Christmas Tree Growers Research Articles

Oomycete communities are influenced by land use and disease status in Christmas tree production in Southern Québec, Canada

AbstractForests are threatened by many natural stressors intensified by climate change and anthropogenic activities, which tend to increase their susceptibility to pests and pathogens. Consequently, oomycete‐related forest decline or dieback cases are increasing in natural, urban, and agricultural landscapes. It is in this context that Christmas tree growers from Southern Québec, Canada, are experiencing root rot problems, with reported incidences up to 25%. In a previous study, seven Phytophthora spp. were associated with this root rot problem, but the overall diversity of oomycetes has not yet been investigated. Hence, in this study, we use a metabarcoding approach to provide an overview of the diversity, richness, and composition of the oomycete community in fir plantations compared to surrounding natural forests. We showed that the P. cryptogea cluster, P. europaea cluster, P. sansomeana, and P. chlamydospora cluster were significantly more abundant in soils collected from plantations under diseased trees and confirmed that the P. europaea cluster (including P. abietivora) was most frequently associated with trees showing Phytophthora root rot‐like symptoms. Finally, we report that land use (anthropogenic activities) shapes oomycete diversity, while plantations can act as a gateway for invading natural forests. In fact, the results presented here suggested that the P. europaea cluster might already have crossed this boundary and that other species might follow, advocating the importance of improved surveillance of oomycete diversity in various environments.

Alternative Integrated Weed Management Options for Clopyralid-Resistant Common Ragweed

Common ragweed (Ambrosia artemisiifolia L.) is an extremely competitive broadleaved summer annual weed found in Christmas tree production systems within Michigan. Common ragweed has been reported to have resistance to glyphosate, PSII inhibitors, PPO inhibitors, and ALS herbicides. There have been reports from Michigan Christmas tree growers of common ragweed resistance to clopyralid, a synthetic auxin herbicide, in Montcalm County, Michigan. The objective of this study was to test alternative post-emergence herbicide combinations and organic mulch on clopyralid-resistant common ragweed for weed control efficacy. The following two stages of common ragweed were used: stage 1 (6–9 leaves) and stage 2 (12–14 leaves). For common ragweed in stage 1 in 2021 and 2022, as well as stage 2 in 2022, at all evaluation dates, mulch + clopyralid + oxyfluorfen provided the highest level of weed control. For stage 1 in 2022, this treatment combination provided 100% control from 2 weeks after treatment (WAT) and always showed better or equal weed control compared to all the other treatments. The combination of mulch + clopyralid + glyphosate provided 100% control by 2 WAT when plants were treated at stage 2 in 2022. For the plants treated at stage 1 in 2022, many of the treatments reached a fresh weight of 0 g, but in 2021, those same treatments resulted in a fresh weight of around 20 g. Based on fresh weight, the greatest plant growth occurred with glyphosate treatment in 2021 and clopyralid and mulch alone in 2022. This is likely due to common ragweed’s resistance to these herbicides.

Michigan Conifer Growers’ Perspectives on Disease Management

A survey of commercial nursery and Christmas tree growers was implemented online and by mail in 2018 to understand disease issues and information preferences. Overall, the majority of the respondents reported that they prefer online sources of information and many are using Extension bulletins and sources. Cultural, chemical, and weed control methods were considered extremely effective by participants and very few used biological control methods to control disease. Participants identified spruce decline, boxwood blight, and hemlock woolly adelgid as emerging disease threats, so future information to growers should focus on identification and management of these threats.

Early Response (2018–2020) to the Threat of Spotted Lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae) in Pennsylvania

Abstract Spotted lanternfly (SLF), Lycorma delicatula (Hemiptera: Fulgoridae) is an invasive planthopper first detected in the United States in one county in Pennsylvania in September 2014. As of October 2020, 43 counties in nine states are under quarantine due to the presence of SLF in those areas, and it has been detected in 10 additional states. The greatest economic impacts from SLF have been reported from grape growers, nurseries, and Christmas tree growers, and it is considered a nuisance pest by residents. Because this insect feeds on over 70 species of herbaceous and woody trees and plants, it has the potential to cause wide ranging damage across agricultural, urban, suburban, and forested landscapes. Due to these widespread impacts, SLF management has demanded cooperation at local, state, regional, and national levels. However, the immediate response to the threat of SLF in Pennsylvania during the early phases of the infestation was a catalyst for initiating these efforts, and this response was coordinated via a partnership between the Pennsylvania Department of Agriculture, the U.S. Department of Agriculture Animal and Plant Health Inspection Service, and the Pennsylvania State University College of Agricultural Sciences. The history of SLF in the United States is recounted, highlighting the early priorities that emerged. The resulting actions taken in 2018–2020 in response to these priorities, which involved research, Extension, and public awareness are summarized, and areas in which improvements are needed that have been identified are discussed.

