Effects Of Mistletoe Research Articles

Preliminary Research Regarding the Antitumor Effects of Mistletoe on A2780 Cells

In Europe, mistletoe extract (Viscum album) is widely used as complementary cancer therapies. The main active component of mistletoe extract is glycoprotein, lectin, that exhibit cytotoxic effects and immunomodulatory activities. The aim of this study was to show if the mistletoe extract, rich in phenolic acids presents anti-carcinogenic potential on A2780 tumor ovarian cells. In the first part of this study, using high performance liquid chromatography (HPLC) analysis we characterized phenolic acid content of mistletoe growing on Malus domestica. And, in the second part, we investigated whether by apoptosis on ovarian tumor cell line A2780 if anti-cancer effect of this extract mistletoe is induced. Cell proliferation was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenylt-etrazolium bromide (MTT) assay. The A2780 cell viability was inhibited to 87% by 50 μg/ml mistletoe extract treatment, and to 79% at 110 μg/ml extract concentration. To find out the apoptotic cell death, 4, 6-diamidino-2-phenylindole (DAPI) staining was performed. Cells treated with mistletoe (110 μg/ml) for 24 h displayed typical morphological features of apoptotic cells, with condensed and fragmented nuclei. Fluorimetric method was used to evaluate total reactive oxygen species content from A2780 ovarian tumor cells after mistletoe treatment. Mistletoe concentration 70μg/ml induces a significant toxic ROS-generating effect. These data indicates that the phenolic acids from mistletoe induce cell death by apoptosis on human tumor ovarian cell line, A2780.

Effect of mistletoe on vascular endothelial growth factor expression in endometrial stromal cells in patients with endometriosis

OBJECTIVE: Endometriosis is a recurrent and intractable condition, but the etiology and pathogenesis is still unclear. In the present study, we evaluated anti-angiogenic effect of an immune modulator (mistletoe) on endometrial stromal cells in patients with endometriosis.

Dwarf mistletoe effects on soil basidiomycete community structure, soil fungal functional diversity, and soil enzyme function: Implications for climate change

We used a combination of molecular, culture and biochemical methods to test the hypothesis that severe infection of pine by dwarf mistletoe (genus Arceuthobium ) has significant effects on structure and function of soil fungal communities, and on carbon cycling in soils. PCR and DNA sequencing of the basidiomycete communities in paired blocks of uninfected and infected trees revealed: (1) that the top, organic soil layer in this system is inhabited almost exclusively by ectomycorrhizal fungi; (2) no difference in species richness (6 species core −1 in both) or Shannon–Wiener evenness (0.740 and 0.747 in uninfected and infected blocks respectively), however Shannon–Wiener diversity was significantly greater in infected blocks (1.19 vs 1.94 in uninfected and infected blocks respectively, P < 0.05); (3) significant differences in basidiomycete species composition, with nearly complete absence of two system co-dominant Russula species in infected blocks, and replacement of one co-dominant Piloderma species with another in infected plots, indicating physiological variability within the genus. Soil fungal physiological diversity measured using the Fungilog system was significantly greater in terms of both number of carbon substrates used by culturable soil fungi (both ascomycetes and basidiomycetes) in infected blocks, and the rate at which these substrates were used. Soil enzyme assays revealed greater laccase, peroxidase, and cellulase activities in soils associated with infected trees. Thus, event cascades associated with severe dwarf mistletoe infection not only significantly affected soil fungal species composition and increased species diversity, but also impacted on carbon-related function and functional diversity. Given the geographic range of this pathogen, and forecasts that epidemics of this disease will increase in range in severity with global climate change, these effects have the potential to significantly impact local and global carbon budgets.

Molecular Mistletoe Therapy: Friend or Foe in Established Anti-Tumor Protocols? A Multicenter, Controlled, Retrospective Pharmaco-Epidemiological Study in Pancreas Cancer

