scholarly journals Patterns and severity of crown dieback in young even-aged stands of european ash (Fraxinus excelsior L.) in relation to stand density, bud flushing phenotype, and season

2013 ◽  
Vol 49 (No. 3) ◽  
pp. 120-126 ◽  
Author(s):  
R. Bakys ◽  
R. Vasaitis ◽  
J.P. Skovsgaard
Keyword(s):  
Disease Severity ◽  
Seasonal Pattern ◽  
Stand Density ◽  
Growing Season ◽  
Fraxinus Excelsior ◽  
Tree Crown ◽  
Ecological Features ◽  
Bud Flushing ◽  
Crown Dieback ◽  
European Ash

The extent and temporal pattern of crown damage (attributed to Hymenoscyphus pseudoalbidus) in even-aged stands of Fraxinus excelsior in relation to bud flushing phenotype, stand density, and season was investigated. Data were collected in 2007 in four statistically designed thinning experiments located in 12–15-years old plantations of ash in Denmark. The study included 21 plots of four contrasting, residual stand densities: (1) 1700–5500 trees/ha (unthinned control plots), (2) 1500 trees/ha, (3) 500 trees/ha, and (4) 100–150 trees/ha. Assessments included estimation of flushing phenotype in May, followed by evaluation of severity of crown damage (percentage of crown killed) in June and September. Simultaneously, for each tree, the presence or absence of crown wilt and dead tops were recorded. The seasonal pattern of disease severity (average crown damage) was similar in all stands, and disregarding stand density the extent of tree crown damage increased significantly towards the end of the growing season (P < 0.005). Disease severity was the worst in unthinned plots, but otherwise unrelated to stand density. Late-flushing trees were most severely affected (P < 0.001). The observed patterns of disease severity are probably associated with ecological features of the pathogen that still remain largely unknown.  

The epidemiology of common root rot in Manitou wheat: disease progression during the growing season

1974 ◽  
Vol 52 (7) ◽  
pp. 1757-1764 ◽  
Author(s):  
P. R. Verma ◽  
R. A. A. Morrall ◽  
R. D. Tinline
Keyword(s):  
Triticum Aestivum ◽  
Disease Severity ◽  
Plant Development ◽  
Root Rot ◽  
Growing Season ◽  
Cochliobolus Sativus ◽  
Infection Rates ◽  
Common Root ◽  
Common Root Rot ◽  
Disease Rating

Common root rot in Triticum aestivum cultivar Manitou caused primarily by Cochliobolus sativus was followed during plant development in 1969, 1970, and 1971 at Matador, Saskatchewan. Plants were sampled at intervals, and three variables based mainly on the occurrence of lesions on subcrown internodes were studied: number of diseased plants per square meter; percentage of diseased plants; and disease rating which integrated percentage of diseased plants and disease severity on each plant. All variables increased with time, and the progression curves in all 3 years were hyperbolic, indicating that the increases were like those of a simple interest disease as described by Van der Plank. In two of the years, almost 100% of the plants were diseased considerably before the end of the season. The transformation proposed by Van der Plank for simple interest diseases, log10[1/(1 − x)], was applied to the percentages of diseased plants, and regressions were calculated. The slopes of these lines (infection rates) were as follows: 1969, 0.99% plants per day; 1970, 1.32%; and 1971, 1.96%. In 1969 the onset of disease was later than in 1970 and 1971, and there was correspondingly less disease at the end of the growing season.

scholarly journals Moisture-Dependent Strength Properties of Thermally-Modified Fraxinus excelsior Wood in Compression

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1647 ◽  
Author(s):  
Edward Roszyk ◽  
Elżbieta Stachowska ◽  
Jerzy Majka ◽  
Przemysław Mania ◽  
Magdalena Broda
Keyword(s):  
Moisture Content ◽  
Strength Properties ◽  
Treatment Temperature ◽  
Thermal Modification ◽  
Fraxinus Excelsior ◽  
Mechanical Parameters ◽  
Saturation Point ◽  
Wood Moisture ◽  
Intrinsic Anisotropy ◽  
European Ash

European ash (Fraxinus excelsior L.) is one of the species commonly used for wood thermal modification that improves its performance. The presented research aimed to investigate a moisture-dependent strength anisotropy of thermally-modified European ash in compression. Wood samples were modified at 180 °C and 200 °C. Their mechanical parameters were determined in the principal anatomical directions under dry (moisture content of 3%) and wet (moisture content above fibre saturation point) conditions. Effect of heat treatment temperature and moisture content on the ash wood mechanical parameters concerning each anatomical direction were determined. The results show that thermal treatment kept the intrinsic anisotropy of wood mechanical properties. It decreased wood hygroscopicity, which resulted in improved strength and elasticity measured for wet wood when compared to untreated and treated samples. Higher treatment temperature (200 °C) increased wood elasticity in compression in all the anatomical directions despite wood moisture content during the measurements. Multivariate analysis revealed that the modification temperature significantly affected the modulus of elasticity perpendicular to the grain, while in the case of compression strength, the statistically significant effect was observed only parallel to the grain. The results obtained can be useful from an industrial perspective and can serve as part of a database for further modelling purposes.

