Concerned home gardeners associate white spots on tree bark with destructive tree diseases such as white rot, mold or tree cancer. Read here what white spots on tree trunks really are.
What do white spots on the tree trunk mean?
White spots on the tree trunk mean thatWhite bark fungus(Athelia epiphylla) is parasitizing green algae or lichens. In autumn and when humidity is high, the spots can coalesce. This process isnot harmful to the tree Rather, the tree bark only serves as a base.
Are white spots on tree trunks harmful?
White spots on the tree trunk arenot harmfulThe spots arise whenWhite bark fungus (Athelia epiphylla) parasitizes green algae and green crustose lichens. The green algae or lichens die due to the fungal attack and turn whitish-gray. In autumn and when humidity is high, the spots can become palm-sized and coalesce. This process does not pose any danger to the tree. The bark only serves as a base for fungi, algae and lichens.
Which trees are susceptible to bark fungus?
Bark fungus causes white spots primarily onsmooth-barked trees. These include:
- Common beech (Fagus sylvatica)
- Hornbeam (Carpinus betulus)
- Maple (Acer)
- Linde (Tilia)
- Spruce (Picea)
- Larch (Larix)
- Occasionally also oak (Quercus) and horse chestnut (Aesculus hippocastanum)
How does the white bark fungus spread?
White bark fungus is a stand fungus and spreads viaBasidiosporesandSclerotia Basidiospore is the technical term for spores that form stand fungi (Basidiomycota). with the aim of multiplying as widely as possible. Sclerotia are 0.2 mm small brownish balls made up of fungal threads, which also serve to spread. Both fungal components also function as permanent organs, with the help of which white bark fungus can overwinter and survive drought stress.
Tip
Harmful white tree trunk mold
In contrast to the harmless white bark fungus, white mold on the tree trunk is an alarm signal. Bloodlice (Eriosoma lanigerum) sit on the tree under a woolly white cover, suck on the branches and cause bloodlice cancer. As an immediate measure, brush off the pests. Cut affected branches back into he althy wood. In March, attach glue rings to the trunk before the hardy beasts crawl up the tree.