EPPO Alert List – Meloidogyne graminicola
Rice root-knot nematode
Meloidogyne graminicola (Nematoda: Meloidogynidae - rice root-knot nematode) was first described in 1965 from grasses and oats in Louisiana (US). Since then, it has been found attacking primarily irrigated rice crops in Asia, and parts of the Americas and Africa. As in July 2016, M. graminicola was detected for the first time in the EPPO region in several rice fields of Northern Italy, the EPPO Secretariat decided to add this nematode to the EPPO Alert List.
All pictures were kindly provided by Alba Cotroneo
and Loredana Carisio (Phytosanitary Service of
Piemonte region, IT) – More pictures
Until recently, M. graminicola was only known to occur in Asia, parts of the Americas and in South Africa. In July 2016, it was detected for the first time in Northern Italy in 7 rice fields in the Piemonte region (provinces of Biella and Vercelli), where eradication measures were put in place. In 2018, it was also found in Lombardia.
EPPO region: Italy (Lombardia and Piemonte regions, under eradication).
Africa: Madagascar, South Africa (only one report).
Asia: Bangladesh, China (Fujian, Hainan, Henan, Hubei, Hunan, Sichuan, Zhejiang), India (Andaman and Nicobar Islands, Andhra Pradesh, Assam, Bihar, Delhi, Gujarat, Haryana, Himachal Pradesh, Jammu & Kashmir, Karnataka, Kerala, Madhya Pradesh, Manipur, Orissa, Punjab, Sikkim, Tamil Nadu, Tripura, Uttarakhand, Uttar Pradesh, West Bengal), Indonesia, Laos, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Singapore, Sri Lanka, Thailand, Vietnam.
North America: USA (Georgia, Louisiana, Mississippi).
South America: Brazil (Rio Grande do Sul, Santa Catarina, Sao Paulo), Colombia, Ecuador.
On which plants
The main economically important host of M. graminicola is rice (Oryza sativa) but this nematode has a wide host range of more than 98 host plants belonging to Poaceae and other plant families. M. graminicola has been found associated with other cereals and grasses, including weeds that are commonly present in rice fields. These weeds can be moderate to good hosts for M. graminicola and act as reservoirs when rice is not present during crop rotations. Within Poaceae, M. graminicola has been recorded on cultivated plants, such as: Avena sativa (oat), Hordeum vulgare (barley), Panicum miliaceum (millet), Pennisetum glaucum (pearl millet), Saccharum officinarum (sugarcane), Setaria italica (foxtail millet), Triticum aestivum (wheat), Zea mays (maize), and many weed species (e.g. Alopecurus spp., Brachiaria spp., Cymbopogon citratus, Cynodon dactylon, Digitaria spp., Echinocloa colona, Imperata cylindrica, Leersia hexandra, Paspalum scrobiculatum, Pennisetum pedicellatum, Phyllanthus urinaria, Poa annua, Sacciolepis indica).
In addition, several cultivated plant species belonging to Asteraceae, Cucurbitaceae, Fabaceae, Solanaceae and a few other families have been recorded as hosts of M. graminicola, such as: Allium cepa (onion), Allium tuberosum (Chinese chives), Brassica juncea (mustard), Brassica oleracea (cabbages), Cucumis sativus (cucumber), Glycine max (soybean), Lactuca sativa (lettuce), Musa sp. (banana), Petunia sp. (petunia), Phaseolus vulgaris (common bean), Pisum sativum (pea), Phlox drummondii, Solanum lycopersicum (tomato), Solanum melongena (aubergine), Solanum tuberosum (potato), Spinacia oleracea (spinach), Vicia faba (broad bean), Vigna spp.
In Italy, M. graminicola has been found associated with rice and weeds growing in the vicinity of affected rice plants (Alisma plantago, Cyperus difformis, Echinocloa crus-galli, Heteranthera reniformis, Murdannia keisak, O. sativa var. selvatica (wild rice), Panicum dichotomiflorum, Panicum spp.
