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Fraser fir (Abies fraseri (Pursh) Poir.) has suffered catastrophic mortality throughout most of its native range from an exotic insect, the balsam woolly adelgid (Adelges piceae Ratz.). To assess the regeneration potential and viability of fir populations, overstory and understory Fraser fir size and age structure were analyzed. The data werecollected from thirty-six 400-m2 permanent plots, stratified into four stand canopy composition types, established near the summits of five mountains in the Great Smoky Mountains. We found that, where canopy mortality was severe, fir advance regeneration was re-entering the overstory. In seriously impacted stands, mortality of large fir and increased recruitment have produced distributions characterized by few large fir and relatively high densities of small fir. Densities of 0- to 10-year-old fir seedlings and fir seedlings =/<0.25 mtall were much lower in stands dominated by dead fir than in mostly intact fir stands. While the lack of reproducing adults appears to bethe main cause, competition with invasive species and higher seedling mortality from environmental factors probably contribute. These results lead to a hypothesis that Fraser fir will undergo a regeneration-mortality cycle with a decrease in the numbers of each successive generation. [ABSTRACT FROM AUTHOR]

Resistance of lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) to western gall rust (Endocronartium harknessii (J.P. Moore) Y. Hiratsuka) was compared between 21-year field infection trials and inoculation of 2-month-old seedlings. The seedlings were produced from seed stored since the original field plantings. Virtuallyall of the seedlings from families identified as susceptible in the field produced galls in the inoculation trial, only 1% of seedlings from these families did not develop galls. Nearly half the seedlings in families classed as resistant in the field trials did not form galls 13 months after inoculation. Only one of these seedlings developed galls in the following 2 years. Seedling inoculation provides a simple early test to assess field resistance to gall rust of lodgepole pine seedlots, and an efficient way to cull at least the most susceptible ones. [ABSTRACT FROM AUTHOR]

American beech (Fagus grandifolia Ehrh.) trees resistant (R = 760) and susceptible (S = 681) to beech bark disease were located and mapped in nine natural stands in West Virginia (WV), Massachusetts (MA), Maine (ME), Nova Scotia (NS), and Prince Edward Island (PEI). Dormant bud tissue collected from each tree was examined by isozyme analysis to characterize the population genetic structure of R and S subpopulations mapped in each of four intensively sampled (R/S) stands, and five additional populations in which only R trees were sampled. Seventeen enzymes (with 9 polymorphic and 14 monomorphic loci) were analyzedto estimate variation across the spatial range of disease occurrence. All populations possessed significant levels of inter- and intra-population diversity; several parameters appeared to increase in magnitude from southwest to northeast across the range. In the R/S stands, percent polymorphic loci averaged 38%, average number of alleles/locus was 1.8 (3.0 for polymorphic loci), and mean expected heterozygosity was 0.165. Most genetic variation resided within populations (97%; GST= 0.03). Analyses of pooled R and S subpopulations demonstrated that observed heterozygosities were up to 26% higher in S trees, i.e., R tree populations exhibited consistent heterozygote deficits. [ABSTRACT FROM AUTHOR]

We used historical distribution data of Scleroderris disease (causedby the fungus Gremmeniella abietina var. abietina (Lagerb.) Morelet)in Ontario to model its probability of occurrence as a function of climate factors. A logistic regression model of the probability of occurrence as a function of the mean temperature of the coldest quarter and the precipitation of the coldest quarter was a very good fit. Theconcordance (index of classification accuracy) of the model was 84%.We subsampled the data repeatedly, generated new parameter estimates, and tested the predictions against data not included in the model. Classification accuracy was similar for each subsample model; therefore, we concluded that the final model is stable. Gridded estimates ofthe climate variables were used to spatially extend the two-variablelogistic regression model and produce a probability of occurrence map for Scleroderris disease across Ontario. The predicted map of probability of occurrence fits well with the map of the observed locationsof the disease. These results lend credence to previous work that suggests that distribution of Scleroderris disease is strongly influenced by climate. The classification results also suggest that this model is a useful tool for assessing the risk of Scleroderris disease throughout Ontario. [ABSTRACT FROM AUTHOR]

