Sycamore Maple Trees Research Articles

Conditions of emergence of the Sooty Bark Disease and aerobiology of Cryptostroma corticale in Europe

The sooty bark disease (SBD) is an emerging disease affecting sycamore maple trees (Acer pseudoplatanus) in Europe. Cryptostroma corticale, the causal agent, putatively native to eastern North America, can be also pathogenic for humans causing pneumonitis. It was first detected in 1945 in Europe, with markedly increasing reports since 2000. Pathogen development appears to be linked to heat waves and drought episodes. Here, we analyse the conditions of the SBD emergence in Europe based on a three-decadal time-series data set. We also assess the suitability of aerobiological samples using a species-specific quantitative PCR assay to inform the epidemiology of C. corticale, through a regional study in France comparing two-year aerobiological and epidemiological data, and a continental study including 12 air samplers from six countries (Czechia, France, Italy, Portugal, Sweden and Switzerland). We found that an accumulated water deficit in spring and summer lower than -132 mm correlates with SBD outbreaks. Our results suggest that C. corticale is an efficient airborne pathogen which can disperse its conidia as far as 310 km from the site of the closest disease outbreak. Aerobiology of C. corticale followed the SBD distribution in Europe. Pathogen detection was high in countries within the host native area and with longer disease presence, such as France, Switzerland and Czech Republic, and sporadic in Italy, where the pathogen was reported just once. The pathogen was absent in samples from Portugal and Sweden, where the disease has not been reported yet. We conclude that aerobiological surveillance can inform the spatial distribution of the SBD, and contribute to early detection in pathogen-free countries.

Atypical myopathy in 2 Bactrian camels.

Atypical myopathy (AM) is an acute seasonal rhabdomyolysis seen primarily in equids, caused by the ingestion of sycamore maple samaras containing hypoglycin A (HGA) and methylenecyclopropyl-glycine (MCPG). Toxic metabolites inhibit acyl-CoA dehydrogenases and enoyl-CoA hydratases, causing selective hyaline degeneration of type I muscle fibers. Two zoo-kept Bactrian camels (Camelus bactrianus) with a fatal course of AM had sudden onset of muscle pain and weakness, recumbency, and dysphagia, accompanied by increased serum creatine kinase activity and detection in serum of HGA, MCPG, and metabolites. Medical treatment was ineffective. At postmortem examination, sycamore maple tree material was found within the first gastric compartment of the 2-y-old gelding. Although musculature was macroscopically normal, histologically, monophasic hyaline degeneration was marked within type I fibers of intercostal and hypoglossal muscles of the gelding, and in neck, tongue, and masticatory muscles of the cow. The ingestion of sycamore maple material can cause AM in Bactrian camels, and trees of the Sapindaceae family should be avoided in enclosures.

Hypoglycin A in Cow's Milk-A Pilot Study.

Hypoglycin A (HGA) originating from soapberry fruits (litchi, and ackee) seeds or seedlings from the sycamore maple (SM) tree (related to Sapindaceae) may cause Jamaican vomiting sickness in humans and atypical myopathy in horses and ruminants. A possible transfer into dairy cow’s milk cannot be ruled out since the literature has revealed HGA in the milk of mares and in the offal of captured deer following HGA intoxication. From a study, carried out for another purpose, bulk raw milk samples from four randomly selected dairy farms were available. The cows were pastured in the daytime. A sycamore maple tree was found on the pasture of farm No. 1 only. Bulk milk from the individual tank or milk filling station was sampled in parallels and analyzed for HGA by LC-ESI-MS/MS. Measurable concentrations of HGA occurred only in milk from farm No. 1 and amounted to 120 and 489 nmol/L. Despite low and very variable HGA concentrations, the results indicate that the ingested toxin, once eaten, is transferred into the milk. However, it is unknown how much HGA the individual cow ingested during grazing and what amount was transferred into the bulk milk samples. As a prerequisite for a possible future safety assessment, carry-over studies are needed. Furthermore, the toxins’ stability during milk processing should also be investigated as well.

Grazing Mares on Pasture with Sycamore Maples: A Potential Threat to Suckling Foals and Food Safety through Milk Contamination.

