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 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 increments from zero (storage yard) to 10 years decay isolate (2, 3, 11) using the methods described by (oldest line installed in 1966) and diameter classes Davidson (2, 3) and Nobles (11). Tentatively identified ranging from 14 to 26 inches (35 to 66 cm) at the isolates were compared macroscopically and micro- groundline. The pole lines were grouped as much as was scopically with named isolates from The Reference feasible to provide samples of similar size representing Culture Collections of wood decay fungi maintained at pole age and size for 5 geographic regions (Northeast, the Center for Forest Mycology Research of the Forest Southeast, South Central, and Northwest regions of Products Laboratory, Madison, Wisconsin. New York and Central Pennsylvania). Additional areas Monocaryons of several decay fungi were identified providing small samples were the Central Hudson River by diploidizing the suspect isolates with monocaryon region of New York and Eastern Massachusetts. Other isolates of named species and verified by the subsequent data tabulated for each pole included preservative and formation of clamp connections.

52 APRIL 1980 The data obtained for the poles and cores were tenuis, Irpex lacteus, and Antrodia serialis.The remain- punched on 80 line computer data cards. The data were ing identified fungi occurred only once, twice, or three programed and sorted primarily to locate major pole times each. The large group of unidentified decay fungi factors associated with the presence or absence of decay, also appeared to represent many individual species, extent and location of decays, and major types of decay with the exception of three groups containing two organisms. isolates each, and one group of five isolates that culturally resembled Phlebia gigantea (Fr.) Donk Results somewhat. Six of the 19 decay fungi identified were, or Wood decay fungi were isolated from 190 (ap- included, some haploid isolates, namely, C. versicolor, proximately 20%) of the 952 treated Douglas-fir poles Poria placenta, A. serialis, Phlebia radiata, Hirschi­ sampled. These decay fungi were isolated primarily oporus pargamenus, and H. abietinus. Many micro- from untreated portions of the poles. The associated fungi were also isolated from the cores and some rapidly decay was judged generally to be in an early stage of growing species occasionally overran the decay fungi. development in many of these poles, based on the high Those most frequently isolated were: Scytalidium frequency of decay isolations obtained from only one lignicola Pesante, Cladosporium herbarum Link ex Fr., core per pole (63%) and the sound visual appearance of Cephal.oascus fragrans Hanawa, Paecilomyces varioti most cores. A total of 305 decay fungi were isolated from Bainer., Aspergillus spp., Penicillium spp., and several the 3,701 increment cores. The 261 identified decay yeast species. Bacteria were also commonly asso- isolates represented the 19 species listed in Table 1. ciated with the decay fungi isolated. Other non- Poria carbonica and P. placenta were the major decay hymenomycetes less frequently isolated were: Oidioden­ fungi obtained and comprised nearly two-thirds of the dron citrinum Barron, Oidiodendron griseum Robak, decay isolates. Other important species listed in decreas- Alternaria tenuis Nees, Periconiella verrucosa Stewart ing order of frequency were Coriolus versicolor, P. & Corden, Phialophora heteromorpha (Nannf.) Wang, Geotrichum spp., Phialophora sp., and Acremonium sp. Generally only a single species of decay fungus was isolated from a pole. However, there were cases of

TABLE 1. - The identity and frequency of decay fungi isolated from several fungi isolated from one pole, a single core, and in Douglas-fir utility poles treated with four preservative types one case from the same core position. Poria carbonica and in service in the Northeast for up to 10 years .

and P. placenta were associated most frequently in the Isolation same pole or core. In the cases where Coriolus versicolor frequency was isolated from the same cores as P. placenta and P. Identitya Poles Cores carbonica, it was found always in the outer core zone. Poria carbonica Overh. 91 148 Poria placenta (Fr.) Cke. 28 48 The five major fungi obtained were grouped by Poria placenta (Fr.) Cke. - haploids 9 10 isolation position in the decayed cores for possible Coriolus versicolor (L. ex Fr.) Quél. - haploids 13 14 inferences as to location and time of origin of the decay Poria tenuis (Schw.) Cke. 8 8 Jrpex lacteus (Fr.) Fr. [Polyporus tulipiferae in the poles. The data are summarized for the poles (Schw.) Overh .] 7 7 treated with penta and CCA in Table 2. These data Antrodia serialis (Fr.) Donk [Trametes] 4 4 Antrodia serialis (Fr.) Donk - haploids 2 2 suggest that more decay fungi were present in innermost Fomitopsis cajanderi (Karst.) Kotl. et Pouz 2 4 and middle portions of the poles. Since this was frustulatus (Pers. ex Fr.) Boid. [ ] 3 6 untreated heartwood, the presence of fungi would have Phlebia radiata Fr. 1 1 Phelbia radiata Fr. - haploids 2 2 Hirschioporus pargamenus (Fr.) Bond. et Sing . [Polyporus] - haploids 2 2 Stereum com plicatum (Fr.) Fr. 1 2 Stereum ochraceo-flavum (Schw.) Ell. 2 2 Stereum gausapatum (Fr.) Fr. 1 1 TABLE 2. - The relationships among isolation frequency, core position, Xylobolus subpileatus (Berk. et Curt.) Boid 1 1 and preservative type for the major decay fungi.

