Steccherinum ochraceum

Steccherinum ochraceum is a wood-decay fungus belonging to the family Steccherinaceae. While primarily recognized as a saprotroph that decomposes dead organic matter, it can behave as a facultative parasite, attacking weakened or stressed living trees and contributing to the development of white rot in the timber of deciduous species.

This pathogen impacts a wide range of woody plants, including various deciduous forest trees such as birch, oak, alder, and aspen. In agricultural and horticultural settings, it frequently affects fruit trees, including apples, pears, and plums, often targeting trees that have already suffered from environmental stress or previous mechanical damage.

The primary symptom of infection is the appearance of ochre-colored, shelf-like, or resupinate fruiting bodies with a characteristic hydnoid (toothed) surface. Internally, the fungus causes a destructive white rot that breaks down the lignin and cellulose in the wood. This makes the wood soft, stringy, and structurally unstable, eventually leading to broken branches and the potential death of the host tree.

The development of the fungus is highly dependent on environmental humidity and the presence of accessible woody substrates. Spores are primarily disseminated by wind and insects. Infection of living trees typically occurs through wounds, including pruning cuts, frost cracks, sunscald areas, or damage caused by bark-boring insects, which serve as entry points for the fungal mycelium.

The economic impact of the disease is linked to the loss of orchard productivity and the structural failure of affected trees. Effective control and prevention rely on maintaining tree vigor and minimizing exposure to the pathogen through the following practices:

• routine sanitary pruning to remove and destroy dead or decaying wood;
• proper wound healing using antiseptic pastes or grafting waxes on large pruning cuts;
• minimizing tree injury through careful cultivation and harvesting;
• proactive management of wood-boring pests to prevent initial infection sites.