Susceptibility Ranking Research Articles

Oxidation of Mesalamine under Phenoloxidase- or Peroxidase-like Enzyme Catalysis.

Mesalamine, also called 5-ASA (5-aminosalicylic acid), is a largely used anti-inflammatory agent and is a main choice to treat Ulcerative Colitis. This report is aimed to investigate enzymatic processes involved in the oxidation of mesalamine to better understand some of its side-effects. Oxidation with oxygen (catalyzed by ceruloplasmin) or with hydrogen peroxide (catalyzed by peroxidase or hemoglobin) showed that these oxidases, despite their different mechanisms of oxidation, could recognize mesalamine as a substrate and trigger its oxidation to a corresponding quinone-imine. These enzymes were chosen because they may recognize hydroquinone (a p-diphenol) as substrate and oxidize it to p-benzoquinone and that mesalamine, as a p-aminophenol, presents some similarities with hydroquinone. The UV-Vis kinetics, FTIR and 1H NMR supported the hypothesis of oxidizing mesalamine. Furthermore, mass spectrometry suggested the quinone-imine as reaction product. Without enzymes, the oxidation process was very slow (days and weeks), but it was markedly accelerated with the oxidases, particularly with peroxidase. Cyclic voltammetry supported the hypothesis of the oxidative process and allowed a ranking of susceptibility to oxidizing mesalamine in comparison with other oxidizable drug molecules with related structures. The susceptibility to oxidation was higher for mesalamine, in comparison with Tylenol (acetaminophen) and with aspirin (salicylic acid).

Methodology for ranking internal corrosion-induced leakage susceptibility in oilfield pipelines

ABSTRACT This investigation focuses on the ranking of pipeline leakage susceptibility of two categories of pipeline systems. One consists of three oilfield water-handling pipeline systems and the other consists of five dry crude systems. Online corrosion monitoring (OCM) method was used for both systems, forthermore, in-line inspection (ILI) method, with Magnetic Flux leakage (MFL) tool, was also used for the dry crude systems. The OCM leakage susceptibility potential is derived from the combined severity of general corrosion, pitting corrosion, fluid corrosivity and sessile bacteria population density in the process streams. The ILI leakage susceptibility potential is derived from the average number of corrosion anomalies greater than 10% of the wall thickness and the maximum depth of the anomalies (as percentage of the wall thickness). In spite of such distinctions, the ranking of pipeline leakage susceptibility for the five dry crude pipeline segments turned out to be identical for the two methodologies.

Regional scale probabilistic procedure for estimating lateral spread displacements

Regional scale liquefaction assessments are currently performed using approaches such as qualitative liquefaction susceptibility rankings based on mapped geology and groundwater information, interpolation of liquefaction vulnerability indices from widely spaced subsurface explorations, or use of proxies for geologic, geotechnical, and groundwater conditions that affect liquefaction triggering calculations. These methods often do not include assessments of the consequences of liquefaction, such as the potential lateral spread displacement and its uncertainty. This study presents a procedure for probabilistically assessing liquefaction-induced lateral spread displacement at the regional scale by estimating a distribution of lateral displacement index (LDI) using models conditioned on surficial geology, depth to groundwater, peak ground acceleration, and earthquake magnitude. Existing topographic correlations are used to convert distributions of LDI to distributions of lateral spread displacement. Case histories illustrate its performance in regional assessments of the lateral spread hazard.

Comparison of different objective weighting methods in a multi‐criteria model for watershed prioritization for flood risk assessment using morphometric analysis

AbstractMorphometric analysis of watersheds coupled with multi‐criteria decision making (MCDM) techniques is a widely used approach in identifying and prioritizing subwatersheds for flood risk assessment. Finding the appropriate weight for each morphometric parameter is one of the most important steps in MCDM methods. The present research focuses on analyzing the effect of using objective weighting methods in watershed prioritization in Daroungar Watershed in Northeast of Iran. To this aim, the weights of morphometric parameters were determined using six objective weighting methods and were used for ranking subwatersheds based on flood generation by a multi‐criteria model. Study results show that the highest weight in various methods belonged to different parameters. Comparison of flood susceptibility ranking maps indicated, except standard deviation method, there is a significant correlation among WM, preference selection index, criteria importance through intercriteria correlation, entropy, and method based on the removal effects of criteria methods; however, the distribution of flood susceptibility classes is not the same in the six weighting methods. The flood hazard ranking map using aggregation methods depicts that subwatersheds 6, 74, 27, and 67 which have high priority for flood hazard, have the same rank in all aggregation methods. Overall, in the present study, the importance of choosing the appropriate weighting method in prioritizing watersheds was emphasized.

