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Persistence of Plasmodiophora brassicae

influence of non-host plants, soil fauna and organic material

Friberg, Hanna (2005). Persistence of Plasmodiophora brassicae. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2005:115
ISBN 91-576-6914-7
[Doctoral thesis]

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Plasmodiophora brassicae, causal agent of clubroot disease of crucifers, has tolerant resting spores that permit its survival in the absence of a host plant. The resting spores are expected to germinate when triggered by specific substances excreted from host plant roots, but they also respond to other cues. As the zoospores emerging at germination are sensitive and short-lived, stimulation of resting spore germination is a potential method for management of clubroot disease. Certain non-host plants have been found to increase resting spore germination. The effect of four non-host plants on P. brassicae was studied in laboratory-, greenhouse- and field studies. In the laboratory, root exudate solution of Lolium perenne (Perennial ryegrass) stimulated germination of resting spores more strongly than other non-host plants tested (Allium porrum, leek; Trifolium pratense, red clover; Secale cereale, winter rye) or the host plant Brassica rapa var. pekinensis (Chinese cabbage). When grown in soil, however, no species-specific effect of any of the plants was observed on the persistence of P. brassicae. It has been claimed that resting spore germination increases in response to substances excreted from decaying plant material or to a general increase in soil biological activity. However, no change in pathogen persistence was observed when infested soil was treated with plant material or with a combination of grass material and earthworms. A bioassay made it possible to correlate disease severity with concentration of resting spores in soil. This analysis provides a coarse estimation of resting spore concentration, and smaller changes in spore load may not have been detected. Nevertheless, none of the treatments showed an influence that would render them useful in dealing with heavily P. brassicae-infested soils within short time periods. The studies emphasise the need for methods for direct and precise quantification of P. brassicae in soil. The gaps in our understanding of the life cycle of the pathogen, including the factors that determine its survival, dispersal and germination are important issues that need to be addressed before we can adequately develop management strategies to control P. brassicae.

Authors/Creators:Friberg, Hanna
Title:Persistence of Plasmodiophora brassicae
Subtitle:influence of non-host plants, soil fauna and organic material
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :November 2005
Number of Pages:26
ALLI. Friberg, H., Lagerlöf, J. & Rämert, B. Germination of Plasmodiophora brassicae resting spores stimulated by a non-host plant. European Journal of Plant Pathology, in press. II. Friberg, H., Lagerlöf, J., & Rämert, B. Are non-host plants useful in management of clubroot disease? (Submitted manuscript). III. Friberg, H., Lagerlöf, J., Hedlund, K. & Rämert, B. Effect of earthworms and incorporation of grass on Plasmodiophora brassicae. (Manuscript). IV. Svensson, K. & Friberg, H. Changes in microbial status as induced by earthworms and grass amendments. (Submitted manuscript). V. Friberg, H. & Hedlund, K. A bioassay method of detecting Plasmodiophora brassicae spore concentrations in soil. (Manuscript).
Place of Publication:Uppsala
Associated Programs and Other Stakeholders:Z - SLU - Library > Odla mera
ISBN for printed version:91-576-6914-7
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:H Protection of plants and stored products > H20 Plant diseases
Subjects:Not in use, please see Agris categories
Agrovoc terms:plasmodiophora brassicae, lolium perenne, trifolium pratense, brassica campestris, dormancy, oligochaeta, exudates, roots, spores, soil fauna
Keywords:Plasmodiophora brassicae, clubroot disease, dormancy, root exudate, germination-stimulating factor, resting spore, Lolium perenne, earthworm, soil fauna
Permanent URL:
ID Code:990
Department:(NL, NJ) > Dept. of Entomology (until 061231)
Deposited By: Hanna Friberg
Deposited On:28 Nov 2005 00:00
Metadata Last Modified:22 Mar 2015 15:13

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