On wild rice
On Heteranthera reniformis
As is the case with other root-knot nematodes, M. graminicola damages plants by affecting the development of their root systems which are distorted by multiple galls and devoid of fine roots. In upland and lowland rice fields infested by M. graminicola, when plants are in their first stages of vegetative development (early summer), patches of plants showing poor growth, loss of vigour, stunting, chlorosis with heavily affected root systems can be observed. In late summer and autumn, the above-ground symptoms may regress after flooding and fertilizing, as patches are colonised by the vegetation of growing and tillering plants. At this stage rice fields appear more uniform but infested plants show poor caryopsis production and empty spikelets. These symptoms are more evident in drained fields than in flooded fields. The infested roots present swellings and characteristic hook-shaped galls of different shapes and sizes, mainly formed at the root tips. According to the literature, it is estimated that M. graminicola can decrease rice yield by 20 to 80%, depending on the mode of cultivation (flooded or dry), environmental conditions, and soil structure. Severe infestation and large galls can be also observed on weeds. In Italy, Alisma plantago, Cyperus difformis, Echinochloa crus-galli, Heteranthera reniformis, Murdannia keisa, Oryza sativa var. selvatica and Panicum dichotomiflorum were found to be infested and showed the same above-ground symptoms as rice plants.
M. graminicola is an obligate sedentary endoparasite. Females lay eggs in masses within the root cortex. Second-stage juveniles (J2) then hatch, either remaining within the maternal gall or migrating in the same root to multiply. Infested roots may contain large numbers of eggs and J2s. M. graminicola can survive in waterlogged soil for long periods, as eggs (within egg masses) or as juveniles. Female and male specimens occur within the same gall. Males can be present in large numbers within galls, but scarcely occur in the soil. Numbers of M. graminicola decline rapidly after 4 months but some egg masses can remain viable for at least 14 months in waterlogged soil. The nematode can also survive in flooded soil to a depth of 1 m for at least 5 months. In flooded conditions, J2s cannot infect rice plants but when fields are drained, they resume their infectivity by attacking the root tips. The optimum soil moisture for M. graminicola is between 20-30% (with a dry soil at rice tillering and panicle initiation). The optimum soil temperature for nematode development ranges from 22 to 29°C. Under these optimal conditions, M. graminicola completes its life cycle in 19-27 days on rice.
Natural spread is very limited, as juveniles can only move over short distances towards roots in the soil. In paddy fields, passive transport may also be facilitated by movements of water and wild animals. As a root-knot nematode species, M. graminicola can easily be disseminated with soil, plants with roots, and root material (roots, tubers and rhizomes). Aerial plant parts on their own (flowers, fruits, seeds and leaves) will not spread the nematode. Eggs and juveniles can be carried by soil (including sand and gravel) transported as such or adhering to clothing, footwear, vehicles, agricultural and other earthmoving machinery.
Plants for planting, soil, soil attached to machinery or other material, soil debris mixed with unselected seeds from countries were the pest occurs. In addition, travelers coming from infested areas may transport the nematode (e.g. on hiking shoes, clothing, collected seeds or plants with adhering soil).
M. graminicola infests many plant species belonging to different families (mainly Poaceae but also Asteraceae, Cucurbitaceae, Fabaceae, Solanaceae) that include cultivated plants of economic importance to the EPPO region. The large host range of M. graminicola and its ability to survive for long periods in environments with low oxygen render its control difficult. Crop rotation with either non-host or poor-host crops is desirable, but may be difficult to implement in practice. Submerging fields with water for more than 18 months can control juvenile populations in the soil. Soil applications of nematicides in dry rice crops, biofumigations, and use of trap-crops in the rotation, can help in significantly reducing nematode populations in the soil. In addition, detection and determination of M. graminicola is difficult. Identification has usually been based on the presence of hook-like root galls on plant roots, however two molecular methods have recently been developed specifically for M. graminicola (i.e. SCAR marker for a rapid and reproducible identification; real-time PCR primers for the nematode quantification in the soil). As the possible establishment of M. graminicola in new areas represents a serious threat for economically important crops, in particular rice, cereals and other Poaceae, it seems desirable to avoid its further spread within the EPPO region.