Simple SummaryEquine atypical myopathy is seasonal poisoning resulting from the ingestion of seeds and seedlings of the sycamore maple that contains toxins. Literature mentions several cases of intoxication among gravid mares and in unweaned foals. The objective of this study was to determine whether the toxins responsible for atypical myopathy could pass to the foal via suckling. Four mares that were pasturing with sycamore in the vicinity were milked. Analysis revealed the presence of toxins in milk. This unprecedented observation could partially explain cases of unweaned foals suffering from atypical myopathy. However, a transplacental transfer of the toxin cannot be excluded for newborn cases. Besides being a source of contamination for offspring, milk contamination by toxins from fruits of trees of the Sapindaceae family might constitute a potential risk for food safety regarding other species’ raw milk or dairy products.Equine atypical myopathy (AM) is seasonal intoxication resulting from the ingestion of seeds and seedlings of the sycamore maple (Acer pseudoplatanus) that contain toxins, among them, hypoglycin A (HGA). Literature mentions several cases of AM among gravid mares and in unweaned foals. The objective of this study was to determine whether HGA and/or its metabolite are present in milk from grazing mares exposed to sycamore maple trees as confirmed by detection of HGA and its metabolite in their blood. Four mare/foal couples were included in the study. Both HGA and its metabolite were detectable in all but one of the milk samples. To our knowledge, this is the first study describing transfer of HGA to the milk. This unprecedented observation could partially explain cases of unweaned foals suffering from AM. However, a transplacental transfer of the toxin cannot be excluded for newborn foals. Besides being a source of contamination for offspring, milk contamination by toxins from fruits of trees of the Sapindaceae family might constitute a potential risk for food safety regarding other species’ raw milk or dairy products.

Wood Quality Characterization of Sycamore Maple (Acer pseudoplatanus L.) and its Utilization in Wood Products Industries

This study quantified the physical and mechanical properties of sycamore maple (Acer pseudoplatanus L.) as a basis for assessing wood quality. The physical properties of oven-dry density, density at 12% MC, green density, basic density, longitudinal, radial, tangential and volumetric shrinkages were tested and the mechanical properties of bending strength, modulus of elasticity at bending, compression strength parallel to grain and compression strength in radial and tangential direction as well as of Brinell hardness on the cross, radial, and tangential section were determined. Five sycamore maple trees from Medvednica region were selected for the purposes of this research. The results were compared with known literature data on sycamore maple wood, beech wood from the same sight, and beech wood from Gorski Kotar region. For a better understanding of sycamore maple physiology, as well as for assessing the quality of wood products, the distribution of wood properties within the tree radius, from pith to bark, was investigated. There was a general bell shaped distribution, in the radial direction, in wood density, and mechanical properties of sycamore maple wood. Shrinkages decreased from pith to bark, except for tangential shrinkage with bell shaped pattern. All investigated wood densities of sycamore maple from Medvednica were similar to the findings of studies known in literature, as well as shrinkages, except for the lower longitudinal shrinkage. Investigated mechanical properties of sycamore maple wood were similar to the findings of studies known in literature, except for the lower bending strength and modulus of elasticity (MOE). Investigated sycamore maple indicated better dimensional stability than beech wood from two locations in the region, although it did not match the beech wood regarding mechanical properties, especially wood hardness.

Answers to the Frequently Asked Questions Regarding Horse Feeding and Management Practices to Reduce the Risk of Atypical Myopathy.

