An interesting note: Black spots may appear on any part of the plant. The spots are urushiol, the resin that causes allergic reactions. When the plant is damaged urushiol is exuded in an attempt to seal off the damaged area. The resin is creamy, turning brown-red then black with oxidation. - MinnesotaSeason
Interesting note: I've always was to the understanding this plant was poisonous to us humans. I turns out I was misinformed. According to a few sources the roots, sprouts, and berries can all be consumed. The berry is said to make a pretty good jelly. Peterson Field Guide; Edible Wild Plants.
This plant is growing at the base of my favorite deer stand. I will have to sample the berry next I'm out.