Is lichen infestation on trees harmful?

How are lichens made?

Lichen are among the longest living creatures on earth. They can live for several hundred years, in exceptional cases even over a thousand years. Strictly speaking, these plants are not plants, but a community of algae and fungi.

The fungus, which absorbs water and minerals from the environment and which forms the body of the lichen, cannot photosynthesize on its own. However, the alga, which itself cannot absorb moisture or nutrients, is able to do this and produces vital sugars during this process. The fungus also protects the algae from drying out and mechanical damage.

Causes of Lichen Growth

Tree lichens, of which 25,000 species are known, occur frequently on the bark of deciduous trees and on some fruit trees. They need similar living conditions as mosses and prefer to thrive in shady places with high humidity.

Lichen depend on good air quality and are therefore considered indicator plants for pollutants in the air. For this reason, it is very rare to find it on busy roads and in metropolitan areas Trees with heavy lichen growth.

Does the lichens harm the tree?

• Since they do not penetrate the interior of the wood, lichens are not harmful.
• They are not an indication of the poor condition of an old tree.
• Thanks to their symbiotic properties, they provide themselves with water and nutrients.
• They just settle on the Tree bark which is even protected from other fungi and bacteria.
• Lichen provide shelter for numerous useful small animals.

When should lichens be removed?

This is only as trunk maintenance in the elderly Fruit trees required as the protective lichen offer protection to overwintering pests. The right time for this measure are the cold winter months. The lichens are brushed off with a special tree brush, which you can get from specialist gardeners. Please do not use a wire brush, as this would permanently damage the bark of the tree.