Presence of Phytophthora species in Swedish Christmas tree plantations

Phytophthora cryptogea, P. gonapodyides, P. lacustris, P. megasperma, P. plurivora, P. taxon paludosa and an unknown Phytophthora species were isolated from waterways and soil samples in Christmas tree fields in southern Sweden. In addition, P. megasperma was isolated from a diseased Norway spruce (Picea abies) plant from one of the fields in Svalov. Inoculation tests were sequentially carried out with one isolate from each of the three species P. cryptogea, P. megasperma, and P. plurivora, all known pathogens on conifers. The same three isolates were used to study a few morphological features to confirm the identification, and temperature-growth relationships were carried out to see how well the organisms fit into Swedish climatic conditions. Seedlings of Norway spruce and Nordmann fir (Abies nordmanniana) were inoculated in the roots and the stems. None of the isolates caused extensive root rot under the experimental conditions, but all three species could be re-isolated from both Norway spruce and Nordmann fir. Phytophthora root rot is currently of minor concern for Christmas tree growers in Sweden. However, the Phytophthora isolations from soil and water indicate the presence of this damaging agent, which may lead to future problems.

Gibberellic acid inhibitors control height growth and cone production in Abies fraseri

ABSTRACTPrecocious cone production in Fraser fir (Abies fraseri) results in substantial economic losses for Christmas tree growers in the United States. Cone removal often represents the second highest labor expense, after shearing. Gibberellins (GAs) regulate both reproductive development and shoot elongation, and are used to enhance cone production in conifer seed orchards. We identified plant growth regulators (PGRs) that inhibit GA biosynthesis – paclobutrazol, applied by foliar spray (PBZ-foliar) or soil injection (PBZ-soil), and chlormequat. We evaluated the effects of PGR treatments on cone production and vegetative growth in three tree size classes (small, medium, and large) at four locations over a three-year period. PGRs were applied in spring 2013, but did not affect growth until 2014, nor did they affect cone production until 2015. In 2014, PBZ reduced leader length by 21–29% across size classes and sites, while also increasing bud density by 11–20%. In 2015, PBZ-soil reduced average cone density (cones/tree) in small, medium, and large trees by 33%, 54%, and 40%, respectively. PBZ-soil also reduced leader length by 20–29% and increased bud density by 16–25%, making it the most effective PGR at controlling height growth and cone production in Fraser fir.

A Survey of Phytophthora spp. Associated with Abies in U.S. Christmas Tree Farms.

Multiple Phytophthora spp. are known to cause Phytophthora root rot (PRR) on Abies spp. Varying host susceptibilities and regional differences in Phytophthora community compositions complicate disease avoidance and management for Christmas tree growers and conifer nurseries. A survey of 32 Christmas tree farms in seven U.S. states representing four major Christmas tree production regions was conducted in 2012 to 2013 to characterize current distributions of root-rotting Phytophthora spp. and assess host responses to disease. Symptomatic tissues from lesion margins on roots and crowns were plated on selective medium to recover Phytophthora Cultures were identified by DNA sequencing of the nuclear internal transcribed spacer and mitochondrial cox I regions. Phytophthora cambivora was the prominent PRR species in western Washington and Oregon, while P. cinnamomi was prevalent in California and North Carolina. In the eastern United States, the undescribed P. taxon kelmania was isolated frequently and was capable of killing fir species considered tolerant of PRR. Completion of Koch's postulates confirmed pathogenicity of 12 previously unpublished Phytophthora-fir associations that were observed during this survey. Information regarding regional pathogen species prevalence and relative host susceptibilities will facilitate disease prevention by improving site management strategies for Phytophthora suppression.

Christmas Economics - A Sleigh Ride

Do you believe that at Christmas time the gas prices, the economy and the number of suicides peak? Do you think that the value of presents you are giving to your beloved is of importance? We show in this paper that conventional wisdom about Christmas is often doubtful. Furthermore, we give an idea of how Santa Claus -- and maybe you -- is able to finance Christmas celebrations, why emergency departments are a place to especially avoid during this time of the year and why Christmas tree growers might care to explain the differences across species to you this year. We cannot clearly establish whether Christmas entails a welfare loss or gain, however, we give you an idea as to which institutional settings might reduce a potential welfare loss. Also, we give advice about which behaviours might get you more Christmas presents from Santa this year. Finally, we find that more research is needed to give conclusive reasons why Santa Claus actually brings presents to (nearly) everyone.

