Susan E. Anagnost

Light Microscopic Diagnosis of Wood Decay

Light micrographs of the anatomical features of brown rot, white rot and soft rot are presented here to facilitate easy identification of each type of decay in birch and pine. This paper presents the light-microscopic observations made during the course of several broad studies of wood deterioration by fungi. A key aids the identification of brown rot, white rot and soft rot in wood and wood products. Features used for identification include bore hole size and frequency, shape of erosion channels and cavities, cell separations and changes in birefringence as observed on unstained sections with polarized light or differential interference contrast microscopy. Included are descriptions of white-rot and soft-rot erosion patterns at several decay stages.

Confirmation and Significance of Bartholin's Method for the Identification of the Wood of Picea and Larix

Eighty-seven Picea and Larix samples from thirty-nine species were examined microscopically to confirm an accurate method of genus separation. The proportions and type of ray tracheid bordered pits as described by Bartholin (1979) were the only wood anatomical feature to correctly identify all specimens.

S2 Orientation of Microfibrils in Softwood Tracheids and Hardwood Fibers

In this study the soft-rot method was applied to measuring the variation of microfibril angle (mfa) in loblolly pine, black cherry, sugar maple and canelo. For loblolly pine and black cherry, measurements of the radial wall indicated a gradual decrease in mfa across the earlywood portion of the growth ring, with an abrupt decrease at the latewood zone for pine, and in contrast only a slight decrease in microfibril angle across an annual ring of black cherry. In loblolly pine microfibril angle measurements indicated that the average microfibril angle in radial sections was very similar to the average for tangential sections of the same block. The average microfibril angles in the intermediate plane, or cell corner, were statistically similar to that of the tangential and radial plane, for pine, cherry, and maple. In canelo, microfibril angles in radial sections were significantly larger than in tangential and intermediate sections. In pine latewood the microfibril angles were less than the average mfa for the entire ring, and the earlywood microfibril angles were greater than the average mfa of the entire ring, thus the average mfa for the growth ring did not represent actual measured mfa values.