European Larch Canker
Lachnellula willkommii

Name and Family

European larch canker, Lachnellula willkommi, is a member of the Hyaloscyphaceae family.


  • European larch canker, caused by the fungus Lachnellula willkommii, is a serious disease in many parts of Europe.
    • The disease is also present in Japan, China, and Russia.
  • In North America, the disease is only found in the Maritime Provinces of New Brunswick, Nova Scotia and Prince Edward Island and in five counties in Maine, USA.
  • The disease was mistakenly introduced to P.E.I. on European larch trees seedlings planted for trial purposes in the Grand River area of the Island. Unfortunately, the intended seedlings were infected with European larch canker upon introduction.
  • The disease is currently regulated both in Canada and the USA. Source: Canadian Food Inspection Agency.

Identification Guide


All Larch (Larix sp.) species


  • As the name of this disease suggests, the fungal pathogen (Lachnellula willkommii) that is the responsible agent for this disease causes large numbers of cankers to form on the branches and trunks of infected trees.
  • The appearance of cankered areas is the first sign of the disease.
  • Seedlings and young trees are killed through girdling (the cambium around the circumference of the trunk or main branch is damaged).
  • The cankers are caused by lesions of the cambium and result from a scarring process.
  • Cankers initially appear as swellings on the smaller branches or as depressions in the larger branches.
  • The cankers are accompanied by exudations of resin, which can become very abundant.
    • This gives the cankers a shiny, slightly bluish appearance.
  • During certain periods of the year, fruiting bodies of the fungus appear on or near the cankers.
    • They are white and hairy and resemble small cups with yellow orange centres.
  • Larch needles on the small stems or branches above the cankers wither in the spring or become discoloured early in the fall.  
  • Source : Natural Resource Canada

The presence of cankers on the trunk is usually a sign that the disease is in an advanced stage. This is accompanied by a significant loss of foliage.

What it does in the ecosystem

  • Larch is a large component of PEI’s woodland landscapes, and one of the most important tree species in Canada. Thus, any disease known to widely impact the tree species may have a broad ecological impact. 
  • European larch canker reduces the fitness of larch trees, makes their wood unsalable, and causes unsightly damage to the tree which reduces the tree’s aesthetic value and affects growth. 
  • In some cases, especially where cankers affect the trunks of trees, mortality is seen.



  • Prevention and early detection are key in the management of invasive species. 
  • When traveling across provincial boundaries, do not bring firewood with you. European larch canker (ELC) can spread through the movement of contaminated wood products. 
  • Avoid long-distance transport of wood. Inspect any wood to be transported. This is crucial in the fight against ELC.
    • It is illegal to move firewood from within a federally regulated quarantine area. 
    • The “Don’t Move Firewood” campaign has placed bins at the two main vehicular entry points to PEI. If you arrive on PEI with imported firewood, simply place the wood in the Don’t Move Firewood bin at either Wood Islands or Borden-Carleton. You will receive a coupon for a free bundle of firewood which can be redeemed at any provincially-operated campground. Wood deposited in the bins will be securely transported from the bins to PEI Energy Systems for incineration. 
    • PEI Invasive Species Council “Don’t Move Firewood” page.
    • “Don’t Move Firewood” campaign website’s PEI-specific information. 


Check any larch trees on your property for signs of the disease, especially if you live within or close to a regulated area. ELC can be spread over long distances by wind. 


  • Part of Prince County, PEI
  • Most of New Brunswick
  • Nova Scotia, except Cape Breton
  • Maine
  • Continental Europe, United Kingdom, Ireland, Russia and the former states and territories of the USSR, and Japan.


  • The best management tactic for tree disease is to maintain a healthy tree population. 
  • Regular tree maintenance and care will strengthen a tree’s resistance to pests and disease. ELC is known to enter trees through damaged bark. 
  • Regulatory measures have been put in place by the Canadian Food Inspection Agency (CFIA) in areas where ELC is present to prevent the movement of contaminated wood from the area.


  • The eradication of ELC has been achieved in the United States historically. 
  • The method of eradication used is the removal and destruction of infected trees and branches. 
  • The trees are cut down, stumps are ground, and all material is burnt on-site. 
  • This practice is sometimes called “slash burning”.  ELC has unfortunately reappeared in Maine.
  • In some cases, when only one branch of the tree is infected, pruning can be a viable option.
    • Prune the tree 10 ft from the infected site. 
    • All pruning equipment should be disinfected between cuts and immediately after finishing pruning work, before leaving the site.
      • This is to prevent the spread of ELC through contaminated equipment. 
  • Burn the affected material on-site if safe to do so.


  • Clean all equipment and vehicles before leaving the site. 
  • The site should be monitored annually for at least the next five years to ensure that any new infections that emerge are dealt with accordingly. 

If you notice a larch tree affected by ELC on PEI, report it to the CFIA and/or the PEI Invasive Species Council (PEIISC). 

  • CFIA: 902-566-7290
  • The J. Frank Gaudet Tree Nursery, Community, Lands and Environment, 902-368-4714 for confirmation of trees with symptoms found inside the regulated area.
  • Include the location, date, photos and descriptions of the affected trees in your report.


European larch canker (

Camp Tamawaby European Larch The History of a Plantation (

Growth and Survival of Exotic Larix in Prince Edward Island A Status Report (

European larch canker – Lachnellula willkommii – Canadian Food Inspection Agency (

Lachnellula willkommii (European larch canker) (

Eastern Larch Canker:Insect & Disease Fact Sheets: Forest Health & Monitoring: Maine Forest Service: Maine DACF

Federal Register :: European Larch Canker; Expansion of Regulated Areas