Mistletoe is often used as complementary therapy in oncology. The anti-tumor effects of mistletoe (Iscador) are well documented in-vitro in respect to inhibition of cell proliferation, induction of apoptosis, segmental activation of immune competent cells and trapping of chemotherapeutic drugs within cancer cells by modulating the inhibitory potential of P-glycoprotein (P-gp)-mediated transport of cell toxifying substances (cytotoxic drugs). However, the clinical activity of mistletoe treatment remains still controversial. Implementation of mistletoe therapy as supportive care into anti-cancer programs should be based on the best evidence and must continually be evaluated to ensure safety, efficacy, collection of new data, and cost-effectiveness. Useful domains that can be evaluated include symptom control, adherence to conventional treatment protocols, quality of life, individual outcome and potential advantages of a whole-system health approach. Here we report the results of a multicenter, controlled, retrospective and observational pharmaco-epidemiological study in patients suffering from a pancreatic carcinoma. After surgery the patients were treated by adjuvant chemotherapy with gemcitabine supported by Iscador, or with gemcitabine alone, or any other best of care, but not including Iscador. Using a novel methodological pharmaco-epidemiological design and statistical approach it could be shown that Iscador offers benefits--symptom control, overall survival--as supportive care within gemcitabine protocols of patients with surgically resected pancreatic carcinoma.

Cytotoxic effect of mistletoe (Viscum album L.) extract on Jurkat cells and its interaction with doxorubicin

Mistletoe preparations are frequently used by cancer patients because of their ability to stimulate the immunity and to improve the quality of life. Moreover mistletoe and its active substances (especially lectins) possess cytotoxic effect on various cancer cell lines. However, only little is known about its interaction with anticancer drugs. Therefore the cytotoxic and apoptosis-inducing effects of aqueous mistletoe extract (VA) and its interaction with doxorubicin (DOXO) were investigated in Jurkat cells. The results show that VA extract as well as DOXO exert cytotoxic effects on Jurkat cells in a dose-dependent manner. Cytotoxicity of DOXO was much stronger (LC(50) = 11.68 ng/mL) than that of VA extract (LC(50) = 35.67 microg/mL). Their combination led to synergism only at those concentrations that were highly cytotoxic alone. Both substances (alone and in combination) induced DNA fragmentation in Jurkat cells. In conclusion, an aqueous extract prepared from mistletoe tops exerted cytotoxic and apoptosis-inducing effects on Jurkat cells alone as well as in combination with DOXO.

Effects of Mistletoe (Viscum Album L., Loranthaceae) Extracts on Arterial Blood Pressure in Rats Treated with Atropine Sulfate and Hexocycline

Acute effects of different extracts of mistletoe stem (Viscum album) were investigated on values of arterial blood pressure in Wistar rats. Arterial blood pressure was registered by direct method in the left carotid artery and the investigated extracts (total ethanol, ether and ethyl acetate) of mistletoe stem were administered into the right jugular vein. The total ethanol extract exhibited the best effect even on the lowest applied concentration (3.33 × 10−5 mg kg−1) and significantly decreased the blood pressure after applied concentration 1.00 × 10−3 mg kg−1. On the contrary, the ether and ethyl acetate extracts exhibited notable activity only by higher administered doses. Atropine as a nonselective blocker of muscarinic receptors reduced the hypotensive effects of ethanol extract of mistletoe. Hexocycline, a selective blocker of muscarine receptors, significantly raised blood pressure and decreased the hypotensive effect of ethanol extract of mistletoe on arterial blood pressure in rats.

Effects of European mistletoe ( Viscum album L. subsp. album ) extracts on activity rhythms of the Syrian hamsters ( Mesocricetus auratus )

Antitumor drugs may have some significant nervous system side-effects such as disrupted sleep, eating and drinking patterns. European Mistletoe has been investigated for many decades for its potential use against cancer. To test the hypothesis that the non-antineoplastic effects of mistletoe might be mediated by the actions on the circadian timing system, we have applied mistletoe extracts and vehicle and have measured locomotor activity, feeding and drinking rhythms under constant darkness. Four groups (vehicle, 20 mg kg−1 ip injection, 40 mg kg−1 ip injection and 6 g kg−1 oral administration) were performed for both heat-treated and freeze-dried extracts. None of the administrations changed the locomotor activity, feeding and drinking rhythms in the groups except for 40 mg kg−1 freeze-dried injected group. The locomotor activity levels decreased in 40 mg kg−1 freeze-dried extract injected group. These results suggest that, side-effects of mistletoe on circadian timing system of the Syrian hamster depend on the dose and the preparation method of the extract.

