Q: I mowed this vine a couple of days ago and have broke out in a red itchy rash on my legs and chest. I used my string trimmer there about a month ago and had a horrible burning in my eyes, mouth and nose. I broke out all over my body in a red itchy rash with tiny blisters. I cannot for the life of me figure out what this is.
A: Wow! The vine is sweet Autumn clematis, Clematis paniculata (Clematis terniflora). Most members of the buttercup (Ranunculus) family, including anemone, clematis, and helleborus contain the chemical Protoanemonin, which can cause a blistering rash if the plant’s sap comes in contact with skin.
My understanding is that once you’re sensitized to an allergic substance, you might have the reaction every time you contact it. Spray the vine with a product that contains glyphosate and triclopyr (Roundup plus Brush Killer )(click for sources). There is no need to exceed the label directions.