European Journal of Plant Pathology (2019) 155, 1319-1332

Sanne Torfs, Kris Van Poucke, Jelle Van Campenhout, An Ceustermans, Sarah Croes, Dany Bylemans, Wendy Van Hemelrijck, Wannes Keulemans and Kurt Heungens (2019)
Venturia inaequalis trapped: molecular quantification of airborne inoculum using volumetric and rotating arm samplers
European Journal of Plant Pathology 155 (4), 1319-1332
Abstract: Site-specific high throughput monitoring of airborne ascospores of Venturia inaequalis, the causal agent of apple scab, can improve existing warning systems. A new qPCR assay was developed to quantify ascospores collected by a simple rotating-arm spore sampler. The qPCR assay was highly specific and sensitive, with a limit of quantification of 20 ascospores per sample. The new detection system was compared to sampling with a traditional Burkard volumetric spore trap and to microscopic quantification. During controlled ascospore release experiments in a closed environment, strong correlations (ρ: 0.96 to 0.99) were observed between the two types of samplers and the two methods of quantification but significantly larger numbers of spores (log difference: 0.43 to 0.69) were obtained when using the rotating-arm sampler and when using molecular quantification. During comparisons under outdoor conditions over a three-year period, reasonable correlations between the techniques (average ρ = 0.61) were observed. When rotating-arm samplers operate continuously they can get saturated but their counts still correlated better with those from the Burkard sampler than when they only operate during rain and until two hours after. This suggests that ascospores were also captured outside of rain events. Based on these comparisons, molecular quantification of spores captured with the rotating-arm sampler appears to be a sensitive and reliable method to determine airborne ascospores of V. inaequalis and holds promise as a tool to guide targeted fungicide applications in commercial orchards as well as to increase our knowledge of the aerobiology of this pathogen.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Kris Van Poucke, Kurt Heungens

Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Venturia inaequalis	Apple (Malus)