Evaluation of two methods for assessing ascospore productivity of the apple scab pathogen, Venturia inaequalis

1981 ◽  
Vol 59 (6) ◽  
pp. 965-968
Author(s):  
C. C. Heye ◽  
J. H. Andrews ◽  
E. V. Nordheim
Keyword(s):  
Leaf Litter ◽  
Coefficient Of Variation ◽  
Unit Area ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Dry Weight ◽  
Weight Basis ◽  
Square Roots ◽  
Leaf Material ◽  
Normally Distributed

The standard water bubbler and a modified tower aspirator for quantifying ascospore productivity were compared. Samples, each consisting of 50 discs, were cut randomly from scab-infected McIntosh apple leaf litter in the spring and 18 samples were processed by each method. The square roots of hemocytometer counts adjusted for unit area or gram dry weight of leaf samples were found to be normally distributed. More spores were harvested from the same amount of leaf material with the bubbler than with the tower. The coefficient of variation for spore yields expressed on a per area or a per gram dry weight basis was smaller for the tower method than for the bubbler, although the values were not significantly different. Where detection of low ascospore productivity is not essential, the tower method is preferable in terms of ease, speed of operation, and the potential for electronic enumeration of harvested ascospores.

scholarly journals Comparative Studies on the Effect of Adjuvants with Urea to Reduce the Overwintering Inoculum of Venturia inaequalis

Plant Disease ◽  
2019 ◽  
Vol 103 (3) ◽  
pp. 531-537 ◽  
Author(s):  
Janna Beckerman ◽  
Chelsi Abbott
Keyword(s):  
Leaf Litter ◽  
Litter Decomposition ◽  
Comparative Studies ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Organic Surfactant ◽  
Comparable Performance ◽  
Improved Sanitation ◽  
Litter Degradation ◽  
Ascospore Production

A 2-year study on the use of organic and conventional adjuvants alone, or mixed with urea, was conducted for management of overwintering inoculum of the apple scab pathogen, Venturia inaequalis. Select adjuvants (LI 700, Bond Max, Latron B-1956, and Organic Wet Betty [OWB]) have the potential to hasten urea-driven leaf litter decomposition and reduce V. inaequalis overwintering inoculum comparable to urea, and that one organic surfactant could perform the same level of leaf decomposition as urea. Combinations of adjuvants with urea significantly improved leaf litter degradation compared with urea alone, concomitant with reducing the number of pseudothecia present and pseudothecium fertility. We demonstrate that the combination of urea with Bond Max or OWB reduced pseudothecia fertility and ascospore production to less than 5% in the remaining pseudothecia, a significantly greater reduction than with urea alone. These results suggest that conventional growers combine urea with Bond Max or OWB to more effectively reduce overwintering inoculum, and that the adjuvant OWB can provide organic growers with comparable performance to urea used in conventional orchards for improved sanitation.

scholarly journals A New Phytosanitary Method to Reduce the Ascospore Potential of Venturia inaequalis

Plant Disease ◽  
2017 ◽  
Vol 101 (3) ◽  
pp. 414-420 ◽  
Author(s):  
Franziska M. Porsche ◽  
Barbara Pfeiffer ◽  
Andreas Kollar
Keyword(s):  
Leaf Litter ◽  
Yeast Extract ◽  
Untreated Control ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Nutrient Media ◽  
Apple Leaves ◽  
Litter Decay ◽  
Ascospore Discharge ◽  
Infection Pressure

Ascospores of Venturia inaequalis, released from pseudothecia in overwintered, infected apple leaves, serve as the primary inoculum for apple scab. In this study, we tested a new sanitation strategy to reduce ascospore inoculum under orchard conditions over three overwintering periods. After leaf fall, nutrient media containing different concentrations of degraded casein or a yeast extract from Saccharomyces cerivisiae were applied to leaf litter infected with apple scab. The application of 30 and 60% yeast extract showed the greatest efficacy, and significantly reduced ascospore discharge by 99% (P < 0.01) in 2013 and 2014. The efficacy of the treatments did not differ from treatment with 5% urea (P > 0.05). Leaf litter decay was accelerated in the plots treated with yeast extract compared with untreated control plots. Moreover, apple leaves treated with yeast extract had completely decayed due to earthworm activity before ascospore maturity. In comparison, up to 26% of the leaves in untreated control plots had not decayed. These results suggest that the treatment of leaf litter with yeast extract can almost completely eliminate apple scab inoculum in the course of the whole primary season. These sanitation practices may be beneficial for both organic and conventional cultivation. The reduced infection pressure may allow growers the usage of fungicides with lower efficacy or to reduce the number of applications needed to manage apple scab in spring.

