National references in nematology
The Libyan Arab Jamahiriya, a Mediterranean country, located in the North African coastal region, has a coastline of more than 1 000 km. After its revolution, the country has been facing very fast socio-economic changes in the form of development at all levels, especially in the agricultural sector. The construction of the so-called Great Man-Made River will bring water from underground reservoirs in the desert to the rich coastal land where it will be used for agriculture.
Because of its subtropical location and large land area, the country is suitable for the growth and establishment of many crop plants. Among the most commonly grown plants are:
· Cereals: wheat, barley, oat, millet and maize which yield approximately 3 to 5.5 tonnes/ha;
· Legumes: peas, groundnuts, beans, broad beans, chickpeas and buckeye peas;
· Vegetables: tomatoes, potatoes, eggplants, cucumbers, melons, onions, garlic, carrots, radishes, turnips and all edible leafy vegetables;
· Forage: alfalfa and medics;
· Fruit crops: date-palms, figs, apricots, grapes, peach, plums, almonds, citrus, apples and olives;
· Ornamental plants: many subtropical plants that are known to be adapted to the country are grown, such as rose, jasmine, geranium;
· Forest trees: most of the areas that are not suitable for cultivation of crops are planted with forest trees especially pine (mountain region) and acacia (inland) mixed with eucalyptus and desert shrubs depending on the soil type and rainfall.
Production levels have increased greatly through the use of advanced technology and better knowledge, compared with 20 years ago. There are at least 20 new projects distributed all over the country, mainly in the field of agriculture, totally directed towards the improvement and development of the living standards of the inhabitants of rural areas. All the crops listed above were found to be subject to attack by various plant-parasitic nematodes (Edongali et al., 1982 to 1989).
Nematology in the Libyan Arab Jamahiriya was one of the sciences introduced in the 1970s. Compared with other disciplines such as plant pathology, little attention was given to nematode problems until the 1980s when they were recognized as causing very serious problems on crops grown in intensive farming systems, especially in plastic houses and greenhouses.
Recently (1980 to 1992), more attention has been given to nematodes, especially plant-parasitic nematodes, in teaching and research. During this period four courses in nematology (two for undergraduates and two at graduate level) were introduced. As well as a graduate programme in plant protection, a master's thesis on nematode problems of the country was also introduced. During the last ten years five students have graduated with a master's degree in nematology. Three of them went on to take Ph.D. degrees at higher schools abroad. There are two institutions in the country that are involved in investigations of nematodes and their importance to crop plants in the Libyan Arab Jamahiriya The first is the Faculty of Agriculture, represented by the Plant Protection Department, where there are two specialist nematologists concerned with teaching and research on nematodes. The second, is the Agriculture Research Centre, which cooperates with the university at all levels to ensure the application of research results and provides extension services.
In the Libyan Arab Jamahiriya, plant-parasitic nematodes are considered a very serious problem on economic crops. The most common serious nematode is the root-knot nematode found throughout the country (Fourgani and Edongali, 1989) with a very wide host-range among all the cultivated crops in the country. The root-lesion nematode (Pratylenchus spp.) has four species which are found to attack a few herbaceous and woody plants such as date-palm. The citrus nematode (Tylenchulus semipenetrans) has been found in all the citrus-growing regions of the country (Edongali and El-Majberi, 1988).
Many other plant-parasitic nematodes are known to occur on various crops, e.g. Xiphinema spp., Longidorus spp., Ditylenchus spp., Globodera spp., Heterodera spp. and many in the Criconemoidea group. The most recent and serious introduction was the burrowing nematode Radopholus similis on bananas from Burkina Faso. It was eradicated immediately after arriving in a plane shipment.
The control of nematodes in the Libyan Arab Jamahiriya is divided into various systems described below.
· Ploughing the soil in the summer and subjecting the nematode to desiccation and starvation;
· Organic manuring of soil to encourage natural enemies of nematodes (a very common practice);
· Crop rotation (not very effective with resistant crops);
· Solarization by covering the soil with plastic during the hot summer after irrigation and ploughing (also very common).
Chemicals are the most commonly used treatment to control nematodes, although they can be dangerous to users and expensive. The chemicals used are:
· methyl bromide (gas) in greenhouses and plastic houses where preplanting treatment is carried out;
· Nemacur (G), as pre- and postplanting treatment on vegetables and established orchards;
· Vydate (G) is widely used as pre- and postplanting treatment;
· other chemicals have been used such as DBCP, Vagan and Tenekil, but they were abandoned internationally.
There is a public concern about the intensive use of chemicals because of their effects on human health, so most crops, especially vegetables, grown in chemically treated soils are not in high demand by consumers. Also it was found from chemical analysis of vegetables that the levels of these chemicals are higher than the tolerance limit for human consumption.
The number of specialists involved and institutions engaged in the programme are not sufficient to tackle the nematode problems in a country like the Libyan Arab Jamahiriya with its large land area and wide cropping diversity.
In addition, full public or government awareness of the importance of these serious pests in agriculture is lacking. The country requires all the support and help it can get to reduce the potential damage from nematodes, especially when they interact with other pests and diseases.
