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Trees of life are among the most popular hedge plants and can be found in numerous gardens throughout Central Europe. Its gorgeous shade of green and dense habit are the reason for the popularity of the plant, which originally comes from North America and East Asia and has established itself in Europe for its appearance and usefulness. Thuja hedges rarely suffer from diseases because they are very robust. When problems arise, you need to identify and deal with them quickly.

Diseases of thuja hedges

In most cases, arborvitae in Germany are kept as hedges, which present themselves attractively in the garden or separate the property from the neighbors as a privacy screen. In itself, the cypress family (bot. Cupressaceae) is a very robust plant that can get by with little care and inspire with its fresh green. Healthy Thujen can be recognized by the following properties:

  • rich green coloring of the leaf scales
  • young leaf scales also green
  • strong growth
  • upright shoots

If the plant is not doing well, this is immediately noticeable, as the scales turn brownish in almost all Thuja hedge diseases. There are a total of ten diseases that can be caused by fungi and care errors. It's important to identify and combat these as early as possible so you don't lose your hedge. Fungal diseases in particular are fatal for Thuja hedges, since the spores can easily pass from one plant to the next. If you suspect a disease, check the conditions below and use the treatment methods to save your hedges.

Cause: maintenance error

In many cases, care errors are the more common cause of Thuja hedge diseases. Fungal infections follow very often, but are not always related. An advantage of nursing errors is the possibility of treating them quickly with the right measures. Three typical care mistakes have a particularly strong effect on the plants. You will learn how to handle these in the following sections.

tip: The gradual browning of the scaly leaves in autumn, which persists through the winter and is slow but continuous in certain species and varieties, is not a maintenance error. These include the western arborvitae (bot. Thuja occidentalis) with the varieties 'Brabant', 'Holmstrup' and 'Columna', and the giant arborvitae (bot. Thuja plicata), which take on a brown tone reminiscent of bronze in various intensities .


Waterlogging in trees of life leads to trunk and root rot, which can be deadly for the plant. Since this is a slow process, it is usually not immediately visible and sometimes even when it is too late. The reason for this is the fact that the scales do not turn brown from waterlogging, as is the case with other diseases. It is therefore hardly noticeable when your tree of life has been flooded. Arborvitae generally prefer slightly moist soil, but the roots must not be permanently wet. If the waterlogging has gotten out of hand, the rot is shown by the following symptoms:

  • plant weakens
  • soft plant parts
  • white coating on the trunk
  • white coating on roots
  • wet earth

If this condition has been like this for a long time, the signs of weakness and rot will cause the plant to die. Because of this, you need to act as soon as you spot waterlogging or rot so you don't have to discard the entire plant. Check the roots first and remove most of the affected parts of the plant. Freshen up the location of the tree of life hedges with dry soil to remove a little moisture and remove possible pathogens. Unfortunately, if the rot has reached the trunk, the tree of life can no longer be saved and must be disposed of. If this happens to you, you shouldn't put the tree on the compost, but at the nearest green waste collection point. Fungal spores may have accumulated on the weakened plant material, which could otherwise be blown away.


Just as much of a problem as waterlogging is drought for Thuja hedges. A big advantage compared to rot, however, are the obvious symptoms that are typical of the plant:

  • leaf scales slowly turning brown
  • plant weakens
  • is slowly wasting away

In addition to the brown leaf scales, you should also check the location. If the substrate is very dry, you can use one lack of water go out. Immediate action is important here, because even short periods of time lead to the death of the plants, quite the opposite to waterlogging. On the other hand, the symptoms can be recognized quickly and you can act much more effectively and do not only notice the damage when the plant can no longer be saved. If you notice a lack of water, do the following:

  • water the site immediately
  • Keep an eye on the plant for the foreseeable future
  • also the location
  • Adjust water additions accordingly

Beware of drought stress, which can become a problem even in winter. Above all, longer periods of frost without snowfall can cause Thuja hedges to dry up. In this case you should wait for frost-free days and water a little to avoid possible damage.

tip: Another cause of browning in thuja plants is the use of the plant as a toilet for dogs. The components of the urine cause the scales to turn brown, the underside to blacken, and they will then die unless you put a barrier around the plant to keep the animals away.

salt excess

An excess of salt occurs in arborvitae mainly in winter and is road salt caused. The road salt has a toxic effect on the cypress plants and can burn the shoot tips in the lower part of the plant. In the worst case, the plant dies when large quantities of salty spray water reach the site and penetrate the soil. Unfortunately, the only thing that helps here is transplanting the thuja, which should not be done in winter, or a protective barrier so that the salt does not get to the plant. In addition, the following measures can help in the short term:

  • Rinse the plant thoroughly
  • water

Water will carry the salt deeper into the ground, which can help.

notice: Similar to an excess of salt from road salt in winter, there is overfertilization with too much mineral fertilizer. In this case, reduce the amount or change the fertilizer so that it does not oversalt the soil.

Cause: fungal diseases

Fungal diseases have a greater impact on the vitality of plants and can cause lasting damage. Since these are diseases that are caused by spores can be transferred to other plants, these must be treated much faster than the care mistakes. In the worst case, entire hedges can be destroyed by the fungi. To avoid this fate, you need to know about the four typical fungal diseases on thuja hedges, which you can combat with the tips below.

honey fungus root rot

Honey fungus root rot is caused by the fungus Armillaria mellea and is recognizable by large clusters of fungi bathed in yellow color variations. For this reason, the fungus is also called honey-yellow honey fungus. The mushrooms sprout directly from the bark. As soon as you notice the fungi on your thuja hedge, you must immediately remove any infested specimens to prevent them from spreading to the healthy specimens. Unfortunately, there are no measures against root rot, which destroy the tree of life within a short time.

Pestalotia dieback

This thuja hedge disease is an infestation by Pestalotiopsis funerea and can be just as devastating as honey fungus root rot. The reason for this is that trees of life are weakened by acidic soils and cannot defend themselves against the fungus. The following symptoms indicate the serious illness:

  • The leaf scales begin to turn brown
  • from the tip of the leaf to the middle of the leaf
  • even shoots are affected
  • dark brown spots, the size of a pin, on shoots
  • entire plant can be affected

The important thing here is to increase the pH of the soil. This should be between 5.5 and 6.5, i.e. slightly acidic, but not too acidic. Likewise, it must not be too high, otherwise the scales will turn yellowish. First remove all parts of the plant and dispose of them in the household waste. After that, the pH of the soil is increased, for example with lime. If the plant is too weak, you must dispose of it together with the potting soil.

Kabatina dieback

You also have to fight the Kabatina thujae fungus, which attacks young leaves and turns them brown. These spread over all leaf scales and even the shoot tips. In addition, black spore bearings, which are distributed throughout the plant. Over time, the shoots and scales die off. Here it helps to thoroughly remove the diseased parts of the plant and freshen up the soil. This should have the following properties:

  • relaxed
  • permeable
  • nutritious

Usually the infestation is limited to the scales and not to the whole plant.

dandruff tan

Dandruff tan and Kabatina dieback are very similar in symptoms. The big difference in Didymascella thujina is the focus on the older leaf scales, which present similar spots and even spore beds. After the older leaf scales have been infested, it is the turn of the young shoots. Thanks to the similarity of the two Thuja hedge diseases, you can proceed here in the same way as with the Kabatina dieback. The location is particularly important for healing.

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