concolor. Native mistletoes species of the genera Arceuthobium, Phoradendron and Psittacanthus can have a deterimental affect on conifers in North America and Mexico. These shrubby, aerial parasites, which are bird dispersed or have explosive fruits, cause deformation of the infected stems, growth loss, increased susceptibility to other disease agents or insects, and reduced longevity. Species of Abies, Cupressus and Juniperus are particularly susceptable to infestation especially if stressed by habitat disturbance.