Lachnellula resinaria

Lachnellula resinaria is a pathogenic fungus that causes significant damage to the bark of various coniferous tree species. Known as a causative agent of resinous cankers, this fungus specifically targets the tissues of the stem and branches, leading to a condition characterized by persistent resin flow and subsequent necrosis of the tree's outer protective layers.

The primary hosts for this pathogen include spruce (Picea) and larch (Larix) species. The fungus typically invades through wounds, frost cracks, or sites previously damaged by insects. By colonizing the cortical tissues, the mycelium disrupts the transport processes within the tree, causing the plant to weaken progressively over several growing seasons.

Visual identification of the disease is facilitated by the presence of copious amounts of resin around the infection site. During the active stages of the fungus, small, bright orange to yellow apothecia (fruiting bodies) emerge through the bark. These cup-shaped structures are highly visible and serve as the primary source of spore dispersal within the infected stand.

Environmental conditions play a crucial role in the development and spread of Lachnellula resinaria. The fungus thrives in humid, cool conditions which are typical of dense coniferous forests. Spores are primarily wind-dispersed, allowing the pathogen to move effectively between trees in a forest stand or nursery setting, particularly following periods of heavy rain or high atmospheric humidity.

The impact of this disease ranges from stunted growth and branch mortality to the total loss of commercial value for timber production. Management strategies focus on sanitation: removing heavily infected limbs and ensuring adequate tree spacing to reduce humidity levels around the foliage and stems. Preventing mechanical damage during forest management activities is also key to reducing new infection sites.