Fine‐tuning of a mowing regime,a method for the management of the invasive plant,Ambrosia artemisiifolia,at different population densities

Common ragweed (Ambrosia artemisiifolia) is an invasive annual plant with highly allergenic pollen. Its spread in introduced and native ranges often occurs on roadsides, where it builds stable and rapidly growing populations. The most sustainable way of controlling the population size of this species is to prevent seed production in order to deplete the soil seed bank. Populations on roadsides are submitted to regular mowing management, which can even exacerbate the situation by inducing resprouting after cutting or by accidentally spreading seeds along the road. The population density in the juvenile stages of development could play an important role in the success of cutting regimes, as it might influence the resprouting capacity of this plant. The influence of the juvenile population density and of seven cutting regimes, differing in the timing and frequency of cuts, on easily measurable reproductive traits was investigated in a glasshouse experiment. The cutting regimes had a strong influence on the reproductive success and on the phenology of the development stages of ragweed. The population density in the juvenile stages did not play a role in further phenological development, but did influence the reproductive traits. The reproduction of ragweed can be lowered by locally adapted combinations of the timing and frequency of mowing. As the optimal management option for the reduction of both the male and female flowers, the authors suggest a first cut just before the start of male flowering, followed by subsequent cuts every 3–4 weeks.     

Epidemiologically non-feasible singleton reactors at the final stage of BoHV1 eradication: Serological evidence of BoHV2 cross-reactivity

A voluntary marker-independent Bovine Herpesvirus 1 (BoHV1) eradication program started in 1986; in 1998 it changed to a compulsory one. Certification of free regions in European member states is based on Article 10 of directive 64/432/EEC. According to this rule Bavaria is listed as free of BoHV1 since October 2011. Surveillance of BoHV1-free dairy cattle farms is currently performed with quarterly bulk-milk testing. Non-negative bulk-milk results must be confirmed by blood tests in cattle older than nine months. An increased regional rate of non-negative bulk-milk samples and the subsequent detection of epidemiologically non-feasible singleton BoHV1-reactors by analysis of blood were observed at the final stage of eradication in southwest Bavaria. Nineteen case farms (734 animals) defined by singleton reactors born at least two years after certification of the farms as BoHV1-free, 23 negative control (NC) farms (NC I: 321 animals) from the same region, 11 NC-farms (NC II: 423 animals) from an already-certified Article 10 region in northeast Bavaria and two BoHV1-infected farms (264 animals) were analysed using BoHV1-, BoHV2- and Feline Herpesvirus 1 (FeHV1)-neutralisation tests (NTs), and three commercially available ELISAs supplied by Idexx Laboratories, B.V., The Netherlands: the CHEKIT? Trachitest 2nd Gen. test for milk or serum (Trachitest), Herdchek? gB- (gB-ELISA) and Herdchek? gE-ELISA (gE-ELISA). Significantly increased levels of BoHV2 antibodies were observed on case farms compared to NC I or II farms. Additionally, reactivity by gB-ELISA and the Trachitest was significantly increased for animals with BoHV2 neutralising antibodies. Singleton BoHV1-reactors tested negative by gE-ELISA even if an elevated cut-off of 0.95±0.05 was applied. At this cut-off, the gE-ELISA was as sensitive and specific as the gB-ELISA. Comparative titration of milk samples from seropositive animals from a BoHV1-infected dairy cattle farm and from singleton BoHV1-reactors performed in CHEKIT? Trachitest 2nd Gen. Milk revealed that the slopes of both groups were distinct; therefore, optimised cut-offs for bulk-milk testing to exclude singleton BoHV1-reactors are proposed.     