Morphometric analysis of low mountains for mapping flash flood susceptibility in headwaters

Morphometric indices from high-resolution DEMs can contribute to the estimation of flash flood susceptibility in mountainous areas. We have screened 25 morphometric indices commonly used in literature, and based on a correlation matrix, selected those which showed the strongest relationship with flash flood generation: area (A), drainage texture (Rt), drainage density (Dd), elongation ratio (Re), form factor (Ff), lemniscate method (k), Gravelius coefficient (GC), forested area (Fa) and relief ratio (Rr). Among them Dd, Rt and Rr had a direct impact on flash flood generation, while A, Re, Fa, Ff, k and GC are in inverse relationship with the intensity of flash floods. Our summary map shows the prioritization of the watersheds on a scale of 0 to 9. The flash flood susceptibility ranking was empirically verified using hydrological data (20-year water regime obtained from 14 official stream gauges). Our conclusions only partially agree with former observations which may be explained by the particular lithology and morphology of the Mecsek Mountains. Since the lower sections of the watersheds are urbanized, for optimal watershed management more detailed GIS analyses of anthropogenic controls on flash flood hazard are needed in the future.

Tree assisted migration in a browsed landscape: Can we predict susceptibility to herbivores?

To promote the sustainability of forest ecosystems and maintain ecosystem services to human populations in the context of climate change, forest managers are considering several adaptation tools. One of those, assisted migration, consists of displacing tree species and/or populations to locations with suitable future climate conditions. Assisted migration plantations, however, could fail to produce viable forests under high herbivory pressure from mammalian herbivores. Thus, selecting species and genotypes with low susceptibility to herbivores could be a key condition for the recruitment of translocated seedlings. We developed an approach to predict susceptibility to mammalian herbivores, based on the seedlings’ chemical content (a proxy of phytochemical defence and susceptibility to herbivores). We used the approach on eight North American tree species of three climate analogues regions each (i.e. locations where the current climate is similar to the future climate at plantation site). We built chemical profiles and ranked species and climate analogue based on their potential susceptibility. To assess the reliability of our approach, we compared the chemical profiles to a systematic review of these species’ chemistry and of mammalian browsing throughout their native geographic range. For most species, our chemical profiles and browse susceptibility rankings were congruent with information available in the literature, both for phytochemical defence and for browsing. Two of the eight species (Pinus strobus and Thuja occidentalis) were more susceptible than predicted based on their chemical profile. These discrepancies could be linked to specific mammalian herbivores, that were unaffected by the phytochemical defence of these species. We observed a generally higher susceptibility of broadleaf species, which could be taken into account when devising adaptive silvicultural strategies. Furthermore, we propose the chemical profiling approach as a preliminary screening tool to identify species more resistant to mammalian herbivores, but also potentially to other herbivores and pathogens. Our chemical profile approach, based on the objective assessment of multivariate analyses results, could be replicated to compare the potential susceptibility of other species. This approach could be especially useful when contending with novel plant-herbivore relationships, such as forestry and conservation assisted migration or species invasion.

Assessment of steam turbine blade failure and damage mechanisms using a Bayesian network

Damage mechanisms that affect components within complex machines are often hard to detect and identify, especially if they are difficult to access, inspect and/or that are under continuous duty, compromising the reliability and performance of systems. In this paper, a Bayesian network model is developed to handle the interactions among common damage mechanisms and failure modes in nuclear steam turbine rotating blades. This model enables maintenance and inspection planning to better predict which portions(s) of the turbine will need repair. To compute the conditional probability tables, the model's unique quantification method combines expert judgement, the Recursive Noisy OR, and a damage mechanism susceptibility ranking that takes into account the synergistic interactions of the damage mechanisms. The approach can be suited to different turbine designs and purposes. The Bayesian network model development is described in detail, validated, and several examples of its application are presented.

Evaluating susceptibility of Ni-base alloys to solidification cracking by transverse-motion weldability test

The transverse-motion weldability (TMW) test, in which the lower sheet in lap welding is moved at a constant speed V in the transverse direction of welding to induce solidification cracking, was applied to Ni-base alloys. Alloys 600, 625, 718 and 800 were used as example materials for demonstration. The relative susceptibility ranking of the alloys was similar to those reported. A similar ranking was calculated based on |dT/d(fS )1/2| near (fS )1/2 = 1 (T: temperature; fS : fraction solid). Based on the transverse micrograph of the weld and V, the critical local strain rate near the crack was estimated. It was significantly higher for 718 than 800, consistent with the significantly lower susceptibility of 718 shown by the TMW test.

