Christmas Tree Industry Research Articles

Problems of the domestic enterprises’ competitive potential formation in the European markets (on the example of the artificial Christmas tree industry)

Introduction. In the conduct of enterprises' activities during the full-scale war of the russian federation against Ukraine, special attention should be paid to the formation of enterprises labor and production potential, since the post-war development of organizations will be based on the involvement of high-quality raw materials and employees who can effectively use them. The paper identifies the main problems with the formation of the level of competitive potential of enterprises producing artificial Christmas trees. As a result, the authors suggests optimal ways to solve these problems, in particular, it is recommended to search for a new approach to assessing the level of development of the labor component of the competitive potential of an enterprise on the basis of a comprehensive set of indicators and to reorient to the application of European standards in the material and raw material supply of the production process of enterprises producing artificial Christmas trees. The purpose of the paper is to identify the problems of selecting and implementing tools to increase the competitive potential of enterprises producing artificial Christmas trees in European markets and provide the recommended ways to solve them. Results. The main problems within the formation of the level of competitive potential of enterprises producing artificial Christmas trees are the imperfection of the formation and assessment of labor potential due to the imperfection of the system of its assessment and the formation of production potential due to the use of raw materials that do not meet the standards and requirements of the legislation of the European Union. Conclusion. Authors’ recommendation is to search for a new approach to assessing the level of development of the enterprises’ competitive potential labor component based on a quantitative and qualitative set of indicators and to reorient to the application of European standards in the raw material supply of the production process of artificial Christmas tree enterprises, which will increase their competitive potential in the EU markets.

Arthropod and Disease Management in Fraser Fir (Pinales: Pinaceae) Christmas Trees in the Southeastern United States

Abstract Fraser fir, Abies fraseri [Pursh] Poir., is one of the most desired Christmas tree species owing to its fragrance, physical appearance, and durability. This species represents a major component of the Christmas tree industry in the southeastern United States, with production occurring in North Carolina, Tennessee, and Virginia. Fraser fir production is a multi-million dollar annual industry despite growing in a limited elevational and latitudinal range. Pest management for Christmas trees is notoriously difficult owing to the near zero-tolerance of most pests, even those causing aesthetic damage. Christmas trees are produced in monocultural environments which make them highly susceptible to several arthropod and fungal pests. We review the major pests affecting Fraser fir Christmas tree production, including their biology, symptoms, and scouting procedures, and current management strategies. In general, pest management in Christmas tree production systems has not changed significantly in the last several decades, and still relies heavily on pesticide usage. We propose several areas in need of research that could help Fraser fir Christmas tree producers mitigate the impacts of climate change and potential new pest species, as well as suggest changes to current or potentially novel integrated pest management strategies which have a chance to provide economic and ecological benefits for this industry.

Assessing Megastigmus specularis (Hymenoptera: Megastigmidae) infestations in a Fraser fir (Abies fraseri (Pursh) Poir.) clonal seed orchard of the southern Appalachians

ABSTRACT The Christmas tree industry is mainly supplied with seeds from natural stands and genetically improved germplasm from clonal seed orchards (CSOs). Chalcid wasps (Megastigmus spp.) have a negative effect on the value of seedlots by reducing the quantity of viable seeds and represent a risk for national and international seed trade. Seed radiographies, field observations and seed-dissections from 25 Fraser fir (Abies fraseri (Pursh) Poir.) clones were used to determine chalcid infestation in a CSO of the southern Appalachians. We provided direct evidence that Mesopolobus cf. pinus is an ectoparasitoid of M. specularis, proposed a model that linked different aspects of the biology of these species and discussed host–insect phenological relationships. Infestation of seeds in some clones across surveys, suggested a potential genetic component to chalcid wasp's prevalence. Cold and dark rearing regimens were used to identify changes in adult insect emergence after variation of overwinter conditions. Both the frequency and the time of emerging M. specularis adults from seeds were affected by the duration of the treatments but not statistical differences were found for Mesopolobus cf. pinus. We present evidence for the efficiency of a gravity-seed cleaning method eliminating upwards of 95% of chalcid-infested seeds.

