Use of Neem products in groundnut pest management in India

Transcription

1 Use of Neem products in groundnut pest management in India Abstract Indiscriminate use of synthetic pesticides in the groundnut ecosystem lead to killing of useful organisms, contamination in the food chain, pollution in the air and water. Though neem is indigenous to India, has been in limited use in the agricultural ecosystem. The potential of the neem as pesticides has been verified in groundnut crop by few researchers in India. The mortality of jassids, aphids, leaf miner in groundnut, action on hairy caterpillars are reported in literature. The negative aspects of neem as pesticides have also been reported. Integrated pest management includes a judicious blend of a multi-pronged approach either reducing the incidence or delaying the build up of the intensity of insect complex. So far, the work done in groundnut ecosystem has been reviewed in this article. Keywords: Neem, pesticide, leaf miner, jassid, aphid, early leaf spot, late leaf spot, IPM. IPC code; Int.cl. 7 A01N65/00 Introduction In recent years groundnut productivity in India has shown some upward trend, but, still remains much below the average productivity of leading groundnut producing countries in the world. The low groundnut productivity is attributed to several production constraints. Biotic factors such as insects and diseases play an important role in affecting the productivity and quality. Use of chemical pesticides for controlling insects and diseases has led to several environmental problems, V Nandagopal* and M P Ghewande National Research Centre for Groundnut, ICAR Post Box 5, Ivnagar Road, Junagadh , Gujarat * Correspondent author, vngpal@nrcg.guj serious health hazards to human-being and animals, development of resistance to pesticides in some insect pests and disease causing agents and destruction of beneficial insects like parasites and predators and pesticide residues. Growing awareness of the environment has made it imperative to search for alternatives to the synthetic chemicals. Since the ancient times, leaves, bark, fruit and seed of neem, Azadirachta indica A. Juss. have been known for insecticidal and anti-microbial activities. Efforts have been made to use neem products for the management of groundnut insect pests at National Research Centre for Groundnut (NRCG), Junagadh since 1986 with a view to develop low cost plant protection technology. Neem as insecticide The insect pests of groundnut can be categorized into: (a) those pests attacking underground parts (White grub: Holotrichia consanguinea (Blanch) and (b) those attacking aerial parts, viz. Leaf miner (Aproaerema modicella Dev.), Tobacco caterpillar (Spodoptera litura (F), Gram pod borer [Helicoverpa (=Heliothis) armigera Hb)], Jassid (Balclutha hortensis Lindb.), Thrips (Caliothrips indicus K.) and Aphids (Aphis craccivora Koch). Aqueous extracts of neem leaf, bark and seed, neem oil and neem-based formulations have been tested under laboratory insectary and field conditions for the reaction and management of major pests of groundnut. The neem based components of the IPM found promising under the laboratory and insectary conditions were also studied in combination with synthetic insecticides, trap crops and plant products under field condition. Besides, experiments were also conducted on the efficacy of neem products singly and in combination with Natural Product Radiance Vol 3(3) May-June 2004

2 Fig.1 : Crude neem oil-dimethoate sprayed plants other components. When 2% crude neem oil was sprayed on the groundnut plants there was dark foliages compared to the plants sprayed with crude neem oil mixed with 0.04% Dimethoate (Fig.1). At NRCG various studies conducted on the role of neem derivatives in the management of major pests by various methods have been summarized below: Ovicidal activity Among the defoliating insects of groundnut, the damage due to Groundnut leaf miner (A. modicella) results in pod loss ranging from 23 to 89%. Neem-based insecticides namely, Jawan and Margoside OK and CK were compared with crude neem oil or its blending with Hostathion. The immediate toxicity of crude neem oil at lowest concentration of 2% either alone or with Hostathion deterred 100 % oviposition of leaf miner and the residual toxicity persisted up to 15 days. Feeding deterrent Neither crude neem oil nor neem seed extract at 2% concentration, when sprayed on groundnut seedlings affected the biology of the groundnut aphids (A. craccivora ), but, it prolonged the duration of second instar of the insect from 3 to 5.5 days. Crude neem oil did not affect the fecundity, pre-oviposition, oviposition and life cycle of the aphid as a whole. The mortality of aphid varied significantly with various concentrations of crude neem oil; higher concentrations (2% and 5%) caused quick mortality. Complete mortality of both nymphs and adults occurred after 6-7 hr of exposure to the lowest concentration (0.2%) of crude neem oil. Of the 16 jassid spp., only two, namely Empoasca kerri and B. hortensis are most harmful to the crops and are a major constituent of the jassid complex in Saurashtra, Gujarat. The jassids cause yield loss of about 584 kg/ ha (Anon, 1988). The investigations carried out on the biology, feeding, oviposition in laboratory conditions showed that neem oil, neem leaf extract and neem leaf decoction at 5% concentration gave 87 to 91% cumulative mortality over 48 hr of exposure of the jassid, B.hortensis (Nandagopal et al, 1990). Neem as communication disruption When crude neem oil was sprayed on the groundnut crop leaving 1 m 2 area at the centre of the total of 25 m 2 area and placed the trap with virgin female prevented attraction of males by the virgin female by 100% for 24 hr, however, after 24 hr, the effect of neem oil was reduced slowly. Neem with synthetic pesticides To rationalise the use of synthetic pesticides, neem derivatives were mixed with the recommended pesticides and their compatibility among them and on the groundnut were investigated. Various concentrations of crude neem oil either alone or blended with synthetic pesticides were used at vegetative, pegging and crop maturity. Crude neem oil at 2% and in combination with Phosphomidon, Endosulfan, Carbendazim or with Mancozeb did not cause phytotoxicity to groundnut foliage. However, more than 2% concentration of neem oil showed phytotoxic effect. Hence, crude neem oil (2%) blended with compatible synthetic pesticides may be used in the groundnut ecosystem. Among the various plant products, use of crude neem oil and neem seed extract was found to be encouraging either alone or in blending with Endosulfan (0.04%) or Phosphomidon (0.02%) in the management of insects in groundnut. The 5% neem seed extract % Phosphomidon had lowest (1.55 %) intensity of leaf miner when compared to control (16.9 %), followed by 2% crude neem oil and gave maximum pod yield of 2068 kg/ha. While, crude neem oil 2% + Dimethoate 0.04% although gave pod yield of 1404 kg/ha, but caused yellowing and scorching of foliage in groundnut, hence, does not appear to be practical utility in the groundnut ecosystem. Similar observations were also made in the insectary study. Integrated Pest Management (IPM) Various components of IPM such as, plant products, trap crops, pheromones and mixture of insecticides with neem oil were studied under field Natural Product Radiance Vol 3(3) May-June