Gloeophyllum saepiarium (Wulf ex Fr.) Karst. [Lenzites] 2 2 Frequency of isolations from a core position.a Poria vaillantii (DC. ex Fr.) Cke. 1 1 Core Poria Poria Coriolus Poria Irpex Poria spissa (Schw .) Cke. 1 1 b Poria cinerascens (Bres.) Sacc. et Syd. 1 1 position carbonica placenta versicolor tenuis lacteus Hirschioporus abietinus (Dicks. ex Fr.) Donk Penta-treated poles IPolyporus] - haploid 1 1 Innermost Unknown decayersb (representing 22 species) 28 31 c (2,995) 54 19 4 6 4 Probable decayers 15 17 Middle d (2,992) 53 24 8 6 5 Totals 226 316 Outer aIn some cases the older, familiar generic or species name is placed in (3,006) 44 16 10 5 4 brackets for reader convenience. CCA-treated poles b Determined to be wood decay fungi (hymenomycetous) on the basis of Innermost clamp connections or isolates (hymenomycetous or soft rot fungi) (346) 48 20 0 0 1 causing at least a 5 percent weight loss in pine sapwood blocks in an Middle agar-type decay test. (344) c 53 17 0 0 2 Isolates judged to be decay fungi based on cultural features but not Outer subcultured due to rapid growing microfungi. (356) 39 15 0 0 2 dThese numbers do not reconcile with the number of decayed poles (190) or cores (305) tabulated in the sample since there were cases where more aIsolates from a core were tabulated with the identified isolates as the than 1 species of decay fungus was isolated from a pole or core. Also this same species, when culturally similar. listing contains isolates from 12 poles in a preliminary sampling that bThe total number of core positions in the sample from which no decay were not included in the computer data. fungi were isolated is placed in parentheses.

FOREST PRODUCTS JOURNAL Vol. 30, No. 4 53 TABLE 3. - The frequency of the major decay fungi isolated from cores and poles and the decay type, or nuclear condition of all identified decay fungi as affected by preservative. Frequency of isolation Species or Pentachlorophenol CCA and ACA Totals decay type (PO and PLPG) groupings Cores Poles Cores Poles Cores Poles Poria carbonica 64 29 80 62 144 91 Poria placenta 29 19 27 18 56 37 Corio/us versicolor 12 11 1 1 13 12 Poria tenuis 8 8 0 0 8 8 lrpex lacteus 5 5 2 2 7 7 Antrodia serialis 1 1 5 5 6 6 Xylobolus frustulatus 6 3 0 0 6 3 White rotters 45(13)a 39 3(2) 3 48 42 Brown rotters 95( 6) 50 118(6) 89 213 139 Dicaryons 116(14) 68 115(5) 86 231 154 Monocaryons 24( 5) 21 6(3) 6 30 27 Totalb 140(19) 89 121(8) 92 261 181 Total number in the sample 3,261 813 440 139 3,701 52 aT he number in parentheses indicates the number of different species included in the group total. The patterns were similar for the poles. bThese numbers do not reconcile with the numbers of decayed cores or poles listed for identified fungi in Table 1 that includes isolates from 12 poles in a preliminary sampling study that were not included in the computer data based on 952 poles.

