REGULATION OF PRIMARY INOCULUM DENSITY OF APPLE SCAB PATHOGEN BASED ON THE USE OF MICROBIOLOGICAL PREPARATIONS

2018 ◽  
Vol 17 ◽  
pp. 136-145
Author(s):  
G.V. Yakuba ◽  
◽  
D.O. Morozov ◽  
R.G. Ivanov ◽  
◽  
...  
Keyword(s):  
Apple Scab ◽  
Inoculum Density ◽  
Primary Inoculum

scholarly journals Temporal and Spatial Dynamics of Primary and Secondary Infection by Armillaria ostoyae in a Pinus pinaster Plantation

2004 ◽  
Vol 94 (2) ◽  
pp. 125-131 ◽  
Author(s):  
Brigitte Lung-Escarmant ◽  
Dominique Guyon
Keyword(s):  
Pinus Pinaster ◽  
Secondary Infection ◽  
Spatial Dynamics ◽  
Spatial Relation ◽  
Gompertz Model ◽  
Inoculum Density ◽  
Initial Inoculum ◽  
Primary Inoculum ◽  
Armillaria Ostoyae ◽  
Epidemic Development

Epidemiological investigations were performed in a 3-ha maritime pine (Pinus pinaster) plantation established on a site heavily infested by Armillaria ostoyae. Geostatistics were used to examine the density and the distribution of the initial inoculum. Disease dynamics were monitored for 17 years after planting. On the whole site, the cumulative mortality rate reached 35% over this period, plateauing at 12 years. Disease progress curves differed according to the density of the initial inoculum, although in all the cases, the Gompertz model described the epidemics well. The epidemiological contributions of both primary (initially colonized stumps) and secondary inoculum (newly dead pines) were evaluated by analyzing their spatial relation to annual mortality. Newly dead pines acted as secondary inoculum from year 3 and their role increased with time. When the initial inoculum density was low, the contribution of secondary inoculum to epidemic development increased faster and halted sooner than when the density of primary inoculum was high. Regardless of its density, the primary inoculum acted throughout the dynamic phase of the epidemic. When the inoculum density was low, the probability of mortality during the first 6 years of the epidemic depended on the tree distance from the nearest stumps colonized by Armillaria sp. When the inoculum density was high, the probability of mortality was higher and not related to the distance between trees and colonized stumps.

scholarly journals Comparative Study of Dutch and Hungarian Environmentally-friendly Apple Orchards on Potential Ascospore Dose of Apple Scab

2002 ◽  
pp. 31-36
Author(s):  
Imre Holb ◽  
Bart Heijne
Keyword(s):  
Apple Scab ◽  
Environmentally Friendly ◽  
Apple Orchard ◽  
Bud Break ◽  
Apple Orchards ◽  
Primary Inoculum ◽  
Medium Level ◽  
Very High ◽  
Epidemic Risk ◽  
Organic Orchards

In a 2-year study, Dutch and Hungarian environmentally-friendly apple orchards were compared as regards the amount of apple scab primary inoculum. The PAD (potential ascospore dose) method was used to quantify the potential amount of primary inoculum (ascospores) per m2 orchard floor. Applying this method, the number of lesions per m2 of leaf in the autumn (LD), the proportion of the orchard floor covered by leaf litter at bud break (LLD) and potential ascospore dose (PAD) were determined. In autumn, LD values ranged between 2.2 and 13.5 in the integrated orchards, while in the organic orchards the values were between 42.5 and 106.2, with especially high values in the Dutch organic orchard. LLD values ranged between 24 and 43% at bud break in both countries. PAD values were 10-60 times higher than those of the integrated orchards. The PAD values were between 673 and 4275 ascospore/m2 orchard floor in the integrated orchards, while in the organic orchards these values were 37102 and 52390 ascospore/m2 orchard floor, respectively. On the basis of the recorded primary inoculum quantity, the Dutch integrated apple orchard is considered to be excellently protected, while the Hungarian orchard has a medium level of protection. However, both countries’ organic orchards can be regarded overall as being very poorly protected. Accordingly, in the integrated orchards the predicted epidemic risk is low or medium, while in the organic orchards it is very high on the basis of PAD values.

scholarly journals Potential of Propane Flamers for Reduction of Apple Scab Primary Inoculum on Orchard Ground

HortScience ◽  
1997 ◽  
Vol 32 (2) ◽  
pp. 267-270 ◽  
Author(s):  
H. Desilets ◽  
S. Rochefort ◽  
J. Coulombe ◽  
S. Yelle ◽  
J. Brodeur
Keyword(s):  
Venturia Inaequalis ◽  
Apple Scab ◽  
Treatment Strategies ◽  
Residual Effect ◽  
Ground Cover ◽  
Ground Level ◽  
Thermal Reduction ◽  
Apple Orchard ◽  
Primary Inoculum ◽  
Testing Facility

The potential impact of propane flamers on the development and release of ascosporic inoculum of Venturia inaequalis (Cke.) Wint. from infected dead apple (Malus domestica Borkh.) leaves that overwintered on the soil of an experimental orchard was assessed. Thermal reduction of scab primary inoculum was first conducted under controlled conditions using an indoor testing facility. At the time of ascospore maturation, heavily infected leaves were submitted to temperature rises ranging from 150 to 200 °C with open-flame burners, thus reducing the number of ascospores subsequently released by 76% and 87%, respectively. During Spring 1995, thermal treatments of overwintered dead leaves were performed directly on the ground of an apple orchard with an experimental propane flamer design to generate uniform heat at ground level. Four thermal treatment strategies, involving two dates of flaming and two heat intensities, were tested. Flaming orchard ground, when performed in early May, before significant development of ground cover, reduced the number of ascopores released from infected dead leaves by half. A significant residual effect of the treatments on ascospore ejection was still observed 2 and 4 weeks after the treatments, thus indicating that ascospore maturation inside the leaves may be reduced by heat treatment. These results indicate potential for propane flamers to reduce apple scab primary inoculum in orchards.

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

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.

Cylindrocladium root rot in Ontario bare-root nurseries: estimate of spruce seedling losses

1988 ◽  
Vol 18 (11) ◽  
pp. 1493-1496 ◽  
Author(s):  
J. Juzwik ◽  
C. Honhart ◽  
N. Chong
Keyword(s):  
Visual Field ◽  
Root Rot ◽  
Disease Incidence ◽  
White Spruce ◽  
Visual Assessment ◽  
Inoculum Density ◽  
Field Assessment ◽  
Causal Fungus ◽  
Bare Root ◽  
Apparently Healthy

Estimates of cylindrocladium root rot losses in three black and three white spruce compartments at five Ontario bare-root nurseries were determined through visual field assessment and seedling isolation. The causal fungus, Cylindrocladiumfloridanum Sob. & C.P. Seym., was isolated from 10–77% of the symptomatic and 0–28% of the apparently healthy seedlings in each compartment. In five compartments, estimates of mean incidence based on seedling isolations and visual assessment, were higher than those based on visual assessment alone. The percentage of living spruce (apparently healthy or symptomatic) estimated to be infected in each compartment was 0.1–32.7%. No fungus isolations were attempted from dead seedlings. Mortality in the plots in the six compartments was 0.02–17.7%. The correlation between the level of Cylindrocladium incidence and the inoculum density was significant (p < 0.01) in two compartments. The use of inoculum density to predict disease incidence warrants further investigation.

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