Christmas hit, forest nightmare: mistletoe takes over trees

In a week, Advent begins, and mistletoe will once again appear in our homes as a holiday decoration to delight the eyes. However, its presence in forests is a major problem. When tree canopies lose their leaves in autumn, it becomes clear how quickly the parasite spreads, capable of bringing a tree to the brink of exhaustion. Foresters warn that the scale of the phenomenon is growing year by year, and mistletoe has become one of the more serious threats to many tree stands in the country.

How mistletoe weakens trees and why it spreads so fast

The spread of mistletoe is largely thanks to birds that feed on its berries and, in the process, carry the seeds to new branches. The fruits are sticky, and the seeds adhere to the twigs where the bird perches or leaves droppings. Once they reach the host bark, the embryo grows into the wood and forms a sucking structure that draws water and minerals from the tree. It drains the tree’s resources without giving anything in return.

Mistletoe conducts its own photosynthesis, but this is not enough for survival. Over time, a single branch can host a dozen or more spherical clumps, and the tree expends energy maintaining the semi-parasite instead of investing it in its own growth. Drought accelerates the host’s death because mistletoe first takes water from it.

Mistletoe, a terror for coniferous trees

In the past, mistletoe was mainly seen on poplars and old deciduous trees. Today, it is rapidly colonizing coniferous forests. In the Poznań Regional Directorate of State Forests, it has already occupied over 24,000 hectares of pine stands – more than the combined area of two large municipalities in the region. Such widespread occurrence is a new phenomenon, as coniferous mistletoe was rare in Poland just a few years ago.

The attack on coniferous species is particularly dangerous: pines grow slower than mistletoe, and their crowns respond to stress by shedding needles. As a result, the death of an entire tree can take just a few years. In areas affected by drought and habitat degradation, the parasite spreads even faster. Studies indicate that the pine’s vascular system is particularly vulnerable to water imbalance, creating favorable conditions for the semi-parasite.

The scale of the problem in Poland – data and observations from endangered areas

According to State Forest analyses, the mistletoe problem is growing particularly fast in the west and center of the country. Some forest districts report annual increases of several percent in the number of infected trees. Foresters note that areas requiring mistletoe removal or forest stand reconstruction are expanding faster than they can eliminate the threat. Monitoring in the West Pomeranian Voivodeship has shown that mistletoe can take over an entire tree within 7–10 years, then move on to the next.

In cities, the problem is equally visible. The most vulnerable species are maples, lindens, and robinias, whose flexible bark allows the embryo to penetrate the wood.

Monitoring and limiting the spread of mistletoe

State Forests conduct a monitoring system that includes tree inspections, removing the parasite in its early development stage, and cutting extremely infected specimens. Unfortunately, it is not always possible to save a tree – if mistletoe occupies more than half of its crown, the dying process is practically irreversible.

In cities, sanitary pruning is applied, and in private gardens, it is recommended to remove mistletoe right at the point of insertion before new clumps develop. A sprig in a vase is a beautiful decoration that poses no threat, but on a tree, it is an enemy that must be actively combated.