Tropical field assessment of combined Trichoderma viride Proteus sp. and urea protective treatment of wood against biodeterioration

Two previous reports showed that decay of wood blocks was inhibited by treatment with combined phosphate buffer (pH7) and Trichoderma viride or urea and ureolytic Proteus sp. A field assessment of the two treatment strategies was therefore carried out in the tropical rainforest for 24 months using the “grave yard method”. The groundline region of stakes treated with buffer/T. viride succumbed to biodegradation after 8 months as indicated by loss of resistance to compression, occurrence of basidiomycete and soft-rot cavities. This was attributed to leaching due to the heavy rainfall, soil microflora and the failure of T. viride to spread due to the dry season effect at the onset of the trials. No signs of degradation were evident until 18 months in stakes treated with urea and Proteus sp. The addition of T. viride to the urea/Proteus treatment system caused a marked improvement as no signs of biodegradation were observed throughout the duration of the field trial. As the concentration of ammonia declined, the hitherto suppressed T. viride began to spread and “fill in the gap”. It can be concluded that the triple combination of urea, Proteus sp. and T. viride, can significantly extend the service life of timber in the field.