"False White Stem Cup" - what a cute name for such an aggressive pest. Hymenoscyphus pseudoalbidus, a dangerous fungus from East Asia, has been up to mischief in Germany since 2007 and is destroying more and more ash trees. Do you suspect that your ash tree could also be infested? Read more about the symptoms of the disease here.
The dangerous fungus that kills the ash trees originally comes from Asia
symptoms
- withered leaves
- discolored bark
- changed growth form of the crown
withered leaves
First, brown necrosis appears on the leaves. From July onwards, these begin to wither before the ash completely sheds them. This process is actually very atypical for the deciduous tree. You can also observe the formation of leaf spots.
Discolored bark
Are the side shoots of your ash turning yellowish or pink? This is also a clear sign. Over time, the shoots will die off completely. A cross-section of the tree clearly shows that unusual veining, which does not correspond to the pattern of the annual rings, is forming.
Altered growth form of the crown
The crown becomes lighter and lighter due to the death of the instincts. The ash reacts to this with strong branching and twigs that grow in tufts.
Infestation of young ash trees
Young ash trees suffer particularly from the infestation of the fungus, since their narrow trunk has little to counteract the dieback of the ash shoots. Fresh shoots are attacked first. The tree usually dies off completely within a year.
Infestation of old ash trees
The disease progresses somewhat more slowly on old trees. They don't die off right away, but they get weaker and weaker over the years. The crown thins out significantly, the ash becomes very susceptible to weathering.
Are there antidotes?
Researchers are currently looking in vain for an effective treatment. However, there is hope from the observation that isolated ash trees that stand next to severely diseased trees only show the symptoms slightly. Presumably they are genetically resistant to the pest.