Simple SummaryEquine atypical myopathy is a severe intoxication of grazing equids resulting from the ingestion of samaras or seedlings of trees from the Acer species. The sycamore maple (Acer pseudoplatanus) is involved in European cases whereas the box elder (Acer negundo) is recognized as the cause of this seasonal pasture myopathy in the Unites States of America. In Europe, young and inactive animals with a thin to normal body condition and no feed supplementation, except for hay in autumn, are at higher risk. The risk is also associated with full time pasturing in a humid environment. Indeed, dead leaves piling up in autumn as well as, the presence of trees and/or woods presumably exposes the horses to the sycamore maple. This manuscript answers the most frequently asked questions arising from the equine field about feeding and management of equines to reduce the risk of atypical myopathy. All answers are based on data collected from 2006 to 2019 by the “Atypical Myopathy Alert Group” (AMAG, Belgium) and the “Réseau d’épidémiosurveillance en Pathologie équine” (RESPE, France) as well as on a review of the most recent literature.In 2014, atypical myopathy (AM) was linked to Acer pseudoplatanus (sycamore maple) in Europe. The emergence of this seasonal intoxication caused by a native tree has raised many questions. This manuscript aims at answering the five most frequently asked questions (FAQs) regarding (1) identification of toxic trees; reduction of risk at the level of (2) pastures and (3) equids; (4) the risk associated with pastures with sycamores that have always been used without horses being poisoned and (5) the length of the risk periods. Answers were found in a literature review and data gathered by AM surveillance networks. A guide is offered to differentiate common maple trees (FAQ1). In order to reduce the risk of AM at pasture level: Avoid humid pastures; permanent pasturing; spreading of manure for pasture with sycamores in the vicinity and avoid sycamore maple trees around pasture (FAQ2). To reduce the risk of AM at horse level: Reduce pasturing time according to weather conditions and to less than six hours a day during risk periods for horses on risk pasture; provide supplementary feeds including toxin-free forage; water from the distribution network; vitamins and a salt block (FAQ3). All pastures with a sycamore tree in the vicinity are at risk (FAQ4). Ninety-four percent of cases occur over two 3-month periods, starting in October and in March, for cases resulting from seeds and seedlings ingestion, respectively (FAQ5).

When scientists become detectives: investigating systematic tree poisoning in a protected cove

The systematic killing of trees is usually aimed at eradicating pests or alien plant species susceptible to harm existing natural ecosystems. In some cases, trees may become the subject of dispute between neighbors, which sometimes ends in tree death after months or years of dispute. In this paper, we analyze a case of clandestine tree killing and look into ways through which evidence left by delinquents can be analyzed a posteriori with state-of-the-art approaches. The investigation presented here looks at a series of old-growth trees that were supposedly poisoned inside a protected, nineteenth century grove in Switzerland. After the sudden, unexplained death of several old Black poplar (Populus nigra) trees along the main alley in fall 2015 and their subsequent removal, the dying of five additional, neighboring Sycamore maple (Acer pseudoplatanus) and English walnut (Juglans regia) trees in 2016 promptly triggered a suite of criminal investigations at the property. During an initial inspection, a large number of boreholes was found in the root plates of the dying trees. We present findings obtained from tree-ring, wood anatomical and dendrogeochemical investigations performed on root, stem and leave material from the assumedly poisoned trees and show that massive amounts of chemical elements – supposedly in the form organic pesticides with high Al, As, Fe, Cr, Ni contents, aluminum phosphides or glyphosate-based pesticides – were injected into 36 boreholes drilled into the roots around September 2016. Results obtained in this study are currently used in criminal investigations, and are a nice example of how scientific detectives can help their “real World” colleagues in identifying delinquents.

Physical Properties of Juvenile and Mature Sycamore Maple (Acer pseudoplatanus L.) Wood from Medvednica Region

Physical properties play an important role in predicting wood quality. The aim of this study was to investigate radial variations in physical properties of sycamore maple (Acer pseudoplatanus L.) wood, to determine the border between juvenile and mature wood and to compare them with analogous variations in beech wood. Radial variation of density in absolutely dry condition, maximum density, nominal density, longitudinal, radial, tangential and volumetric shrinkage, maximum moisture content and annual ring width on five sycamore maple trees from Medvednica region in Croatia were determined. Observing the trend curves and comparing average values of physical properties, different zones in the cross section of the trunk were determined. In the first zone, from the pith to about 30th annual ring, more rapid changes in physical properties occurred. It is followed by transitional zone, which ranges roughly from 30th to 40th annual ring. After 40th annual ring, less pronounced changes in measured physical properties occurred. Sharp boundary between juvenile and mature wood zones could not be determined. According to the results, the first zone is considered to be juvenile wood, while mature wood starts after the 30th annual ring .

