Datasheet
Meloidogyne graminicola (rice root knot nematode)
Index
- Pictures
- Identity
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Description
- Distribution Table
- Risk of Introduction
- Habitat
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- Symptoms
- List of Symptoms/Signs
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Pathway Vectors
- Plant Trade
- Impact
- Diagnosis
- Detection and Inspection
- Prevention and Control
- References
- Distribution Maps
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Top of page| Picture | Title | Caption | Copyright |
|---|---|---|---|
| Females and symptoms on roots | Left: Female nematodes and eggs inside rice root gall. Right: Characteristic hooked, root tip galls on rice. | J. Bridge/CABI BIOSCIENCE |
Identity
Top of pagePreferred Scientific Name
- Meloidogyne graminicola Golden & Birchfield 1965
Preferred Common Name
- rice root knot nematode
EPPO code
- MELGGC (Meloidogyne graminicola)
Taxonomic Tree
Top of page- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Nematoda
- Family: Meloidogynidae
- Genus: Meloidogyne
- Species: Meloidogyne graminicola
Notes on Taxonomy and Nomenclature
Top of page The taxonomy of the genus Meloidogyne is complex and becoming more so - many species can only be reliably identified by an expert.Description
Top of page Measurements (After Golden and Birchfield, 1965)20 females: L = 0.445-0.765 (0.573) mm; width = 0.275-0.520 (0.419) mm; a = 1.2-1.8 (1.37); stylet = 10.64-11.20 (11.08) µm.
20 males: L = 1.020-1.428 (1.222) mm; a = 72.8-215.0 (117.4); length of oesophagus (anterior end to base of oesophagus) = 196.0-250.0 (222.0) µm; stylet = 16.24-17.36 (16.8) µm.
20 second-stage juveniles: L = 0.415-0.484 (0.441) mm; a = 22.3-27.3 (24.8); b = 2.9-4.0 (3.2); c = 5.5-6.7 (6.2); stylet = 11.20-12.32 (11.38) µm.
20 eggs: L = 96-101 (99) µm; width = 42-47 (44) µm.
Description (after Mulk, 1976)
Female
Pearly white, globular to pear-shaped with small neck; cuticle distinctly annulated but often marked with irregular punctations. Lip region smooth, anteriorly flattened, not distinctly set off from neck, with inconspicuous framework. Stylet slender and delicate; knobs rounded with posteriorly sloping anterior margins. Orifice of dorsal oesophageal gland 3.2 (2.8-3.9) µm behind stylet base. Excretory pore conspicuous, anterior to median oesophageal bulb, more than one stylet length posterior to stylet knobs and 7-16 annules behind lip region. Procorpus elongate cylindrical; median oesophageal bulb large, situated in the hind part of the neck, highly muscular, rounded to hemispheroid, 20-23 µm long and 10-12 µm wide with strongly cuticularized valve in the middle; isthmus short and narrow; three oesophageal glands, each with a prominent nucleus, extend ventrally and ventro-laterally over the intestine. Nerve ring obscure.
Ovaries two, well developed, convoluted, filling body cavity and overlying the intestine; uterus with several eggs. Six large radially arranged, uninucleate rectal glands with prominent nuclei, surround the rectum. Posterior cuticular pattern (= perineal pattern) dorso-ventrally oval, sometimes almost circular; dorsal arch low with smooth striae; tail tip marked with prominent, coarse, fairly well separated and disorganized striae, forming an irregular tail whorl; sometimes a few lines converge at either end of vulva. Lateral fields obscure or absent. A few well-marked, irregular, short, zig-zag striae, distinct from the rest and interrupting the general pattern, distinguish it from other species. Phasmids minute, rather close together; distance between the phasmids about two-thirds the length of the vulva. Distance from anus to vulva about 2.5-3.0 times the distance between anus and level of phasmids.