Spread of Heterobasidion annosum (Fr.) Bref. was investigated in a 60-year-old Norway spruce (Picea abies (L.) Karst.) stand in central Lithuania. Of the 375 trees sampled, H. annosum was isolated from 85 (22.7%). Forty nine (56.3%) of the isolates belonged to the S group and 38 (43.7%) to the P group. Among the S-group isolates, 35 genets occupied 49 trees (1.4 trees per genet on average). In the P group, 24 genets were detected in 37 trees (1.5 trees per genet on average). The largest S and P genets were 21 and 20 m in diameter, respectively. The S group spread was more extensive within stems than for the P group; mean length of the decay column for S-group isolates was 459 1 159 cm (mean 1 SD), and it was 327 1 101 cm for P-group isolates (p = 0.0001). Average stump area affected by decay was 56 1 15%for the S group, and 47 1 16% for the P group (p = 0.016). This is the first published field data on intersterility group related difference in decay extension in tree stems. The S group is better adapted than the P group to growth in Norway spruce wood. [ABSTRACT FROM AUTHOR]

The carbon isotope composition (delta13C) of cellulose extracted from wood samples was measured on 26-year-old maritime pine trees (Pinus pinaster Ait.) of the mesic French provenance Landes and of the drought-resistant Moroccan provenance Tamjoute, all growing atthe same location in France. Analysis of spatial variability revealed that intra-ring delta13C values varied over a range of about 0.5%o (mean SD = 0.12%o) for circumference and of about 1%o (mean SD = 0.22%o) for height and that interannual variability of delta13C was 3%o. The successive year-to-year delta13Cvalues on four trees (from 1972 to 1991) were found to roughly parallel the variations of a water stress index, calculated by taking intoaccount climatic variables as well as the level of the water table in the soil: delta13C increased with drought. The two provenances (30 trees per provenance) were compared at a juvenile stage (old rings) and at a mature stage (recent rings). The drought-resistantprovenance (Tamjoute) presented lower delta13C values, independent of ring age. Relationships between delta13C and tree height are discussed both at the within- and between-provenance levels. [ABSTRACT FROM AUTHOR]

Stability of 76 interior lodgepole pine (Pinus contorta ssp. latifolia Engelm.) provenances in resistance to western gall rust (Endocronartium harknessii (J.P. More) Y. Hiratsuka) and needle cast (Lophodermella concolor (Dearn.) Darker) was investigated from 19 and 23 sites in the British Columbia interior, respectively. Provenances, sites, and provenance by site interaction had significant effects on severitylevel of infection of both diseases. Susceptible provenances contributed mainly to the interaction. The resistant provenances to both diseases were very stable and essentially homeostatic across sites (regression coefficient approaching 0). Resistant provenances were concentrated in the jack pine (Pinus banksiana Lamb.) - lodgepole pine hybrid zone and adjacent areas, and provenances from the low-elevation interior wetbelt were also very resistant to needle cast. Geographic patterns of provenance variation revealed that the closer a lodgepole pine provenance is to the limit of jack pine distribution, the higher and more stable is its resistance to western gall rust and needle cast. The current multiple-site evaluation supports for the hypothesis that jack pine introgression influences pest defence in lodgepole pine and suggests genetic selection can be effective. [ABSTRACT FROM AUTHOR]

A 19-kDa protein, Pin m III, was recently shown to be associated with overwintering and frost hardiness of western white pine (Pinus monticola Dougl. ex D. Don) seedlings. Here, we report that this protein is up-regulated by the fungusCronartium ribicola Fisch, the causal agent of white pine blister rust in western white pine trees. Between 1991 and 1994, bark samples of mature western white pine trees (resistant with no stem cankers and susceptible with stem cankers) were collected in winter, spring, and fall. Proteins were extracted and analyzed by Western immunoblot utilizing specific rabbit polyclonal anti-Pin l I (a homologue of Pin m III) antibodies. During all collection dates, but particularly in the spring, susceptible trees had more Pin mIII than resistant trees. In July 1995, 43 previously inoculated 7-year-old white pine seedlings were also analyzed. In all susceptible seedlings (cankered) tested, cankered tissue had high levels of Pin m III, and samples collected from the outside edge of the canker marginhad low levels of Pin m III; this protein was also detected in some healthy bark of cankered trees. Since the level of Pin m III in healthy white pine trees is normally lowest in summer months, the high level Pin m III in summer samples of infected tissues is a consequence of the fungal infection. [ABSTRACT FROM AUTHOR]