Marker‐trait association analysis for postharvest needle retention/abscission in balsam fir (Abies balsamea)

AbstractBalsam fir the principal tree species of the Christmas tree industry, is a major export commodity of Atlantic Canada region. However, postharvest needle abscission poses a main concern leading to low consumer satisfaction and a shift in preference towards artificial trees. The search for diverse balsam fir lines with high needle retention is very crucial for quality improvement programmes. In this regard, a panel of 75 balsam fir genotypes exhibiting diversity for needle retention traits were randomly selected from a set of 220 genotypes evaluated for needle retention characteristics for two consecutive years (2012 and 2013) and genotyped with 41 bi‐allelic single nucleotide polymorphism (SNP)/insertion/deletion markers. The cluster analysis and population structure identified four and seven subpopulations. We observed an SNP marker with significant association (p < 0.05) with the needle retention/abscission trait by using general linear model and mixed linear model approaches. The present study lays the foundation for analysing the genetic mechanisms underlying needle retention/abscission, as well as the use of molecular markers to target specific traits in balsam fir.

Detection of Delphinella shoot blight in plantations of balsam fir (Abies balsamea) Christmas trees in Quebec, Canada

Christmas trees produced in Quebec, Canada, mostly include balsam fir (Abies balsamea), which is a species susceptible to Delphinella shoot blight. Over the past decade, the Canadian forests and Christmas tree industry have encountered an increase in Delphinella shoot blight, and only a few studies have assessed and quantified the damage caused by this disease. The different developmental stages of the disease were studied and the presumed causal pathogenic agent was isolated from infected needles in this work. Delphinella balsameae was isolated less frequently than its phylogenetically closely related pathogen Sydowia polyspora. Furthermore, species-specific PCR protocols to detect both D. balsameae and S. polyspora were developed and the occurrence of these species in infected and symptomless needles sampled in Christmas tree plantations was evaluated. While D. balsameae was detected only in diseased needles, S. polyspora was frequently found in both asymptomatic needles and in needles displaying shoot blight. Experiments showed that D. balsameae is the more prevalent agent associated with fir tree shoot blight in Quebec.

Pathogenicity of Neonectria fuckeliana on Norway Spruce Clones in Sweden and Potential Management Strategies

The fungus Neonectria fuckeliana has become an increasing problem on Norway spruce (Picea abies) in the Nordic countries during recent years. Canker wounds caused by the pathogen reduce timber quality and top-dieback is a problem for the Christmas tree industry. In this study, four inoculation trials were conducted to examine the ability of N. fuckeliana to cause disease on young Norway spruce plants and determine how different wound types would affect the occurrence and severity of the disease. Symptom development after 8–11 months was mainly mild and lesion lengths under bark were generally minor. However, N. fuckeliana could still be reisolated and/or molecularly detected. Slow disease development is in line with older studies describing N. fuckeliana as a weak pathogen. However, the results do not explain the serious increased damage by N. fuckeliana registered in Nordic forests and Christmas tree plantations. Potential management implications, such as shearing Christmas trees during periods of low inoculum pressure, cleaning secateurs between trees, and removal and burning of diseased branches and trees to avoid inoculum transfer and to keep disease pressure low, are based on experiments presented here and experiences with related pathogens.

Novel Temperature-Dependent Development Rate Models for Postdiapause Egg Eclosion of Three Important Arthropod Pests Found in Commercial Christmas Tree Plantations of Southern Québec, Canada.

The balsam twig aphid Mindarus abietinus Koch (Hemiptera: Aphididae), the spruce spider mite Oligonychus ununguis (Jacobi) (Acari: Tetranychidae), and the pine needle scale Chionaspis pinifoliae (Fitch) (Hemiptera: Diaspididae) are three important pests for the Christmas tree industry of Québec, Canada. Temperature-dependent development rates for postdiapause overwintering eggs of these species have never been studied for populations of southern Québec, where the vast majority of Christmas trees are grown. The accumulation of physiological time in growing degree days (GDD) is a standard tool to predict egg eclosion dates for pests, when first generation immatures are most vulnerable to insecticidal control. Development rates for postdiapause eggs were tested at four or five constant temperatures in the 11-23°C range under controlled conditions, based on time before hatching for eggs collected in a balsam fir plantation in late winter. The standard linear model and three published nonlinear models were fitted to the data and compared for their ability to estimate key biological temperature parameters and to predict development rates of postdiapause eggs. Validation of model predictions of egg eclosion time on balsam fir in the field was reasonably accurate using the classical linear model where field-accumulated GDD were calculated with a particular interpretation of the average method based on daily maximum and minimum temperatures. The linear model could predict mean egg eclosion within around 5 d of eclosion dates observed in the field.

