The present study aimed to evaluate the biological resistance of teak (Tectona grandis) heartwood and sapwood to the action of Trametes versicolor and Gloeophyllum trabeum fungi in laboratory accelerated decay assays. The mass loss evaluation of the samples was performed periodically. The heartwood presented a higher percentage of extractives and the sapwood of holocelluloses. The sapwood and heartwood subjected to the fungus Gloephyllum trabeum remained stable. For the Trametes versicolor fungus, there was an increasing loss of mass over time for both regions, presenting a mass loss of 40% for the sapwood and of 20% for the heartwood at the conclusion of the assay. Teak wood was classified as highly resistant to the fungus Gloeophyllum trabeum, and moderately resistant to Trametes versicolor.
RESUMO A durabilidade natural da madeira é essencial na definição do seu uso. Assim, objetivou-se avaliar a deterioração ao longo de 12 meses da madeira tratada e não tratada de Corymbia citriodora, Eucalyptus camaldulensis x Eucalyptus grandis, e Eucalyptus camaldulensis em ensaio de campo. Os materiais de 5 anos, confeccionados em toretes de 40 cm de comprimento, foram tratados com Arseniato de cobre cromatado (CCA tipo C), e tiveram massa inicial determinada a 0% de umidade. Sequencialmente, foram instalados em ensaio de campo. Realizou-se três avaliações em intervalos de 4 meses, em que foram analisados o Potencial de Ataque Fúngico (PAF), Índice de Deterioração (ID) e Perda de Massa (PM). Os resultados mostraram que o PAF foi maior entre outubro e abril. Para as madeiras tratadas houve baixa PM e deterioração ao longo do tempo. Já as não tratadas sofreram maiores danos, principalmente no período entre 4 e 8 meses. O PAF apresentou pouca relação com a deterioração, visto os padrões de deterioração das madeiras; a preservação foi eficiente no aumento da durabilidade das madeiras; inicialmente a deterioração foi maior, diminuindo e se estabilizando com o tempo; os materiais genéticos não apresentaram diferenças significativas para ID e PM.Palavras-chave: durabilidade, preservação, potencial de ataque fúngico, CCA. Deterioration of Eucalyptus and Corymbia wood in field testABSTRACT The natural durability of wood is essential in defining its use. Thus, the objective was to evaluate the durability over time of treated and untreated wood of Corymbia citriodora, Eucalyptus camaldulensis x Eucalyptus grandis, and Eucalyptus camaldulensis in field test. Small logs, 5 years old, were treated with copper chromate arsenate (CCA type C), and had initial mass determined at 0% moisture. Sequentially, they were installed in field test. Three evaluations were carried out, with a fourmonth interval, analysing the Potential for Fungal Attack (PAF), Deterioration Index (ID) and Mass Loss (PM). The PAF was higher between October and April. The treated wood presented low deterioration and PM over time. The untreated ones suffered more damages, mainly in the period between 4 and 8 months. The PAF showed little relation with the deterioration, considering the deterioration of patterns of the woods; preservation was efficient in increasing wood durability; initially the deterioration was greater, decreasing and stabilizing with time; the genetic material did not present significant differences for ID and PM.
The properties of wood influence its use as a final product, so it is essential to know their relation and influence on the quality of preservation. In this sense, for the present study we aim at the determination of the physical properties of Corymbia citriodora [Eucalyptus citriodora Hook]; Eucalyptus camaldulensis Dehnh. and Eucalyptus camaldulensis Dehn. x Eucalyptus grandis, and the quality of the preservative treatment with CCA-C in an autoclave. We determined diameter, heartwood and sapwood percentages, and their relationship, as well as the basic density for the three genetic materials. The quality of the preservation was evaluated through the area treated and not treated by CCA, besides its penetration and retention. The highest proportion of sapwood, treated area, and highest density value was found in C. citriodora, whereas the hybrid E. camaldulensis x E. grandis presented the highest level of CCA retention. The diameter and density showed the highest correlation with CCA retention in wood, the length and moisture of the small logs also shown to be influential. All clones presented satisfactory chemical treatment quality for use as fence posts.
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