The EPPO Secretariat wishes to warmly thank Dr Giovanna Curto (Nematology Laboratory, Servizio Fitosanitario, Emilia-Romagna, Bologna, IT) who has kindly provided the information presented above. Warm thanks are also due to Alba Cotroneo and Loredana Carisio (Phytosanitary Service of Piemonte region, IT) who have provided all pictures.
Bellafiore S, Jougla C, Chapuis E, Besnard G, Suong M, Vu PN, De Waele D, Gantet P, Thi XN (2015) Intraspecific variability of the facultative meiotic parthenogenetic root-knot nematode (Meloidogyne graminicola) from rice fields in Vietnam. Comptes Rendus Biologies 338(7), 471-483.
Birchfield W (1965) Host parasite relations and host range studies of a new Meloidogyne species in southern USA. Phytopathology 55,
Bridge J, Page SLJ (1982) The rice root-knot nematode, Meloidogyne graminicola, on deep water rice (Oryza sativa subsp. indica). Revue de Nématologie 5(2), 225-232.
Bridge J, Starr JL (2007) Plant nematodes of agricultural importance: A color handbook. San Diego: Academic Press.
Bridge J, Plowright RA, Peng D (2005) Nematode parasites of rice. In: M Luc, RA Sikora, & J Bridge (Eds.), Plant parasitic nematodes in subtropical and tropical agriculture (pp. 87–130). Wallingford, Oxfordshire, CABI Bioscience.
CABI (2017) Invasive Species Compendium. www.cabi.org/isc/datasheet/33243
Chapuis E, Besnard G, Andrianasetra S, Rakotomalala M, Nguyen HT, Bellafiore S (2016) First report of the root-knot nematode (Meloidogyne graminicola) in Madagascar rice fields. Australasian Plant Disease Notes 11(32). https://doi.org/10.1007/s13314-016-0222-5
Chen JW, Chen SY, Ning XL, Shi CH, Cheng X, Xiao S, Liu GK (2019) First report of Meloidogyne graminicola infecting Chinese chive in China. Plant Disease 103(11), p 2967.
Commission Implementing Regulation (EU) 2022/1372 of 5 August 2022 as regards temporary measures to prevent the entry into, the movement and spread within, the multiplication and release in the Union of Meloidogyne graminicola (Golden & Birchfield). OJL 206, 16-27 http://data.europa.eu/eli/reg_impl/2022/1372/oj
Dutta TK, Ganguly AK, Gaur HS (2012) Global status of rice root-knot nematode, Meloidogyne graminicola. African Journal of Microbiology Research 6(31),
Lotte obbligatorie - Nematode galligeno del riso (Meloidogyne graminicola) http://www.regione.piemonte.it/agri/area_tecnico_scientifica/settore_fitosanitario/vigilanza/nematode.htm
Katsuta A, Toyota K, Min YY, Maung TT (2016) Development of real-time PCR primers for the quantification of Meloidogyne graminicola, Hirschmanniella oryzae and Heterodera cajani, pests of the major crops in Myanmar. Nematology 18, 257-263.
Liu MY, Huang W, Peng D (2021) First report of Meloidogyne graminicola on rice in Henan Province, China. Plant Disease (early view). https://doi.org/10.1094/PDIS-02-21-0303-PDN
MacGowan JB, Langdon KR (1989) Hosts of the rice root-knot nematode Meloidogyne graminicola. Nematology Circular No. 172. December 1989. Contribution No. 397, Bureau of Nematology. Florida Department of Agriculture and Consumer Services. Division of Plant Industry.