Temperature-manipulated dynamics and phenology ofMindarus abietinus(Hemiptera: Aphididae) in commercial Christmas tree plantations in Québec, Canada

AbstractThe balsam twig aphidMindarus abietinusKoch (Hemiptera: Aphididae) is a major pest of economic importance for the Christmas tree industry. Global warming during the 21st century could potentially increase local population densities and reinforce the pest status of this aphid in commercial fir (AbiesMiller; Pinaceae) plantations in Québec, Canada. During this study, we tested the effects of a warmer environment on colony growth rates ofM. abietinusand aphid morph composition during the second generation of its cycle, which is key to colony size growth and potential damage to Christmas trees. We monitoredM. abietinuspopulations on two host fir species and one host fir variety, in order to understand the early season dynamics of this aphid and its host tree. It was possible to distinguish the two overlapping generations of winged aphids leaving colonies, which led to observing a much higher proportion of wingless daughters, produced by the stem mother, than what had previously been reported. Colony growth rates were significantly higher in a warmer environment than in the nearby plantation, suggesting that warmer temperatures in late spring and early summer may provide the suitable conditions required forM. abietinuscolonies of greater density.

Field trials with Abies lasiocarpa progenies from plus trees and seed orchard clones for Christmas tree production in Norway

ABSTRACTThe Christmas tree industry in Norway is increasing and Abies lasiocarpa is, together with Abies nordmanniana, the most common exotic species for Christmas tree production. A. lasiocarpa today constitutes ca. 50% of the fir sold in Norway, and there is high demand for sufficient supply of high-quality seed and knowledge of seed sources with a potential for high Christmas tree quality. Two experimental plots were established to identify seed sources with potentially high survival and satisfactory Christmas tree quality. The high variation in traits on the two sites indicates promising possibilities for further selection of A. lasiocarpa clones for growing Christmas trees in Norway. Selection for late bud break to avoid spring frost is important. Pathogens were not found in any of the studied trials, but are an important factor to consider when selecting seed sources for Christmas trees. Due to the early bud break of this species, it is also of high importance to choose planting sites with minimal risks for spring frost. Good localities are slopes where the frost drains away during cold nights. In eastern Norway, A. lasiocarpa should be used with care in districts and sites where spring frost is commonly occurring.

Response of Turkish and Trojan fir to Phytophthora cinnamomi and P. cryptogea

ABSTRACTPhytophthora root rot, primarily caused by the oomycete Phytophthora cinnamomi, is a large problem for the Christmas tree industry in North Carolina. Fraser fir (Abies fraseri) has no known innate resistance to this pathogen while some exotic fir species, such as Trojan (Abies equi-trojani) and Turkish (Abies bornmuelleriana) fir display varying amounts of resistance. A Phytophthora-resistance screening trial was completed with 1600 seedlings from 12 Turkish and Trojan fir families and Fraser and momi fir (A. firma). Seedlings from each family or species were inoculated with each of eight Phytophthora isolates, six P. cinnamomi and two Phytophthora cryptogea, in an effort to describe variability in isolate aggressiveness. Mortality was assessed as percent shoot necrosis bi-weekly for 16 weeks. Overall, rankings of resistance in fir species confirmed previous single-isolate-based results; momi fir was the most resistant, followed by Turkish, Trojan, and Fraser fir. P. cinnamomi isolates were generally more aggressive than P. cryptogea isolates. The two P. cryptogea isolates resulted in 5.6% and 0.8% mortality on Turkish fir, and 10.9% and 6.7% mortality on Trojan fir, the first reported resistance screen of these host-pathogen combinations. Pearson’s correlation testing identified a high degree of correlation between most isolates and overall mean mortality. Turkish and Trojan fir families appear to possess resistance to Phytophthora species common in North Carolina.