scholarly journals Estimation of Gross Primary Productivity (GPP) Phenology of a Short-Rotation Plantation Using Remotely Sensed Indices Derived from Sentinel-2 Images

2020 ◽  
Vol 12 (13) ◽  
pp. 2104
Author(s):  
Maral Maleki ◽  
Nicola Arriga ◽  
José Miguel Barrios ◽  
Sebastian Wieneke ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Seasonal Pattern ◽  
Vegetation Indices ◽  
Canopy Structure ◽  
Growing Season ◽  
Gross Primary Productivity ◽  
Imaging Spectrometer ◽  
Short Rotation ◽  
Medium Resolution ◽  
Sentinel 2

This study aimed to understand which vegetation indices (VIs) are an ideal proxy for describing phenology and interannual variability of Gross Primary Productivity (GPP) in short-rotation coppice (SRC) plantations. Canopy structure- and chlorophyll-sensitive VIs derived from Sentinel-2 images were used to estimate the start and end of the growing season (SOS and EOS, respectively) during the period 2016–2018, for an SRC poplar (Populus spp.) plantation in Lochristi (Belgium). Three different filtering methods (Savitzky–Golay (SavGol), polynomial (Polyfit) and Harmonic Analysis of Time Series (HANTS)) and five SOS- and EOS threshold methods (first derivative function, 10% and 20% percentages and 10% and 20% percentiles) were applied to identify the optimal methods for the determination of phenophases. Our results showed that the MEdium Resolution Imaging Spectrometer (MERIS) Terrestrial Chlorophyll Index (MTCI) had the best fit with GPP phenology, as derived from eddy covariance measurements, in identifying SOS- and EOS-dates. For SOS, the performance was only slightly better than for several other indices, whereas for EOS, MTCI performed markedly better. The relationship between SOS/EOS derived from GPP and VIs varied interannually. MTCI described best the seasonal pattern of the SRC plantation’s GPP (R2 = 0.52 when combining all three years). However, during the extreme dry year 2018, the Chlorophyll Red Edge Index performed slightly better in reproducing growing season GPP variability than MTCI (R2 = 0.59; R2 = 0.49, respectively). Regarding smoothing functions, Polyfit and HANTS methods showed the best (and very similar) performances. We further found that defining SOS as the date at which the 10% or 20% percentile occurred, yielded the best agreement between the VIs and the GPP; while for EOS the dates of the 10% percentile threshold came out as the best.

Gigantism in tadpoles of the Neogene frogPalaeobatrachus

Paleobiology ◽  
2006 ◽  
Vol 32 (4) ◽  
pp. 666-675 ◽  
Author(s):  
Zbyněk Roček ◽  
Ronald Böttcher ◽  
Richard Wassersug
Keyword(s):  
Thyroid Gland ◽  
Environmental Factors ◽  
Growing Season ◽  
Tropical Species ◽  
Large Size ◽  
Ecological Features ◽  
Pathological Conditions ◽  
Seasonal Ponds ◽  
Pond Size ◽  
Pseudis Paradoxa

We describe three giant palaeobatrachid fossil tadpoles of the genusPalaeobatrachus(Nieuwkoop-Faber [NF] stages 60–64) from the Miocene of Randecker Maar, Germany. The largest was 150 mm at the beginning of metamorphosis (stage 60), whereas the smallest was 100 mm and approaching the end of metamorphosis (stage 64). In contrast, normal palaeobatrachid tadpoles and their pipid relatives, both extinct and extant, rarely exceed 60 mm in length. We review here both ecological and pathological conditions that are conducive to the development of gigantism in tadpoles. Tadpoles that lack a thyroid gland become exceptionally large and arrest development at early hindlimb stages (NF stages 53–56). However, the advanced metamorphic stages of the giantPalaeobatrachustadpoles indicate that they were able to metamorphose, and thus were not athyroid. Environmental factors—pond size and permanence, predators, duration of the growing season—may all contribute to tadpole gigantism in certain extant anuran species. We identify suites of ecological features that distinguish extant anurans with large tadpoles from high-latitude and high-altitude permanent lakes in temperate regions (e.g., certainRanaandTelmatobius) from tropical species, such asPseudis paradoxa, whose tadpoles normally achieve large size in temporary seasonal ponds. The paleoecology of Randecker Maar suggests thatPalaeobatrachustadpoles lived in a permanent semitropical lake, but one with few predators.

scholarly journals Landscape-scale assessment of tree crown dieback following extreme drought and heat in a Mediterranean eucalypt forest ecosystem

2012 ◽  
Vol 28 (1) ◽  
pp. 69-80 ◽  
Author(s):  
Niels Brouwers ◽  
George Matusick ◽  
Katinka Ruthrof ◽  
Thomas Lyons ◽  
Giles Hardy
Keyword(s):  
Forest Ecosystem ◽  
Landscape Scale ◽  
Extreme Drought ◽  
Tree Crown ◽  
Eucalypt Forest ◽  
Scale Assessment ◽  
Crown Dieback

scholarly journals Rising out of the ashes: additive genetic variation for susceptibility to Hymenoscyphus fraxineus in Fraxinus excelsior