Parasites boost productivity: effects of mistletoe on litterfall dynamics in a temperate Australian forest

The importance of litter in regulating ecosystem processes has long been recognised, with a growing appreciation of the differential contribution of various functional plant groups. Despite the ubiquity of mistletoes in terrestrial ecosystems and their prominence in ecological studies, they are one group that have been overlooked in litter research. This study evaluated the litter contribution from a hemiparasitic mistletoe, Amyema miquelii (Lehm. ex Miq.) Tiegh., in an open eucalypt forest (Eucalyptus blakelyi, E. dwyeri and E. dealbata), at three scales; the forest stand, single trees and individual mistletoes. Litter from mistletoes significantly increased overall litterfall by up to 189%, the amount of mistletoe litter being proportional to the mistletoe biomass in the canopy. The high litter input was due to a much higher rate of mistletoe leaf turnover than that of host trees; the host litterfall and rate of leaf turnover was not significantly affected by mistletoe presence. The additional litter from mistletoes also affected the spatial and temporal distribution of litterfall due to the patchy distribution of mistletoes and their prolonged period of high litterfall. Associated with these changes in litterfall was an increase in ground litter mass and plant productivity, which reflects similar findings with root-parasitic plants. These findings represent novel mechanisms underlying the role of mistletoes as keystone resources and provide further evidence of the importance of parasites in affecting trophic dynamics.

Suppressive Effect of a Standardized Mistletoe Extract on the Expression of Activatory NK Receptors and Function of Human NK Cells

Despite long-term use of mistletoe extracts for cancer treatment, their mode of action remains elusive. In this study, it was studied in vitro if mistletoe extract is able to modulate the expression of natural cytotoxic receptors (NCRs) and NKG2D receptor, which stimulate natural killer cell-mediated cytotoxicity. Unexpectedly, a mistletoe extract, ABNOBA viscum Fraxini, inhibited the expression level of NKp46 and NKG2D receptors in dose- and time-dependent manners. The levels of NKp30 and NKG2D receptors were remarkably induced and NKp44 was slightly induced after 48 h treatment with IL-2 and IL-15 in both mRNA and surface expression. The activatory NK receptors were not induced significantly after treatment with IL-12, IL-18, and IL-21 for 48 h. Induction of activatory NK receptors by IL-2 and IL-15 was suppressed almost to the untreated levels by treatment with mistletoe extract, which appeared to induce apoptosis of NK cells in a dose-dependent manner. However, the treatment with IL-2 and IL-15 did not prevent the mistletoe-induced NK-cell death. Mistletoe extract inhibited significantly the cytotoxic activity of resting and IL-2- or IL-15-stimulated NK cells. These results suggest that inhibition of survival and function of NK cells by mistletoe extract may curtail in part the therapeutic effects of mistletoe.

Dwarf mistletoe effects on fuel loadings in ponderosa pine forests in northern Arizona

Southwestern dwarf mistletoe ( Arceuthobium vaginatum (Willd.) J. Presl ssp. cryptopodum ) infests about 0.9 million ha in the southwestern United States. Several studies suggest that dwarf mistletoes affect forest fuels and fire behavior; however, few studies have quantified these effects. We compared surface fuel loadings and predicted fire behavior among four levels of dwarf mistletoe infestation (none, light, moderate, and severe) in a total of 239 plots on 11 sites on basaltic soils in northern Arizona. In each plot we measured tree attributes, dwarf mistletoe rating and surface fuel loading. Stands severely infested by dwarf mistletoe had lower (P &lt; 0.05) tree density and higher snag density, but higher (P &lt; 0.05) total surface fuel loadings and total fuel loadings &gt;7.62 cm and &lt;7.62 cm, than non-infested stands. However, there were no statistical differences in any canopy fuel variables among infestation classes. Predicted fire behavior indicated that the wind speed required to promote the spread of a surface fire into the canopy was lower in severely infested stands than in non-infested stands. These results suggest that stands in northern Arizona that are severely infested with dwarf mistletoe should be priority areas for fuels treatments.