Development of Milk Powder Reference Materials BCR-CRM 187,188. Part I. Preparation, Homogeneity, and Stability

1990 ◽  
Vol 73 (5) ◽  
pp. 773-776
Author(s):  
Jan K Quirijns ◽  
Kees G Van Der Paauw ◽  
Ed J Mulders ◽  
Bernard Griepink
Keyword(s):  
Reference Materials ◽  
Coefficient Of Variation ◽  
Milk Powder ◽  
Dry Weight ◽  
Weight Basis ◽  
Heptachlor Epoxide ◽  
Hch Isomers ◽  
Stability Data ◽  
The Mean ◽  
Natural Milk

Abstract Two milk powders were prepared and tested as reference materials for 9 organochlorlne pesticides and metabolites: hexachlorobenzene, HCH Isomers (a-HCH, jS-HCH, 7-HCH), 0-heptachlor epoxide, dleidrin, endrln, p.p'-DDE, and p,pf- DDT. The reference materials, a natural milk powder (CRM 187) and a spiked milk powder (CRM 188), contain the analytes at concentrations of 1.5 to 69 /ig/kg on a dry weight basis. Preparation and testing for homogeneity and stability of the powders are discussed. The mean coefficient of variation In the homogeneity tests was about 4.5%, which indicates that the homogeneity of the samples Is very good. Stability data over 12 months do not show any trend that suggests lack of stability

Persistence of seed produced from single seed crops of subterranean clover on sandy soils near Esperance, Western Australia

1987 ◽  
Vol 27 (1) ◽  
pp. 81 ◽  
Author(s):  
MDA Bolland ◽  
WJ Collins
Keyword(s):  
Unit Area ◽  
Sandy Soils ◽  
Subterranean Clover ◽  
Dry Weight ◽  
Weight Basis ◽  
Single Strain ◽  
Single Seed ◽  
Second Year ◽  
Seed Crops ◽  
Number Of Seeds

The number and weight of seeds per unit area, and weight per seed were measured for single seed crops of 6 subterranean clover cultivars grown as dense single strain swards on sandy soil near Esperance, W.A. In the sowing year, weight and number of seeds and weight per seed varied with cultivar and year of sowing. In the regeneration years, weight of seed decreased by about 60% between the first and the second year (range 50-75%, depending on cultivar and year of sowing), by a further 27% between years 2 and 3 (range 20-3g%), and a further 3.2% between years 3 and 4 (range 1.7-5.0%). The relative decrease in numbers of seed per unit area, to year 4, followed almost identical trends. Individual seed weight was constant for each cultivar sown in the same year, with the exception of 1 experiment sown in 1982 when seed collected in the next 2 regeneration years was 1.1-1.4 times as heavy as seed produced in the sowing year. In the sowing year, seed collected about 1 week after the clover had dried off contained less than 4% moisture (dry weight basis) and most of the seed were impermeable (hardseeded).

Constituents from Morus root bark against Venturia inaequalis – the causal agent of apple scab

Planta Medica ◽  
2007 ◽  
Vol 73 (09) ◽  
Author(s):  
JM Rollinger ◽  
R Spitaler ◽  
M Menz ◽  
P Schneider ◽  
EP Ellmerer ◽  
...  
Keyword(s):  
Venturia Inaequalis ◽  
Apple Scab ◽  
Causal Agent ◽  
Root Bark

ERRORS ASSOCIATED WITH HERBAGE DISSECTION ANALYSES 2. Problems of species identification

1976 ◽  
pp. 213-225
Author(s):  
I.M. Ritchie ◽  
C.C. Boswell ◽  
A.M. Badland
Keyword(s):  
New Zealand ◽  
Dry Weight ◽  
Analytical Tool ◽  
Species Level ◽  
Weight Basis ◽  
Plant Identification ◽  
Leaf Fragment ◽  
Research Division ◽  
Or Groups ◽  
Botanical Analysis