Mountain Pesticide Education and Safety Outreach Program: A Model for Community Collaboration to Enhance On-Farm Safety and Health

This article showcases the outcomes of the Mountain Pesticide Education and Safety Outreach program, a collaborative effort between Christmas tree growers, cooperative extension, farmworkers, farmworker health outreach staff, and others to reduce pesticide exposure and on-farm injuries. Lessons learned during the project that can be adopted by other communities will also be shared.

Grafting Fraser Fir (Abies fraseri): Effect of Grafting Date, Shade, and Irrigation

Grafting fraser fir [Abies fraseri (Pursh) Poir.] scions onto rootstocks of turkish fir (Abies bornmuelleriana Mattf.) is a strategy used by some Christmas tree growers in the southern Appalachian Mountains of North Carolina to reduce losses by phytophthora root rot caused by Phytophthora cinnamomi Rands. This study compared the traditional time of grafting (April) with eight summer/early fall grafting dates from mid-July through mid-October. Shade and irrigation treatments were also superimposed on the grafting dates. To ensure optimal grafting success, grafting should be performed in the late winter/early spring (April) when scions are dormant and the rootstocks are becoming active. April graft success was 95% but when grafting fresh scions in summer/fall, graft success decreased from 52% in July to 0% in October. Shade improved summer graft success (52% with, 38% without). Irrigation did not significantly affect graft success or subsequent growth. In a supplemental storage study, grafting of stored scion material in summer/early fall was not successful (less than 1%).

Field Note: Alternative Leader Growth Control for Fraser Fir and Korean Fir Christmas Trees

Abstract Excessive leader growth is a challenge for Christmas tree growers who are seeking about 30–35 cm (12–14 in.) shoot elongation for good balance between height and lateral growth. Current cultivation practices include manually pruning leaders to 30–35 cm. In this studywe investigated the use of a growth regulator Ethyl-naphthaleneacetate acid (NAA) and a girdling process using a five-bladed plier (Top-Stop Nipper, Monterey Lawn and Gardens Products, Inc., Fresno, CA) as alternative methods to slow leader growth in Fraser fir (Abies fraseri [Pursh]Poir.), and Korean fir (Abies koreana Wils). NAA applications at rates of 40–160 ml/L reduced the height growth in both Fraser fir and Korean fir. However, in Fraser fir, other morphological parameters such as the leader straightness and bud density were generally adversely affected.The highest rates of 250 and 500 ml/l caused unacceptable reduction in growth and in many cases leader death. NAA applications on Korean fir resulted in significant reduction of leader growth and significantly increased the bud density without negative impact on leader straightness. Partialgirdling of stems was not effective at reducing the leader height in both Fraser fir and Korean fir.

Controlling Growth of Tabletop Christmas Trees with Plant Growth Retardants

Tabletop Christmas tree growers whose greenhouse-grown conifers have undesirable shoot growth may alleviate this problem by applying plant growth retardants (PGRs). Some of the most common PGRs in the horticulture industry were evaluated to determine their effectiveness in controlling plant height: ancymidol at 100 μL·L-1 (ppm), daminozide at 5000 μL·L-1, paclobutrazol at 60 μL·L-1, chlormequat at 1500 μL·L-1, uniconazole at 15 μL·L-1, and ethephon at 500 μL·L-1 compared to a nontreated control. The following conifer species were used: colorado blue spruce (Picea pungens), black hills spruce (P. glauca var. densata), serbian spruce (P. omorika), noble fir (Abies procera), grand fir (A. grandis), fraser fir (A. fraseri), concolor fir (A. concolor), arborvitae (Thuja occidentalis), port orford cedar (Chamaecyparis lawsoniana), and douglas-fir (Pseudotsuga menziesii). Chlormequat was the only PGR that caused phytotoxicity and damage to the foliage was minimal. Noble fir, douglas-fir, colorado blue spruce, and arborvitae were unaffected by any PGR treatment. Daminozide reduced growth of port orford cedar and concolor fir; uniconazole reduced growth of black hills spruce and serbian spruce; paclobutrazol reduced growth of fraser fir; and ethephon reduced growth of grand fir.

