Fungi Associated with Decay in Treated Douglas-Fir Transmission Poles in the Northeastern United States
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Fungi Associated With Decay In Treated Douglas-fir Transmission Poles In the Northeastern United States Robert A. Zabel Frances F. Lombard Allen M. Kenderes the preservatives used for protection. It also may Abstract provide useful clues on the inoculum sources and the Decay was detected by cultural methods in 190 of 952 timing and sites of decay inception, important in control (approximately 20%) treated Douglas-fir transmission poles programs. For these purposes lists of the major fungi installed for up to 10 years in the northeastern United States . Preservative systems and treatments for the poles sampled associated with decay in various wood products, were penta in petroleum oil, penta in liquefied petroleum gas , including wood poles, in service in the United States chromated copper arsenate, and ammoniacal copper arsenate. have been assembled by Cowling (1) and Duncan and Isolations were made from various radial positions on several Lombard (4). Information on the principal fungi in increment cores selected from the groundline zone and deep North America associated with decay development in check vicinity for each pole. The decay was in early stages, utility poles, classified by timber species and regions, often localized, and in many cases, detectable only by cultural has been assembled by Eslyn (5). His report stated a mea ns. The decay fungi, representing 19 identified species, need for additional studies to determine the fungi were isolated primarily from untreated inner pole sections and associated with decay development in utility poles in at the groundline. Poria carbonica, a decay fungus known service in the Northeast. primarily from the western United States, and Poria placenta, were the two species isolated most frequently. Six of the Wood poles used by the power utilities in the nineteen species were in themonocaryon nuclear condition and transmission and distribution of electricity are an identified by cross matching with known monocaryon isolates important use of wood and represent a large capital and subsequent formation of clamp connections. Decay investment. The soil contact by poles favors decay frequency in the poles generally increased with check depth. development. Thus the use of decay resistant species or The time of occurrence and location of the decay in many poles effective preservative treatments to insure long, suggests that in some cases early decay may escape preser- economical service is required. vative treatment or becomes established shortly thereafter in the storage yard. Decay may also start shortly after installa- A growing need for large poles has resulted in the tion and be associated with check development into untreated installation of increasing numbers of treated Douglas- wood. The data suggest that pole preparation or treatment fir poles in the northeastern United States. Graham and practices that would increase preservative penetration and Mothershead (8) studied decay development in Douglas- reduce check development would minimize decay development. The authors are, respectively, Professor, Dept. of En- vironmental and Forest Biology, SUNY, College of En- vironmental Science and Forestry at Syracuse; Mycologist, Center for Forest Mycology Research USDA, Forest Prod. Lab.; and Engineer New York State Electric & Gas Corpora- INFORMATION ABOUT the identity and roles of the tion. We thank J. L. Lowe, M. J . Larsen, and H. H. Burdsall, J r., fungi associated with decay development in various for aid in identifying the basidiocarps that developed in some wood products has both fundamental and practical cultures; Karen Nakesone for assistance with cultural iden- tifications; F. Terracina for identifying the nonhymen- values. Such information may lead to a better un- omycetes reported; and R. E. Benson and F. G. Picciano of New derstanding of the relationships among micro- York State Electric & Gas Corp., for accommodating, whenever feasible, the inspection program of their transmission lines to organisms in the initiation and development of wood our research purposes. We also thank W. Stiteler for statistical decay. It permits more effective selection of test fungi for advice. This paper was received for publication in June 1979. toxicant evaluations and provides better judgments on © Forest Products Research Society 1980. FOREST PRODUCTS JOURNAL Vol. 30, No. 4 51 fir poles in the Pacific Northwest. A useful culture assay treatment type, companies supplying treated poles (a for detection of early decay and procedures for the total of 11), soil condition (wet or dry) at the groundline, treatment of early decay in poles in situ with fumi- and land use (agricultural or forest). These important gant type fungicides was developed by Graham, variables could not be included proportionally in the Mothershead, and Helsing (6, 7, 8). stratified regional samples. A large utility corporation with transmission lines In the summer of 1976, 93 poles were sampled. in New York and Pennsylvania recently initiated a Initially, 11 poles were aseptically sampled, radially, major inspection program to determine decay frequency with increment borers (5 mm diameter) for isolation in their system. This project provided a unique oppor- purposes, 1 foot below the groundline, at groundline, and tunity to isolate and collect fungi associated with decay 1 and 2 feet above the groundline. Another 82 poles were at the groundline in Douglas-fir poles in service in the sampled at the groundline and either 1 foot above in wet Northeast and to study various pole, site, and treatment soil or 1 foot below in dry soil. In these samples the factors affecting decay frequency and severity. largest number of decay fungi were obtained consistent- ly from the groundline sections and nearest deep checks. Based on this sampling data in the summer of 1977 an Objectives additional 859 poles were studied. Three increment cores The objectives of the study were: a) to isolate, were taken from each pole at the groundline zone about identify, and determine the relative frequency of the 120° apart. The first core was taken several inches to the principal decay and other wood-inhabiting fungi side of the largest check. An additional fourth core was associated with decay development at the groundline taken vertically directly above the first core and zone, b) to determine the frequency and extent of decay adjacent to the deepest portion of the check . Each core in poles as affected by time in service, and c) to was then subdivided positionally into equally sized determine the effects of additional factors such as pole outer, middle, and inner zones. The outer zone included size, checking patterns, preservative treatment, and soil the treated sapwood and generally an outer untreated type on the frequency and extent of decay. heartwood zone, the middle zone contained the middle untreated heartwood, and the inner zone contained the untreated inner heartwood and frequently the pith. Materials and Method Immediately after collection the cores were rated A total of 890 poles were sampled from a total visually for the presence or absence of decay in the three population of approximately 20,000 Douglas-fir treated zones (sound, early, or advanced decay), depth of poles in the New York State Electric & Gas Cor- preservative penetration, and whether the section poration's transmission systems located in New York appeared wet or dry. The diagnosis of early decay was and Pennsylvania. An additional sample of 62 treated based on color and texture changes and advanced decay Douglas-fir poles were obtained from transmission lines on structural disruption of the wood. Water was visibly of the Central Hudson Gas & Electric Corporation in present in the cores judged to be wet at collections. New York and the New England Power Corporation in Within 48 hours after collection isolations were Massach use tts. Numbers of poles available for study in made from each core zone. The cores were aseptically cut various preservative systems and treatment types were into several 3 to 4 mm disks representative of the three pentachlorophenol in petroleum oil (PO), commonly core zones . All isolations from the outer zone were made known as " penta," 781; chromated copper arsenate from the treated-untreated boundary. Preliminary (CCA), 125; pentachlorophenol in liquefied petroleum studies indicated that isolations from treated sections of gas where the solvent is recovered (PLPG), 32; and the outer zone were consistently negative. All other zone ammoniacal copper arsenate (ACA), 14. These preser- isolations from cores were from untreated wood. The vative systems and treatments were commercial disks were then surface sterilized by quick passage over processes generally following specifications of the a flame, partially embedded in 3.5 percent malt extract American Woo d-Preservers' Association. The poles were agar medium in petri dishes, and incubated at 28°C. The located in 17 operating lines and several storage yards. plates were inspected twice weekly for 1 month. Suspect Poles were randomly preselected by computer, but in a wood decay fungi were subcultured for subsequent study few cases it was necessary to limit core sampling to and identification. Also, cultures of other fungi most those poles primarily in reasonably accessible portions frequently isolated or associated in initial isolations of lines. with the decay fungi were retained. Cultural and Poles were selected to represent service ages in microscopic features were determined for each putative yearly