Plant Pathology (2011) 60, 811-819

D.C. Rennie, V.P. Manolii, T. Cao, S.F. Hwang, R.J. Howard and S.E. Strelkov (2011)
Direct evidence of surface infestation of seeds and tubers by Plasmodiophora brassicae and quantification of spore loads
Plant Pathology 60 (5), 811-819
Abstract: Using quantitative PCR, DNA of Plasmodiophora brassicae, the causal agent of clubroot, was detected and quantified on canola, pea and wheat seeds, as well as on potato tubers, all harvested from clubroot-infested fields in Alberta, Canada. Quantifiable levels of infestation were found on seven of the 46 samples analysed, and ranged from <1·0 × 10³ to 3·4 × 10⁴ resting spores per 10 g seeds; the vast majority (80-100%) of resting spores on these samples were viable, as determined by Evan's blue vital staining. However, the levels of infestation found were generally lower than that required to cause consistent clubroot symptoms in greenhouse plant bioassays. While the occurrence of P. brassicae resting spores on seeds and tubers harvested from clubroot-infested fields suggests that seedborne dissemination of this pathogen is possible, practices such as commercial seed cleaning may be sufficient to effectively mitigate this risk.
(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): Stephen E. Strelkov

Research topic(s) for pests/diseases/weeds:
transmission/dispersal of plant diseases

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Plasmodiophora brassicae	Potato (Solanum tuberosum)	Canada (west)
	Plasmodiophora brassicae	Rape/canola (Brassica napus)	Canada (west)
	Plasmodiophora brassicae	Wheat (Triticum)	Canada (west)
	Plasmodiophora brassicae	Pea (Pisum sativum)	Canada (west)