3 conditions during rainy seasons of 1990 and Pheromones, trap crops and 2% crude neem oil mixed with synthetic insecticides 0.02% Phosphomidon or 0.04% Endosulfan were tried either alone or in suitable combinations. The pesticide mixture 2% crude neem oil % Endosulfan % Phosphomidon was sprayed on main crop, trap crop or on both in the presence of trap crops and pheromone. The jassids, leaf miners and thrips populations were drastically suppressed throughout the growth period when insecticides mixture including neem oil were sprayed. The role of neem based insecticides mixture proved efficient in the management of these pests. The trap crops were also useful in trapping the insects as they lowered the pest population in groundnut, considerably. The judicious integration of these IPM components may solve the insect pests menace on groundnut without causing undesirable atmospheric pollution. Following IPM model was developed. Target insects Aphid (A. craccivora), Jassid (B. hortensis), Thrips (C. indicus) and Leaf miner (A. modicella). Components of IPM (a) Trap crops: Soybean as an intercrop; bajra as a barrier crop and castor as a border crop around the field. Three rows of bajra as a barrier crop around the field border followed by one row of castor. (b) Insecticides mixture: 2% crude neem oil. (c) Planting pattern: Sown groundnut and soybean (susceptible variety), crop in a row ratio of 3:1 (equidistant row spacing of 45cm, and plant to plant spacing 10 cm) followed by three rows of bajra around the field and one row of castor at 1m spacing between plants. (d) Spray schedule (need based): First spray of insecticide mixture be done at days after sowing to protect the crop from sucking pests (jassid, thrips and I st brood of leaf miner) and to take care of stray incidence of tobacco caterpillar (Spodoptera litura) and gram pod borer (Helicoverpa armigera). The second and third sprays are given at and days of crop growth to take care of sucking pests and second and third broods of leaf miner and other defoliators, respectively. (e) Pheromones: The pheromone 8/ha, respectively for mass trapping the male moths of leaf miner, tobacco caterpillar (Fig. 2) and gram pod borer be placed randomly at a height of 45 cm from ground level for Fig. 2 : Pheromones traps leaf miner and at 90 cm for other two pests. Neem as fungicide Several fungal, viral and nematode pathogens attack foliar and underground plant parts of groundnut. The major foliar fungal pathogen diseases include Early leaf spot (Cercospora arachidicola Hori), Late leaf spot [Phaeoisariopsis personata (Berk & Curt) V.Arxm], Rust (Puccinia arachidis Speg.), Alternaria leaf spot (Alternaria alternata Keissler), and Alternaria (Alternaria tenuissima). Soil-borne pathogens include Collar rot (Aspergillus niger Van Tieghem), Crown rot/seedling blight [A. pulverulentus (McAlp) Thom], Stem rot/sclerotium wilt (Sclerotium rolfsii Sacc.), and Dry wilt/dry root rot [Macrophomina phaseolina (Tassi) Goid.]. Among the foliar fungal diseases, early leaf spot (ELS), late leaf spot (LLS) and rust cause severe yield losses ranging from 10 to over 50 per cent. The chemical control of foliar diseases of groundnut through the spray of Carbendazim 0.05% + Mencozeb 0.2% is effective but expensive. As an alternative, 5% aqueous neem leaf extract was tried at the National Research Centre for Groundnut, Junagadh to control foliar diseases during rainy seasons. The effect of neem leaf extract on growth, seed infection and colonization of Alternaria species was also studied under laboratory condition. The main objective of using aqueous neem leaf extract was to generate information and develop low cost protection technology within the reach 152 Natural Product Radiance Vol 3(3) May-June 2004