Cholesteatoma after lateral bulla osteotomy in two brachycephalic dogs

This report describes a French bulldog and a pug that presented to the authors' hospital following total ear canal ablation (TECA) and lateral bulla osteotomy (LBO), with signs of recurring otitis media and difficulty opening their mouths. The bulldog also had unilateral facial paralysis and sensory deficits of the trigeminal nerve on the ipsilateral side. Computed tomography and MRI scans suggested cholesteatoma in the bulldog, but showed only slight enlargement of the bulla in the pug. Histopathologic examination of samples yielded cholesteatoma in both cases. The authors suspect that development of the cholesteatomas was linked to the TECA/LBO surgery in both cases. Cholesteatomas may occur more frequently than currently thought. Even if only slight changes of the bulla wall are detected on CT, early-stage cholesteatoma should be considered. The narrow anatomic conditions in brachycephalic dogs possibly predispose such breeds to develop cholesteatoma after middle ear surgery because complete removal of all inflammatory and epithelial tissue can be more difficult than in other breeds. To the authors' knowledge, this is the first report of an aural cholesteatoma causing sensory deficits of the trigeminal nerve.     

Climatic signal from <Emphasis Type="Italic">Pinus leucodermis</Emphasis> axial resin ducts: a tree-ring time series approach

Developing long-term chronologies of tree-ring anatomical features to evaluate climatic relationships within species might serve as an annual proxy to explore and elucidate the climatic drivers affecting xylem differentiation. Pinus leucodermis response to climate was examined by analyzing vertical xylem resin ducts in wood growing at high elevation in the Apennines of peninsular Southern Italy. Early- and latewood tree-ring resin duct chronologies, spanning the 1804–2010 time period, were constructed. We analyzed the relationships between resin duct chronologies and climate over the last century using correlation and response function analyses. Overall, results showed that ring width and resin duct relationships differed between early- and latewood, which indicated conditions affecting growth were not associated with resin duct production. Results also revealed differential responses to climate between early- and latewood resin duct chronologies. A notable observation was a positive and stable relationship between latewood resin duct number chronology and July maximum temperature throughout the twentieth century. This result suggested resin ducts might be a suitable proxy to evaluate P. leucodermis response to climate in the study area.     

Restoration of degraded ecosystems in the Afromontane highlands of Ethiopia: comparison of plantations and natural regeneration§

The scale of deforestation in sub-Saharan Africa underscores the need for forest restoration. Information is scarce for evidence-based restoration options. Sown Senna didymobotrya, planted Ficus thonningii cuttings, sown S. didymobotrya and planted F. thonningii combined, and previously occurring native non-browse shrubs (NNS) were compared for their effect on selected plant nutrients and occurrence of Olea europaea subsp. cuspidata in north-west Ethiopia. The treatments were applied to experimental units established on previous grazing land. At the end of the fourth year, 60% of planted F. thonningii stakes survived. The leaf biomass production was encouraging. Senna didymobotrya attained close to 1 m height and crown width. Natural regeneration of O. europaea was observed only under previously occurring shrubs. Six previously occurring NNS species were identified. Soils immediately under these shrubs were richer in nutrients than between shrubs in the open spaces. Our results suggest that vegetative stakes and NNS could be promising tools for ecological restoration of decimated ecosystems in the highlands of Ethiopia. Management interventions, which aim at steering succession close to pre-disturbance forest community structure by facilitation, should be selective of the shrub species.     

Growth recovery of mature Norway spruce and European beech from chronic O<Subscript>3</Subscript> stress

Elevated O₃ levels can strongly impair the health and vitality of forest ecosystems. Free-air exposure systems reveal that forest tree and stand growth can be reduced strongly under chronic O₃ stress. Detailed knowledge of the effect of O₃ exposure on photosynthesis, carbon sequestration, allometry and growth during chronic stress is available. However, knowledge of growth response after O₃ reduction is scarce. Here, we analyse the growth of mature Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus sylvatica L.) in the free-air O₃ fumigation experiment at Kranzberg Forest. We compare tree growth over a 9-year period (2008–2016) after exposure to O₃ (2000–2007). During 2?×?O₃ exposure, the annual basal area growth of Norway spruce and European beech decreased by 24 and 32%, respectively. After cessation of 2?×?O₃ exposure, the annual basal area growth of Norway spruce and European beech not only recovered but exceeded the growth of the trees in the control condition by 14 and 24%, respectively. The growth resilience and resistance of trees previously exposed to 2?×?O₃ towards drought stress and late frost was hardly lower than that of the trees in the control condition. The capacity for growth recovery even after long-term chronic O₃ stress emphasizes the strong beneficial effect of air pollution control on the health of forest ecosystems and on the global land carbon sink.     

