Tropolone Content of Increment Cores as an Indicator of Decay Resistance in Western Redcedar


  • Jeffrey D. DeBell
  • Jeffrey J. Morrell
  • Barbara L. Gartner


<i>Thuja plicata</i>, tropolones, thujaplicins, decay resistance


The high decay resistance of western redeedar (Thuja plicata Donn) is due to the presence of toxic extractives, called tropolones, in the heartwood. Therefore, tropolone content may be used as an indicator of decay resistance. With increment core-sized samples of western redcedar heartwood, we used gas chromatography to measure tropolone content and soil block tests to assess decay resistance. Results showed that decay resistance was extremely variable at low tropolone levels, but was uniformly high at tropolone levels of 0.25% or greater. Analyzing tropolone content of western redeedar increment cores is a useful way to assess decay resistance of standing trees.


Barton, G. M., and B. F. MacDonald. 1971. The chemistry and utilization of western red cedar. Canadian For. Serv. Publ. No. 1023, 31 pp.nFrazier, C. E. 1987. The essential oil of western red cedar, (Thuja plicata). M.S. thesis, University of Washington, Seattle, WA. 112 pp.nJohnson, E. L., and A. J. Cserjesi. 1975. Gas-liquid chromatography of some tropolone-TMS ethers. J. Chromatog. 107(2):388.nJohnson, E. L., and A. J. Cserjesi. 1980. Weathering effect on thujaplicin concentration in western redcedar shakes. Forest Prod. J. 30(6):52-53.nNault, J. 1987. A capillary gas chromatographic method for thujaplicins in western redecdar extractives. Wood Sci. Technol. 21(4):311-316.nNault, J. 1988. Radial distribution of thujaplicins in old growth and second growth western red cedar (Thuja plicata Donn). Wood Sci. Technol. 22(1):73-80.nRennerfelt, E. 1948. Investigations of thujaplicin, a fungicidal substance in the heartwood of Thuja plicata D. Don. Physiologia Plantarum 1(3):245-254.nRudman, P. 1962. The causes of natural durability in timber. IX. The antifungal activity of heartwood extractives in a wood substrate. Holzforschung 16(3):74-77.nRudman, P. 1963. The causes of natural durability in timber. Part XI. Some tests on the fungi toxicity of wood extractives and related compounds. Holzforschung 17(2):54-57.nScheffer, T. C., J. J. Morrell, and M. A. Newbill. 1987. Shellrot control in western redcedar: potential replacements for pentachlorophenol spray. Forest Prod. J. 37(7/8):51-54.n






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