Rhizina root rot

The family Rhizinaceae contains notable fungal pathogens, most importantly Rhizina undulata, commonly known as the fungus causing Rhizina root rot. This pathogen specifically targets coniferous trees and is well-documented for its ability to devastate young plantations following forest fires.

The fungus acts as a necrotrophic pathogen that invades the root systems of healthy trees by spreading through the soil. The mycelium colonizes the roots, causing extensive necrosis, which effectively strangles the tree's vascular system, leading to rapid decline and eventual death of the affected specimen.

Symptoms of the disease are often observed in clusters and include rapid discoloration of needles, changing from healthy green to yellow and finally reddish-brown. The base of the infected tree may exhibit the fungus's fruiting bodies, appearing as dark brown, wavy, crust-like discs that are firmly attached to the soil surface.

The spread and development of the pathogen are strongly influenced by high soil temperatures. Heat triggers the germination of the fungus's spores, which is why reforestation efforts on sites recently affected by fire or prescribed burning are particularly vulnerable to sudden outbreaks of this infection.

Management strategies focus primarily on silvicultural practices rather than chemical fungicides. Effective control includes:

• avoiding burning debris on sites intended for reforestation;
• thorough removal of stumps and root debris from soil;
• ensuring a mandatory waiting period of several years between fire events and replanting activities.