Paraquat is a contact herbicide that injures any green plant tissue. It does not move in plants, so injury is confined to treated parts. Sprayed leaves develop brown spots within 2 to 3 days and may drop, depending on the amount of exposure. When young canes are sprayed, reddish-brown spots develop on the green bark. Canes may be stunted or killed if much of the bark surface is injured. Young injured canes may be more susceptible to Phomopsis infection and winter injury.