Protective potential of mistletoe (Viscum album coloratum) against oxidative stress and cellular premature senescence

The protective activity from oxidative stress and antiaging potential of mistletoe (Viscum album coloratum) were investigated under in vitro and cellular system using LLC-PK1 renal epithelial cell and WI-38 human lung fibroblast cells. The water extract from the mistletoe (Korean product) showed nitric oxide (NO) and hydroxyl radical scavenging activity as concentration dependent-manner. Moreover, under LLC-PK1 cellular model, the mistletoe extract ameliorated oxidative stress induced by 2,2′-azobis (2-amidinopropane) dihydrochloride, the generator of peroxyl radical. In addition, the protective effect of mistletoe from NO under cellular oxidative stress was also studied. The LLC-PK1 cells showed the decreases in cell viability by the treatment with generators of peroxynitrite, 3-morpholinosydnonimine, and its precurors NO and superoxide anion produced by sodium nitroprusside and pyrogallol, respectively. However, the mistletoe led to the significant increases in the cell viability with dose-dependence. Furthermore, the protective potential from oxidative stress-induced aging was studied using WI-38 cells. The WI-38 cells exerted the characteristics of cellular premature senescence by the treatment of hydrogen peroxide, but mistletoe protected against stress-induced cellular senescence. The present study suggests that mistletoe extract would have the protective activity from oxidative stress caused by free radicals and the promising anti-aging potential against oxidative stress-induced aging process.

Effective Induction of Apoptosis by Mistletoe Plant Extracts in an Acute Lymphoblastic Leukemia Model.

Mistletoe (Viscum album) is one of the most used alternative cancer therapies applied as monotherapy or in combination with conventional therapies. Anti-tumor effects of mistletoe (MT) extracts were related to cytostatic and immunomodulatory effects observed in vitro. Aqueous MT extracts contain the three mistletoe lectins I, II and III as one predominant group of biologically active agents. The MT lectins inhibit protein biosynthesis by inactivating the 60S ribosomal subunit. Mistletoe lectin-I (ML-I) is one important apoptosis inducing compound. It is a heterodimer that consists of a cytotoxic A-chain (ribosome inactivating protein, RIP type 1) linked by a carbohydrate binding B-chain for cellular lectin uptake. However, although MT is widely used, there is a lack of scientific preclinical and clinical data. Here, we describe for the first time efficacy and mechanism of MT extracts against lymphoblastic leukemia in vitro and in vivo.For this purpose, we first investigated both the cytotoxic effect and mechanism of action of two standardized aqueous MT extracts (MT obtained from fir trees (MT-A); MT obtained from pine trees (MT-P)) and isolated ML-I, in three human acute lymphoblastic leukemia (ALL) cell lines (NALM-6, sup-B-15 and REH). MT-A, MT-P and ML-I clearly inhibited cell proliferation as determined by LDH reslease assays at very low concentrations (ML-I LD50 from 0,05 ng/ml to 10 ng/ml depending on the host tree) with MT-P being the most cytotoxic extract. The mechanism of cell death was determined by DNA-fragmentation assays. These indicated dose dependent induction of apoptosis as the main mechanism of cell death.Finally, we evaluated the efficacy of MT-A and MT-P in an in vivo SCID-model of pre-B ALL (NALM-6). For this purpose, mice (n=8/group) were injected i.v. with 1 × 106NALM6 cells and treated by intraperitoneal injections four times per week for 3 weeks (day 1–4; 7–11; 14–18) at varying doses (1, 5 and 50 mg/Kg (plant weight/body weight)). Mice (n=8) treated with PBS and cyclophosphamide (100 mg/kg, once on day 1) were used as negative and positive controls, respectively. Toxicity, peripheral blood counts, bodyweight and survival was determined over time.Interestingly, both MT extracts in all tested concentrations significantly improved survival (up to 55,4 days) in contrast to controls (34,6 days). Furthermore, no hematologic side effects were observed from this treatment as indicated by completely stable blood counts. Also the body weight of treated animals remained stable over time indicating a complete absence of systemic toxicity in the selected dose range.In summary, we demonstrate for the first time efficacy and mechanism of MT extracts against ALL in vitro and in vivo and hereby provide an important base line for the design of clinical trials with these compounds.

Neurophysiological effects of mistletoe (Viscum album L.) on isolated rat intestines

Mistletoe (Viscum album L.) is well known as a medicine from ancient times and the earliest notes. Today it is used as a remedy. The aim of this research was to examine the effects of mistletoe extracts and their components on some neurophysiological parameters in rat intestines. The tonus and contractile responses of isolated intestinal segments (duodenum, ileum and distal colon) were analysed. The experiment was carried out in three groups. In the first group (control group) different concentrations of acetylcholine were added into the organ bath (10-50 nmol/L). In the second group, mistletoe extracts were added into the organ bath with increasing concentrations and in the third group, atropine, a non-selective muscarinic receptor antagonist, was added into the organ bath (concentration 10(-7) mol/L) and after atropine plant extracts were administered. The results obtained suggest that extracts from different parts of mistletoe have neurophysiological effects and change intestinal contractions. The results also suggest that the effects of mistletoe extracts on intestinal contractility act via cholinergic pathways, activating muscarinic receptors in the intestines. However, in order to establish the subtype of receptors, further investigations are necessary where selective antagonists of muscarinic cholinergic receptors should be used.

