The Douglas fir is a stately plant that, from the outside, is just bursting with strength. Is there really nothing stopping this tree from growing taller? Or are there perhaps diseases that can bring him to his knees?

Douglas firs are very susceptible to root rot

Native and imported diseases

About 200 years ago, the Douglas fir migrated from North America to Europe, where it feels very comfortable and is now quite common. Unfortunately, it is also susceptible to some native tree diseases.

In the meantime, pathogens have also been introduced from their homeland of origin and more may be added.

Young trees are more susceptible to disease

Young Douglas firs in particular are susceptible to disease because they are not yet sufficiently strong. It is primarily fungi that cause problems for the tree. The following diseases should be mentioned first:

  • Rusty Douglas Fir Shed (Rhabdocline pseudotsugae)
  • Sooty Douglas Fir Shed (Phaeocryptopus gäumannii)
  • root rot

tips

When young, Douglas firs can be treated preventively with plant strengtheners.

Rusty Douglas Fir Shed

In humid locations and when the planting is too dense, the two Douglas firs caused by sac fungi can spread. The rusty Douglas fir chute makes itself felt with the following symptoms:

  • Needles turn yellow-brown
  • Needle loss soon follows
  • there is a strong loss of growth
  • if the infestation is severe, pests or other types of fungi follow

This fungal disease rarely leads to the death of the tree, as the upper parts of the tree are usually spared. However, if bark beetles or honey fungus also spread, the life of the tree is seriously threatened.

tips

The so-called coastal Douglas fir is characterized by less susceptibility and is therefore often planted.

Sooty Douglas Fir Shed

This sac fungus spreads faster, which is why the tree often dies within a year.

  • in spring the needles turn yellow
  • starting from the middle of the tree
  • later they fall off completely

Although spraying with fungicides alleviates the visible symptoms, they do not eliminate the cause of the disease, which is why they ultimately remain ineffective.

Different root rot fungi

The Douglas fir is one of the most sensitive conifers when it comes to root rot. Injuries to the bark and roots make it easier for a fungal pathogen to penetrate inside the tree, where it remains undetected for a long time and gradually decomposes the tissue. If it is discovered because it forms visible fruiting bodies on the trunk, any help will come too late.

That is why it is important to avoid any injury. When planting, care must be taken not to damage the roots. This also applies to all excavations in the root area.

Category:

Trees