Resistance to Fusarium head blight in oats based on analyses of multiple field and greenhouse studies

Fusarium head blight (FHB) and the mycotoxins produced by its causal agents in oats (Avena sativa L.) have become a growing problem in northern countries over the last decades. The development of resistant cultivars would offer a highly needed and economical solution to the problem. To tackle the high genotype×environment interaction of FHB, a combined analysis was carried out on eight greenhouse and 13 field experiments inoculated with DON-producing Fusarium species. Our data included 406 oat genotypes consisting of Nordic cultivars, breeding lines and potentially resistant gene bank accessions. High variation in the DON accumulation estimates in the material shows that the selection of genotypes with better resistance would be valuable. The greenhouse and field studies resulted in significantly different oat genotype susceptibility rankings for both DON and Fusarium infected kernels. The results obtained from the field experiments have more practical relevance for farmers and breeders for the identification of DON resistant cultivars than greenhouse screenings. Days to maturity and the plant height of the genotypes both significantly affected the Fusarium infections and DON in the field. The relationship between Fusarium infected kernels, DONand germination capacity provide an insight into the composition of genotypes with resistance. The core set of 30 oat genotypes, which were phenotyped in several experiments, provides valuable examples of both highly susceptible and moderately resistant oat genotypes.

Using the surface free energy (SFE) method to investigate the effects of additives on moisture susceptibility of asphalt mixtures

Conventional methods for evaluating the effects of additives on moisture damage resistance of asphalt mixtures are either empirical or unable to quantify the contributions of material component properties to the overall mixture performance. To overcome these drawbacks, this study proposes a surface free energy (SFE) method to investigate the effects of various additives on moisture susceptibility of asphalt mixtures. One neat asphalt and one acidic gravel aggregate are selected as the test materials along with 6 commonly-used additives: a warm mix asphalt additive, two nano-materials, a hydrated lime, a Portland cement and a non-amine liquid asphalt anti-stripping agent. All the additives are blended with the neat asphalt to fabricate modified asphalt binders. The SFE components of these modified asphalt binders and the gravel aggregates are measured with the Wilhelmy plate method and the vapor adsorption method, respectively. An energy ratio, defined as the ratio of adhesion of asphalt-aggregate to that of asphalt-aggregate-water, is calculated and used to rank the asphalt mixtures that consist of gravel and asphalt binders modified with different additives in terms of their moisture susceptibility performance. In order to validate the proposed SFE method, two mixture moisture susceptibility tests, the modified boiling water test and the indirect tensile strength test, are conducted on loose and compacted asphalt mixtures, respectively. A consistent moisture susceptibility ranking is obtained from the SFE method and the mixture moisture susceptibility tests, which validates the SFE method proposed in this paper can be used to accurately quantify the effects of additives on the moisture susceptibility of asphalt mixtures.

Characterization of surface free energy of mineral filler by spreading pressure approach

Surface free energy of mineral filler plays an important role in evaluating the adhesion of asphalt mastic (mineral filler plus asphalt binder), which is usually measured through the capillary rise approach. However, this approach has been verified to hold only for the low energy materials, which does not apply to the high energy mineral filler. To overcome this limitation, the paper devises a new approach for measuring the surface free energy of the mineral filler based on a generalized Washburn equation. First, a reference liquid is selected to conduct the vapor adsorption test on the mineral filler to measuring its spreading pressure, in which a modified Brunauer-Emmett-Teller (BET) model is employed to determine the filler specific surface area. This reference liquid is again used to perform the capillary rise measurement to calculate the resultant effective capillary radius of the filler bed. Three independent liquids are subsequently selected to conduct the capillary rise test to measure their spreading pressure values with respect to the same mineral filler. By substituting the measured spreading pressure values of the three liquids into the Good-van Oss-Chaudhury (GvOC) equation, the surface free energy components of the mineral filler are finally determined. This newly developed approach is then successfully applied to measure the surface free energy for four typical types of the mineral filler. The moisture susceptibility rankings obtained from the energy ratios of the proposed approach are experimentally found to be consistence with those measured from a standard moisture susceptibility test for the corresponding asphalt mastics. In this regard, the proposed approach is believed to be capable of accurately characterizing the surface free energy of the mineral filler.