Enhancement of Lymphokine-Activated Killer Cell Cytotoxicity by Mistletoe Plant Extracts.

Anthroposophical cancer therapies focus on the use of mistletoe (MT) preparations and extracts from European mistletoe (Viscum album l.) belong to the complementary therapeutic regimens. Although widely used in Europe as an additional therapy in the treatment of patients suffering from different malignancies, these cancer therapies have remained relatively unknown in North America. To date, mistletoe is the most commonly used complementary cancer drug in Germany, applied as monotherapy or in combination with conventional therapies. ABNOBAviscum fraxini is a standardized extract from all parts of fresh mistle, obtained from the ash tree. This study aims to investigate the effects of MT on the activity of lymphokine-activated killer (LAK) cell cytotoxicity in vivo.Here, we demonstrate that in vivo treatment of mice with a standardized MT plant extract results in activation and function of LAK cells. We show an enhanced cytotoxicity against the NK-sensitive target cell line YAC-1 by flow cytometry. Our data show that in vivo application of MT can double the cytotoxic activity against malignant disease and suggest that one mechasim of action of MT is the induction of LAK-cell mediated immune response.

Oncopharmacological Perspectives of a Plant Lectin (Viscum album Agglutinin-I): Overview of Recent Results from In vitro Experiments and In vivo Animal Models, and Their Possible Relevance for Clinical Applications.

An old goal of natural complementary medical therapy has been to aim at a long-term stimulation of natural resistance in order to restrain cancer progression or improve defective immunological conditions without toxic side effects. Mistletoe extracts were applied to a large number of cancer patients because of their modulatory effect on the natural immune system. By carefully removing lectins, an essential group of components, from mistletoe extracts, a significant reduction of their effectiveness on several cellular immune parameters could be observed in vivo (1). That is the reason why, for the last 14 years, biological research of mistletoe extracts has focused on lectins. Meanwhile, the quantitatively dominant lectin, Viscum album agglutinin (VAA)-I has become available in a recombinant form (rVAA). Other constitiuents of plant extracts such as viscotoxins (2,3), poly- and oligosaccharides (4), flavonoids (5,6), chitin-binding mistletoe lectin (7) and arginine have also been investigated in connection with the effects of mistletoe extracts on the host defense. However, little evidence has been found that these substances contribute to the effects of mistletoe in vivo (8).

Effects of mistletoe on diversity: a case-study from southern New South Wales

The influence of mistletoe density on avian diversity has been noted previously, with several studies demonstrating a close positive relationship between the two variables. All previous work has been correlative, exploiting naturally occurring variation in mistletoe density, and hence unable to demonstrate a causative link between mistletoe density and avian richness. Here I compare the avifauna of two adjacent woodland remnants, one of which has had most mistletoe plants removed, but otherwise comparable in area, vegetation and grazing history. Ten-hour inventories were conducted in each remnant in both spring and summer, resulting in a total of 40 hours of censuses. Of the 71 species recorded overall, 52 were recorded from the treatment site (with reduced mistletoe density) and 61 species from the control site. Significantly more woodland-dependent species and species known to feed on mistletoe were recorded in the control site, while there was no significant difference for those species known to nest in mistletoe. These results broadly support the idea that mistletoe is a keystone resource, with mistletoe density having a significant positive effect on species richness. These findings reinforce previous correlative studies, and further highlight the importance of mistletoe in Australian woodlands and forests.