Male
Body cylindrical, vermiform, tapering more towards anterior than posterior extremity. Cuticle prominently annulated. Annules about 2.1-2.5 µm apart near mid-body. Lip region continuous with body or slightly offset by a constriction, nearly flat anteriorly, 3.5-4.0 µm high and 8.5-9.0 µm wide, consisting of a prominent labial annule followed by 1 or sometimes 2 wide post-labials. Cephalic framework conspicuously sclerotized. Stylet fairly strong with rounded posteriorly sloping knobs, 3.5-4.0 µm across; anterior conical part of stylet about 50% of the whole length. Orifice of the dorsal oesophageal gland 3.5-4.8 µm (2.80-3.92 µm according to Golden and Birchfield, 1965) from base of stylet. Anterior and posterior cephalids at about 2nd and 7th annules behind lip region. Excretory pore distinct, 51-64 annules behind lip region (about 0-7 annules posterior to nerve ring). Hemizonid 1-2 annules wide, 1-3 annules anterior to the excretory pore. Hemizonion a few annules behind excretory pore but inconspicuous. Procorpus elongate, cylindrical, wider than isthmus. Median oesophageal bulb hemispheroid to fusiform with strongly cuticularized valve in the middle. Isthmus, a narrow tube, encircled by nerve ring near middle; three oesophageal glands forming a compact lobe overlie intestine ventrally and ventro-laterally. Lateral fields 7.7 (6.2-9.5) µm wide or about one quarter of body-width, marked with 4 incisures in young and 8 in large and old specimens, near mid-body. Outer incisures crenate and outer bands areolated at extremities. Testis single, outstretched, sometimes reflexed anteriorly. Spicules arcuate or slightly bent ventrally near middle, 28.1 (27.4-29.1) µm long medially. Gubernaculum rod-shaped 6.1 (5.6-6.7) µm long. Tail 11.1 (6.2-15.1) µm wide with smooth terminus. Phasmids small, postanal, located near middle of tail.
Second-stage juveniles
Body cylindrical, vermiform, tapering towards posterior extremity. Cuticle finely marked with distinct transverse striae, about 1 µm apart near mid-body. Lip region continuous with body, weakly sclerotized, marked with 3 faint post-labial annules. Stylet delicate with posteriorly sloping rounded knobs. Orifice of dorsal oesophageal gland 2.8 (2.8-3.4) µm from base of stylet. Excretory pore at level of nerve ring or slightly behind. Hemizonid just anterior to excretory pore. Median oesophageal bulb rounded, almost spherical, with prominent refractive valve. Lateral fields with 3 incisures, occupying one-quarter to one-third of body width near middle. Outer incisures finely crenate. Tail 70.9 (67.0-76.0) µm long, including the irregularly annulated posterior hyaline portion, which is 17.9 (14.0-21.2) µm long and 4-5 times as long as the anal body width. Tail terminus rounded, often slightly clavate.
Distribution Table
Top of pageThe distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
Risk of Introduction
Top of page It is a quarantine pest in all countries, particularly rice-growing countries, in which it does not, as yet, occur.Habitat
Top of page M. graminicola is found in upland soils, shallow flooded soils and deep flooded soils.Hosts/Species Affected
Top of page The following plants have been assessed as hosts in experiments: Amaranthus spinosus, Amaranthus viridis, Avena sativa, Bannaya brachiata, Beta vulgaris, Brassica juncea, Brassica oleracea, Capsicum annuum, Colocasia esculenta, Coriandrum sativum, Cyperus brevifolius, Cyperus ferax, Desmodium trifolium, Fimbristylis podocarpa, Jussiaea repens [Ludwigia repens], Lactuca sativa, Oplismenus compositus, Panicum miliaceum, Pennisetum typhoides [P. glaucum], Phaseolus vulgaris, Portulaca oleracea, Saccharum officinarum, Solanum melongena, Spinacia oleracea, Stellaria media, Triticum aestivum, and Vicia faba.For further information on host range see: Birchfield (1965), Rao et al. (1970), Buangsuwon et al. (1971), Roy (1977), Yik and Birchfield (1979), Myint (1981), Siciliano et al. (1990).
Host Plants and Other Plants Affected
Top of pageGrowth Stages
Top of page Seedling stage, Vegetative growing stageSymptoms
Top of page M. graminicola can be detected when plants are uprooted as it causes swellings and galls throughout the root system. Infected root tips become swollen and hooked, a symptom which is especially characteristic of this nematode.In upland conditions and shallow intermittently flooded land, it can cause severe growth reduction, unfilled spikelets, reduced tillering, chlorosis, wilting and poor yield. Symptoms often appear as patches in a field.
M. graminicola is known to cause serious damage to deepwater rice. Prior to flooding, symptoms are the typical stunting and chlorosis of young plants. When flooding occurs, submerged plants with serious root galling are unable to elongate rapidly, and do not emerge above the water level (Bridge and Page, 1982). This causes death or drowning out of the plants leaving patches of open water in the flooded fields.
List of Symptoms/Signs
Top of page| Sign | Life Stages | Type |
|---|---|---|
| Roots / galls along length | ||
| Roots / galls at tip | ||
| Roots / reduced root system | ||
| Roots / swollen roots | ||
| Seeds / empty grains | ||
| Whole plant / dwarfing |
Biology and Ecology
Top of page EcologyM. graminicola is found in upland soils, shallow flooded soils and deep flooded soils. It is well adapted to flooded conditions and can survive in waterlogged soil as eggs in egg masses or as juveniles for long periods. Numbers of M. graminicola decline rapidly after 4 months but some egg masses can remain viable for at least 14 months in waterlogged soil (Roy, 1982). M. graminicola can survive in soil flooded to a depth of 1 m for at least 5 months (Bridge and Page, 1982), it cannot invade rice in flooded conditions but quickly invades when infested soils are drained (Manser, 1968). All Meloidogyne spp. can be spread in soil and on seedlings of other crop hosts planted to a field. Because M. oryzae and, especially, M. graminicola are found in flooded rice there is the additional danger of dissemination in irrigation and run-off water.