Comparison of Methods for Monitoring Mindarus abietinus (Homoptera: Aphididae) and Their Potential Damage in Christmas Tree Plantations

The balsam twig aphid, Mindarus abietinus Koch, causes distortion, loss, or both, of needles on balsam fir Christmas trees. Insecticides are often applied for control of twig aphids with little monitoring of population levels or their subsequent damage. This study compared the utility of 2 techniques (beating discs and visual counts of infested shoots) that could easily be used by Christmas tree growers to monitor aphids. A beating technique was better than visual counts for detecting numbers of fundatrices before and during budbreak, whereas visual counts of midcrown infested shoots were more feasible for estimating aphid abundance after budbreak. Sample size analysis indicated that a minimum of 15 trees could be used for either method to estimate mean numbers of fundatrices or mean proportions of potentially infested shoots. Correlation analyses between mean numbers of aphids or proportions of infested shoots and resulting proportions of undamaged shoots were variable with a significant and negative correlation between infested shoots and subsequent undamaged shoots ( r = −0.83). Paired comparisons were also made between selected and nonselected Choose-and-Cut Christmas trees to evaluate public perception of aphid damage. The public did not differentiate between aphid-damaged and undamaged trees, but they did show a preference for larger trees. Our results indicate that growers need to monitor aphids before budbreak and limit insecticide applications to trees with predictable levels of infestation (e.g., 2 or more fundatrices per disc results in ≈50% infested shoots) that will be harvested for shipment rather than grown for Choose-and-Cut.

Soil Nutrients and Microbial Biomass Following Weed-Control Treatments in a Christmas Tree Plantation

Control of competing vegetation in Christmas tree plantations is an important part of management, as uncontrolled weed growth can affect the growth and form of lower branches. Herbicide application is the most common weed-control strategy, but some Christmas tree growers prefer organic mulches. Although both herbicides and other weed-control strategies are available, there is little information about their effects on soil nutrients and microbial biomass, which determine long-term site productivity. A field experiment was conducted in a Christmas tree plantation in eastern Kentucky to examine the effects of four weed-management strategies-sulfometuron methyl herbicide (methyl 2[[[[(r,6-dimethyl-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]benzoate) (Oust) at two application rates, sawdust mulch, and rubber-tire mulch-on soil nutrients and microbial biomass. We tested the cumulative (3 yr) and re-treatment effects of the four treatments. Soil organic matter, moisture content, and total N were significantly higher in the sawdust-treated soils than in all other treatments. Inorganic N and extractable P were higher in the Oust-treated soils. The Oust and rubber-tire mulch treatments generally had negative cumulative and re-treatment effects on soil cations and pH. Significantly higher microbial biomass occurred in the sawdust treatment. This was most likely due to increased soil water content under the sawdust mulch and coincided with higher total N and soil organic matter for the cumulative and re-treatment periods. Sawdust was the best of the four weed-control strategies for long-term Christmas tree production because of the positive effects on soil physical, chemical, and biological characteristics, an important consideration for growers choosing a weed-control strategy for use on land expected to produce Christmas trees for many years.

Seed Source Variation for Growth and Quality Traits of Fraser Fir Christmas Trees: Rotation Age Results

Abstract Open-pollinated Fraser fir (Abies fraseri [Pursh] Poir.) progeny from several elevations on each of 5 mountain sources were assessed at 8 yr (rotation age) for growth and quality traits. Seed sources varied significantly in total height, crown diameter, branch diameter, straightness, crown density, USDA Christmas tree grade, and Christmas tree value. Age 8 yr results were very similar to both 1 and 4 yr results; lower elevation, southern sources showed superior performance in most traits including wholesale value. The common commercial seed sources on Roan mountain performed poorly by comparison. Statistically significant seed source X location interaction found for height, crown diameter, branch diameter, and value proved practically unimportant. Top-ranked seed sources overall maintained superiority at all sites. Potential rotation age tree wholesale value gains to Christmas tree growers through changing from the current chief commercial seed source on Roan Mt. to superior seed sources may exceed 7%. South. J. Appl. For. 19(4):157-161.