Effect of different headspace concentrations of bornyl acetate on fecundity of green peach aphid and balsam woolly adelgid

ABSTRACTBalsam woolly adelgid (Adelges piceae) (Hemiptera: Adelgidae) (BWA) is an exotic pest introduced from Europe to North America in the early 1900s. Subsequent introductions and spread have enabled this pest to infest native Fraser fir stands in the Southern Appalachians and become a troublesome pest for the region’s Christmas tree industry. Means to study its fecundity and control it are consequently of high importance. Headspace solid phase micro-extraction coupled with gas chromatography and mass spectrometry were used to compare chemical differences in stem tissue between a resistant species, Veitch fir (Abies veitchii) and the susceptible Fraser fir (Abies fraseri). Comparisons demonstrated that bornyl acetate (BA), a terpenoid, was qualitatively more abundant in resistant Veitch fir than Fraser fir. Varying headspace concentrations of BA were tested to ascertain any biological impacts on egg eclosion of BWA, as well as fecundity of green peach aphid (Myzus persicae) (GPA), an insect serving as a proxy. Varying concentrations of BA and a known number of adelgid eggs did not indicate any impact of concentration on egg eclosion success. However, defoliated Veitch fir branches in treatment jars produced a significant negative impact on BWA eclosion success. Implications of these findings are discussed.

Increased diversity of Phytophthora species in Fraser fir Christmas tree plantations in the Southern Appalachians

ABSTRACTPhytophthora root rot (PRR) disease afflicts significant economic losses to the Fraser fir Christmas tree industry. In previous surveys conducted in 1972 and from 1997 to 1998 in North Carolina, the incidence of PRR was ∼9.5% with Phytophthora cinnamomi identified as the predominant causal species isolated from infected roots of Fraser fir. Due to increased use of out-of-state planting stock since 2000, we suspected increased diversity of Phytophthora species. During 2014, we surveyed Fraser fir Christmas tree plantations in the Southern Appalachians of North Carolina, Tennessee and Virginia to determine the occurrence of pathogenic root-rotting species of Phytophthora. A weighted sampling strategy based on Christmas tree acreage was deployed to collect symptomatic Fraser fir roots from 103 commercial production fields in 14 counties. Six species of Phytophthora were isolated from infected roots sampled from 82 sites in 13 counties. Phytophthora cinnamomi, P. cryptogea and P. pini represented 70.3%, 23.1% and 1.1% of the 91 isolates. Phytophthora citrophthora, P. europaea and P. sansomeana accounted for the remaining 5.5% of the isolates and have not been identified in previously published Fraser fir surveys conducted in the region. The pathogenicity of P. citrophthora on Fraser fir was confirmed based on completion of Koch’s postulates.

Gall-maker Paradiplosis tumifex (Diptera: Cecidomyiidae) and its inquiline Dasineura balsamicola (Diptera: Cecidomyiidae): an update on epidemic episodes and seasonal ecology in Québec, Canada

AbstractThe balsam gall midge Paradiplosis tumifex Gagné (Diptera: Cecidomyiidae) is a major pest for the Christmas tree industry. This galler is frequently associated with the inquiline Dasineura balsamicola (Lintner) (Diptera: Cecidomyiidae), which is involved in the dynamics of the galler. Despite their importance, seasonal ecology of both midges under the climatic conditions prevailing in eastern Canada is still poorly understood. More importantly, nothing has yet been done to fully assess the impact of temperature on these insects, at key events such as adult emergence and larval overwintering. Here we followed P. tumifex and D. balsamicola spring phenology in the field, as well as their survival during winter diapause under simulated climatic scenarios in the laboratory. We observed spring asynchrony between fir host trees and P. tumifex in the first year of study, but under prevailing epidemic conditions, we observed no impact on summer abundance. We clarified available knowledge on their ecology, showing that overwintering habitats and strategies differ between the galler and its inquiline, which should alter pest control strategies. Experimental overwintering data suggest that diapausing conditions affect these species differentially and could potentially impact the spring sex ratio of their midges, which tends to be strongly female biased.

Understanding the Physiology of Postharvest Needle Abscission in Balsam Fir.

