Mistletoe is best known as a messenger of love during the Christmas season – but it will harm your trees. Find out why you should remove mistletoe from trees and how to do it here.
Especially at Christmas, mistletoe is often hung in the living room or above the front door. But mistletoe is spreading rapidly, especially in forests and orchards.
Why does mistletoe endanger fruit trees?
Mistletoe is a so-called hemiparasite, i.e. a semi-parasitic plant that uses suckers to extract water and nutrients from its host, but also carries out photosynthesis itself.
The vitality of infested trees declines sharply, especially in the case of multiple infestations; branches break off and the entire trees die. In common parlance, mistletoe is therefore also called the “strangler of the apple tree”.
Even though apple trees are the most commonly affected, they are not the only plants that can be attacked by mistletoe. To be mentioned are:
- Mountain ash
- Lime tree
- Silver fir
It is interesting to note that pear, plum and cherry have no problem with mistletoe infestation. Pear trees have even developed a protective mechanism against mistletoe: as soon as the sucker roots bore into the bark, the tissue under the tree bark dries up. The mistletoe can no longer draw water from the branches and dies.
Before the mistletoe leaves appear, the first signs of mistletoe infestation are usually seen on the parts of the shoots outside the attachment site, which begin to die. Later, the vitality of the whole tree decreases and whole branches and crown parts die. Often the last vital part of the fruit tree is still mistletoe.
Removing mistletoe correctly from fruit trees
When removing mistletoe, there are now two options that will cause as little damage to the tree as possible.
If the tree is infested outside, you should completely remove the branches with mistletoe. Late winter and spring are appropriate times to do this because the trees are dormant then.
Here’s how to do it:
- Locate the attachment point of the mistletoe on the branch and mark the intersection, which should be about 50 cm away in the still-healthy wood.
- Do not simply tear down the mistletoe, this will cause damage to the healthy wood.
- Saw off the branch straight!
- Check the cut to see if they have removed all the sucker roots of the mistletoe. If this is not the case, you need to shorten the branch further.
- Optionally, you can now treat the cut with a resin-based tree care product to prevent other pests from entering the wood.
If many branches of the fruit tree are infested with mistletoe or the mistletoe is not growing in the outer area of the tree crown but further inside, you can remove the mistletoe by cutting the shrub flat at the branch surface just above the tree bark.
The sucker roots of the mistletoe will remain in the branch. This will not get rid of the parasite infestation, but the measure will help the tree cope better with the mistletoe infestation.
Once the green shoots have been removed, it takes about four years for the mistletoe to grow again to the point where it can bear fruit and continue to spread. You should also consistently remove the new shoots of mistletoe.
Mistletoes have developed a well-adapted dispersal mechanism. They bloom from February to April – the fertilized flowers give rise to white berries in the fall, with a tough mucilage coating around the core. In winter, these berries are readily eaten by birds: The mistle thrush is even named after its favorite food!
To remove the sticky pulp of the berries from their beaks, the birds repeatedly brush their beaks against the branches. In this way, the seeds of the mistletoe are dispersed throughout the tree canopy. When the birds swallow a seed, the indigestible shell causes them to be excreted in the droppings. If the droppings land on a branch, the mistletoe seed they contain begins to germinate and form adhesive roots. The seedling then drives a sinker into the conduits of the branch, where it subsequently spreads along their length.
From existing mistletoe initially located in the upper crown of the tree, mistletoe can also spread in the tree crown by the fact that falling berries can stick to lower-lying branches with their sticky sheath.
For a long time, mistletoe did not pose a problem to forests and orchard meadows. However, these ecosystems have been increasingly less maintained since the 1950s. The lack of pruning and removal of mistletoe from fruit trees has allowed it to proliferate almost explosively in recent years.
Many trees, already stressed by drought summers and parasite infestations, can no longer cope with the flood of mistletoe and suffer greatly from the infestation.
Stop the spread of mistletoe
Simple tree care measures are all that is needed to stop the explosive spread of mistletoe. However, the goal should not be to eradicate mistletoe completely. Despite its semi-parasitic lifestyle, it is a valuable plant that provides food and shelter for numerous bird species and insects. Nevertheless, it is advisable to remove mistletoe from gardens, trees that are subject to road safety regulations, and orchards.
Mistletoe is said to have healing powers!
And not only for the comic heroes Asterix and Obelix, who are given a magic potion containing mistletoe by their druid before they go into battle. The leaf extracts of mistletoe are used in human medicine to lower blood pressure, in arteriosclerosis and in cancer therapy.
When combating mistletoe, it is first important to check the trees regularly and remove the mistletoe at the seedling stage, which is easy to overlook. In the first two to three years, the mistletoe plant can still be completely removed from the bark of the branch. After that, it has spread its sucker roots into the conduits of the host tree. With increasing age, these reach up to half a meter.
Mistletoe is already known from Europeanic and Celtic mythology, it was considered a sacred good luck charm and was the sign of the gods, because it could grow and bloom without contact with the earth. Perhaps this is why a French-British custom states that a couple must kiss when standing under mistletoe? The kiss promises a happy future together.
Mistletoe, by the way, is not a protected species. Of course, you can’t just remove mistletoe on someone else’s property – the owner must be informed in advance and actively give his consent, because mistletoe counts as property. For commercial collection, as with all wild plants, you need a permit from the authority responsible for nature conservation and landscape management.
Removing mistletoe ultimately not only benefits your fruit trees – you also bring your own Christmas decorations from the garden into your home! For more ideas on Christmas, Christmas trees and decorations, click here.