HERBACE DISSECTION is the process in which samples of herbage cut from trials are separated by hand into component species. Heavy reliance is placed on herbage dissection as an analytical tool ,in New Zealand, and in the four botanical analysis laboratories in the Research Division of the Ministry of Agriculture and Fisheries about 20 000 samples are analysed each year. In the laboratory a representative subsample is taken by a rigorous quartering procedure until approximately 400 pieces of herbage remain. Each leaf fragment is then identified to species level or groups of these as appropriate. The fractions are then dried and the composition calculated on a percentage dry weight basis. The accuracy of the analyses of these laboratories has been monitored by a system of interchanging herbage dissection samples between them. From this, the need to separate subsampling errors from problems of plant identification was, appreciated and some of this work is described here.

Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments of the Brisbane River (Australia) – Preliminary Results

1989 ◽  
Vol 21 (2) ◽  
pp. 161-165 ◽  
Author(s):  
S. I. Kayal ◽  
D. W. Connell
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
River Estuary ◽  
Dry Weight ◽  
Weight Basis ◽  
Sediment Samples ◽  
Preliminary Results ◽  
Treated Sewage ◽  
Polycyclic Aromatic ◽  
Petroleum Refineries

Results of the analysis of twenty-three composite sediment samples revealed that PAHs are widely distributed in the Brisbane River estuary. Mean concentrations for individual compounds, on a dry weight basis, ranged from 0.03 µg/g for dibenz [ah] anthracene to 2.34 µg/g for fluoranthene. Observed PAH assemblages were rich in compounds having pyrolytic origins. However, the presence of petroleum derived compounds was indicative of the importance of petroleum as a PAH source in the estuary. Petroleum refineries, a coal loading terminal and a major treated sewage outfall located at the mouth were not indicated as major contributing sources of PAH pollution in the estuary.

Mineral nutrition, dinitrogen fixation, and growth of Alnuscrispa and Alnusglutinosa

1985 ◽  
Vol 15 (5) ◽  
pp. 855-861 ◽  
Author(s):  
G. Prégent ◽  
C. Camiré
Keyword(s):  
Mineral Nutrition ◽  
Dry Weight ◽  
Optimal Growth ◽  
Maximum Growth ◽  
Dinitrogen Fixation ◽  
Weight Basis ◽  
Critical Levels ◽  
N Status

Invitro cultures of Alnuscrispa (Ait.) Pursh and Alnusglutinosa (L.) Gaertn. were used to estimate critical foliage levels of selected nutrients for optimal growth and dinitrogen (N2) fixation. For A. crispa to obtain 90% of maximum growth and N2 fixation, foliar levels of 0.12% P, 0.13% Mg, <0.31% K, and <0.04% Ca on a dry weight basis were needed. For A. glutinosa, the critical levels were 0.138% P, 0.10% Mg, 0.29% Ca, and ~0.20% K. From all the deficiencies observed, P had the more pronounced effects on N status of both species.

scholarly journals Functional ecology of the biological soil crust in semiarid SE Spain: sun and shade populations of Diploschistes diacapsis (Ach.) Lumbsch.

2005 ◽  
Vol 37 (5) ◽  
pp. 425-432 ◽  
Author(s):  
Ana PINTADO ◽  
Leopoldo G. SANCHO ◽  
T. G. Allan GREEN ◽  
José Manuel BLANQUER ◽  
Roberto LÁZARO
Keyword(s):  
Water Content ◽  
Chlorophyll Content ◽  
Unit Area ◽  
Biological Soil Crust ◽  
Dry Weight ◽  
Mean Annual Precipitation ◽  
Plant Colonization ◽  
Soil Crust ◽  
Active Time ◽  
Exposed Population