to be explained by entry through deep checks pene- TABLE 4. - Decay incidence in penta- and CCA-treated utility poles as trating the outer treated shell or by pretreatment affected by time over a 10-year period. Time of pole PO poles CCA poles invasions that survived the preservative treatment b b cycle. Only Coriolus versicolor was isolated in highest treatment decay incidence decay incidence Installationa frequency from the outer core zone in the penta-treated 1966 13/ 64 (20%) _ _ poles. This is in accord with its known tolerance for 1967 21/ 221 (10%) _ _ 1968 34/ 164 (21%) _ _ penta. Also a comparison of isolate frequency with the 1969 6/ 63 (10%) _ _ total number of cores sampled indicates that Poria 1970 18/ 88 (20%) _ _ carbonica and P. placenta were isolated about 10 times 1971 1/5 (20%) 2/ 2 (100%) 1972 0/ 1 0 43/ 50 ( 86%) more frequently from CCA-treated poles than the penta- 1973 28/ 50 ( 56%) treated poles. 1974 8/ 49 (16%) _ _ 1975 3/ 14 (21%) _ _ The species of fungi isolated and various groupings 1976 2/ 20 (10%) _ _ of these fungi were sorted out by preservative type and Total 106/ 689 (15%) 73 / 102 ( 72%) Storage yard treatment in order to determine whether treatment was 1971 0/ 1 _ _ _ affecting fungus type and frequency of occurrence 1973 _ _ 0/ 2 _ (Table 3). These data indicate a substantially larger 1975 0/20 _ 2/ 16 (12%) 1976 0/ 4 number of white rot and monocaryon forms of the decay 1977 1/9 (11%) 0 / 5 _ fungi were obtained from the penta-treated poles. Also Total 1/34 ( 3%) 2/ 23 ( 9%) the higher incidence of Poria carbonica and P. placenta · aPO=penta in oil. The data assume all poles were installed in a in CCA- and ACA-treated poles is indicated. Since these transmission line during the same year of treatment. Occasional poles may have remained longer in storage yards as extras or reserves. treatments do not involve the use of high temperatures, bDecay incidence is expressed as the ratio and percentage (parentheses) possible fungus invasion in western pole storage yards of decayed to total poles in a service age group. In the penta-treated poles, the age of 58 (4 decayed) poles could not be determined with is suggested. certainty and are excluded. Further analysis of the pole data to determine factors associated with decay incidence and extent was limited primarily to the penta-treated poles and CCA- treated poles since the other two treatments involved small numbers of poles or represented a limited number of service age groups. The effects of age in service and Because Poria carbonica and P. placenta were the time in a storage yard on the decay incidence are major fungi isolated, and the former is uncommon in the summarized in Table 4. These data indicate that some Northeast, we were interested in when they entered the decay was present already in the stored poles and an poles. An analysis of the isolation frequency of these early and erratic development of decay occurred in the fungi per pole for the various pole age groups is various age groups. They also suggest a possible presented in Table 5. The highest incidence of the increase in decay incidence with age of service only for occurrence of Poria carbonica and P. placenta was in the CCA-treated poles. These data are suggestive only poles treated and installed in 1972 and 1973. and were not analyzed statistically because substantial Decay incidence increased substantially and linear- and unexpected variation in decay incidence occurred ly with maximum check depth in the poles as measured between poles treated by different companies. This from groundline to 6 feet above. Groupings of penta-and would bias any age effect. CCA-treated poles, by check depth and decay incidence,