Balsam fir (Abies balsamea) trees are commonly used as a specialty horticultural species for Christmas trees and associated greenery in eastern Canada and United States. Postharvest needle abscission has always been a problem, but is becoming an even bigger challenge in recent years presumably due to increased autumn temperatures and earlier harvesting practices. An increased understanding of postharvest abscission physiology in balsam fir may benefit the Christmas tree industry while simultaneously advancing our knowledge in senescence and abscission of conifers in general. Our paper describes the dynamics of needle abscission in balsam fir while identifying key factors that modify abscission patterns. Concepts such as genotypic abscission resistance, nutrition, environmental factors, and postharvest changes in water conductance and hormone evolution are discussed as they relate to our understanding of the balsam fir abscission physiology. Our paper ultimately proposes a pathway for needle abscission via ethylene and also suggests other potential alternative pathways based on our current understanding.

Genetic variation in resistance to Phytophthora cinnamomi in seedlings of two Turkish Abies species

Genetic variation in resistance to Phytophthora cinnamomi was investigated for two fir species endemic to the Republic of Turkey. Open-pollinated families of seedlings of Trojan fir (Abies equi-trojani) and Turkish fir (Abies bornmuelleriana) were grown from seed in a greenhouse for approximately 15 months, inoculated with rice grains colonized with P. cinnamomi, and subsequent mortality assessed biweekly for 16 weeks. Final seedling mortality was higher in Trojan fir (56.4 %) compared to Turkish fir (32.9 %). Mortality in both species varied by geographic origin, decreasing from west (59.8 %, Open image in new window) to east (21.4 %, Karabuk). As mortality increased following inoculation, both narrow-sense individual-tree \( \left( {h_i^2} \right) \) and family mean \( ( {h_f^2} ) \) heritabilities increased, plateauing at 0.62 ± 0.162 and 0.97 ± 0.011 for Trojan fir and 0.50 ± 0.102 and 0.96 ± 0.01 for Turkish fir, respectively. Terminal and lateral branch bud break assessed under greenhouse conditions were also under strong genetic control. For terminal bud break, individual-tree heritabilities for Trojan and Turkish fir were 0.49 ± 0.146 and 0.45 ± 0.099, respectively, while family mean heritabilities were 0.88 ± 0.035 and 0.88 ± 0.027, respectively. The family mean correlation between bud break and final disease mortality was not significant for lateral buds but positive and significant for terminal buds (r = 0.32) suggesting that selection for resistance would either not alter, or slightly reduce, early bud break. These are encouraging results for ongoing tree improvement efforts in North America and Europe to develop planting stock for the Christmas tree industry.

Two Novel Techniques to ScreenAbiesSeedlings for Resistance to the Balsam Woolly Adelgid,Adelges piceae

Since its introduction into the Southern Appalachians in the 1950s, the balsam woolly adelgid, Adelges piceae Ratzeburg (Hemiptera: Adelgidae), has devastated native populations of Fraser fir, Abies fraseri (Pursh) Poir. (Pinales: Pinaceae), and has become a major pest in Christmas tree plantations requiring expensive chemical treatments. Adelges piceae—resistant Fraser fir trees would lessen costs for the Christmas tree industry and assist in the restoration of native stands. Resistance screening is an important step in this process. Here, four studies directed toward the development of time— and cost—efficient techniques for screening are reported. In the first study, three methods to artificially infest seedlings of different ages were evaluated in a shade—covered greenhouse. Two—year—old seedlings had much lower infestation levels than 7 year—old seedlings. Placing infested bark at the base of the seedling was less effective than tying infested bark to the seedling or suspending infested bolts above the seedling. Although the two latter techniques resulted in similar densities on the seedlings, they each have positive and negative considerations. Attaching bark to uninfested trees is effective, but very time consuming. The suspended bolt method mimics natural infestation and is more economical than attaching bark, but care must be taken to ensure an even distribution of crawlers falling onto the seedlings. The second study focused on the density and distribution of crawlers falling from suspended bolts onto paper gridded into 7.6 × 7.6 cm cells. Crawler density in a 30 cm band under and to each side of the suspended bolt ranged from 400 to over 3000 crawlers per cell (1 to 55 crawlers per cm2). In the third study, excised branches from 4 year—old A. fraseri and A. vetchii seedlings were artificially infested with A. piceae to determine whether this technique may be useful for early resistance screening. The excised A. fraseri branches supported complete adelgid development (crawler to egg—laying adult), and very little adelgid development occurred on A. vetchii branches. The fourth study compared infestation levels and gouting response on excised versus intact branches of 4 year—old A. fraseri seedlings from three different seed sources, and excised branches from 4 year—old and 25 year—old trees. There were no differences in infestation levels between excised versus intact branches nor in very young versus mature trees; gouting response was observed only on intact branches.