The Tabernas badlands in semiarid south-east Spain is one of the driest regions in Europe with a mean annual precipitation of c. 240 mm. The landscape is deeply dissected, with canyons, ramblas and sparsely vegetated eroded badland slopes. The vegetation is predominantly a biological soil crust consisting of different types of lichen-rich communities, one of the more conspicuous being dominated by Diploschistes diacapsis (Ach.) Lumbsch. This lichen is mainly restricted to the north- facing slopes, where it forms extensive whitish carpets and probably plays an important role in preventing erosion of the slopes and allowing plant colonization. South-facing slopes are much more eroded and generally lack vegetation. %The photosynthetic performance of north (shade) and south-facing (sun) populations of D. diacapsis was studied to determine if these different populations showed any adaptations to the microclimatic conditions of their individual habitats. The response of CO2 exchange to light intensity, temperature and water content was measured under controlled conditions in the laboratory. Dry weight-based net photosynthetic rates were higher in the southern-exposed population but quantum efficiency, and light compensation points were similar. Thallus weight per unit area (LMA) was considerably higher for shade specimens but maximum water content and optimal water content were very similar and chlorophyll content on a dry weight basis was also similar. Chlorophyll content on an area basis was higher in the northern-exposed population and always much larger than those reported in other studies on the same species (up to 8 times larger) with the result that NP values on a chlorophyll basis were relatively low. The larger LMA meant that shade thalli stored more water per unit area which should ensure longer active periods than sun thalli. The results support a strategy pair of high NP and short active time versus low NP and long active time, both having been reported for other soil crust species. However, the visibly larger biomass of the shade D. diacapsis suggests that the lichen is at the limit of its adaptability in these habitats.

scholarly journals Apple Autotetraploids with Enhanced Resistance to Apple Scab (Venturia inaequalis) Due to Genome Duplication-Phenotypic and Genetic Evaluation

2021 ◽  
Vol 22 (2) ◽  
pp. 527
Author(s):  
Małgorzata Podwyszyńska ◽  
Monika Markiewicz ◽  
Agata Broniarek-Niemiec ◽  
Bożena Matysiak ◽  
Agnieszka Marasek-Ciolakowska
Keyword(s):  
Venturia Inaequalis ◽  
Leaf Shape ◽  
Apple Scab ◽  
Early Period ◽  
Physiological Parameters ◽  
Aflp Analysis ◽  
Poor Growth ◽  
Enhanced Resistance ◽  
Apple Cultivars ◽  
Old Trees

Among the fungal diseases of apple trees, serious yield losses are due to an apple scab caused by Venturia inaequalis. Protection against this disease is based mainly on chemical treatments, which are currently very limited. Therefore, it is extremely important to introduce cultivars with reduced susceptibility to this pathogen. One of the important sources of variability for breeding is the process of polyploidization. Newly obtained polyploids may acquire new features, including increased resistance to diseases. In our earlier studies, numerous tetraploids have been obtained for several apple cultivars with ‘Free Redstar’ tetraploids manifesting enhanced resistance to apple scab. In the present study, tetraploids of ‘Free Redstar’ were assessed in terms of phenotype and genotype with particular emphasis on the genetic background of their increased resistance to apple scab. Compared to diploid plants, tetraploids (own-rooted plants) were characterized with poor growth, especially during first growing season. They had considerably shorter shoots, fewer branches, smaller stem diameter, and reshaped leaves. In contrast to own-rooted plants, in M9-grafted three-year old trees, no significant differences between diplo- and tetraploids were observed, either in morphological or physiological parameters, with the exceptions of the increased leaf thickness and chlorophyll content recorded in tetraploids. Significant differences between sibling tetraploid clones were recorded, particularly in leaf shape and some physiological parameters. The amplified fragment length polymorphism (AFLP) analysis confirmed genetic polymorphism of tetraploid clones. Methylation-sensitive amplification polymorphism (MSAP) analysis showed that the level of DNA methylation was twice as high in young tetraploid plants as in a diploid donor tree, which may explain the weaker vigour of neotetraploids in the early period of their growth in the juvenile phase. Molecular analysis showed that ‘Free Redstar’ cultivar and their tetraploids bear six Rvi genes (Rvi5, Rvi6, Rvi8, Rvi11, Rvi14 and Rvi17). Transcriptome analysis confirmed enhanced resistance to apple scab of ‘Free Redstar’ tetraploids since the expression levels of genes related to resistance were strongly enhanced in tetraploids compared to their diploid counterparts.

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