Fraser Fir Seedlings Research Articles

Diversity and density of the EM fungal community present in high elevation Fraser fir forests of Great Smoky Mountains National Park

A study of the diversity and density of ectomycorrhizal (EM) fungi in two Fraser fir stands near Clingmans Dome, Great Smoky Mountains National Park was conducted over a period of three years. Plots were established in three naturally occurring age class treatments including mature tree, sapling, and low regeneration (no trees) sites. Lesser vegetation data were determined for nine plant species within all plots including two ferns and two grasses that impeded survival of Fraser fir seedlings. Diversity and densities of vegetation were significantly greater in low regeneration plots as compared to other treatments. For each plot bryophyte mat forest floor percent occurrence/cover was obtained and percent root colonization/sclerotia of the EM fungus taxa were collected from the three management treatments including 11 decomposers and 33 ectomycorrhizal species. Clavulina cristata occurred in 22.5% of all plots and had a frequency of 1.7% in low regeneration treatments. Four species of Laccaria occurred in 17.3% of all plots, and Laccaria laccata and L. laccata var. pallidifolia were the most common of these species, the former having the highest frequency of occurrence (1.9%) in low regeneration treatments. Four species of Cortinarius occurred in 10.3% of the plots, and Cortinarius anomalus s.l., the most common Cortinarius , occurred in 4.4% of all plots. Seven of the 44 species had significantly greater percent frequency among the three treatments, and six of those were the most frequent in sapling plot treatments at the two locations. Species found at the two locations were similar, although in 2009 their frequency values were greater than in 2010 and 2011 due to greater total precipitation. Mature and sapling plot frequency values were significantly greater than those for low regeneration sites due to the low establishment of Fraser fir. Significant results for species richness, diversity and evenness between years, locations and treatments are present below. Based on percent frequency values, Laccaria could be used in reforestation of Fraser firs in all plots. A project is underway to evaluate seedling establishment and survival following inoculation with Laccaria spp. on a low regeneration site at Mount Buckley.

Fungicide Efficacy in Prevention of Root Rot Incited by Phytophthora cactorum and Phytophthora drechsleri in Fraser Fir Seedlings

The most serious disease problem in fraser fir (Abies fraseri) Christmas tree production is phytophthora root rot (PRR). The efficacies of six fungicide treatments in preventing PRR incited by Phytophthora cactorum and P. drechsleri in 2-year-old fraser fir seedlings were evaluated in 2010 and 2011 in central Pennsylvania. The study examined five fungicide drench treatments [dimethomorph, fosetyl-aluminum (fosetyl-Al), hydrogen dioxide, mefenoxam, propamocarb hydrochloride] and one soil spray treatment (mefenoxam) in raised planting boxes. Dimethomorph applied on 14-day intervals prevented foliar disease symptoms and mortality in fraser fir seedlings exposed to either P. cactorum or P. drechsleri. One-time application of fosetyl-Al or mefenoxam were effective at times in preventing foliar disease symptoms and mortality in fraser fir seedlings exposed to P. drechsleri but were not as effective against P. cactorum.

Growth, Biomass, and Nitrogen Use Efficiency of Containerized Fraser Fir (Abies fraseri) as Related to Irrigation and Nitrogen Fertilization

Growth and nutrient uptake of containerized fraser fir (Abies fraseri) seedlings in response to irrigation and fertilization was investigated for 2 years in a greenhouse experiment. Height and stem diameter growth increased 12% to 35% and 4% to 32%, respectively, with increased irrigation. There was an inverse relationship between irrigation and foliar nitrogen content and no irrigation effect on foliar phosphorus, potassium, magnesium, and manganese. Irrigation increased foliar calcium. Approximately 2.0% to 4.5% of applied nitrogen was lost through leaching. Increases in total biomass in high irrigation treatments were caused by higher root and stem biomass. Higher irrigation treatments increased nitrogen use efficiency (NUE) and assimilatory nitrogen use efficiency probably as a result of increase in carbon assimilation efficiency leading to increase in net primary productivity. There was no clear effect on the root weight ratio, but the index nitrogen availability per unit of foliage indicated a higher availability in plants receiving the lowest irrigation. This suggests that under water stress, the decrease in assimilation and NUE may be buffered by an increase in the plant's ability to provide nitrogen and other nutrients to various organs.

