Paratrichodorus allius




Rev 05/02/2022

a stubby-root nematode

Classification Hosts
Morphology and Anatomy Life Cycle
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Distribution Management
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             Paratrichodorus allius (Jensen, 1963) Siddiqi 1974



Trichodorus allius Jensen, 1963

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Morphology and Anatomy:



Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:

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Paratrichodorus allius which prefers sandy soils (Ayala et al., 1970) and is sensitive to moisture levels below

field capacity (Mojtahedi et al., 1999). The nematode has been found 60-cmt deep in soil (Ingham et al., 2000). However, vertical migration resulting in transmission of corky ringspot virus in potato rarely exceeds 30 cm (Motjahedi et al., 2000).


Potato (Solanum tuberosum) is considered a relatively poor host for species in the Trichodoridae, including P. allius (Hooker, 1981). Populations of P. allius appear to decline after planting potato and remain at low densities throughout the growing season (Charlton, 2006; Ingham et al., 2000; Mojtahedi and Santo, 1999).


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Economic Importance:

D-rated pest in California Nematode Pest Rating System.

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Ectoparasitic; feeds on epidermal cells at and just behind root tips.

Feeds by repeated thrusting of the onchiostyle within a polysaccharide feeding tube.  Cell contents move along the groove along the dorsal side of the onchiostyle.

Virulifeous nematodes transmit corky ringspot, a tobacco rattle virus of poteto.



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For an extensive host range list for this species, click


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Life Cycle:

Ecophysiological Parameters:

For Ecophysiological Parameters for this species, click If species level data are not available, click for genus level parameters


The optimum temperature range for development and reproduction of Paratrichodorus allius is 21 to 24º C (Ayala et al. (1970).

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Paratrichodorus allius was demonstrated to transmit Tobacco Rattle Virus (TOBRA Virus) by Jensen and Allen (1964).  It is the most important nematode vector of the Corky ringspot strain of Tobacco rattle Virus to potatoes in the western United States (Mojtahedi and Santo, 1999).


Tobacco rattle virus causes a disease called spraing or corky ringspot in potatoes.  The disease is characterized by lesions and pits on the tuber surface and necrotic lesions within the tuber.


Corky ringspot disease was first reported in the United States in 1946 and from Oregon in 1963 and Washington in 1975 (Ingham et al., 2000).


Low population levels of P. allius are capable of spreading Tobacco Rattle Virus to potato plants. As few as two P. allius/250 g soil at planting resulted in heavy corky ringspot damage. Although the virus does not affect tuber yield, its presence can lead to grade reduction or complete rejection of tubers destined for fresh market or processing channels (Charlton, 2006; Ingham et al., 2000).


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Host Plant Resistance, Non-hosts and Crop Rotation alternatives:

For plants reported to have some level of resistance to this species, click

The levels pof tobacco Rattle Virus in fields infested with Paratichodorus allius vectoring corky ringspot virus can be reduced by growing alfalfa and plant varieties that are resistant to TRV infection. A recently developed potato variety, Castle Russet and alfalfa variety Vernema are resistant to TRV infection and do not develop symptoms of CRS disease. Both are poor hosts of P. allius..They may potentially be used to eliminate the virus from fields affected by CRS (Quick et al., 2020).

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Ayala, A., M.W. Allen, and E.M. Noffsinger. 1970. Host range, biology, and factors  affecting survival and reproduction of the stubby root nematode. J. Agr. Univ. Puerto Rico 64:341-369.

Charlton, B.A. 2006. Effects of oxamyl on suppression of the Tobacco rattle virus vector Paratrichodorus allius and corky ringspot disease of potato in the Klamath Basin of south-central Oregon.  MS Agronomy Thesis,  Oregon State University
Ingham, R.E., P.B. Hamm, R.E. Williams, and W.H. Swanson. 2000. Control of Paratrichodorus allius and corky ringspot disease of potato in the Columbia Basin of Oregon. Supplement of the Journal of Nematology 32 (4S):566-575.
Jensen, H.J., and T.C. Allen. 1964. Trichodorus allius, a potential nematode vector of TRV. Phytopathology 54:1434.
Mojtahedi, H., and G.S. Santo. 1999. Ecology of Paratrichodorus allius and its relationship to the corky ring-spot disease of potato in the Pacific Northwest. American Journal of Potato Research 76:273-280.

Quick, R.A., Cimracki, L., Mojtahedi, H., Sathuvali, V., Feldman, M.J., Brown, C.R., 2020. Elimination of Tobacco rattle virus from viruliferous Paratrichodorus allius in greenhouse pot experiments through cultivation of castle russet. J. Nematology 52: | DOI: 10.21307/jofnem-2020-011.


Copyright © 1999 by Howard Ferris.
Revised: May 02, 2022.