In recent years, the bark of apple trees has become increasingly red in some regions. However, this does not necessarily have to be a symptom of a tree-threatening disease.
What causes red bark on apple trees?
Red bark on an apple tree can be caused by the red pustule fungus or harmless green algae. In the case of red pustule fungus, infected areas should be removed and disposed of properly. Green algae, on the other hand, is not harmful and can be brushed off if necessary.
A red color on the tree trunk can have different causes
Basically, the red color alone is not a sufficient indicator for an accurate statement about the he alth of an apple tree. While reasons such as blood lice laying eggs can be ruled out if the red color occurs over a large area, other phenomena and fungal diseasescan still be the reason for a noticeable red color on the trunk. Take a close look at the bark and determine whether the red color is only in spots or rather flat and thin. While the former would speak for the red pustule fungus, the latter indicates so-called green algae.
The red mushroom is not something to be trifled with
The discoloration caused by the red pustule fungus initially only appears as inconspicuous dots on the trunk bark. The ascomycete belongs to the order of crustaceous fungi and is a serious threat to tree he alth. If you don't take action against it, it will soon reveal its fruiting bodies in more and more places on the apple tree trunk. Fungicides have only insufficient effect against it, even in commercial cultivation. Since the fungus drains the apple tree's strength, infected areas should be cut back into the he althy wood and the material disposed of far away from the apple trees. The following steps are necessary:
- Determination by a garden professional
- Removing the affected branches and trunk
- Professional disposal of the affected wood
- Wound care as protection against new fungal infestation
The harmless explanation: green algae
It sounds a little hard to believe, but in fact improved air quality and fewer pollutants in the air are responsible for the fact that red colors in the form of so-called green algae (Trentepohlia umbrina) are now appearing on more and more trees in the garden. This coloring may seem a bit dangerous at first glance, but green algae on the trunk bark should not be classified as a disease because it does not cause any damage to the tree. If you want to remove the algae for visual reasons, carefully dispose of the algae parts that have been removed with a brush, otherwise they can spread even more to nearby tree trunks.
Tips & Tricks
If the red color of the tree bark occurs together with stunted growth and other symptoms, a problematic location with incorrect soil can also be the reason.