Susceptibility of Fraser Fir to Phytophthora capsici.

Phytophthora cinnamomi, P. drechsleri, P. citricola, and P. cactorum limit Fraser fir production, whereas P. capsici affects Solanaceous, Cucurbitaceous, and Fabaceous crops. Some vegetable growers in Michigan plant conifers for the Christmas tree market in fields infested with P. capsici. To determine the susceptibility of Fraser fir to P. capsici, stems (no wound or 1- or 3-mm-diameter wound) or roots (2 or 4 g of infested millet seed or 2 or 5 × 103 zoospores/ml of a zoospore suspension) of seedlings were inoculated with each of four P. capsici isolates and incubated in growth chambers (20 or 25°C). In addition, Fraser fir seedlings were planted in two commercial fields naturally infested with P. capsici. All P. capsici isolates tested incited disease in the seedlings regardless of incubation temperature or inoculation method. Seedlings (72%) planted in P. capsici-infested fields developed disease symptoms and died. Most of the P. capsici isolates obtained from the Fraser fir seedlings infected while in the field were recovered from root tissue. Identification was confirmed by species-specific direct colony polymerase chain reaction. The pathogen was successfully recovered from stems of all stem-inoculated seedlings, and from roots and stems of all root-inoculated seedlings; the phenotype of the recovered isolate matched the phenotype of the inoculum. This study suggests that planting Fraser fir in fields infested with P. capsici could result in infection and that adjustments in current rotational schemes are needed.

Evaluating the Pathogenicity of Pythium vexans Isolates from Fraser Fir in North Carolina

The pathogenicity of Pythium vexans isolates collected from fir samples with typical root rot symptoms in North Carolina was evaluated on Fraser fir seedlings (Abies fraseri). Two replicated pathogenicity trials involving seven treatments were conducted in the lath house and greenhouse. Although the P. vexans isolates examined in these trials were able to colonize Fraser fir root systems, they did not cause mortality or incite root rot symptoms. In comparison, Phytophthora cinnamomi, a known aggressive pathogen of Fraser fir, caused severe root rot symptoms in all plants. These experiments provided no evidence that P. vexans is a pathogen of Fraser fir. Accepted for publication 12 July 2008. Published 6 October 2008.

Effects of nitrogen form on nutrient uptake and physiology of Fraser fir ( Abies fraseri)

Shade-tolerant conifer species are generally thought to prefer NH 4 + as a source of inorganic N and may perform poorly on recently disturbed sites or agricultural soils with high rates of nitrification. Fraser fir ( Abies fraseri) is a highly shade-tolerant climax species characteristic of acidic forest soils that is now planted on a wide range of soils for Christmas tree production. We hypothesised that poor N nutrition of Fraser fir Christmas trees on calcareous soils resulted from: (1) an inability to take up and assimilate N in the form of NO 3 − and (2) a specific antagonism between uptake of Mg 2+ and NH 4 +. Four-year-old Fraser fir seedlings were grown for 80 days in sand culture with nutrient solutions varying in NH 4 +:NO 3 − ratio (100:0, 75:25, 50:50, 25:75, 0:100) and Mg:Ca ratio (22:78, 33:67, 44:56). The NH 4 +:NO 3 − ratio of nutrient solution strongly affected virtually every measure of plant performance, whereas Mg:Ca ratio exerted significant effects only on base cation nutrition. Contrary to our original hypothesis, Fraser fir was able to utilize NO 3 − as a sole N source and typically performed better under NO 3 − dominated N supply compared to NH 4 + dominated N supply. Also contrary to our original hypothesis, we found no evidence for a specific antagonism between NH 4 + and Mg in Fraser fir nutrition. Foliar nutrition, uptake of N, P, K, Ca and Mg, and photosynthetic capacity all decreased with increasing proportion of NH 4 + in nutrient solutions. In vivo NO 3 − reductase activity was induced in Fraser fir roots exposed to NO 3 − demonstrating that this species is capable of taking up and assimilating NO 3 −. Our results clearly demonstrate that Fraser fir seedlings are able to utilize NO 3 −, and plants grown on 75–100% NO 3 − outperformed those grown on high NH 4 + concentrations in terms of growth, nutrition and photosynthesis. This suggests that commercial production of Fraser fir in high nitrifying soils is not likely to be limited an inability to acquire N in the form of NO 3 −.