Comparison of test methods used to analyze stress corrosion cracking of differently tempered 7xxx alloys

This paper compares and critically analyzes various test methods used to assess stress corrosion cracking susceptibility of the alloy EN AW‐7075 (Al‐Zn‐Mg‐Cu) in various temper conditions. Constant load test in an alternating immersion environment was used as the standard reference test. Constant displacement tests in the form of U‐bend specimens and four‐point loaded bend specimens was conducted in a neutral and acidic salt‐spray fog test environment, an alternating salt‐spray fog environment and alternating immersion environment. A novel incremental step load test was also carried out, in a continuous immersion environment. It was observed that the susceptibility ranking from U‐bend test and the standard constant load test correlated well, while the ranking obtained by the 4‐point loaded bend test, showed lower correlation. The same susceptibility ranking was observed in all the test environments. It was shown that the neutral salt‐spray fog test environments could potentially substitute the alternating immersion test for testing SCC susceptibility. The T4 treated material showed maximum SCC susceptibility followed by T6 treated and the overaged T7 showed least susceptibility.

Foraminiferal Solubility Rankings: a Contribution To the Search For Consensus

Abstract Factors intrinsic to foraminiferal tests result in different degrees of susceptibility to dissolution. Differential resistance to dissolution among planktonic foraminifera has been studied in several regions, but no previous work has been reported for the western South Atlantic. The goal of this research was to develop a dissolution susceptibility ranking for planktonic foraminifera from the western South Atlantic Ocean, to compare the solubility between benthic and planktonic foraminifera, and to evaluate changes in the oxygen isotopic signal (δ18O) associated with dissolution. Two experiments were carried out by immersing tests in acetic acid or distilled water for 200 days. Our comparison revealed that tests of planktonic foraminifera were more resistant to dissolution than the benthic species tested, which has implications for use of the planktonic/benthic ratio (P/B) as a preservation proxy. Solubility of tests is directly proportional to the Mg content in the calcite structure, which varies widely across benthic taxa but is consistently low in planktonics. The δ18O increased during dissolution, probably due to the preferential dissolution of the internal chambers, making the remaining calcite progressively reflect the composition of the last chambers. Our solubility ranking for planktonic foraminifera agreed in part with rankings for foraminifera from other regions. Neogloboquadrina pachyderma and Globorotalia inflata proved to be resistant species; Globigerinella calida, Globigerinella siphonifera, Globorotalia hirsuta, Candeina nitida, and Trilobatus trilobus were moderately resistant; and Globorotalia fimbriata and Orbulina universa were most susceptible to dissolution. Presence and condition of benthic genera such as Quinqueloculina, Hoeglundina and Bulimina, and the planktonic species O. universa can be used to indicate limited dissolution in paleoceanographic studies. Small variations in the dissolution index may also reflect oceanographic changes that influence the composition of the tests, indicating the importance of regional solubility rankings, such as this study for the western South Atlantic.

Studies on Biology and Antibiosis Resistance in Mango (Mangiferae indica) Varieties Against Mango Mealy Bug, Drosicha mangiferae Green (Hemiptera: Margarodidae)

Abstract Mango is known as king of fruits. Among mango pests, mango mealy bug, Drosicha mangiferae (MMB), is considered one of the most destructive pests of mango orchards and other plantations. Whenever it enters in any orchards it is difficult to eradicate it from those orchards. The experiment was conducted at Entomological Research Sub Station, Multan-Punjab, Pakistan, during 2009 and 2010, to evaluate fitness of mango mealy bug on different varieties of mango and biology on ‘Chaunsa’ variety. Mango mealy bug, Drosicha mangiferae Green (Hemiptera: Coccoidea: Margarodidae), is matter of concern, as it is widespread pest of woody plants even in urban areas. A study was conducted on cultivar resistance and fecundity of mango mealy bug. The ‘Chaunsa’ cultivar of mango proved highly susceptible to mango mealy bug with maximum number of eggs laid, i.e. 335.90, and maximum weight, i.e. 0.239 g of the female, was recorded on the cultivar ‘Chaunsa’. The maximum length, i.e. 1.63 cm, and width, i.e. 0.80 cm of female, was observed on ‘Chaunsa’, which showed a susceptible response and did not differ significantly with the width of female on ‘Black Chaunsa’. Regarding biology, the 1st instar male and female duration on an average is 56.3 days, whereas the 2nd instar has 26 days. In case of the 3rd instar, female has duration 19.5 days and male has three days. Male has pupal stage, while it is absent in female. On an average two study years, the ranking of susceptibility of mango cultivars was as under: ‘Chaunsa’ > ‘Black Chaunsa’ > ‘Malda’ > ‘Fajri’ > ‘Retaul-12’ > ‘Langra’ > ‘Sensation’ > ‘Sindhri’ > ‘Dusehri’ > ‘Sufaid Chaunsa’ > ‘Anwar Reutul’ and > ‘Tukhmi’.