54 APRIL 1980 (125); penta (PLPG), 9.4 percent (32); and ACA, 7.1 TABLE 5. - Decay incidence of Poria carbonica and P. placenta as affected by time of pole treatment and installation percent (14). High decay rates in poles were traceable to for all preservative treatments . some treating companies and appeared to be indepen­ Time of pole Decay incidence in polesb dent of length of exposure and may indicate some treatment (Installationa) Poria carbonica Poria placenta unusual conditions prior to or subsequent to treatment 1966 3 / 6 4 ( 5%) 1/64 ( 2%) of the poles. From one company supplying penta-treated 1967 2/221 ( 1%) 4/221 ( 2%) poles conditioned by the Boulton process, only one out of 1968 12/164 ( 7%) 6/164 ( 4%) 1969 0/63 ( 0%) 2/63 ( 3%) 48 poles developed decay with a 12 to 30 hour con­ 1970 8/102 ( 8%) 5/102 ( 5%) ditioning cycle, while 8 poles out of 48 developed decay with a shorter 6-hour conditioning cycle. 1971 1/22 ( 5%) 1/22 ( 5%) 1972 33/51 (65%) 12/51 (24%) There was little difference in decay incidence 1973 27/53 (51%) 5 /53 ( 9%) regardless of preservative treatment between poles in 1974 1/49 ( 2%) 0/49 ( 0%) 1975 0/19 ( 0%) 0/19 ( 0%) service in forest soils (21%;116 decayed poles in a sample 1976 1/20 ( 5%) 0/20 ( 0%) of 544) and in agricultural soils (20%; 70 decayed poles in Storage yard 2/66 ( 3%) 0/66 ( 0%) a sample of 342). · aThe da ta assume all poles were installed in a transmission line during The poles in this study had no clear pattern of the same year of treatment . Occasional poles may have remained longer in storage yards as extras or reserves. The age of some poles in the study externally visible decay evidences. Also, there was no could not be determined with certainty and they were excluded in this clear relationship between the visual judgments of listing. decay made on freshly extracted cores and subsequent bDecay incidence is expressed as the ratio and percentage (parentheses) of decayed to total poles in a service age group. bioassay confirmations. Decay fungi were frequently, but not always, obtained in isolations from zones where core sections appeared to be in intermediate or advanced stages of decay. Discolored zones were not a good visual indicator of decay, and decay fungi were isolated from many core sections that appeared to be sound. In these cases generally the cores had been judged visually to be wet. Frass piles at the groundline indicative of carpenter ant colonies were observed in 79 poles. Decay was detected in only 26 of these poles. Carpenter ant colonies were largely restricted to the larger diameter poles with deep checks. The ants observed in some of these poles were the single species Componotus pennsylvanicus (DeGeer). There were no regional differences in decay in­ cidence in the poles when those with similar treatments , sizes, and treating companies were grouped and compared. Discussion and Conclusions The high incidence of decay (approximately 20%) in these treated Douglas-fir poles in service in the Northeast for up to 10 years corresponds in general to reports from the Pacific Northwest (8). Decay was detected primarily in untreated portions of poles. It is Figure 1. - Relationships between decay frequency in poles and maximum significant to note that in many of these poles the decay check depths In the groundline zone for penta and CCA. Ratios are the numbers of decayed and undecayed poles in the point sample. Correlation was both in an early stage and localized, suggesting that coefficients from left to right are 0.861 and 0.830, respectively. eradicative treatments with fumigants (7, 8) may be highly beneficial. The increased decay incidence associated generally with check depth, and the frequent observation of are presented in Figure 1. Correlation coefficients were untreated wood in the inner zone of the deeper checks, 0.861 and 0.830, respectively, and are significant at the indicates that some enlarged and extended into un­ 0.01 percent level. Again these data are trend-suggestive treated wood after preservative treatment. This poses only as sample sizes varied considerably. Untreated the question of whether the seasoning procedures wood was clearly discernible in some of the deeper practiced prior to preservative treatments, or the checks. Also in general the deeper checks were treatment conditions were adequately reducing pole associated with the larger-diameter poles. moisture contents to expected equilibrium moisture The incidence of decay in the poles varied substan­ contents prevailing in the Northeast. tially with preservative type and supplier. Pole decay Though many cases of decay appear to be related to percentages for the various preservative types are checks the time of decay inception in many poles is summarized (with sample sizes in parentheses) as unclear. A low level of decay was detected in stored follows: penta, 14.3 percent (781); CCA, 60.8 percent treated poles. A substantial number of decayed poles