White Grub (Coleoptera: Scarabaeidae) Population Density in Relation to Root Damage to Fraser Fir Seedlings in Transplant Beds

Abstract A field experiment was conducted in 2002 to evaluate the effect of five grub densities of second instar Phyllophaga anxia (LeCont) Glasgow larvae on feeding damage to roots of young seedlings of Fraser fir, Abies fraseri (Pursh) Poir., Christmas trees in a transplant bed. Larval densities were equivalent to approximately 0, 31, 62, 93, and 124 larvae per m2 (≈ 0, 3, 6, 9, and 12 larvae per ft2). Larval survival and variations in larval and seedling weight were also evaluated. Regardless of the larval density, when P. anxia grubs were present, all Fraser fir seedlings experienced significant root damage as well as subsequent plant injury (i.e., decline or mortality). Larval density as low as one grub per 0.11 m2 (≈ 3 larvae per ft2) caused heavy to severe root damage to young, two-year-old, P2-0 Fraser fir seedlings. An inverse relationship was observed between plant weight and root damage.

Grafting Fraser Fir onto Rootstocks of Selected Abies Species

Orthotropic shoots (tips of primary axes) from 3-year-old Fraser fir seedlings [Abies fraseri (Pursh) Poir.] were grafted onto rootstocks of Fraser fir, Korean fir (A. koreana Wils.), momi fir (A. firma Sieb. & Zucc.), Nordmann fir (A. nordmanniana (Steven) Spach.), Turkish fir (A. bornmuelleriana Mattf.), and West Virginia balsam fir from Canaan Valley (Canaan fir) [A. balsamea (L.) Mill. var. phanerolepis Fern.]. Firstyear survival in the greenhouse was 92% to 98% except for momi fir (83%). The percentage of grafted plants with orthotropic shoots was 92% to 98%, except for Korean (81%) and momi fir (86%). Plants were subsequently established in replicated field experiments on three sites in the piedmont and mountains of North Carolina. In general, leader elongation of grafted Fraser fir scions was greater than leader growth on nongrafted transplants, including Fraser fir. Differences in survival appear to reflect interspecific variation in resistance to phytophthora root rot and/or tolerance of warm environments. Grafting may offer the potential to grow Abies Christmas trees on previously unsuitable sites, or to reclaim or continue using sites already seriously impacted by root rot.

Harvest Time and Nitrogen Source Influence In Vitro Growth of Apical Buds from Fraser Fir Seedlings

Information was obtained concerning appropriate bud harvest time and nitrogen source to be used in the tissue culture of Fraser fir [Abies fraseri (Pursh) Poir] apical buds from 2-year-old seedlings. April was the preferred time to harvest buds for culture, as summer buds had a high contamination frequency, and fall and winter buds did not develop well. Shoot elongation of buds collected in April (1.6 cm) was more than twice that of buds collected in February (0.7 cm) after 100 days in culture; during the same period, shoot fresh mass increased 5-fold (0.21 g in April, 0.04 g in February). Inclusion of a nitrate source reduced the frequency of bud browning, and glutamine was superior to ammonium as a source of reduced nitrogen. Litvay's basal medium containing 10 mm glutamine and 10 mm nitrate was the best nitrogen source combination tested when considering bud browning frequency and shoot fresh mass and length after 100 days in culture.