Study the HVAC system photodegradation caused by the low level UVC light irradiance used for coil maintenance and air stream disinfection

This paper studied the detrimental effects of low (50–750 µW/cm2) level ultraviolet C (UVC) irradiation used for coil maintenance and air stream disinfection on the surfaces of different HVAC materials and components. Photoreactors were initially used to study low level UVC photodegradation of materials with the highest UVC susceptibilities and demonstrated that the rates/mechanisms of surface damage are highly dependent on the material processing history as well as polymer structure. Due to the low levels of damage after months of exposure (UVC damage equal in magnitude to surface roughness of polished surfaces), the low level UVC photoreactor results described herein were unable to establish a mathematical relationship between UVC irradiation level and photodegradation rate, especially for the less susceptible materials. However, the results did indicate that the UVC susceptibility rankings were unaffected by UVC irradiation levels, which indicated that high UVC irradiation levels are suitable for shortening the test times required to obtain sufficient surface photodegradation to rank the UVC susceptibilities of polymers/materials used in HVAC systems. To make the UVC susceptibility testing suitable for nonlaboratory settings, a test cell fixture designed to house a single sample, a variable power UVC LED, and an optical photodegradation measuring device was constructed and evaluated. The ability to run each test cell at a different UVC level by simply adjusting the LED input power level allowed multiple samples to be run simultaneously under a wide range of UVC levels/environmental conditions.

Susceptibility of eucalyptus species and hybrids to the gall wasp Leptocybe invasa (Hymenoptera: Eulophidae) in northern Misiones, Argentina

Aim of study: To analyze the susceptibility of Eucalyptus and hybrids species to Leptocybe invasa through field assays.Area of study: The north of the Argentine province of Misiones (Colonia Delicia). Material and methods: A total of 11 Eucalyptus species and 2 hybrids were surveyed for damage and severity of L. invasa infestation. Six evaluations were made during an annual period.Main results: The susceptibility ranking to L. invasa from highest to lowest was E. tereticornis > E. propinqua > E. dunni > E. camaldulensis > E. grandis > E. major > E. longistrata >E. grandis × E. camaldulensis. However, E. moluccana, E. urophylla × E. grandis and E. urophylla were tolerant to L. invasa.Research highlights: This study suggests that in Misiones, E. tereticornis is the most sensible eucalyptus species to gall wasp attack, whereas other species and hybrids presented low damage levels or tolerance to L. invasa region.

<b>Glyphosate efficacy on sourgrass biotypes with suspected resistance collected in GR-crop fields

In Brazil, infestations of crop areas with glyphosate-resistant (GR) sourgrass ( Digitaria insularis (L.) Fedde) biotypes has risen significantly, increasing crop production costs. Glyphosate efficacy on three biotypes (GO, BA and MT) of sourgrass with suspected resistance was evaluated. A susceptible biotype (MG) was used as the control. The results confirmed that the MG and GO biotypes were susceptible to glyphosate (control > 90%). The MG biotype exhibited growth reduction and mortality by 50% (GR 50 and LD 50 , respectively) with mean glyphosate doses of 243.7 and 431.6 g ae ha -1 . The resistance index of the biotypes with suspected resistance ranged from 2.8 to 6.1 in relation to GR 50 and between 1.4 to 26.7 in relation to LD 50 . The glyphosate susceptibility ranking of the sourgrass biotypes was MG < GO < MT < BA. The MT and BA biotypes demonstrated high glyphosate resistance levels, and the GO biotype had a high potential to develop resistance. Farmers should avoid the application of glyphosate overdoses to minimize the selection pressure on weeds.

