A defect study of 1,725 logs cut from 498 trees provided the basis for determining the relationships between tree age, volume, and defect. Red rot was responsible for 8.6 percent, brown rots 7.3 percent, and other defects 3.3 percent of the total 19.2 percent defect. Red rot, found in 68 percent of all trees, was the most important cause of defect.

The ability of the fluorescent-coupled lectins wheat germ agglutinin (WGA) and concanavalin A (Con A) to react with selected Basidiomycetes, Ascomycetes, and Fungi Imperfecti was evaluated using pure cultures of thirty-five fungi grown on malt extract agar. WGA, which is specific for residues of N-acetylglucosamine present in fungal chitin, reacted with nearly all hyaline fungal structures, but did not react with dematiaceous (dark) structures. Con A, which is specific for a-D-mannosyl and a-D-glucosyl residues, reacted with about one half of the fungi that reacted with WGA. This lectin was less useful for detecting fungal decay. The results indicate that WGA is a highly specific probe for detecting fungal chitin and fungal colonization by non-dematiaceous fungi. The sequence of changes that occurred in wood over progressive stages of fungal decay was also studied using Douglas-fir heartwood [Pseudotsuga menziesii (Mirb.) Franco] and ponderosa pine sapwood (Pinus ponderosa Dougl. ex Laws.). The fungi used were Poria carbonica Overh., a brown-rot fungus, Coriolus versicolor (L. ex Fr.) Quel., a white-rot fungus, and Chaetomium globosum Kunze ex Fr., a soft-rot fungus. Incident light and fluorescence microscopy were used to observe wood sections. Poria carbonica and Coriolus versicolor caused high weight losses at the early stages of exposure, while Chaetomium globosum caused lower weight losses. As expected, weight losses were generally greater in pine blocks. Poria carbonica displayed a greater tendency to attack ponderosa pine than Douglas-fir. The cellulolytic enzymes of the brown-rot fungus in ponderosa pine were capable of penetrating and acting within the cell walls at early stages of decay, while attack of Douglas-fir was concentrated on the more readily accessible ray parenchyma. The attack patterns found with Coriolus versicolor were similar to those found with P. carbonica on Douglas-fir, but bore holes were less common in the advanced stages of white rot attack. The hyphae of C. versicolor were widespread in ponderosa pine in early stages of decay. Passive penetration via the pits was prevalent in the early stages of decay (

Pp. 32.

Metham sodium or NaMDC is one of the four major soil fumigants that are currently registered for controlling internal decay of wood products in use. Fumigants are used primarily in utility poles but are also applied to piling, timbers and other large wood members. NaMDC must decompose to fungitoxic compounds to become effective. A variety of volatile and non-volatile decomposition products are produced during NaMDC breakdown in wood but the role these components play in the overall fungitoxicity of metham sodium is poorly understood. Volatile methylisothiocyanate (MITC) is believed to be the primary fungitoxic NaMDC breakdown product but it has been suggested in previous studies that some synergistic activity between MITC and other volatile NaMDC decomposition products in wood might occur, resulting in an enhanced MITC fungitoxicity. A fumigation apparatus was designed to examine the toxicity of two NAMDC volatile decomposition products, carbon disulfide and methylisothiocyanate, against six decay fungi (basidiomycetes) and one mold (ascomycete) established in Douglas-fir and Ponderosa pine. Fumigations were performed with the individual compounds at different concentrations for a period of ten days to determine sublethal dosages of each chemical. Fumigant effects were assessed by grinding blocks and plating a portion of the ground material in malt extract agar. The resulting number of colony forming units (CFU's) provided a measure fungal survival. A stimulus in the number of CFU's was observed for most species treated with lower fumigant concentrations suggesting that some fungi had the ability to metabolize sulfur-containing fumigants when growing in a low sulfurcontaining environment. Large variations in number of CFU's were exhibited among the fungi but CT90 values showed that the CS2/MITC mixture was more fungitoxic to most fungi than fumigations with the individual fumigants. The results indicate that NaMDC decomposition products can interact synergistically to enhance fungal control in wood. The effect may help to explain the effectiveness of NaMDC as a wood fumigant despite its relatively low MITC yield. Further studies using other decomposition products would help to better define other interactions in this process.