Mistletoe is commonly associated with Christmas cheer and sneaking a kiss beneath a bough in a doorway on a cold winter night. What many don’t realize is that the plant itself is actually a parasite, and while socially it may bring good cheer, biologically it can be quite damaging to trees.
Mistletoe is a common parasitic plant to over 30 tree species in North America and 1,300 worldwide. The fruit of mistletoe are small, white berries, though often mistakenly thought to be red due to mistletoe’s common appearance with holly, which does have red berries, during the holidays.
Mistletoe attaches itself to the tree by a sticky seed carried by a bird or mammal to the new host, but it does not derive all of its food from the host tree. Once mistletoe germinates, it develops a root system that penetrates the tree bark, taking important water and nutrients while also producing energy through the photosynthetic process that takes place in the plant’s leaves. This is why mistletoe is specifically considered a hemiparasite – obtaining its food partly from its host and partly making its own.
In Texas, tree species affected by mistletoe can include oak, sugarberry, elm, several species of pine in West Texas and more.
It’s unlikely that mistletoe kills trees directly, but tree branches may die as a result of mistletoe infection. Due to the damage it can cause, trees infested with mistletoe should be treated when possible.
Pruning is usually the primary method of mistletoe control. When its presence is limited, pruning can be a safe and effective means of eliminating the parasite from the tree. Mistletoe plants mature in two to three years, so mechanically removing the visible portion of the plant before it matures and produces seeds is the most beneficial.
If extensive pruning is needed, a certified arborist should be contacted to assess the tree and the extent of infestation. To find a certified arborist in your area, visit https://www.treesaregood.org/findanarborist/arboristsearch.
Mistletoe can be toxic if consumed by wildlife or livestock but is typically only an issue if the animal eats large amounts.
A common misconception is that mistletoe and ball moss have similar impacts on a tree; however, ball moss is an epiphyte, meaning it is an air plant, so it does not have parasitic qualities like mistletoe does.
To learn more about mistletoe, visit: https://tfsweb.tamu.edu/Mistletoe/
Source and Photo credit: Texas A&M Forest Service
