With its lush crown and robust bark, the elm makes an almost majestic, imperturbable impression. But the picture is deceptive. Although the elm is widespread throughout almost the entire northern hemisphere, its population is declining. Diseases that occur specifically on the deciduous tree are to blame. Research is still being carried out into effective treatments to prevent the elm from becoming extinct. If your elm also suffers from a disease, there are still some measures that can help in this case. On this page you will learn how to recognize symptoms and how to treat them successfully.
Leaf spots are not a good sign
The most common diseases of the elm
- the elm disease
- fungal leaf spot pathogens
The elm disease
It starts with the elm bark beetle. Once the pest has transmitted the wilt fungus, the elm usually dies within 2-5 years. Dutch elm disease is considered the most dangerous disease of the deciduous tree and has already claimed numerous lives since it spread throughout Europe and North America. The disease originally comes from Asia and reached the Netherlands via wood imports. The fungus cuts off the elm's water supply, so to speak, by clogging the pathways in the trunk. Some elm species such as the golden elm are less susceptible to this disease, while others such as the field elm are severely affected. Unfortunately, experts are still looking for a reliable control agent.
Fungal leaf spot pathogens
The fungal leaf spot pathogens include
- the Phloespora leaf spot disease
- and Platychora leaf spot disease
You can recognize the former disease by the yellowish spots on the leaves of the elm, which turn brown after a short time. In addition, fruiting bodies develop on the underside of the leaves, which soon produce white, fluffy tufts. A layman often confuses Phloespora leaf disease with a mineral deficiency due to the similar symptoms. Don't be fooled if the fungus suddenly disappears. It only overwinters in fallen leaves, but reappears next summer. A fight is only for the optics. The fungus does not cause much damage.
Shady locations and high humidity promote infestation, which triggers Platychora leaf spot disease. The black spots, surrounded by a dark green halo, are clearly visible to the naked eye. The fallen leaves are primarily affected, which means that this fungus is also relatively harmless.