Ріст і формування дубових деревостанів за участю липи дрібнолистої в умовах свіжої грабової діброви Західного Поділля

Досліджено лісівничо-таксаційні показники та санітарний стан дубових деревостанів різного віку за участю у їх складі липи дрібнолистої. Встановлено, що тут формуються складні деревостани за участю дуба звичайного, ясена звичайного, граба звичайного, липи дрібнолистої, в’яза голого, кленів гостролистого і явора та інших деревних видів. Частка липи у їх складі становить від поодиноких дерев до 6-8 одиниць. Серед них переважають деревостани, в яких частка липи становить 2-4 одиниці. Дуб звичайний росте за ІІ-Іb бонітетом та досягає максимальної продуктивності (Іа-Іb бонітет) у деревостанах, де частка липи у складі змінюється в межах 2-8 одиниць і відстає в рості від дуба за висотою на 10,0-46,1%. Найгіршим ростом дуб звичайний характеризується в деревостанах, де відмінності за висотою між ним і липою становлять до 7%.
 Повнота деревостанів і запас стовбурової деревини відзначаються високою варіабельністю навіть у межах вікових груп. У середньовікових деревостанах абсолютна повнота становить 21,4-34,0 м2/га, а запас деревини – 172-374 м3/га. У пристигаючих деревостанах ці показники, відповідно, становлять 24,6-34,9 м2/га і 263-409 м3/га, а в стиглих – 26,6-40,3 м2/га і 330-487 м3/га. Найбільшого запасу (409-487 м3/га) досягають дубові деревостани, де частка липи у їх складі становить 3-6 одиниці. Водяні пагони у дерев дуба не виявлено на 20% дослідних ділянок. В інших деревостанах різної повноти і продуктивності кількість дерев дуба з водяними пагонами становить 5,3-53,3%. У деревостанах переважають дерева І і ІІ категорій санітарного стану. Сухі дерева трапляються на 70% дослідних ділянок в кількості 1,2-7,2%. Індекс санітарного стану дуба змінюється в межах 1,36-2,65.

The Sycamore Maple Bacterial Culture Collection From a TNT Polluted Site Shows Novel Plant-Growth Promoting and Explosives Degrading Bacteria.

Military activities have worldwide introduced toxic explosives into the environment with considerable effects on soil and plant-associated microbiota. Fortunately, these microorganisms, and their collective metabolic activities, can be harnessed for site restoration via in situ phytoremediation. We characterized the bacterial communities inhabiting the bulk soil and rhizosphere of sycamore maple (Acer pseudoplatanus) in two chronically 2,4,6-trinitrotoluene (TNT) polluted soils. Three hundred strains were isolated, purified and characterized, a majority of which showed multiple plant growth promoting (PGP) traits. Several isolates showed high nitroreductase enzyme activity and concurrent TNT-transformation. A 12-member bacterial consortium, comprising selected TNT-detoxifying and rhizobacterial strains, significantly enhanced TNT removal from soil compared to non-inoculated plants, increased root and shoot weight, and the plants were less stressed than the un-inoculated plants as estimated by the responses of antioxidative enzymes. The sycamore maple tree (SYCAM) culture collection is a significant resource of plant-associated strains with multiple PGP and catalytic properties, available for further genetic and phenotypic discovery and use in field applications.

Atypical myopathy in Père David's deer (Elaphurus davidianus) associated with ingestion of hypoglycin A.

From 2004 until 2016, 21 Père David's deer (Elaphurus davidianus) have died for unknown reason at Zoo Duisburg. These deer, also known as milu, have succumbed from a myopathy that occurred seasonally in autumn and in spring. The clinical signs shown by the animals closely resembles those of a disease called equine atypical myopathy (EAM), which is formerly known in horses. The cause for EAM in Europe was found in the ingestion of hypoglycin A, contained in samaras and seedlings of the sycamore maple tree (Acer pseudoplatanus). To test the hypothesis that the mortality of milus was caused by ingestion of hypoglycin A, 79 sera from all zoos and wildlife parks that have kept milus in Germany and Austria, including 19 diseased and 60 healthy animals, were used. Selected biochemical values and additionally hypoglycin A, methylenecyclopropyl acetic acid-carnitine (MCPA-carnitine), and acylcarnitines, which have been found in horses suffering from EAM, were determined. The results showed greater values of serum activities of creatine kinase (P < 0.001) and aspartate aminotransferase (P < 0.001) in diseased milus comparing to healthy ones confirming a myopathy in affected animals. Moreover, hypoglycin A and MCPA-carnitine were found in the blood of Père David's deer and thus, hypoglycin A intoxication was considered to be a potential cause for the myopathies by ingestion of sycamore maple samaras that were present in the enclosure of the affected animals. Hypoglycin A values were greater in diseased animals (P < 0.01) as well as MCPA-carnitine levels (P < 0.05). Additionally, affected milus showed greater C5-OH-carnitine (P < 0.01) and C6-carnitine (P < 0.001) values. Until now hypoglycin A intoxication was only known in the family of Equidae, in humans, and in laboratory rats, and it has not been previously described in other zoological families. Comparing to horses, ruminants do have a different digestive tract and it will need further investigation to find out if several factors are involved to trigger an outbreak in ruminants.