Restriction fragment length polymorphism analysis (RFLP) of the intergenic region (IGR-1) between the 3' end of the 26S ribosomal RNA gene and the 5' end of the 5S rRNA gene was used to identify 39 isolatesof Armillaria species collected from live or recently dead bigtooth aspen (Populus grandidentata Michx.) trees and sucker sprouts in the Tioga State Forest, Pennsylvania. The unknown isolates were identified by comparing their restriction fragment patterns with 18 isolates of known Armillaria species common to the northeastern United States. Twenty of the unknown isolates (50%) were identified as either Armillaria gallica or Armillaria calvescens. Eighteen (46%) of the isolateswere identified as Annillaria ostoyae. One isolate of Armillaria sinapina was obtained from a recently dead aspen tree. One isolate of Armillaria mellea, considered to be the most divergent of the Armillaria species, was obtained from basidiomes fruiting on a recently dead aspen tree near Berwick, Pennsylvania. In some instances, amplification of DNA was possible by adding mycelial scrapes directly to the polymerase chain reaction (PCR) mix, thus precluding the need for DNA extraction. Advancements in RFLP analysis may offer a method able to provide rapid and precise identification of most North American and European Armillaria isolates. [ABSTRACT FROM AUTHOR]

This paper reports the occurrence of two types of pathogenic bacilliin cadavers of spruce budworm, Choristoneura fumiferana, larvae and pupae on balsam fir, Abies balsamea (L.) Mill., foliage sampled in several locations in New Brunswick, Canada. One type forms spores and protein crystals at sporulation typical of Bacillus thuringiensis (B.t.), while the other forms spores but no crystals. The noncrystal-producing bacillus is likely Bacillus cereus rather than an acrystalliferous variety of B.t.. The bacilli infect budworm during most of its life cycle, from hibernating second-instar larvae to pupae, with varying rates of infection, but are never a major cause of mortality. The bacilli also infect other lepidopterous species occurring on balsam fir foliage. Circumstantial evidence indicates that both bacilli occur naturally on the foliage, despite the history of aerial application of B.t.-based insecticides near, if not directly over, our study plots. A subtle impact of these bacilli on the dynamics of spruce budworm populations is discussed. [ABSTRACT FROM AUTHOR]

Variation in response of green ash (Fraxinus pennsylvanica Marsh,) to infection by ash yellows (AshY) phytoplasmas was assessed. Twenty seedlings of each of 35 half-sib families from 15 sources (37--50 deg.N, 70--98 deg.W) were planted in pairs (two-tree plots) in a randomized complete block design at Ithaca, N.Y. One plant of each pair was inoculated at age 2 years, and some of these plants again at age 3 years, with New York strains of AshY phytoplasmas by bark-patch grafting. DAPI tests revealed 99% of inoculated trees and 2% of controls werediseased 4 years after first inoculation. incidence of dieback and mortality associated with winter damage and transplanting shock was significantly higher in diseased trees than in noninfected controls. Foliage of many diseased trees appeared lighter green than foliage of noninfected controls. Foliar color, measured with a Minolta SPAD-502 chlorophyll meter 4 years after first inoculation, varied significantly (p < 0.005) between diseased trees and controls, among families, and in response to family x treatment interaction. Analyses 5 years after first inoculation revealed significant (p < 0.01) phytoplasma-associated suppression of growth in height, stem diameter, and volume index (diam.2 x height x 10-2). Average increase in volume index of diseased trees in years 4 + 5, as a proportion of the increase in noninfected controls, was 0.44 and varied among families from 0.13 to 0.84. Family x treatment interaction on volume growthwas significant (p < 0.001). Heritability of volume growth response to phytoplasmal infection was 0.60 ~ 0.17 (mean ~ SE) for families and 0.52 for individual trees. These findings indicate potential for selection or breeding of AshY-tolerant green ash. [ABSTRACT FROM AUTHOR]

