The suppression of ascospore production to facilitate the control of apple scab (<i>Venturia inaequalis</i> (Cke.) Wint.)

Burchill, R. T.; Hutton, K

doi:10.1111/j.1744-7348.1965.tb01237.x

Cited by 27 publications

(11 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Many factors can explain these dispersal distance differences, including orchard conditions and differences in wind direction and velocity (see [16]). In this study, we confirmed that dispersal of the greater part of V. inaequalis spores in orchards was intrinsically very restricted, which is in agreement with several other authors (e.g., [54-56]), who demonstrated that no scab lesion development was detected at 15 to 60 metres beyond an inoculum source. We do not dismiss the sporadic events of Long Distance Dispersal (LDD).…”

Section: Discussionsupporting

confidence: 93%

The genetic structure of a Venturia inaequalis population in a heterogeneous host population composed of different Malusspecies

et al. 2013

View full text Add to dashboard Cite

BackgroundAdaptation, which induces differentiation between populations in relation to environmental conditions, can initiate divergence. The balance between gene flow and selection determines the maintenance of such a structure in sympatry. Studying these two antagonistic forces in plant pathogens is made possible because of the high ability of pathogens to disperse and of the strong selective pressures exerted by their hosts. In this article, we analysed the genetic structure of the population of the apple scab fungus, Venturia inaequalis, in a heterogeneous environment composed of various Malus species. Inferences were drawn from microsatellite and AFLP data obtained from 114 strains sampled in a single orchard on nine different Malus species to determine the forces that shape the genetic structure of the pathogen.ResultsUsing clustering methods, we first identified two specialist subpopulations: (i) a virulent subpopulation sampled on Malus trees carrying the Rvi6 resistance gene; and (ii) a subpopulation infecting only Malus trees that did not carry this resistance gene. A genome scan of loci on these two subpopulations did not detect any locus under selection. Additionally, we did not detect any other particular substructure linked to different hosts. However, an isolation-by-distance (IBD) pattern at the orchard scale revealed free gene flow within each subpopulation.ConclusionsOur work shows a rare example of a very strong effect of a resistance gene on pathogen populations. Despite the high diversity of Malus hosts, the presence of Rvi6 seems sufficient to explain the observed genetic structure. Moreover, detection of an IBD pattern at the orchard scale revealed a very low average dispersal distance that is particularly significant for epidemiologists and landscape managers for the design of scab control strategies

show abstract

Section: Discussionsupporting

confidence: 93%

The genetic structure of a Venturia inaequalis population in a heterogeneous host population composed of different Malusspecies

et al. 2013

View full text Add to dashboard Cite

show abstract

“…Knowledge of dispersal distance and factors affecting ascospore spread is essential for disease management. Earlier studies showed that incidence of leaf and fruit scab was negligible 15–60 m from a point source of inoculum (Palmiter, 1946; Hirst and Stedman, 1962; Burchill and Hutton, 1965) and only a few airborne ascospores were trapped at a distance of 60 m (Hirst and Stedman, 1962). Moreover, one study demonstrated that the number of ascospores in the air was negligible 5.4 m from the source of inoculum (Kaplan, 1986).…”

Section: Introductionmentioning

confidence: 99%

Dispersal of Venturia inaequalis Ascospores and Disease Gradients from a Defined Inoculum Source

