Decay resistance of two-step freezing–heat-treated fast-growing eucalyptus wood

The present study aimed at evaluating the decay resistance of Eucalyptus grandis wood modified by two-step freezing–heat treatments, using brown-rot (Gloeophyllum trabeum) and white-rot (Trametes versicolor) fungi. Five treatments, combining freezing (at − 22 °C) and termorretification (at 180 °C and 200 °C), were performed. The decay resistance tests were conducted as per relevant standard. Both freezing and thermal treatments were effective in reducing the mass losses attributed to the brown-rot fungus. The two-step treatment, in which the freezing was prior to the thermal treatment at 200 °C, yielded the highest decay resistance to the eucalyptus wood, leading to a hindered access to the nutrients in cellulose and hemicelluloses. Only two-step treatments were effective for protecting the wood against the white-rot fungus, which may be due to modifications in both lignin and wood extractives related to synergic effects from both freezing and heat.