Mantelin S, Bellafiore S, Kyndt T (2016) Meloidogyne graminicola: A major threat to rice agriculture. Molecular Plant Pathology 18, 3-15.
Negretti RRRD, Gomes CB, Mattos VS, Somavilla L, Manica-Berto R, Agostinetto D, Castagnone-Sereno P, Carneiro RMDG (2017) Characterisation of a Meloidogyne species complex parasitising rice in southern Brazil. Nematology 19(4), 403-412 (abst.).
NPPO of Italy (2018-08, 2020-03, 2022-12, 2023-04).
Pokharel RR, Abawi GS, Duxbury JM, Smat CD, Wang X, Brito JA (2010) Variability and the recognition of two races in Meloidogyne graminicola. Australasian Plant Pathology 39, 326-333.
Rao YS, Israel P (1973) Life history and bionomics of Meloidogyne graminicola, the rice root-knot nematode. Indian Phytopathology 26(2), 333-340.
Pokharel RR, Abawi GS, Zhang N, Duxbury JM, Smart CD (2004) Characterization of isolates of Meloidogyne from rice-wheat production fields in Nepal. Journal of Nematology 39(3), 221-230.
Rahaman Khan M, Mondal S, Singh A, Pal S (2023) First report of rice root-knot nematode (Meloidogyne graminicola) infecting wild jute (Corchorus aestuans). Australasian Plant Disease Notes 18, 12. https://doi.org/10.1007/s13314-023-00497-z
Rich JR, Brito JA, Kaur R, Ferrell JA (2009) Weed species as hosts of Meloidogyne: A review. Nematropica 39, 157-185.
Salalia R, Walia RK, Somvanshi VS, Kumar P, Kumar A (2017) Morphological, morphometric, and molecular characterization of intraspecific variations within Indian populations of Meloidogyne graminicola. Journal of Nematology 49(3), 254-267.
Singh I, Gaur HS, Briar SK, Sharma SK, Sakhuja PK (2003) Role of wheat in sustaining Meloidogyne graminicola in rice-wheat cropping system. International Journal of Nematology 13(1), 79-86.
Singh AK, Paschapur AU, Kushwaha AK, Mishra K, Kant L (2023) Detection of Meloidogyne graminicola (RRKN) in Kumaon region of the Indian Himalayas. Indian Journal of Agricultural Sciences 93(7), 710-714. https://doi.org/10.56093/ijas.v93i7.135351
Song ZQ, Zhang DY, Liu Y, Cheng FX (2017) First report of Meloidogyne graminicola on rice (Oryza sativa) in Hunan Province, China. Plant Disease 101(12), p 5153.
Tian ZL, Barsalote EM, Li XL, Cai RH, Zheng JW (2017) First report of root-knot nematode, Meloidogyne graminicola, on rice in Zhejiang, Eastern China. Plant Disease 101(12), p 2152.
Triviño C, Navia-Santillán D, Velasco L (2016) Plant-parasitic nematodes associated with rice in Ecuador. Nematropica 46(1), 45-53.
Unità di Crisi -19 Ottobre 2022 Piano di Azione Meloidogyne graminicola. https://fitosanitario.regione.lombardia.it/wps/portal/site/sfr/DettaglioRedazionale/organismi-nocivi/nematodi/red-meloidogyne (includes a map of the demarcated area).
Xie JL, Xu X, Yang F, Xue Q, Peng YL, Ji HL (2019) First report of root-knot nematode, Meloidogyne graminicola, on rice in Sichuan Province, Southwest China. Plant Disease 103(8), p 2142. DOI: https://doi.org/10.1094/PDIS-03-19-0502-PDN
Yik CP, Birchfield W (1979) Host studies and reactions of rice cultivars to Meloidogyne graminicola. Phytopathology 69(5), 497-499.
Entry date 2017-11