Epiphytes in wooded pastures: Isolation matters for lichen but not for bryophyte species richness.

Sylvo-pastoral systems are species-rich man-made landscapes that are currently often severely threatened by abandonment or management intensification. At low tree densities, single trees in these systems represent habitat islands for epiphytic cryptogams. Here, we focused on sycamore maple (Acer pseudoplatanus) wooded pastures in the northern European Alps. We assessed per tree species richness of bryophytes and lichens on 90 sycamore maple trees distributed across six study sites. We analysed the effects of a range of explanatory variables (tree characteristics, environmental variables and isolation measures) on the richness of epiphytic bryophytes and lichens and various functional subgroups (based on diaspore size, habitat preference and red list status). Furthermore, we estimated the effect of these variables on the occurrence of two specific bryophyte species (Tayloria rudolphiana, Orthotrichum rogeri) and one lichen species (Lobaria pulmonaria) of major conservation concern. Bryophytes and lichens, as well as their subgroups, were differently and sometimes contrastingly affected by the variables considered: tree diameter at breast height had no significant effect on bryophytes but negatively affected many lichen groups; tree phenological age positively affected red-listed lichens but not red-listed bryophytes; increasing isolation from neighbouring trees negatively affected lichens but not bryophytes. However, the high-priority bryophyte species T. rudolphiana was also negatively affected by increased isolation at small spatial scales. Orthotrichum rogeri was more frequent on young trees and L. pulmonaria was more frequent on trees with thin stems and large crowns. The results indicate that local dispersal is important for lichens, whereas long distance dispersal seems to be more important for colonisation by bryophytes. Furthermore, our study highlights that different conservation measures need to be taken depending on the taxonomic and functional species group or the individual species that is addressed. In practice, for the conservation of a high overall richness in sylvo-pastoral systems, it is crucial to sustain not only old and large trees but rather a wide range of tree sizes and ages.

Germination and Relations between Seed Quality Characteristics for Acer pseudoplatanus and Acer pseudoplatanus ‘Atropurpureum’

Summary The purpose of this paper is to analyze relations between seed quality characteristics and the influence of contaminated urban areas on seed quality of sycamore maple trees in different locations across Novi Sad (Serbia). This research analyzed seed germination of 29 adult trees of sycamore maple (Acer pseudoplatanus L.) and its red leaf variety (Acer pseudoplatanus ‘atropurpureum’ Späth.). Our results indicate a medium strong positive correlation between seed weight and viable seed. Sycamore maple trees from the same urban typology do not have significant influence on seed quality characteristics, while different urban typology has such influence. These results explain the negative influence of urban areas on seed quality characteristics. For selection of high value trees in urbanized and contaminated areas, seed quality can be the indicator of adaptability to stress related conditions.

Solitary trees increase the diversity of vascular plants and bryophytes in pastures

Wooded pastures are semi-natural ecosystems that are often considered biodiversity hotspots and are valuable for nature conservation. Ongoing land-use changes, such as management intensification, threaten these ecosystems. Several studies have assessed the effect of tree density and cover on plant species richness, but the individual effects of single trees have not been addressed previously. We studied the effects of single sycamore maple trees (Acer pseudoplatanus) in sycamore maple wooded pastures on vascular plant and ground bryophyte species richness at six sites in the northern European Alps. In total, we found 346 vascular plant species and 264 bryophyte species. Alpha- and beta-diversity were positively influenced by the trees and positively related to tree size- and tree age-related variables. The positive effect of the trees on the species richness of epigeic bryophytes was reduced at high levels of management intensity, possibly due to severe disturbance by cattle trampling under the trees. However, our data showed that the diversity of the ground vegetation increased when trees were present, even in intensively managed pastures. Our findings highlight the high species richness present in sycamore maple wooded pastures at different spatial scales. The trees in sycamore maple wooded pastures can thus be considered keystone structures providing a range of important functions and conservation policies should particularly emphasize the conservation of large and old trees as well as the planting of young trees in these ecosystems.