Characterization and quantitation of polyphenolic compounds in bark, kernel, leaves, and peel of mango (Mangifera indica L.)

The contents of secondary plant substances in solvent extracts of various byproducts (barks, kernels, peels, and old and young leaves) in a range of Brazilian mango cultivars were identified and quantitated. The results show that the profiles of secondary plant substances such as xanthone C-glycosides, gallotannins, and benzophenones in different byproducts vary greatly but are fairly consistent across cultivars. The free radical scavenging activity of the solvent extracts was evaluated using a high-performance liquid chromatography-based hypoxanthine/xanthine oxidase assay and revealed dose-dependent antioxidant capacity in all extracts. Four (mangiferin, penta- O-galloyl-glucoside gallic acid, and methyl gallate) of the major phenolic compounds detected were also evaluated in additional in vitro bioassay systems such as oxygen radical absorbance capacity, 2,2-diphenyl-1-picrylhydrazyl, and ferric reducing ability of plasma. Mangiferin in particular, detected at high concentrations in young leaves (Coite = 172 g/kg), in bark (Momika = 107 g/kg), and in old leaves (Itamaraka = 94 g/kg), shows an exceptionally strong antioxidant capacity.     

Pyrrolizidine alkaloid production of Jacobaea aquatica and contamination of forage in meadows of Northern Austria

Jacobaea aquatica (=Senecio aquaticus, Asteraceae), marsh ragwort, grows regionally in low management intensity wet grasslands in various European countries. The plant can be regarded as a noxious weed as it contains pyrrolizidine alkaloids (PAs), which cause health problems in livestock. In the Waldviertel region of Northern Austria, marsh ragwort has established dense populations as the fertilizing and production intensity of the meadows changed during the last decades. Ragwort biomass production and alkaloid concentration in J. aquatica were recorded during three consecutive years at three sites to study the effects of two treatments: cutting twice a year either early in June plus September, or in July plus August, respectively. Six PAs (Z‐erucifoline > senecionine > integerrimine > seneciphylline > acetyl‐erucifoline and acetyl‐seneciphylline) were evaluated. The alkaloid contents were highest in July and August when 600–1,400 mg/kg dry matter (DM) total PAs occurred in most ragwort samples. Consequently, the forage can easily be contaminated with 40–80 mg/kg DM of PAs and may present a health risk for domestic animals and also affect human health as these alkaloids are transferred into milk.     

Saccharomyces Cerevisae and Arabidopsis Thaliana: Useful Model Systems for the Identification of Molecular Mechanisms Involved in Resistance of Plants to Toxins

Secondary metabolites produced by pathogens during the infection process are thought to play a role as pathogenicity or virulence determinants in many plant diseases. Baker's yeast and the plant Arabidopsis thaliana are attractive models for elucidating molecular mechanisms of resistance to toxic substances. For the Fusarium mycotoxin deoxynivalenol, the following resistance mechanisms were identified in yeast: (1) reduced toxin uptake due to the ABC transporter protein Pdr5p (molecular efflux pump), (2) detoxification by the acetyltransferase Ayt1p, and (3) modification of the ribosomal target by amino acid changes in the ribosomal protein L3 (Rpl3p). PDR5-like genes exist in plant genomes as large gene families and could play an important role as a first line of defence against a broad range of toxic metabolites. Amino acid alterations in the highly conserved RPL3 genes could likewise play a role in trichothecene resistance in plants. The knowledge obtained using model systems should be valuable in biotechnological approaches to disease control and marker-assisted resistance breeding.