Phialophora wood stain

The causative agent of the disease is the microscopic ascomycete fungus Phialophora lagerbergii, which belongs to the group of wood-staining fungi. This pathogen acts as a specialized agent of sapstain, primarily affecting the cell walls and the content of parenchyma cells in coniferous timber.

The primary hosts of the fungus are coniferous tree species, such as Scots pine, European spruce, and fir. The pathogen enters the wood through bark wounds, cut surfaces, or the tunnels made by wood-boring insects, developing actively in freshly felled timber and weakened standing dead trees.

Symptoms of the infection manifest as a characteristic change in sapwood coloration. The wood acquires a grayish-blue or dark brown hue, which is linked to the accumulation of the fungus's pigmented mycelium within the ray cells and tracheids. On cross-sections, this appears as radial streaks or irregular spots.

Favorable conditions for fungal development include high wood moisture content (above 30%) and moderate temperatures ranging from 15 to 25 degrees Celsius. An important factor in its spread is the presence of wood-boring insects, which carry the pathogen's spores on their bodies, facilitating the rapid contamination of healthy forest areas.

The harmfulness of Phialophora lagerbergii lies in the significant loss of commercial timber quality. Although the fungus does not cause deep decay and does not break down lignin, the discoloration makes the wood unsuitable for the production of high-quality finishing materials, significantly reducing the market value of the products.

Protection measures include timely harvesting and removal of timber from the forest during the spring and summer, as well as immediate debarking of logs to rapidly reduce their moisture content. Preventive treatments of timber with antiseptic agents, which inhibit spore germination and mycelium growth on the surface of log stacks, are also effective.