Do you care for your elm conscientiously, water regularly and ensure a nutrient-rich substrate with species-appropriate fertilizer? Still, the tree doesn't seem to thank you for your actions? In this case, your elm tree may be suffering from a pest infestation. Check your plant for the following pests.
Which pests attack elm trees and what helps against them?
The most common pests on elms are gall mites, bladder lice and Dutch elm scale insects. They can be recognized by toad-skin-like knots, conspicuous galls on the tops of leaves and wax threads on young shoots. Affected leaves should be removed and approved control products used.
The most common pests of the elm tree
The elm tree is primarily attacked by three pests:
- the gall mite
- the bladder louse
- the elm scale insect
The gall mite
An infestation of the gall mite is comparatively easy to detect. On the leaves of entire branches there are clearly knots that are reminiscent of toad skin. With minor infestations, the elm only suffers passive damage by becoming more susceptible to external circumstances such as weather and other diseases. However, their growth is not affected. To remove the gall mite, it is recommended to remove the affected leaves immediately.
The bladder louse
The bladder louse primarily plagues field and mountain elms. The pests attach themselves to the underside of the leaves. They produce conspicuous galls on the upper side of the leaves, which initially have a rich green color. The pustules only turn yellow over the course of the summer before they turn brownish in autumn and finally dry up. The gall louse does not cause any significant damage, but it attracts ants and makes the leaves appear unaesthetic. In summer it even flies out and attacks surrounding grasses. But once he has chosen an elm tree, he always returns to it to lay his eggs. Here too you should remove affected leaves.
The elm scale insect
You can recognize an infestation by the elm scale insect by a wreath of wax threads, which you usually find on young shoots. It almost looks as if there are small snowflakes on the trees. You can rid your elm of the pest using a legally approved pesticide.