Distribution of Hylobius pales and Pissodes nemorensis (Coleoptera: Curculionidae) within Christmas Tree Plantations with Procerum Root Disease

Procerum root disease caused by Leptographium procerum (Kendrick) Wingfield is the most serious disease problem facing Virginia Christmas tree growers producing eastern white pine, Pinus strobus L. Studies have shown an association between procerum root disease-affected trees and insect infestations, and L. procerum has been recovered from field-collected insects. To determine the species and spatial distribution within Christmas tree plantations, potential insect vectors were collected weekly, April-September 1988–1991, from plots containing baited pitfall traps. Plots were located in plantations with procerum root disease, plantations without procerum root disease, in forested areas outside both types of plantations, and in an urban setting. Trees within the plots were inspected for development of procerum root disease. Insects recovered included two weevil species, Hylobius pales (Herbst) and Pissodes nemorensis Germar, and bark beetles from the genera Ips De Geer, Pityophthorus Eichoff, Pityogenes Bedel, Orthotomicus Ferrari, and Xyleborus Eichoff. In plantations with procerum root disease, there were Significantly more (P ≤ 0.05) H. pales than P. nemorensis , and Significantly more H. pales were contaminated with L. procerum. In plantations where procerum root disease was absent, there was no significant difference between the numbers of either weevil species or proportions contaminated with the fungus. Within the plots with procerum root disease, 27% of the trees developed symptoms of the disease during 3 yr of observation, but no trees developed disease symptoms in the asymptomatic plots.

Results and Future Production and Marketing Estimates Projected from a Survey of Christmas Tree Growers in Georgia

Abstract Virginia pine (Pinus virginiana Mill.) is the most planted Christmas tree in the South and its production has remained stable over the past few years. Leyland cypress [x Cupressocyparis leylandii (A.B. Jacks. and Dallim.) and Dallim. and A.B. Jacks.] is relatively new to the market, but the number of trees harvested has increased dramatically in the past 5 years (over 600%) where as Redcedar (Juniperus virginiana L.) production shows little market growth over the past 5 years. Due to the long lag period from planting to harvest, the data to correlate planting to harvests of White pine (Pinus strobus L.) was limited. Pearson correlation coefficients support the idea that future Christmas tree harvests can be reliably estimated from existing and estimated tree planting data for Virginia pine, White pine, Redcedar and Leyland cypress in the short term. With this information, growers can make better decisions regarding the numbers and species of trees to produce and be able to choose an appropriate marketing approach.

Tax Reform and Christmas Tree Profits in the Lake States

Abstract The Tax Reform Act of 1986 had a large impact on the profits of Christmas tree growers. Growers have significant costs for at least 7 years before they realize any returns. Prior to the Tax Reform Act, 60% of these returns were exempt from federal income tax if they qualified as long-term capital gains. Currently 100% of these returns are subject to taxation. Using a comprehensive survey of production costs of Michigan Christmas tree growers, this study found that after-tax rates of return dropped from 41% down to 31.6% for Scotch pine on an 8-year rotation. Other species and rotation showed corresponding decreases. North. J. Appl. For. 7:89-91, June 1990.

Applying Diagnosis and Recommendation Integrated System to Fraser Fir Christmas Trees

Fraser fir [Abies fraseri (Pursh) Poir.] is responsive to nutrient additions. Christmas tree growers are attempting to take advantage of this responsiveness in order to produce higher quality and therefore more valuable trees. The Diagnosis and Recommendation Integrated System (DRIS) was applied to this tree crop to assess its usefulness for diagnosing nutrient needs. Of 12 tree attributes, basal diameter at a given age proved to be the best substitute for yield in DRIS calculations. The basal diameter used to separate highand low-quality populations was 30 mm for trees in 3-yr-old plantations. This number corresponded to the 90th percentile commonly used in other DRIS applications. Significantly different variances in both nutrient and dry-matter ratios between high and low basal diameter indicate that nutrient concentration as well as balance among nutrients influence basal-diameter growth. The DRIS technique appears promising for diagnosing the nutrient needs of this crop. View complete article To view this complete article, insert Disc 5 then click button8

Introduction to the Symposium: An Extension Worker's View

Abstract Extension workers often identify production, marketing, managerial, or educational constraints that reduce agricultural efficiencies. In Oregon, problems expressed by growers of several horticultural crops appeared to have a common soil management component. Some Christmas tree growers, for example, complained about poor vigor and growth of 2nd- or 3rd-cycle trees that were planted immediately after harvest of the previous crop. Growers reasoned that poor growth (and reduced marketability) might be caused by increasing concentrations of herbicide residues that resulted from yearly applications of atrazine or hexazinone, rather than soil erosion and related soil management problems. Grape producers and lily bulb growers were concerned about soil erosion, since crops were planted parallel to the slope. Frequent mechanical harvesting of brambles led to growers’ fears of soil compaction, while fruit growers noted slower rates of water infiltration in orchards where natural vegetation is managed with a flail compared to areas interplanted with a sod.