· Dr Ezarug A. Edongali (Ph.D. 1980, UCR) (Professor of Plant Pathology and Nematology)
· Dr Khalifa H. Dabaj (Ph.D. 1991, Hungary) (Assistant Professor of Plant Pathology and Nematology)
· Ms Gazzalla M. Fourgani (M.Sc.) (Researcher, University of Alfatih, Tripoli)
· Mr Mahmoud K. El-Houti (M.Sc.) (Assistant Lecturer, Aullia Institute of Agriculture, El-Marj)
· Mr A. El-Malin (M.Sc.) (Lecturer, University of El-Bida, College of Agriculture)
· Mr S. El-Majberi (M.Sc.) (Lecturer, University of El-Bida, College of Agriculture)
Dabaj, K.H. & Jenser, G. 1987. List of plants infected by root-knot nematodes in Libya. Int. Nematol. Network Newsl., 4(3): 28-33.
Dabaj, K.H. & Khan, M.W. 1981. Incidence of root-knot disease in tomato and potato and identity of the causal species in the western region of the Libyan Arab Jamahiriya. Libyan J. Agric., 10: 103-109.
Dabaj, K.H. & Khan, M.W. 1982. Root-knot nematodes on indoor cucumbers in Tripoli region of the Libyan Arab Jamahiriya. Plant Disease, 66: 819-820.
Edongali, E.A. 1986. Cyst-forming nematodes in Libya. In F. Lamberti & C.E. Taylor, eds. Cyst nematodes. 389 pp.
Edongali, E.A. 1987. Plant-parasitic nematodes associated with crop plants in southern regions of Libya. Proc. desert region conference. Murzuk, Libyan Arab Jamahiriya.
Edongali, E.A. 1989. Plant-parasitic nematodes associated with olive trees in Libya. Int. Nematol. Network Newsl., 6(1): 36-37.
Edongali, E.A. & Ben-Othman, K.A. 1988. Needle nematode Paralongidorus pisi in Libya. Int. Nematol. Network Newsl., 5(1): 22.
Edongali, E.A. & Dabaj, K.H. 1982a. Preliminary survey of nematodes associated with vegetable crops in western Libya. Libyan J. Agric., 11:201-204.
Edongali, E.A. & Dabaj, K.H. 1982b. Cauliflower Brassica oleracea cv. capitata cyst nematode in Libya. Libyan J. Agric., 11: 205-206.
Edongali, E.A. & Dabaj, K.H. 1986. Nematodes associated with date-palms (Phoenix dactylifera L.) in some regions of Libya. Proc. 2nd symposium of the date palm. Saudi Arabia.
Edongali, E.A. & El-Majberi, S.H. 1988. Plant-parasitic nematodes associated with citrus plantations in Libya. Pak. J. Nematol., 6: 23-24.
Edongali, E.A. & El-Malih, A.K.R. 1988. Pratylenchus thornei on almond in Libya. Int. Nematol. Network Newsl., 5(3): 44.
Edongali, E.A., Khalifa, M. & Dabaj, M. 1988. Apricot decline, possible cause(s) and control. Libyan J. Agric., 13.
El-Malih, A.R. & Edongali, E.A. 1988a. Plant-parasitic nematodes associated with apple trees in eastern regions of Libya. Libyan J. Agric., 13.
El-Malih, A.R. & Edongali, E.A. 1988b. Plant-parasitic nematodes associated with grape vines in eastern regions of Libya. Libyan J. Agric., 13.
El-Malih, A.R. & Edongali, E.A. 1988c. Plant-parasitic nematodes associated with peach orchards in Libya. Libyan J. Agric., 13.
Faraj, I.S., Khan, M.W. & Dabaj, K.H. 1980. Root-knot disease of cabbage and lettuce from Tripoli Province - a new record for Jamahiriya. Libyan J. Agric., 9: 123-126.
Fourgani, G.M. & Edongali, E.A. 1989. Speciation of root-knot nematodes (Meloidogyne spp.) associated with crop plants in Libya. Int. Nematol. Network Newsl., 6(1): 38-39.
Khan, M.W. 1979. State of knowledge of root-knot nematodes in the Libyan Arab Jamahiriya. Proc 2nd research and planning conference on root-knot nematodes, Meloidogyne spp., p. 127-129. Region VII, Athens, Greece, 26-30 November. (International Meloidogyne Project, Contract No. AID/ta-o-1234.) Raleigh, NC, USA, North Carolina State University.
Khan, M.W. & Dabaj, K.H. 1980. Some preliminary observations on root-knot nematodes of vegetable crops in Tripoli region of the Libyan Arab Jamahiriya. Libyan J. Agric., 9: 127-136.
Khan, M.W. & Siddiqi, Z.A. 1986. Some comments on root-knot infecting vegetables in Libya. Int. Nematol. Network Newsl., 3(2): 18-20.
Siddiqi, M.R. 1981. Six new genera of dorylaimid nematodes. Nematologica, 27: 397-421.
Siddiqi, M.R. & Siddiqi, Z.A. 1983. Paratrophurus acristylus sp. n. and Tylenchorhynchus graciliformis sp. n. (Nematoda: Tylenchida) from wheat fields in Libya. Proc. Helminthological Society of Washington, 50: 301-304.
Siddiqi, Z.A. & Khan, M.W. 1986a. Nematodes causing damage to wheat crops in Libya. Int. Nematol. Network Newsl., 3(1): 23.
Siddiqi, Z.A. & Khan, M.W. 1986b. A survey of nematodes associated with pomegranate in Libya and evaluation of some systemic nematicides for their control. Pale. J. Nematol., 4: 83-90.
Siddiqi, Z.A., Rashid, A., Farooqi, N. & Bisheya, F.A. 1987. A survey of plant-parasitic nematodes associated with citrus in Libya and trials on chemical control. Indian J. Nematol., 17: 76-80.