Life Cycle
M. graminicola from Bangladesh has a very short life cycle on rice of less than 19 days at temperatures of 22-29°C (Bridge and Page, 1982), and an isolate from the USA completed its cycle in 23-27 days at 26°C (Yik and Birchfield, 1979). In India the life cycle of M. graminicola is reported to be 26-51 days, depending on time of year (Rao and Israel, 1973).
Infective, second-stage juveniles of M. graminicola invade rice roots in upland conditions just behind the root tip (Buangsuwon et al., 1971; Rao and Israel, 1973). Females develop within the root and eggs are mainly laid in the cortex (Roy, 1976a). Juveniles can remain in the maternal gall or migrate intercellularly through the aerenchymatous tissues of the cortex to new feeding sites within the same root (Bridge and Page, 1982). This behaviour appears to be an adaptation by M. graminicola to flooded conditions enabling it to continue multiplying within the host tissues even when roots are deeply covered by water. Juveniles that migrate from rice roots in flooded soil cannot re-invade.
Natural enemies
Top of page| Natural enemy | Type | Life stages | Specificity | References | Biological control in | Biological control on |
|---|---|---|---|---|---|---|
| Myrothecium verrucaria | Pathogen |
Notes on Natural Enemies
Top of page Many natural antagonistic organisms attack root knot nematodes (Kerry, 1987) including M. graminicola, but no specific organisms have been selected or recommended for control of this species in the field. Other Meloidogyne spp. can be attacked by the bacterium Pasteuria penetrans and the fungus Verticillium chlamydosporium.Pathway Vectors
Top of page| Vector | Notes | Long Distance | Local | References |
|---|---|---|---|---|
| Clothing, footwear and possessions | Eggs and juveniles in soil. | Yes | ||
| Containers and packaging - wood | Eggs and juveniles in soil. | Yes | ||
| Land vehicles | Eggs and juveniles in soil. | Yes | ||
| Eggs and juveniles in soil. | Yes | |||
| Soil, sand and gravel | Eggs and juveniles in soil. | Yes |
Plant Trade
Top of page| Plant parts liable to carry the pest in trade/transport | Pest stages | Borne internally | Borne externally | Visibility of pest or symptoms |
|---|---|---|---|---|
| Bulbs/Tubers/Corms/Rhizomes | adults; eggs; juveniles | Yes | Yes | Pest or symptoms not visible to the naked eye but usually visible under light microscope |
| Growing medium accompanying plants | adults; eggs; juveniles | Yes | Pest or symptoms not visible to the naked eye but usually visible under light microscope | |
| Roots | adults; eggs; juveniles | Yes | Yes | Pest or symptoms not visible to the naked eye but usually visible under light microscope |
| Seedlings/Micropropagated plants | adults; eggs; juveniles | Yes | Yes | Pest or symptoms not visible to the naked eye but usually visible under light microscope |
| Plant parts not known to carry the pest in trade/transport |
|---|
| Bark |
| Flowers/Inflorescences/Cones/Calyx |
| Fruits (inc. pods) |
| Leaves |
| Stems (above ground)/Shoots/Trunks/Branches |
| True seeds (inc. grain) |
| Wood |
Impact
Top of page M. graminicola can cause economic yield loss in upland, lowland and deepwater rice. In upland rice, there is an estimated reduction of 2.6% in grain yield for every 1000 nematodes present around young seedlings. The population levels which cause 10% loss in yield of upland rice are 120, 250 and 600 eggs/plant at 10, 30 and 60 days age of plants in direct seeded crops (Rao et al., 1986). In flooded rice, damage by M. graminicola is caused in nurseries before transplanting - the tolerance limit of seedlings is <1 J2 per cubic centimetre of soil (Plowright and Bridge, 1990). Damage also occurs prior to flooding where rice is sown directly in well-drained soils. Experiments have shown that 4000 juveniles/plant of M. graminicola can cause destruction of up to 72% of deepwater rice plants by drowning out. Losses as high as this in the field are unlikely as natural root populations vary considerably (Bridge and Page, 1982).Diagnosis
Top of page The presence and populations of M. graminicola in rice roots can be determined by standard root staining techniques. Root extractions will only isolate hatched juveniles and males, and a combination of root maceration and staining of a known weight of roots can be a more efficient and practical way of determining populations of sedentary females within roots. Assessing the severity of root damage by the amount of galling (root-knot index) is a practical and speedy method, but can be difficult with rice. One useful rating system is to rate only the percentage of affected large roots with the root tip galls characteristic of Meloidogyne on rice (Diomandé, 1984).Detection and Inspection
Top of page M. graminicola can be detected when plants are uprooted as it causes swellings and galls throughout the root system. Infected root tips become swollen and hooked, a symptom which is especially characteristic of this nematode.In upland conditions and shallow intermittently flooded land it can cause severe growth reduction, unfilled spikelets, reduced tillering, chlorosis, wilting and poor yield . Symptoms often appear as patches in a field.