Balsam woolly adelgid (Homoptera: Adelgidae): effects on growth and abnormal wood production in Fraser fir seedlings as influenced by seedling genetics, insect source, and soil source

Fraser fir, Abiesfraseri (Pursh) Poir., seedlings were grown in the greenhouse and at four field sites in the southern Appalachian Mountains to study the effects of infestation by the balsam woolly adelgid (BWA), Adelgespiceae (Ratz.). Swelling in the main stem was used as an indicator of abnormal wood (i.e., "rotholz") production induced by infestation. At three of the four field sites, the main stems of infested seedlings were significantly more swollen than those of uninfested seedlings. The amount of swelling caused by BWA generally was not affected by seed source (half-sib family), soil source (soil from higher or lower elevations), or interactions of these variables. At two of four field sites, infestation was associated with a significant increase in root:shoot ratio. Variability in root:shoot ratios and total dry weights of seedlings was influenced by interactions of infestation, soil source, and seed source. This result demonstrates that both tree genetics and environment play a significant role in the growth responses of infested Fraser fir seedlings. Results from the greenhouse study indicated that BWA might be represented by two or more biotypes in the southern Appalachians. Shoot weights and diameter increases were relatively large for Mount Mitchell seedlings infested by BWA from Mount Rogers, and relatively small when infested by BWA from Mount Mitchell. For seedlings from Mount Rogers, the converse was true. Overall, these results suggest that environment is probably more important than tree or insect genetics in explaining why so many infested trees have died in the Black Mountains of North Carolina.

Effects of long-term ozone fumigations on growth and gas exchange of fraser fir seedlings

Fraser fir seedlings from two seed sources in the Southern Appalachians (Mt Mitchell, North Carolina, a declining population; and Mt Rogers, Virginia, a relatively healthy population) were subjected to long-term (2·5 years) intermittent ozone fumigations (0·025, 0·070, and 0·150 ppm) while being grown through five growth cycles in an accelerated-growing regime. Fumigations took place during bud break, stem elongation and bud set. Following each growing cycle, gas exchange parameters and dry weights were determined. The ozone fumigations did not produce any effect on seedling growth. The ozone fumigation effects on gas exchange parameters were inconsistent, and generally not statistically different, with no differences occurring between seed sources. There was no correlation between photosynthetic rates and seedling growth. These results provide no evidence that ozone may be contributing to the differences in decline noted between the Mt Rogers and Mt Mitchell populations of Fraser fir.

Intermittent Short Days and Chilling, and Benzylaminopurine Affect the Growth and Morphology of Fraser fir Seedlings

Abstract Fraser fir (Abies fraseri (Pursh.) Poir.) seedlings were either grown continuously under long days (16 hr) or intermittently exposed to short days (8 hr) to induce bud set followed by a chilling period. Additionally, half the seedlings in each treatment received a foliar application of 444 uM benzylaminopurine (BAP). Seedlings that were allowed to set buds, followed by chilling, obtained the greatest height, but this treatment in combination with BAP reduced seedling height. BAP applied to seedlings grown continuously under long days stimulated height growth and prevented long dormant periods typical for non-chilled seedlings. Continuously grown, BAP-treated seedlings had 1.3 times larger root collar diameter, and 1.7 times more biomass, compared to other treatments. Root/shoot ratios for continuously grown, BAP-treated seedlings were comparable to intermittently chilled, non-BAP treated seedlings. These results suggest that either intermittent short days followed by chilling, or foliar BAP applications can be used to accelerate growth of containerized Fraser fir seedlings. However, the combination of chilling and BAP resulted in poorer development than either treatment alone.

Accelerating Fraser Fir Seedling Growth with Benzylaminopurine Sprays

Foliar application of the synthetic growth regulator BA was evaluated for increasing the duration and extent of Fraser fir [Abies fraseri (Pursh.) Poir.] seedling growth. Aqueous solutions of 0, 222, or 444 μm BA (0, 50, or 100 ppm) were sprayed on the shoots of Fraser fir seedlings biweekly from 18 until 38 weeks after planting. Foliar sprays of 444 μm BA increased seedling height 19%, increased shoot weight 57%, reduced root weight 22%, and increased total weight 27%. Apical meristem activity was stimulated and the long periods of dormancy typical of Fraser fir seedlings were avoided. Chemical name used: 6-benzylaminopurine (BA).