Root vitality of Fagus sylvatica L., Quercus petraea Liebl. and Acer pseudoplatanus L. in mature mixed forest stand

Abstract The main task of the present study was to investigate the root vitality of common beech Fagus sylvatica L., sessile oak Quercus petraea Liebl. and sycamore maple Acer pseudoplatanus L. in the optimal g rowth conditions in south-western Poland. The study was carried out in 130-year-old mixed stand located within natural range of studied tree species. The density of roots (g/100 cm3 of soil) and biomass of fine roots (g/m2) in topsoil layers (0-5 cm, 5-15 cm) were determined in the tree biogroups of the same species. The mean total root density ranged from 0.248 to 0.417 g/100 cm3 in the 0-5 cm soil layer, and it decreased in the deeper soil layer (5-15 cm). There were found no statistically significant differences of total root densities between tree biogroups in topsoil layers. Diversity of fine root biomass was comparable in the tree biogroups (H’ = 1.5), but common beech showed more intensive growth of fine roots in the topsoil 0-15 cm when compared to sessile oak and sycamore maple. The results of the study point out the stability of the multi-species structure of the mixed stand studied, and consequently - the ability of beech, sessile oak and sycamore maple trees to coexist in the mixed stands - in the area of natural range of these species.

Hidden crown jewels: the role of tree crowns for bryophyte and lichen species richness in sycamore maple wooded pastures

Tree crowns typically cover the vast majority of the surface area of trees, but they are rarely considered in diversity surveys of epiphytic bryophytes and lichens, especially in temperate Europe. Usually only stems are sampled. We assessed the number of bryophyte and lichen species on stems and in crowns of 80 solitary sycamore maple trees (Acer pseudoplatanus) at six sites in wooded pastures in the northern Alps. The total number of species detected per tree ranged from 13 to 60 for bryophytes, from 25 to 67 for lichens, and from 42 to 104 for bryophytes and lichens considered together. At the tree level, 29 % of bryophyte and 61 % of lichen species were recorded only in the crown. Considering all sampled trees together, only 4 % of bryophyte, compared to 34 % of lichen species, were never recorded on the stem. Five out of 10 red-listed bryophyte species and 29 out of 39 red-listed lichen species were more frequent in crowns. The species richness detected per tree was unexpectedly high, whereas the proportion of exclusive crown species was similar to studies from forest trees. For bryophytes, in contrast to lichens, sampling several stems can give a good estimation of the species present at a site. However, frequency estimates may be highly biased for lichens and bryophytes if crowns are not considered. Our study demonstrates that tree crowns need to be considered in research on these taxa, especially in biodiversity surveys and in conservation tasks involving lichens and to a lesser degree also bryophytes.

Hypoglycin A Concentrations in Maple Tree Species in the Netherlands and the Occurrence of Atypical Myopathy in Horses.

BackgroundAtypical myopathy (AM) in horses is caused by the plant toxin hypoglycin A, which in Europe typically is found in the sycamore maple tree (Acer pseudoplatanus). Owners are concerned about whether their horses are in danger if they graze near maple trees.Hypothesis/ObjectivesTo measure hypoglycin A in the most common maple tree species in the Netherlands, and to determine whether concentration of toxin is a predictor of AM in horses.MethodsA total of 278 samples of maple tree leaves, sprouts, and seeds were classified by species. Mean concentrations of hypoglycin A were compared for the type of sample, the season and the occurrence of AM in the pasture (non‐AM versus AM). Statistical analysis was performed using generalized a linear model (SPPS22).ResultsAlmost all Acer pseudoplatanus samples contained hypoglycin A, with concentrations differing significantly among sources (P < .001). Concentrations were significantly higher in seeds from the AM group than in seeds from the non‐AM group (856 ± 677 and 456 ± 358 mg/kg, respectively; P = .039). In sprouts and leaves this was not the case. Acer platanoides and Acer campestre samples did not contain detectable concentrations of hypoglycin A.Conclusions and clinical importance Acer platanoides and campestre seem to be safe around paddocks and pastures, whereas almost all Acer pseudoplatanus samples contained hypoglycin A. In all AM cases, Acer pseudoplatanus was found. Despite significantly higher concentration of hypoglycin A in seeds of pastures where AM has occurred, individual prediction of AM cannot be made by measuring these concentrations because of the high standard deviation.

