Meloidogyne chitwoodi




Rev 06/24/2015

Columbia Root-knot Nematode Classification Hosts
Morphology and Anatomy Life Cycle
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           Meloidogyne chitwoodi Golden, O'Bannon, Santo, and Finley
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Morphology and Anatomy:


Female:  Anterior;  note excretory pore on right and dorsal esophageal gland opening into esophagus lumen.
Mature Female:  Body morphology.
Female:  Perineal pattern.
Male:  Anterior Male:  Posterior - spicules and gubernaculum, no caudal alae.

Second-stage juvenile

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The Columbia root-knot nematode, Meloidogyne chitwoodi, is a major pest of potatoes in the northwestern United States.  

Potato-growing regions of Colorado, Idaho, Utah, Washington, and the Klamath Basin of northern California and southern Oregon are infested with the nematode. (Nyczepir et al., 1982; Pinkerton and McIntyre, 1987; Santo et al., 1980). M. chitwoodi is widespread throughout the Pacific Northwest and most western states. It is also found in Mexico, Argentina, Turkey and South Africa (Elling, 2013). Recorded from South Africa (Fourie et al., 2002).

Meloidogyne chitwoodi was first described in 1980 (Santo et al., 1980), but specimens from the Klamath Basin deposited in the nematode collection of the California Department of Food and Agriculture in the mid-1960s suggest that the nematode was previously designated as M. thamesi (R. W. Hackney and A. C. Weiner, personal communication).


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Economic Importance:

B-rated pests in California. 

Soils of the Klamath basin of north-east California and south-east Oregon that are used for a potato cropping system are frequently infested with M. chitwoodi and Pratylenchus neglectus.

Approximately 9300 ha of "Russet Burbank" potatoes are grown in the Klamath Basin, primarily for the fresh market (mid 1990s data). Conditions become suitable for soil tillage and planting in mid-May, and the potato crop is usually harvested by early October. The nematode reproduces on both potato roots and tubers, which facilitates its spread to previously uninfested areas with seed tubers.

In potato tubers, almost all (96%) of the nematodes are found in the outermost 5.25 mm of the tuber, which corresponds to the vascular ring (Elling, 2013).

There is little evidence of yield reduction caused by the direct effect of the nematode population on potato crop growth (Griffin, 1985; Pinkerton and Santo, 1986). The major damage to potato tubers is a nematode-induced blemish which lowers or negates tuber marketability. When 10% or more of the tubers are blemished, the crop is usually unmarketable.

 The nematode infects a broad range of plants, including potatoes, vegetables, wheat, corn, alfalfa, and numerous weeds. It can also parasitize several Brassica spp. (Elling, 2013).

To limit future spread of this nematode, regulatory agencies in many countries have designated M. chitwoodi as quarantine pest, which limits trade of infested shipments and enhances
the economic impact (Elling, 2013).


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Sedentary endoparasite of roots and tubers.

Feeding site establishment and development typical of genus.

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Potato, barley, wheat, alfalfa (race 2).

For an extensive list of host plant species and their susceptibility, copy the name

Meloidogyne chitwoodi

select Nemabase and paste the name in the Genus and species box


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Life Cycle:

Nematode damage to the potato crop is caused by the second and third generation of M. chitwoodi in a given growing season.  

The overwinter population penetrates roots, develops, and produces eggs about 600 degree-days (>5C) after planting (Westerdahl, Pinkerton, Ferris).  

Second-stage juveniles of the second generation penetrate roots and (bulking?) (young) tubers commencing about 800 DD after planting, although very young tubers appear resistant or unattractive to the nematodes (Santo).  A third generation of the nematode may be reached by mid-September, resulting in further invasion of the tubers prior to harvest.    

On crops that are hosts to M. chitwoodi or P. neglectus, seasonal multiplication rates of the nematodes were log-linearly related to populations measured the previous fall. The relationship between crop yields, or nematode multiplication rates, and spring nematode population levels were weaker due to the lower precision of spring population assessments. Overwinter survival rates of both nematode species were log-linearly related to population levels measured in the fall.