M. graminicola is known to cause serious damage to deepwater rice. Prior to flooding, symptoms are the typical stunting and chlorosis of young plants. When flooding occurs, submerged plants with serious root galling are unable to elongate rapidly, and do not emerge above the water level (Bridge and Page, 1982). This causes death or drowning out of the plants leaving patches of open water in the flooded fields.
Prevention and Control
Top of page IntroductionIncreasing soil fertility can compensate for some damage by M. graminicola. Resistant cultivars hold out the most promise for effective and economic control, and some resistance to the different species has been found. Chemical control on the field scale is generally uneconomic, particularly with low-yielding upland rice, but could be an economic proposition for nursery soils.
Flooding
M. graminicola will survive normal flooding but damage to the crop can be avoided by raising rice seedlings in flooded soils thus preventing root invasion by the nematodes (Bridge and Page, 1982). Continuous flooding is highly effective in controlling M. graminicola in Vietnam (Kinh et al., 1982).
Resistance
The majority of rice cultivars are susceptible to M. graminicola. However, there are a number of cultivars from India, Thailand and USA which are reported to be resistant to this nematode (Bridge et al., 1990).
Crop Rotation
Certain crops are resistant or poor hosts of M. graminicola and could be used in rotation to reduce nematode populations e.g. castor, cowpeaa, sweet potatoes, soyabeans, sunflower, sesame, onion, turnip, Phaseolus vulgaris, jute and okra (Rao et al., 1986). Long rotations, greater than 12 months, will be needed to reduce M. graminicola soil populations to low levels. Introducing a fallow into the rotation will also give control of the nematodes but, to be effective, it needs to be a bare fallow free of weed hosts and is therefore impractical in most circumstances (Roy, 1978). However, one weed, Eclipta alba, is toxic to M. and could be grown and incorporated into the field soil to kill the nematodes (Prasad and Rao, 1979).
Soil Amendments
The use of decaffeinated tea waste and water hyacinth compost as organic soil amendments has been suggested to control M. graminicola (Roy, 1976b).
References
Top of pageAVA, 2001. Diagnostic records of the Plant Health Diagnostic Services, Plant Health Centre, Agri-food & Veterinary Authority, Singapore.
Bastidas H; Montealegre SFA, 1994. Aspectos generales de la nueva enfermedad del arroz llamada entorchamiento. Arroz, 43:30-35.
Birchfield W, 1965. Host parasite relations and host range studies of a new Meloidogyne species in southern USA. Phytopathology, 55:1359-1361.
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Golden AM; Birchfield W, 1965. Meloidogyne graminicola (Heteroderidae) a new species of root-knot nematode from grass. Proceedings of the Helminthology Society of Washington, 32:228-231.
Khuong NB, 1983. Plant-parasitic nematodes of South Viet Nam. Journal of Nematology, 15(2):319-323
Manser PD, 1968. Meloidogyne graminicola, a cause of root knot of rice. FAO Plant Protection Bulletin, 16:11.
Manser PD, 1971. Notes on the rice root-knot nematode in Laos. FAO Plant Protection Bulletin, 19:138-139.
Mulk MM, 1976. Meloidogyne graminicola. C.I.H. Descriptions of Plant-parasitic Nematodes, Set 6, No. 87:4 pp.
Rao YS; Prasad JS; Panwar MS, 1986. Nematode problems in rice: crop losses, symptomatology and management. In: Swarup G, Dasgupta DR, eds. Plant Parasitic Nematodes of India: Problems and Progress. New Delhi, India: Indian Agricultural Research Institute, 279-299.
Roy AK, 1976a. Pathological effects of Meloidogyne graminicola on rice and histopathological studies on rice and maize. Indian Phytopathology, 29:359-362.
Roy AK, 1977. Weed hosts of Meloidogyne graminicola. Indian Journal of Nematology, 7(2):160-163
Zainal-Abidin AA; Monen-Abdullah MA; Azawiyah AH, 1994. Meloidogyne graminicola: a new threat to rice cultivation in Malaysia. 4th International Conference on Plant Protection in the Tropics 28-31 March, 1994, Kuala Lumpur, Malaysia, 246-247.
Distribution Maps
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