Don’t Let Mistletoe Kiss Your Tree

Christmas is just around the corner and the romantic appeal of a sprig of mistletoe is high. However, mistletoe in Colorado has a much different meaning for our beloved forests.

What is the difference in mistletoes?
Unlike the more decorative varieties you see in stores, Colorado’s mistletoes, dwarf mistletoes (Arceuthobium species) and juniper mistletoe (Phoradendron juniperinum), are leafless parasitic plants that infect conifers and junipers respectively. Mistletoes produce root-like structures that extract water and nutrients from their host plants, eventually leading to death.

What does mistletoe infection look like?
Dwarf mistletoes will spread through explosively discharged seeds that adhere to branches and germinate over the course of a few years. An infection at the top of trees can possibly rain down seeds to trees below. Birds generally spread juniper mistletoe seeds, but they have been known to spread dwarf mistletoe as well. From the ground, infected coniferous trees may appear to have yellow or reduced foliage, abnormally dense/distorted green foliage, witches’ brooms, and upper branch death. Closer examination of branches of affected trees will reveal the segmented shoots of the plant. Infected juniper trees will have large, yellowish-green masses of small branches in the crown, but will not produce witches’ brooms.

How long does it take mistletoe to kill a tree?
Depending on the severity of the infection, it may take decades to kill a tree by itself, but, when combined with other pests and diseases, it may only take a few years. Sufficiently stressed trees can attract mountain pine bark beetle and Ips bark beetles that can shorten life expectancy of the trees.

How do you manage mistletoe?
Mistletoe can thankfully be pruned out. Completely removing infected branches will usually reduce or eliminate the infection. At worst, the infected tree may need to be removed to protect nearby trees.

Although it is not often found in the Denver area, if you are seeing witches’ brooms, yellowing foliage, or upper branch death, then please feel free to reach out to our ISA certified arborists for a free estimate. Our experts can help you identify and solve the problem immediately!