There are a few plants that are toxic to humans, Poison Ivy, Poison Sumac, and Poison Oak. Toxicodendron Radicans have a chemical in them called Urushiol, the oil in the plant that is poisonous to humans. Most animals are immune to this toxin, such as goats, who regularly eat this plant. Dogs are also immune to this toxin, but can carry the Urushiol Oil on their fur. and transfer it to humans who pet them. Humans that are sensitive to Urushiol have big problems with the effects of these plants, causing a infectious rash that is contagious if not controlled. There is a neglected space next to my garden that has become overgrown with these toxic plants, and I feel I need to take action before they encroach upon the garden space.