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The major damage to the tubers is a nematode-induced blemish which lowers or negates their marketability.  Field experiments indicate little evidence of yield reduction by the direct effect of the nematode population on crop growth.   The surface blemish rating of a summer-grown potato crop has a log-linear relationship with the population level of M. chitwoodi measured either the previous fall, or with lower reliability, in the spring before potato planting (Ferris et al, 1994).

Since very few second-stage juvenile in the overwintering generation can result in substantial second- and third-generation population levels, the economic threshold for the nematode measured in the spring is at or below the limit of detection.  The nematode population may be best measured in the fall, at the end of the previous crop, as a basis for management decisions.


Symptoms include stunting and yellowing above-ground and small galls on roots and tubers without secondary roots emerging from them.  Eggs hatch at 6C so that invasion of roots occurs early in the growing season (Elling, 2013).

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Only a few second-stage juveniles in the overwintering population will produce substantial second- and third-generation population levels. Thus the economic threshold for tuber blemish may be at or below the limit of detection when the M. chitwoodi population is measured in the spring. Nematode management decisions in the potato-based cropping system of the Klamath Basin can be based on the relationship between potato tuber blemish rating and population level of M. chitwoodi the previous fall as a primary criterion. Individuals are more abundant then, and there is more time available for sample processing and management decisions (Ferris, 1985). At least one composite sample of between 12 and 20 soil cores should be taken to for every 5 acres of relatively uniform edaphic conditions (Ferris et al., 1990).

The population level of M. chitwoodi the previous fall resulting in 10% blemished tubers was 133 eggs and juveniles per L soil. That population level is measurable, but our ability to detect and assess the fall population level that would result in 5% potato blemish (18 per L soil) is questionable (Ferris et al., 1990).


The availability and acceptability of nematicide options for nematode management are diminishing. In the Klamath Basin region of northern California and southern Oregon, much of the soil is silty clay loam with 12% organic matter content. Efficacy of fumigant nematicides on this soil has been poor or inconsistent (Westerdahl et al., 1992).

Crop Rotation

A logical strategy for the management of the Columbia root-knot nematode, and the reduction of its potential damage to potato crops in the Klamath Basin, is the use of nonhost or resistant crops in the rotation.  Season length and marketing constraints  have limited current rotation crops in the cropping system to alfalfa (Medicago sativa) and barley (Hordeum vulgare). Although economically questionable for the cropping system, especially in short-term rotations, both crops are used for agronomic benefits to the soil. Further, alfalfa, although a nonhost to the prevalent biotype (biotype 1) of the Columbia root-knot nematode, is a host to another root-knot nematode occurring in the area, M. hapla.    Both crops are hosts of the lesion nematode, Pratylenchus neglectus, which occurs in the same fields (Griffin, 1991; Griffin and Gray, 1990; Mojtahedi and Santo, 1992; Umesh and Ferris, 1992). Sugar beets (Beta vulgaris), which are being introduced into the area, are hosts of M. chitwoodi (Ferris et al., 1993).

Alternate crops have been investigated for infested regions throughout the Pacific Northwest of the USA (Ferris et al., 1993; Griffin, 1991; Mojtahedi et al., 1991; Griffin and Asay, 1989; Santo and Ponti, 1985; Santo et al., 1988).

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

For a list of plant species or cultivars (if any) reported to be immune or to have some level of resistance to this nematode species, copy the name

Meloidogyne chitwoodi

select Nemabase Resistance Search and paste the name in the Genus and species box


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CIH 106

Elling, A.A. 2013. Major Emerging Problems with Minor Meloidogyne Species. Phytopathology 103:1092-1102.

Ferris, H., H. Carlson, D. Viglierchio, B. Westerdahl, F. Wu, C. Anderson, A. Juurma, and D. Kirby. 1993. Host status of selected crops to Meloidogyne chitwoodi. Ann. Appl. Nematol. 25:849-857.

Ferris, H., H. L. Carlson and B. B. Westerdahl. 1994. Nematode population changes under crop rotation sequences: consequences for potato production. Agronomy Journal 86:340-348.

Ferris, H., T.A. Mullens, and K.E. Foord. 1990. Stability and characteristics of spatial description parameters for nematode populations. J. Nematol. 22:427-439.

Fourie, H., C. Zijlstra, A.H. McDonald and G. A. Venter. 2002.  Advances in applied nematode research in South Africa after introduction of the SCAR-PCR technique for nematode identification. Nematology  4:160-161.

