Tree diseases

Various pathogens can cause diseases in forest trees. Many of them are microscopic organisms whose presence is often only indicated by external symptoms. We study and diagnose pathogens and develop countermeasures.

Fungi are the most important agents of forest diseases. However, bacteria, nematodes, oomycetes, phytoplasmas or viruses can also damage trees. Many pathogens are indigenous (e.g., some species of Armillaria), but international trade and global warming enable new pathogens to establish and spread in Switzerland (see also invasive species).

Quarantine organisms are particularly dangerous organisms for the forest that can cause great damage if introduced and spread (see Quarantine organisms). One example is the oak wilt pathogen Bretziella fagacearum, which originated in North America and can endanger various oak species. Once introduced, dangerous diseases can spread rapidly, as demonstrated by ash dieback. We can study such organisms, as well as opportunities for biological control, under high-security conditions in our Plant Protection Laboratory and greenhouses.

WSL has two dedicated research groups for tree diseases:

  • Swiss Forest Protection, the Swiss Centre of Expertise for forest protection issues, diagnoses forest pests, provides information and advice.
  • The group Phytopathology studies diseases of woody plants under changing environmental conditions and develops biological control methods.