Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
The Columbia root-knot nematode, Meloidogyne
chitwoodi, is a major pest of potatoes in the northwestern United
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).
in California Nematode Pest Rating System.
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
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,
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 enhancesthe economic impact (Elling, 2013).
Sedentary endoparasite of roots and tubers.
Feeding site establishment and
development typical of genus.
Potato, barley, wheat, alfalfa (race
Nematode damage to the potato crop is
caused by the second and third generation of M. chitwoodi in a given
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.
major damage to the tubers
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,
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 6Ã‚Â°C
so that invasion of roots occurs early in the growing season (Elling, 2013).
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).
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
sativa) and barley
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,
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
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