Griffin, G.D. 1985. Host-parasite relationship of Meloidogyne chitwoodi on potato. J. Nematol.17:395-399.

Griffin, G.D. 1991. Differential pathogenicity of four Pratylenchus neglectus populations on alfalfa. J. Nematol. 23:380-385.

Griffin, G.D., and K.H. Asay. 1989. Pathological reaction of crested wheatgrass cultivars to four Meloidogyne chitwoodi populations. J. Nematol. 21:446-452.

Griffin, G.D., and F.A. Gray. 1990. Biology and pathogenicity of Pratylenchus neglectus on alfalfa. J. Nematol. 22:546-551.

Inserra, R.N., G.D. Griffin, and D.V. Sisson. 1983. Effects of temperature and root leachates on embryonic development and hatching of Meloidogyne chitwoodi and M. hapla. J. Nematol. 15:123-127.

Mojtahedi, H., and G.S. Santo. 1992. Pratylenchus neglectus on dryland wheat in Washington. Pl. Dis. 76:323.

Mojtahedi, H., G.S. Santo, A.N. Hang, and J.H. Wilson. 1991. Suppression of root-knot nematode populations with selected rapeseed cultivars as green manure. J. Nematol. 23:170-174.

Mojtahedi, H., G.S. Santo, and J.N. Pinkerton. 1988. Differential response of Thor Alfalfa to Meloidogyne chitwoodi races and M. hapla. J. Nematol. 20:410-416.

Nyczepir, A.P., J.H. O'Bannon, G.S. Santo, and A.M. Finley. 1982. Incidence and distinguishing characteristics of Meloidogyne chitwoodi and M. hapla in potato from the northwestern United States. J. Nematol. 14:347-353.

Pinkerton, J.N., and G.A. McIntyre. 1987. Occurrence of Meloidogyne chitwoodi in potato fields in Colorado. Pl. Dis. 71:192.

Pinkerton, J.N., and G.S. Santo. 1986. Control of Meloidogyne chitwoodi in commercially grown Russet Burbank potatoes. Pl. Dis. 70:860-863.

Pinkerton, J.N., G.S. Santo, and H. Mojtahedi. 1986. Population dynamics of Meloidogyne chitwoodi in relation to Russet Burbank potato tuber penetration. J. Nematol. 18:627 (abstr.)

Santo, G.S., H. Mojtahedi, and J.H. Wilson. 1988. Host-parasite relationship of carrot cultivars and Meloidogyne chitwoodi races and M. hapla. J. Nematol. 20:555-564.

Santo, G.S., and J.H. O'Bannon. 1981. Effect of soil temperature on the pathogenicity and reproduction of Meloidogyne chitwoodi and M. hapla on Russet Burbank potato. J. Nematol. 13:483-486.

Santo, G.S., J.H. O'Bannon, A.M. Finley, and A.M. Golden. 1980. Occurrence and host range of a new root-knot nematode (Meloidogyne chitwoodi) in the Pacific Northwest. Pl. Dis. 64:951-952.

Santo, G.S., and R.P. Ponti. 1985. Host suitability and reaction of bean and pea cultivars to Meloidogyne chitwoodi and M. hapla. J. Nematol. 17:77-79.

Umesh, K.C., and H. Ferris. 1992. Effects of temperature on Pratylenchus neglectus and on its pathogenicity to barley. J. Nematol. 24:504-511.

Umesh, K.C., and H. Ferris. 1994. Influence of temperature and host plant on the interaction between Pratylenchus neglectus and Meloidogyne chitwoodi. J. Nematol. 26:65-71

Umesh, K.C., and H. Ferris, and D.E. Bayer. 1994. Competition between Pratylenchus neglectus and Meloidogyne chitwoodi. J. Nematol. 26:286-295.

Westerdahl, B.B., H.L. Carlson, J. Grant, J.D. Radewald, N. Welch, C.A. Anderson, J. Darso, D. Kirby, and F. Shibuya. 1992. Management of plant-parasitic nematodes with a chitin-urea soil amendment and other materials. Ann. Appl. Nematol. 24:669-680.

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Copyright 1999 by Howard Ferris.
Revised: June 24, 2015.