Last spring and summer I “declared war” on the poison ivy growing in various places around the house. Since I didn’t want to use expensive chemicals for the job, I chose white vinegar. I put undiluted white vinegar on the ivy and waited a couple days. The combination of vinegar and hot sun turns the ivy leaves black or brown and withers them. You can douse stems and any visible roots with vinegar as well.
In some cases, especially after a heavy rain, it’s necessary to put more vinegar on. But unlike some toxic chemicals formulated especially to kill plants, vinegar can be applied without regard to whether a day is windy or not, and people sensitive to chemicals can use it without concern. Another benefit is that vinegar will not harm children or animals.
One caution: vinegar will also kill any grass or other plants it happens to get on, so keep this in mind when applying it.
I first discovered this use for vinegar when I took some “well-aged” barbeque sauce out of the refrigerator and rather than throwing it in the garbage (it had been sitting in the ‘fridge about a year) doused it on some poison ivy. The next day the poison ivy leaves were black. One of the major ingredients in barbeque sauce is vinegar. Voila! I had a new use for vinegar!