Screening Exotic Firs for the Midwestern United States: Interspecific Variation in Adaptive Traits

Conifers represent a sizeable portion of nursery and landscape sales in the upper midwestern U.S. Several conifer species have been overplanted to the point where disease problems and insect pressures have developed. Although more than 40 true fir (Abies Mill.) exist throughout the northern hemisphere, use of firs in the landscape and Christmas tree industry has been limited to relatively few species. This is largely due to perceived intolerance of many site conditions. However, recent research suggests Abies are more tolerant of varying site conditions than originally thought. Successful introduction of new exotic fir species for landscape use will require a systematic approach to identify species that are adapted to environmental stresses. In this article we review the extent and nature of inter-specific variation among Abies species in traits commonly associated with tolerance of stresses found in the upper midwestern U.S. Specifically, we focus on cold hardiness, budbreak, photosynthetic gas exchange and water relations, and response to soil pH. It is important to match plants possessing necessary adaptive characteristics with the existing site conditions. Therefore, multiple screening factors should be met when identifying species or trees from different provenances for future introduction.

True Firs (Abies sp.): New Conifers for the Midwestern Landscape

The genus Abies is a member of the family Pinaceae and consists of approximately 55 species found mainly in upper latitudes or higher elevations in the northern hemisphere. Firs generally prefer cool, well-drained sites with acidic soil. Fir trees are occasionally used as landscape trees but are more commonly grown as Christmas trees. Recently, the Michigan State Univ. Forestry Dept. and the Michigan Christmas tree industry initiated a field test of exotic firs (Abies sp.) for potential use as Christmas trees. In the present study we expanded the evaluation of these exotic fir species to include their suitability as landscape trees and to characterize their tolerance to various environmental stresses. We compared foliar nutrition, gas exchange, chlorophyll fluorescence, and shoot morphology of 23 Abies species and hybrids planted at three horticultural research stations in Michigan. Foliar nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sulfur (S), boron (B), zinc (Zn), and copper (Cu) were correlated (P < 0.05) with soil pH. Species and hybrids varied (P <0.05) in maximum photosynthetic rate, water use efficiency, chlorophyll fluorescence, and the ratio of total needle area to projected needle area. We will discuss the significance of these traits in relation to selecting trees adapted for use in the Midwestern landscape.

Chrysomyxa weirii on Colorado Blue Spruce in Wisconsin.

In early June 2002, yellow spots and bands with erumpent telia on previous year's needles of Colorado blue spruce (Picea pungens) were noted in landscape tree nurseries in both northern (Sawyer County) and southern (Dane County) Wisconsin. Many 1 to 2 m tall trees were symptomatic at each location. Based on the age of affected needles, time of year of telium development, and telial characteristics including the size and shape of teliospores, the pathogen was identified as Chrysomyxa weirii, the cause of Weir's cushion rust (1,2). Identification of the pathogen was confirmed by Dale Bergdahl, (School of Natural Resources, University of Vermont), who also observed basidiospores. C. weirii is an autoecious microcyclic rust pathogen known to affect P. englemanii, P. glauca, P. mariana, P. pungens, and P. sitchensis. Although this fungus has been reported in the western United States from the Black Hills of South Dakota to Washington State, in the eastern United States from the southern Appalachian Mountains (Tennessee and West Virginia) to Vermont, and in most Canadian provinces and territories (1,2), to our knowledge, this is the first report from the Great Lakes Region of the United States. The occurrence of Weir's cushion rust in Wisconsin has direct implications for the economically important nursery and Christmas tree industry in this region.

Pesticide exposure beliefs among Latino farmworkers in North Carolina's Christmas tree industry

Pesticide exposure beliefs among Latino farmworkers in North Carolina's Christmas tree industry