Excavated truffle

Excavated truffle (latin Tuber excavatum) is a species of ascomycete fungus that often acts as a significant competitor in commercial truffle orchards. While it is a natural fungus, in the context of controlled truffle farming, it is considered an unwanted intruder that competes for space and nutrients in the rhizosphere.

The causative agent belongs to the genus Tuber. Unlike highly prized culinary truffles, Tuber excavatum has a distinct morphology featuring small, hollowed-out fruit bodies with a rough, deeply pitted texture. Its rapid growth and ability to colonize tree roots make it a threat to the biodiversity of mycorrhizal systems.

This fungus primarily affects trees used in truffle inoculation, including various species of oak (Quercus), hazel (Corylus), and hornbeam (Carpinus). By occupying the root space, Tuber excavatum prevents the establishment and expansion of more valuable symbiotic fungi, effectively hijacking the host plant's resources.

Signs of infestation include a noticeable decline in the productivity of high-value truffles in a specific zone of the plantation. The presence of the fungus is confirmed by finding its characteristic small, irregular fruit bodies during the harvest period. Affected trees may show slightly reduced growth vigor due to the displacement of beneficial mycorrhizal symbionts.

Protection and management strategies focus heavily on preventive measures:

• Stringent quality control of inoculated seedlings before planting.
• Use of molecular diagnostic methods (such as PCR) to verify the purity of fungal strains in the rhizosphere.
• Maintaining optimal environmental conditions that favor the target truffle species over aggressive opportunistic fungi.
• Regular soil management to improve aeration and prevent stagnant conditions that promote Tuber excavatum growth.