Birds occasionally may spread the seeds to uninfected trees. Dwarf mistletoe seeds generally are dispersed in August and early September. Mistletoes spread slowly from tree to tree. In closely spaced trees of about the same height, this spread is 1 to 2 feet per year. The spread from large to small trees can extend 60 feet, but the average usually is less than 30 feet.
Dwarf mistletoes grow into the bark and phloem of the tree.
Older ones become embedded deep in the wood as twigs grow. These sinkers provide the parasite with water and nutrients obtained from the host. Dwarf mistletoes kill by slowly robbing the tree of food and water. Diseased trees decline and die from the top down as lower infected branches take more food and water. This allows for long-term disease management.