be aware that, even after you kill poison ivy plants, they remain toxic. So be careful in disposing of the roots of the dead vines after pulling back the smothering agent (even if you've waited for years).
Herbicides can also be used to get rid of poison ivy. Roundup spray is a popular glyphosate-based herbicide used to get rid of poison ivy. Another widely-available herbicide is Ortho Brush-B-Gon, which is triclopyr-based. These products will kill a great variety of woody plants, making them effective not only in getting rid of poison ivy, but also another nuisance vine: oriental bittersweet. But they will kill many other plants, too, so don't use them near specimens you wish to keep. If you choose to apply these herbicides by spraying, here's what to do:
•You'll need a tank sprayer; mix the product with water, according to directions.
•Apply when the poison ivy is fully leafed out.
•Pick a day with little or no wind for spraying. Also, check your forecast: don't spray if rain is predicted at any time within the next 24 hours.
•For poison ivy plant growing on the ground or on a wall, heavily spray the leaves and vines. Older poison ivy has large hairy vines -- another dead giveaway for identifying them.
•For poison ivy climbing up a tree, you may wish to "paint" the herbicide on, so as to preclude damaging the tree with a stray mist from your sprayer."