Classification trees and linear regression analysis were used to build models to predict probabilities of infestation and amount of tree mortality in terms of basal area resulting from roundheaded pine beetle, Dendroctonus adjunctus Blandford, activity in ponderosa pine, Pinus ponderosa Laws., in the Sacramento Mountains, New Mexico. Classification trees were built for combined habitat types sampled and for each habitat type series or type sampled. Cross-validation estimates ofclassification accuracy ranged from 0.64 to 0.79. The data suggest that stands attacked by the roundheaded pine beetle exhibit poor growth during the last 5 years prior to attack, abundant host type, and smaller diameter than uninfested stands. Trees prone to attack by the roundheaded pine beetle within infested points also exhibited reduced growth rates and smaller diameters than uninfested trees. Linear regression analysis indicates that initial amount of ponderosa pine basalarea is a good predictor variable for the amount of basal area affected. [ABSTRACT FROM AUTHOR]

Sixty-eight western hemlock (Tsuga heterophylla (Raf.) Sarg.) and 51Sitka spruce (Picea sitchensis (Bong.) Carriere) trees with bole wounds were selected from six locations in southeast Alaska. Each tree was dissected and measured for extent of internal stain and decay to determine wood volume losses over time caused by fungi. The margins ofstain and decay associated with bole injuries that ranged from 1 to 80 years old were marked on the surface of 30 cm long bole segments of each tree and then photographed. Areas occupied by stain and decay were measured for each bole segment using AutoCAD digitizing techniques and then the amount of affected volume was computed for each tree.In regression models, original sear width, original scar area, and atransformation of scar age are significantly correlated with the ln(volume of stain + decay) for hemlock, original scar length and a transformation of original sear width are significantly correlated with volume of stain + decay for spruce. Decay extended less than 1 m abovewounds and consumed less than 5% of gross tree volume in all but a few trees which had large, old scars. Decay development in hemlock wasless extensive than reported in Oregon and Washington; models from these areas greatly overestimate decay in wounded trees in southeast Alaska. Tangential callus growth (one side of the wound) was 2.1 and 1.7 mm/year for spruce and hemlock, respectively. Forest managers may use this information to design stands with acceptable heart rot levels by predicting the development of decay in wounds and by altering schedules of stand thinning and final harvest of wounded trees. [ABSTRACT FROM AUTHOR]

A hybrid poplar clone, 'Ogy' (Populus x euramericana), was transformed with the potato proteinase inhibitor II (PI II) gene (pin2) to test the importance of serine proteinases in host-pathogen and host-insect interactions. The gene product PI II is a specific inhibitor of trypsin and chymotrypsin. Transformants were obtained using an Agrobacterium binary vector system with a disarmed Ti plasmid (EHA 101) and plasmid pRT104 containing pin2 regulated by a CaMV 35S promoter and a selectable gene-encoding neomycin phosphotransferase II (NPT II). Putative transformed shoots from co-cultured leaves were selected using three different kanamycin toxicity assays. Ten plantlets, selected from 431 shoots derived from co-culture, were selected for nucleic acidand protein analysis. DNA analysis (Southern blots and PCR) and protein gel blots (Western blots) confirmed pin2 integration and expression in transformant number TR5. [ABSTRACT FROM AUTHOR]

Natural mycorrhizal colonization and frequency of root rot were surveyed on eastern white pine (Pinus strobus L.) seedlings at St. Williams nursery in southern Ontario over the growing season (June, July, and August). Percentages of total mycorrhizal colonization for 2- and 3-year-old seedlings were very high (range of means: 88--93%). In August, it was possible to distinguish six mycorrhizal types: four ascomycetes (Tuber sp., an E-strain fungus, Phialophora finlandia Wang & Wilcox, and an unidentified "red type") and two basidiomycetes (Hebeloma sp. and Thelephora terrestris Ehrh.:Fr.). Ascomycetes were the dominant colonizers (69.8% of the root tips), while basidiomycetes colonized 24.4% of the root tips. E-strain, a common colonizer in nurseries and disturbed sites, was the dominant mycorrhiza former, occupying 50.9% of the root tips examined. Frequencies of root rot were consistently higher among 3-year-old seedlings (range of means: 14.8- -30.5%) than among 2 year olds (range of means: 7.4--9.2%). There were no significant correlations between overall mycorrhizal density and root rot. However, T. terrestris was negatively correlated with root rot (r{sub}s{end} = - 0.500, p < 0.001), suggesting that its presence may have some antipathogenic effects. [ABSTRACT FROM AUTHOR]