Holb

Heijne

Withagen

et al. 2004

Journal of Phytopathology

View full text Add to dashboard Cite

Aerial concentration of ascospores of Venturia inaequalis and incidence of apple scab were monitored in an orchard during the ascospore release seasons in 1999, 2000 and 2001 on susceptible (Jonagold) and moderately resistant (Schone van Boskoop) apple cultivars. A 1-ha orchard was divided into an inoculum source block (approximately 0.34 ha) and an inoculum-free block (approximately 0.66 ha) where inoculum was excluded by covering the soil surface with polythene sheets. Ascospore numbers and disease incidence were measured within the inoculum-free block at different distances from the inoculum block. Ascospores were sampled with three Burkard volumetric spore traps located at 0, 21 and 45 m from the border of the inoculum block. To determine the incidence of infection, clusters of leaves were assessed at six distances from the border of the infected source from the time the first symptoms appeared. Each year, the aerial ascospore concentration significantly decreased with distance from the source, as did the incidence of infected clusters. Cultivar susceptibility to apple scab markedly influenced incidence of infected clusters and disease gradients. The effect of horizontal distance from the source was identifiable up to 18 m and 33 m for cv. Schone van Boskoop and cv. Jonagold, respectively, beyond which disease was negligible. The disease gradients for cultivar Jonagold in 1999, 2000 and 2001 were well described by an exponential model with gradient coefficients of )0.036, )0.042 and )0.047, respectively. The number of infected clusters at the source border for this cultivar differed significantly over the 3 years. A single exponential model with a gradient coefficient of )0.035 adequately described the disease gradients for cultivar Schone van Boskoop in each of the 3 years. Further analysis showed highly significant correlations (r > 0.85, P < 0.01) between the annual cumulative spore catches and the annual mean number of infected leaf clusters in each year and for both cultivars. The aerobiological and epidemiological implications of these findings are discussed.U. S.

show abstract

“…Fifty leaf discs were placed in each of 10 metal mesh bags, inside a shade netting box (1 m×1 m×10 cm) during winter within 2 km from the trial orchard (as described in Schwabe et al 1989). Every 2 weeks a bag was taken out and ascospores were extracted, as previously described (Burchill and Hutton 1965). Ascospore maturity was evaluated by counting spore numbers once every 2 weeks under a stereomicroscope at 100× magnification.…”

Section: Monitoring Of Ascospore Maturationmentioning

confidence: 99%

A method to monitor airborne Venturia inaequalis ascospores using volumetric spore traps and quantitative PCR

et al. 2014

View full text Add to dashboard Cite

Apple scab caused by the fungus Venturia inaequalis can result in significant crop losses if not managed effectively. Sanitation as part of an integrated management strategy aims to significantly reduce primary inoculum to lower the disease pressure. This study evaluates the possibility of molecular detection and quantification of ascospore discharge and the use of this method to test for efficacy of orchard sanitation treatments. A method to detect and quantify airborne ascospores was developed using volumetric spore traps (VSTs). V. inaequalis specific primers were tested on daily VST samples from two orchard sections (leaf litter removed compared to leaf litter left) during spring. A molecular method to detect and quantify ascospores was tested by amplifying genomic regions of the mitochondrial CYP51A1 gene, and the ITS region using SYBR® green. Timing of ascospore discharge was compared to predicted infection risk and a degree day model using weather data. The average spore detection limit was estimated to be at levels of 1 pg μl −1 DNA (approximately 37 ascospores) per daily spore trap reading using CYP51A1 primers. Using the CYP51A1 primer pair, primary inoculum was estimated to be 51 % lower in the orchard sections where leaves had been removed, indicating that this method could be used to evaluate the efficacy of alternative control strategies such as leaf removal to reduce potential ascospore dose. This is the first report of combining VSTs and quantitative PCR to monitor airborne V. inaequalis ascospores.

show abstract

The suppression of ascospore production to facilitate the control of apple scab (Venturia inaequalis (Cke.) Wint.)

Cited by 27 publications

References 4 publications

The genetic structure of a Venturia inaequalis population in a heterogeneous host population composed of different Malusspecies

The genetic structure of a Venturia inaequalis population in a heterogeneous host population composed of different Malusspecies

Dispersal of Venturia inaequalis Ascospores and Disease Gradients from a Defined Inoculum Source

A method to monitor airborne Venturia inaequalis ascospores using volumetric spore traps and quantitative PCR

Contact Info

Product

Resources

About