Modelling discoloration and duration of branch occlusion following green pruning in Acer pseudoplatanus and Fraxinus excelsior

The production of defect-free, high quality stem wood may be promoted through pruning of branches in hardwood species, yet this practice may also lead to wood defects, such as stem discoloration.Here, models to predict stem discoloration and the time of branch occlusion were developed for Acer pseudoplatanus L. (sycamore maple) and Fraxinus excelsior L. (common ash) based on a pruning experiment in southwest Germany. The dataset consisted of 449 completely occluded branches originating from 115 destructively sampled sycamore maple and common ash trees that had been pruned either in late winter or summer, or had not been pruned and underwent natural branch shedding instead. We analyzed these data with linear and generalized linear mixed-effects models to predict (1) the time until branch occlusion, (2) the length of branch discolorations and (3) the occurrence of discolorations in the stem wood. For all treatments, the time until complete branch occlusion was negatively related to stem radial increment during branch occlusion and positively related to the branch diameter in case of green pruning or the length of the dead branch portion in case of natural branch shedding. The extent of branch discoloration was positively correlated with branch diameter (green pruning) or the dead branch length (natural shedding), which was itself correlated to branch diameter. The probability of stem discoloration after pruning increased with branch diameter and showed large interspecific differences, with a much higher risk for common ash. Thresholds for decay risk based on pruned branch diameters are reported for each species. In both branch and stem discoloration models, there was no evidence of significant effects related to the time of pruning.When analyzing a subset of the original data containing only branches with diameters up to 30mm, we found that green pruning significantly reduced the duration of branch occlusion. The extent of branch discoloration was positively related to branch diameter and occlusion time and was not affected by pruning treatment or species.Our results indicate that pruning reduces the duration of branch occlusion and, hence, has the potential to increase the proportion of defect-free wood. Furthermore, the duration of branch occlusion after artificial pruning should be minimized in order to reduce the risk of discoloration and decay. Therefore, green pruning should start early in the life of a tree when its branches are still thin and be applied only to vigorous trees that can occlude the wounds rapidly.

Development of the rosalia longicorn Rosalia alpina (L.) (Coleoptera: Cerambycidae) in the sycamore maple Acer pseudoplatanus L. – the first report from Poland

AbstractIn 2012 the development of the rosalia longicorn Rosalia alpina (L.) was confirmed in the sycamore maple Acer pseudoplatanus L., a new host plant in Poland. In the laboratory, one adult beetle was reared from a branch obtained from the Magura National Park (Beskid Niski Mts., Carpathians, SE Poland). The breeding material was collected at a site located in the fertile Carpathian beech forest association Dentario glandulosae-Fagetum, in a stand with an admixture of sycamore maple trees. In the paper the importance of the sycamore maple as a host plant is discussed.

DETECTION OF THE WOOD DECAY ASCOMYCETE KRETZSCHMARIA DEUSTA IN URBAN MAPLE TREES IN ITALY

In June 2008, a basal stem failure of a sycamore maple tree (Acer pseudoplatanus) occurred in Turin (Italy). The failed tree did not show any external signs of fungal disease. However, the wood at the point of stem breakage was decayed and permeated by black lines. Isolations from decayed wood samples, performed on potato dextrose agar (PDA), yielded white fungal colonies that later turned greyish-brown producing hyaline, smooth and ovate conidia (5.5-7×2.5-3.5 μm) on tufts of sparsely branched conidiophores. Using a multiplex PCR assay (Nicolotti et al., 2009), the fungal cultures were identified as Kretzschmaria deusta. The features of the decayed wood and the morphological traits of pure cultures were also consistent with this diagnosis. After this finding, 77 maple trees, comprising those adjacent to the failed tree, were surveyed and sampled using the drilling method by Guglielmo et al. (2010). Although no overt signs of K. deusta in- fection were observed, multiplex PCR identified this fungus in five trees, comprising four sycamore maples and a Norway maple (Acer platanoides). Three of these infected trees were very close to the failed one, thus suggesting a clustering of infection. Inci- dence of K. deusta was higher than that of other wood decay fun- gi detected by multiplex PCR. Although K. deusta is known as a threat for the stability of different broadleaf trees in the urban context of northern and central Europe, to our knowledge this is the first report of this pathogen in urban maple trees in Italy.