Variability in sub-regional impacts of dwarf mistletoe on mature lodgepole pine

Impact of lodgepole pine dwarf mistletoe was determined in six sub-areas of Forest Inventory Zone H, near Prince George, British Columbia, using a roadside survey and measurements of mature infected trees. Mistletoe effects on DBH were evident only in two of the sub-areas surveyed (Westlake and Nechako). After correcting DBH measurements for competition (stand density), dbh of 100–120 year old and 121–150 year old trees was reduced 10% and 17% respectively, in the highest mistletoe rating (DMR) category (4.5–6.0). Height/DBH relationships were affected by dwarf mistletoe only in the Nechako area. Mistletoe effects in the Nechako and Westlake areas, in stands older than 120 years with mistletoe ratings of 4.5–6.0, resulted in volume reductions of 28–42%, depending on the effects of mistletoe on height. Further losses might accrue in lodgepole pine stands if clear-cut harvesting were restricted by the BC Forest Practices Code, unless infected stems are selectively removed. Key words: roadside survey, dwarf mistletoe rating (DMR), Forest Practices Code

Isolation and partial characterization of a small chitin-binding lectin from mistletoe ( Viscum album)

A novel lectin, called VisalbCBA, was isolated from European mistletoe (Viscum album). This lectin differs completely from the classical galactose/ N-acetylgalactosamine-binding mistletoe lectins MLI, MLII and MLIII. Biochemical analyses indicated that VisalbCBA is a dimeric protein composed of two identical subunits of approx. 10 kDa. VisalbCBA exhibits specificity towards oligomers of N-acetylglucosamine and shows sequence homology to the previously isolated chitin-binding plant proteins. Although VisalbCBA is less toxic than the other mistletoe lectins, it definitely exhibits cytotoxic properties. The possible involvement of VisalbCBA in the biological and therapeutic effects of mistletoe is discussed.

Impact of mistletoes ( Amyema miquelii) on host ( Eucalyptus blakelyi and Eucalyptus melliodora) survival and growth in temperate Australia

The damaging effects of mistletoes Amyema spp. on host eucalypts in rural Australia concern many landholders, but few data are available to evaluate mistletoe impacts or formulate management strategies. We used an experimental disinfection approach to determine the effects of a putative pest mistletoe, Amyema miquelii, on its two principal hosts, Blakely's red gum ( Eucalyptus blakelyi) and yellow box ( Eucalyptus melliodora), on pastoral properties in northern New South Wales. For each host species, pairs of nearby trees were matched for heigth, diameter at breast height, level of mistletoe infestation and distance to neighbouring trees. One tree per pair was chosen at random and all the mistletoes pruned. After 33 months all treated trees were still alive, but among control trees seven of 29 red gums and one of 20 yellow box trees had died. The difference in survival between treated and control trees was significant for red gum. Among surviving pairs of trees, treated trees of both species had significantly greater diameter increments and significantly more foliage than untreated trees. After 33 months, the average increase in relative host foliage biomass attributable to removal of mistletoes was 22% in red gum and 24% in yellow box, compared with untreated controls. The average increase in radial growth attributable to mistletoe removal was 55% in red gum and 49% in yellow box. Diameter increment was negatively and linearly related to mistletoe infestation level in control trees of both species. The differences between infected and disinfected trees in this experiment may underestimate the impact of Amyema miquelii on host growth because small amounts of host biomass were unavoidably lost during disinfection. In a separate experiment, loss of host biomass had a significant negative impact on diameter increment. Although the results indicate that control of serious Amyema miquelii infestation of individual trees will be worthwhile in terms of immediate host survival and higher growth rate, prudent long-term management may well allow for the loss of small numbers of farm trees to mistletoes when planning tree recruitment and utilisation.

Crown efficiency of oak standards as affected by mistletoe and coppice removal

Effects of mistletoe ( Loranthus europaeus Jacq.) and coppice removal on the efficiency of crown projection area and the growth of sessile oak ( Quercus petraea Liebl.) standards were studied in a 2×2 factorial experiment with nine replications. Four treatments were applied in 1980: control, coppice removal only, mistletoe removal only and removal of both coppice and mistletoe. After 11 years, the basal area increment, the crown efficiency (basal area increment per square metre of crown projection area) and the crown projection area increment showed statistically significant interactions between initial crown size, coppice removal and mistletoe removal. The basal area increment increased strongly with increasing crown size, but crown efficiency was maintained at the same low threshold for all crown sizes when the coppice remained, regardless of whether mistletoe was removed or not. This constant crown efficiency may be attributed to a decrease in crown projection area of larger trees rather than to higher increments. The effect of coppice removal was highest for small crowns and was independent of mistletoe removal. For larger crowns, the effect of coppice removal was much more pronounced when mistletoe was also removed.