Thelephora palmata

Thelephora palmata is a basidiomycete fungus that functions as a facultative pathogen in forestry, primarily affecting the root collar and stems of young coniferous seedlings. While often saprotrophic, it can become detrimental in dense, moist nursery environments, causing root and collar decay.

The host range is focused on coniferous species, with spruce, pine, and fir seedlings being particularly susceptible. The fungus encircles the base of the plant, physically inhibiting gas exchange and nutrient transport, which often leads to chlorosis and sudden collapse of the affected seedlings.

The most distinctive symptom is the emergence of brownish, finger-like or fan-shaped basidiocarps around the base of the infected plants. These fruiting bodies are often accompanied by a distinct, unpleasant odor, signaling a mature fungal colony capable of releasing a large volume of spores.

Development is heavily favored by poorly drained, compact soils and high atmospheric humidity. The fungus thrives in shaded, stagnant conditions where air circulation is restricted, allowing the mycelium to spread from infected plant debris to healthy living tissues throughout the seedbed.

Economic damage is primarily seen in large-scale nursery losses, requiring integrated pest management strategies:

• Improving soil drainage to prevent stagnant water.
• Managing plant density to ensure adequate ventilation and light penetration.
• Sanitation, including the removal of infected organic material and debris.
• Applying preventive fungicides specifically targeted at soil-borne basidiomycetes.