Evaluation of solidification cracking susceptibility in ERNiCr-3 (Filler Metal 82) weld metal using the cast pin tear test

A study has been conducted on the solidification cracking behavior of three heats of Filler Metal 82 (FM 82) which have only small differences in chemical composition but exhibit large differences in cracking susceptibility during production welding. The cast pin tear test (CPTT) was utilized to determine the solidification cracking response and relative susceptibility ranking of each heat. Additional CPTT work was conducted to determine the effect of dilution of a resistant heat by a susceptible heat. The solidification behavior was also evaluated using Thermo-Calc™ software to estimate the solidification temperature range fraction eutectic that forms at the end of solidification. Light optical microscopy (LOM), scanning electron microscopy (SEM), and fractography were performed to determine differences in microstructural features between a susceptible and resistant heat. CPTT results showed excellent correlation and repeatability relative to previous testing that had been conducted, and the susceptibility ranking confirmed the behavior observed during production welding. The dilution study showed that as little as 10% dilution of a resistant heat by a susceptible heat increased the cracking susceptibility significantly demonstrating not only the potency of the “bad” heat but also the sensitivity of the CPTT to small compositional changes. Thermodynamic calculations showed no direct correlation between solidification temperature range and solidification cracking susceptibility, suggesting that differences in cracking response may be attributed to the phenomenon of crack healing by liquid backfilling. Additionally, characterization techniques identified different levels of eutectic backfilling between “good” and bad” heats as well as a variation in precipitate morphology.

GIS-based evaluation of mining-induced subsidence susceptibility considering 3D multiple mine drifts and estimated mined panels

This paper presents a case study of subsidence hazard mapping in the vicinity of an abandoned coal mine within geographic information system (GIS) environment. A geospatial database was constructed using mine drift maps, topographic maps, land use maps, road maps, building maps, borehole data, and subsidence inventory maps showing occurrences of past subsidence events. Six raster-type factor layers (i.e., an influential area instability (IAI) layer calculated using multiple mine drifts and estimated mined panels, land use, distance from nearest railroad, distance from nearest road, and slope gradient) were generated and extracted from the database to identify relationships between past subsidence occurrences and the factors. Two IAI factors incorporate the complex effects of ground IAI and are calculated using the depths of each underground cavity and its angle of draw. A weight of evidence model was used to establish optimal correlations, expressed as contrast values (CVs) for subsidence inventory data, and inputs of all factors. Six CV layers (one for each factor) were linearly combined to generate a subsidence hazard map representing the relative vulnerability to subsidence in the study area. The area under the cumulative frequency diagram technique was then used to verify predicted subsidence hazards by comparing estimated susceptibility rankings over the entire range of grid cells with actual subsidence occurrences; the proposed GIS analysis model showed an accuracy of 91.09 % in the prediction of subsidence occurrences. Moreover, field surveys showed buildings with severe subsidence-related damage (damage level 4 or 5, according to the National Coal Board) in regions with very high subsidence hazard indices. Finally, a factor negatively correlated with subsidence prediction (slope angle) was determined from the sensitivity analysis.

Pathogenicity of Hymenoscyphus fraxineus towards leaves of three European ash species: Fraxinus excelsior, F. angustifolia and F. ornus

This study aimed to demonstrate the association of the ash dieback pathogen Hymenoscyphus fraxineus with leaf symptoms on Fraxinus excelsior and to test its pathogenicity towards leaves of three European ash species, F. excelsior, F. angustifolia and F. ornus, in wound inoculation experiments. On F. excelsior, H. fraxineus was isolated from 94% of leaf rachises with necrotic lesions and from 74% of necrotic leaflet midribs. Following wound inoculation of leaf rachises, in two separate experiments performed in 2010 and 2011, the ash dieback pathogen caused symptoms (necrotic rachis lesions, leaf wilting and premature leaf shedding) on all three ash species, while control leaves remained symptomless. Hymenoscyphus fraxineus was consistently reisolated from fungus‐inoculated rachises. All 10 isolates tested were pathogenic to the three ash species and varied in virulence. Koch's postulates for H. fraxineus as causal agent of leaf symptoms on F. excelsior were fulfilled in this study. Complemented with the isolation of the fungus from naturally infected, symptomatic leaf rachises of F. angustifolia and F. ornus in previous investigations, H. fraxineus was confirmed to be a leaf pathogen of these ash species as well. The leaf inoculation experiments showed that F. excelsior was highly susceptible to H. fraxineus, F. angustifolia was equally or slightly less susceptible, whereas F. ornus was the least affected species; however, F. ornus should also be regarded as a host tree for the ash dieback pathogen. This susceptibility ranking corresponds well with field observations and previous stem inoculation experiments.