A Preliminary Study of Geographic Variation in Fraser Fir Seedlings

Abstract Open-pollinated progeny of Fraser fir (Abies fraseri: [Pursch] Poir.) from several elevations in each of five provenances were planted in the greenhouse, transplanted to a nursery, and then transplanted to three field locations in western North Carolina. Seedling total height, number of terminal buds, and root collar diameter were examined to determine the magnitude and patterns of variation in seedlings among and within populations. Significant differences among families were detected. Trees from low-elevation (1,500-1,650 m) of southern mountain sources such as Richland Balsam and Clingman's Dome showed better performance in all three field plantings than those from high-elevation and northern sources. Roan Mountain, where most seed is collected for commercial use, showed the least height growth in the study. South. J. Appl. For. 12(2):128-132.

Effect of root competition and nitrogen on growth and mineral content of Abiesfraseri

Three-year-old (3 + 0) Fraser fir seedlings (Abiesfraseri (Pursh) Poir.) were grown in a controlled-environment chamber under four N regimes, with and without root competition from orchard grass (Dactylisglomerata L.) or white clover (Trifoliumrepens L.). New shoot, stem, and root growth of Fraser fir were harvested 30, 60, and 90 days after budbreak. In the absence of root competition, dry weight and N content increased in a significant curvilinear manner with increasing N. With root competition, dry weight decreased linearly with increasing N, while N content increased linearly with increasing N levels. Responses of P and K content varied with seedling part. Cal content was not affected by root competition, while Mg content decreased in all seedling parts for trees grown with root competition. Orchard grass decreased growth and nutrient accumulation more than white clover.

Distribution and Disease Progress of Phytophthora Root Rot of Fraser Fir Seedlings

Distribution and Disease Progress of Phytophthora Root Rot of Fraser Fir Seedlings

Regeneration of Fraser Fir at Mt. Mitchell, North Carolina, After Depredations by the Balsam Woolly Adelgid

Abstract The long-term ecological consequences of balsam woolly adelgid (Adelges piceae(Ratzeburg)) damage to Fraser fir (Abies fraseri (Pursh) Poir.) are considered. Study areas were established and vegetation sampled during 1966 in western North Carolina near and on Mt. Mitchell in each of three forest types: fir, spruce-fir, and spruce-fir-hardwood. Study areas were resampled in 1978. In 1966, mortality caused by the balsam woolly adelgid on Fraser fir stems over 244 cm tall averaged 82, 98, and 95 percent in the fir, spruce-fir, and spruce-fir-hardwood types, respectively. The average number of live Fraser fir seedlings per hectare for all study areas in 1966 and 1978 were 25,809 and 14,026, respectively. The height class distribution of Fraser fir seedlings changed dramatically with approximately 1 percent of the trees over 61-cm tall in 1966, and 75 percent over 61-cm tall in 1978. The fir, spruce-fir, and spruce-fir-hardwood types are well-stocked with Fraser fir regeneration and fir should be an important species in all three forest types in the future. Forest Sci. 32:585-594.

Effect of Transplanting Time on Growth and Development of Fraser Fir Seedlings

Abstract Three-year-old (3-0) Fraser fir seedlings were transplanted into an irrigated transplant bed at 2-week intervals between 1 Aug. and 15 Oct. and once the following spring prior to budbreak. Following one growing season in the transplant bed, seedlings established the previous August and early September had the greatest dry weight, stem diameter, and shoot elongation.

Effect of Flooding on Development of Phytophthora Root Rot in Fraser Fir Seedlings

Effect of Flooding on Development of Phytophthora Root Rot in Fraser Fir Seedlings

Effects of Metalaxyl on Growth and Ectomycorrhizae of Fraser Fir Seedlings

Les effets secondaires du metalaxyl sur la croissance de Abies fraseri, et sur le developpement d'ectomycorhizes, ont ete examines dans deux pepinieres et dans un peuplement forestier naturel