Meloidogyne naasi




Rev 01/06/2023

Barley root-knot nematode Classification Hosts
Morphology and Anatomy Life Cycle
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Distribution Management
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        Meloidogyne naasi  Franklin, 1965

Barley root-knot nematode.

The specific name is derived from the initials of the UK National Agricultural Advisory Service.

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Morphology and Anatomy:


A,B,C=male; D,E,F=female; G,H,I,J,K=second-stage juvenile

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

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Temperate areas of the United States and Europe. Originally described from field crops (cereals, grasses, sugarbeet) in England and Wales.

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Economic Importance:

B-rated pest in California Nematode Pest Rating System.

In California, this species can cause yield losses of 50-75% in barley grown under continuous cropping in the Tulelake innermountain region. 


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 Feeding site establishment and development typical of genus.

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Type Host: Spring barley (Hordeum vulgare).

Grasses, cereals, and weeds. 

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


Egg hatch in water is very limited unless eggs have been chilled by storage below 5C for 1 to 7 weeks  (Franklin et al, 1971). 

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Galls are generally cylindrical, spindle-shaped, or hooked. Heavily infected plants are stunted, have a yellowish appearance and may die. Surviving plants tend to remain stunted and do not produce normal seed heads (Allen et al., 1970; Scaheck, 2023).

Feeding causes necrosis, hyperplasia, and hypertrophy of cortex; also causes disorganization of xylem elements. 

Severely affected plants wilt readily, even when soil moisture is sufficient, because galled roots have less ability to absorb and transport water. Nutrient deficiency symptoms including chlorosis may result from the reduced ability of galled roots to absorb and transport nutrients, even when levels are adequate in the soil. Stunting is a frequent result (Scheck, 2023).


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Crop rotation can be effective in California (1 year fallow or 2 seasons of potatoes increased barley yield - Allen, 1970).

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

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


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Allen, M., Hart, W. and Baghott, K., 1970. Crop rotation controls barley root-knot nematode at Tulelake. California Agriculture, 24(7), pp.4-5.

CABI CPC 2022. Meloidogyne naasi.

CIH Descriptions of Plant-parasitic Nematodes, Set 2, No. 19 (1973)

Franklin, M.T., 1965. A root-knot nematode, Meloidogyne naasi n.sp. on field crops in England and Wales. Nematologica 11: 75-86.

Franklin, M.T., S.A. Clarke and J.A. Course. 1971. Nematologica 17:575-590.

Scheck, H.J. 2023. California Pest Rating Proposal for Meloidogyne naasi Franklin 1965 Barley root knot nematode  CDFA, Sacramento, California, USA

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Copyright © 1999 by Howard Ferris.
Revised: January 06, 2023.