FOREST PRODUCTS JOURNAL Vol. 30, No. 4 55 were found after the first few years of installation and carbonica and P. monticola were isolated in larger thereafter decay incidence increased generally though numbers from CCA-treated poles, we speculate that this erratically. This suggests that decay became estab- reflects an unusual treatment condition rather than lished in many poles shortly after pole installation. treated substrate selectivity. However, the high frequency of Poria carbonica in some No useful external indicators of decay were deter- pole age classes (Table 5) raises the interesting question mined other than the frequency of decay occurrence with of where and when this fungus entered the poles, deep checks and particularly those with visibly un- because this species does not occur naturally in the treated, inner wood. It is significant that careful visual forests of the eastern United States. inspection of many cores in the field failed to detect early Many of the poles decayed by Poria carbonica were decay subsequently confirmed by isolation. On the other associated with CCA treatments and some can be traced hand there were cases of obvious intermediate decay to treatment cycles with moderate temperature regimes. from which no fungi could be cultured. We speculate that these pole invasions by decay fungi Cultural detection of decay as conducted in these may have occurred in the trees, in the poles prior to studies is judged to be a conservative estimator of decay treatment, or shortly after treatment and during storage due to the limited point sampling inherent in the in the West. While the poles sampled in the storage yards increment boring procedure. Also because some decay had a low decay incidence, the sample was small and not fungi were rapidly overrun by microfungi we probably representative of the range of treating companies in the failed to recognize some decay species in the initial study. In some cases only a single core was taken from phases of isolation from cores. the top side of the reasonably accessible poles. We did Surprising differences in decay incidence occurred not anticipate the possibility that some decay fungi in poles from different treating companies using the might escape a pressure preservative treatment. Ad- same preservatives and treatment method. These data ditional research is needed to check this point. Two suggest that pole seasoning or preparation practices, possible explanations posed are that treatment which would increase preservative penetration or reduce temperatures do not reach deep enough into the pole to subsequent check development (kerfing) could do much in activate established infections or that poles inade- to reduce decay development, particularly in larger quately dried prior to or during treatment subsequently poles. Also, where feasible, conditioning or treatments dry, and checks develop into untreated wood. at temperatures and times to kill decay fungi, which It is interesting to note the appearance of many may be present in poles prior to treatment, are rec- white rot fungi and some fungi usually associated with om mended. Careful inspections for conformance to hardwood. substrates among the isolates. Also, the specifications, especially in regard to penetration and occurrence of monocaryons of six species was unusual. retention, are basically essential to obtain anticipated Several of the white rot fungi were isolated only as pole protection. monocaryons. Nobles (10) reported the repeated isola- tion of monocaryotic mycelia of various species from decays in trees. These occurrences suggest that undue reliance on substrate and presence of clamp connections in cultures, may result in misidentifications of some Literature Cited 1. COWLING, E. B. 1957. A partial list of fungi associated with decay of common fungi in preliminary routine cultural and wood products in the United States. Plant Dis. Rep. 41:894-896. microscopic screenings. 2. DAVIDSON, R. W., W. A. CAMPBELL, and D. J. BLAISDELL. 1938 . Differentiation of wood-deca ying fungi by their reactions on gallic or Studies were conducted to determine whether the tannic acid medium. J. Agri. Res. 57:683 95. haploids isolated were more tolerant to penta- 3. ______, ______, and D. B. VAUGHN. 1942. Fungi causing decay of living oaks in the eastern United States and their cultural chlorophenol than their corresponding dicaryons. Both identification. USDA Tech. Bui. 785, 65 pp. technical and analytical grades of penta were tested. No 4. DUNCAN, C . G., a nd F. F. Lo MBARD. 1 965. Fungi associated with consistent differences in resistance were obtained, so princip a l decay in wood produc ts in the United Sta tes. USDA Forest Serv. Res. Pa p. WO-4, 31 pp. some explanation other than the selective pressure of 5. ESLYN, W. E . 1970. Utility pole decay. Part II. Basidiomycetes the treated substrate must be sought. associated with decay in poles. Wood Sci . and Tech. 4:97-103 . 6. . GRAHAM , R. D. 1973. Preventing and stopping internal decay Many of the unidentified decay isolates represented of Dougla s-fir poles. Holzforschung 27:168-173. single species. This suggests that the number of fungi 7. ______and G. G. HELSING. 1979 . Wood pole maintenance capable of decaying treated poles in service may be manual: inspection and supplemental treatment of Douglas-fir and western redcedar poles. Forest Research Lab., Oregon State Univ., much larger than generally believed. Nearly one-half of Corvallis, Oreg. Res. Bull. 24. 62 pp. the 40 unidentified isolates were white rot fungi as 8. ______and J. S. MOTHE RSHEAD . 1 967. Inspecting and treating indicated by positive Bavendam reactions on gallic and western redcedar and Douglas-fir poles in service. Forest Research La b., Oregon State Univ., Corvallis, Oreg. Information Circular 21. tannic acid media (2). 34 pp. 9. ______, T. C. SCHEFFER, G. HELSING, and J. D. LEw. 1976. White rot fungi were isolated most frequently from Fumigants can stop internal decay of Douglas-fir poles for at least 5 the penta-treated poles. This poses the question as to years. Forest Prod. J. 26(7):38-41. whether the lignin decomposing enzymes in these fungi 10. NOBLES, M. K. 1958. Cultural characters as a guide to the and phylogeny of the Polyporaceae. Can. J. Bot. 36:883-962. permit them to adjust to higher levels of toxic phenolics 11. ______1965. Identification of cultures of wood inhabiting in wood than those of brown rot fungi. While Poria hymenomycetes. Can. J. Bot. 43:1097-1139 .

56 APRIL 1980