I didn't know that, but was just talking with a friend of mine down in Colchester. He tells me that somebody knocked his mailbox down, so he had to replace it. When he picked the whole thing up, apparently there were some poison ivy plants attached to it. He had on a short sleeved t-shirt and it got on his arms - He tells me that poison ivy plants are effective year around - I am assuming that the leaves do not stay green in the winter, but this is how they look in the summer:Poison Ivy in the fall still very potent so be cautious: