Development of wood decay in wound-initiated discolored wood of eastern red cedar

Abstract

Abstract Logs of eastern red cedar, Juniperus virginiana L., with well-developed bands of light-colored wood (“included sapwood”) within heartwood can be unsuitable for sawn wood products. This finding is in contrast to published information that the “included sapwood” is (1) a heartwood anomaly rather than sapwood and (2) its occurrence is not a reason to exclude this type of wood from commercial use. The alternative view presented here is that “included sapwood” is wound-initiated discolored wood which is the starting point for wood decay in living trees and which has adversely altered wood properties before the development of decay symptoms. Our study of the patterns of discoloration and decay, electrical resistance properties, elemental analysis, wood acidity, solubility in dilute NaOH, total phenol content, and tests of wood decay resistance indicated that the so-called included sapwood was discolored wood. This light-colored discolored wood had no greater decay resistance than sapwood, a common finding in other tree species in which “included sapwood” is found. Half the sample disks sent to our laboratory had symptomatic decay within the bands of light-colored discolored wood bounded by a phenol-enriched protective layer on the bark side and phenol-enriched heartwood on the pith side of the band. This ring-rot, even in its pre-symptomatic stage, can cause problems during processing for sawn wood products. Therefore, logs with well-developed bands of light-colored discolored wood should be considered high-risk material for some products, although they could be useful for others.