2015 ◽  
Author(s):  
F. Muñoz ◽  
B. Marçais ◽  
J. Dufour ◽  
A. Dowkiw
Keyword(s):  
Genetic Variation ◽  
Fraxinus Excelsior ◽  
Narrow Sense ◽  
Narrow Sense Heritability ◽  
Ash Dieback ◽  
Family Effects ◽  
Hymenoscyphus Fraxineus ◽  
Natural Range ◽  
Spatio Temporal ◽  
Crown Dieback

AbstractSince the early 1990s, ash dieback due to the invasive ascomycete Hymenoscyphus fraxineus is threatening Fraxinus excelsior in most of its natural range. Previous studies reported significant levels of genetic variability for susceptibility in F. excelsior either in field or inoculation experiments. The present study was based on a field experiment planted in 1995, fifteen years before onset of the disease. Crown and collar status were monitored on 788 trees from 23 open-pollinated progenies originating from 3 French provenances. Susceptibility was modeled using a Bayesian approach where spatio-temporal effects were explicitly taken into account. Moderate narrow-sense heritability was found for Crown Dieback (CD, h2=0.42). This study is first to show that Collar Lesions are also heritable (h2=0.49 for prevalence and h2=0.42 for severity) and that there is significant genetic correlation (r=0.40) between the severities of both symptoms. There was no evidence for differences between Provenances. Family effects were detected, but computing Individual Breeding Values (IBV) showed that most of the genetic variation lies within families. In agreement with previous reports, early flushing correlates with better crown status. Consequences of these results in terms of management and breeding are discussed.

scholarly journals Fungicides against diseases of lawn grass leaves

2019 ◽  
pp. 7-9
Author(s):  
S. Retman ◽  
O. Nychyporuk ◽  
О. Shevchuk
Keyword(s):  
Powdery Mildew ◽  
Technical Efficiency ◽  
Disease Severity ◽  
Growing Season ◽  
Disease Spread ◽  
Septoria Leaf Blotch ◽  
Leaf Blotch ◽  
Chemical Groups ◽  
Positive Effect

Goal. To evaluate the effectiveness of the use of fungicides of various chemical groups against the leaf diseases turfgrass. Methods. The research was carried out in 2015—2017 on the lawn mixture «Universal» in the zone of the Polissya of Ukraine. The effect of fungicides of various chemical groups was investigated (Impact T, SC; Bumper Super, EC; Amistar Extra 280 SC, SC; Alto Super 300 EC, EC; Maxim 025 FS, FS; Horus 75 WG, WG). Fungicides were applied twice. The first spraying was carried out when development of diseases in control plot reached 3—5%, the second — in 30 days. The assessments were performed according to generally accepted methods, disease spread, disease severity and technical efficiency of pesticides were determined. Results. During the period of research, the most common leaf diseases of turfgrass, which eveloped annually and had a significant severity during the growing season, were powdery mildew and septoria leaf blotch. After two-time spraying, the technical efficiency of fungicides against powdery mildew reached 82.2—92.2%, against septoria leaf blotch up to 80.2%. The most effective against powdery mildew was the use of Alto Super 330 EC, EC (0.5 l / ha), Amistar Extra 280 SC, SC (0.75 l / ha) and tank mixture of Maxim 025 FS, FS (0.75 l / ha and 1.0 l / ha) with Horus 75 WG, VH (0.6 kg / ha). Against the septoria leaf blotch, the highest efficiency was shown by Alto Super 330 EC, EC (0.5 l / ha), Bumper Super, EC (0.8 l / ha) and Maxim 025 FS, FS (1.0 l / ha) + Horus 75 WG, WG (0.6 kg / ha). In addition, due to the reduction of disease severity, a positive effect of fungicides on the quality of the lawn was achieved and the projective coating increased to 92—93%. Conclusion. The use of fungicides contributes to the reduction of disease and the formation of quality herbs. The best indicators against flour dew and septoriosis of leaves were obtained for the treatment of Alto Super 330 EC, CE (0.5 l / ha) and tank Maxim 025 FS, tc.s. (1.0 l / ha) + Horus 75 WG, VH (0.6 kg / ha).

scholarly journals Investigations on the dormancy of Fraxinus excelsior L. buds II. Bud dormancy on shoots in various parts of the tree crown

2015 ◽  
Vol 43 (3) ◽  
pp. 421-426 ◽  
Author(s):  
L. Witkowska-Żuk ◽  
W. Kozłowska
Keyword(s):  
Water Bath ◽  
Fraxinus Excelsior ◽  
Bud Dormancy ◽  
Warm Water ◽  
Tree Crown ◽  
Breaking Dormancy ◽  
Lateral Shoots ◽  
Terminal Buds

The course of the particular phases of dormancy of terminal buds from various parts of the tree crown of 12-year-old <i>Fraxinus excelsior</i> trees was investigated. The following treatments breaking dormancy were applied: defoliation, a warm water bath and chilling. Significant differences in the depth of bud dormancy between the main and lateral shoots were noted only in the period of correlated inhibition. No differences could be found either in the course of rest and imposed dormancy or in the process of their receding.

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