4 of groundnut growing small and marginal farmers of the country (Ghewande et al, 1997). The aqueous neem leaf extract of 2% during rainy seasons of 1985 and 1986 and 5% during kharif 1989 and 1990 was sprayed 3 times at 2 week intervals starting from 4 to 5 weeks after planting. The mean data showed that the spray application of 2% aqueous neem leaf extract reduced early leaf spot (ELS) by 13.6% (mean of 1989 and1990), late leaf spot (LLS) by 22.2% (mean of 4 years, 1985,1986,1989 and 1990) and rust by 30.6% (mean of 2 years 1985 and 1986) and increased pod yield by 26.1% (mean of 4 years) over control with an additional pod yield of 279 kg/ha with a net return of Rs The growth of Alternaria alternata, A. tenuissima and A. raphani causing leaf spot, leaf blight and leaf blotch of groundnut was reduced by 77.8 to 95.7, 70 to 95 % and 88.5 to 92.4%, respectively with 1 to 5% aqueous neem leaf extract (Table 1). The aqueous neem leaf extract (1-5%) also inhibited seed infection by 41.2 to 100% and seed colonization by 20 to 100 % of groundnut by these fungi under laboratory conditions (Table 2). Holistic Integrated Pest Management (HIPM) After four consecutive experimentation in entomological, pathological and weed management by the concerned scientists, a Holistic IPM was tested for three rainy seasons of 1994,1995 and 1996 combining all the feasible components of the IPM. Table 1 : Growth of Alternaria species in aqueous neem leaf extract at 28 ± 1 C after 10 days Aqueous neem leaf extract (%) Table 2 : Effect of aqueous neem leaf extract and colonization by Alternaria species Control (sterilised distilled water) S. Em ± C.D. ns ns ns 7.54 ns (P=0.05) Source: Ghewande et al, 1993 Mycelia growth in g/l A. alternata A. tenuissima A. raphani Control (Glucose nitrate medium) S. Em ± C.D. (P=0.05) C.V Source: Ghewande et al, 1993 Aqueous Mean seed infection (%) Mean seed colonisation (%) neem leaf A. A. A. A. A. A. extract % alternata tenuissima raphani alternata tenuissima raphani Natural Product Radiance Vol 3(3) May-June

5 Components of HIPM 1. Seed treatment: Seed treatment with Trichoderma viridae 4g/kg of seeds for seed borne fungi. 2. Cultural practices: (a) Soil amendments with castor cake or mustard cake or neem 1000 kg/ha (preferably 15 days before sowing) for soil borne diseases like stem rot and collar rot. (b) Intercropping of groundnut with red gram/pearl millet/sorghum (3:1) depending upon the locally recommended intercrops for foliar fungal diseases. (c) Use of trap crop such as cowpea/ soybean/castor as border crop for sucking/defoliating insects. (d) One hand weeding after the application of pre-emerged weedicide Flochloralin@ 1.5 kg a.i/ha. 3. Biological control: Use of commercially available preparations of Trichoderma sp. for the control of stem rot and seed rot. (a) Seed 4g/kg seed. (b) Soil 25 to 62.5 kg/ ha. (c) Application of B.T. (Bacillus g/ ha) for Spodoptera and Helicoverpa (between days). (d) Use of pheromone traps for Spodoptera (10 per ha), Helicoverpa (10 per ha) and leaf miner (25 per ha). (e) Need based application of chemicals e.g. foliar spray of 2% crude neem oil in teepol (for both foliar fungal and sucking pests). (f) Weeding: Interculturing and hand weeding/ line weeding. The results indicated that the pest population were reduced to below ETL and the pod yields were significantly higher during all the three years experimentations. Cost effectiveness The cost of neem based mixture of insecticides was worked out to be Rs. 1185, Rs and Rs. 660/ha in case of crude neem oil, neem seed extract and neem leaf extract, respectively with synthetic insecticides. This scheme gives the option for rich as well as poor farmers. The rich farmers can spray the whole field while the poor farmers can manage even one third of the expenditure by spraying only the trap crops. Recommendations to the farmers Based on the review of literature and the experiments conducted at the NRCG the following recommendations can be made to the farmers. (i) Neem-based formulations at lower concentrations are compatible with the commonly used chemical pesticides. (ii) Aqueous extract of neem leaf, seed and oil (2%) in teepol may be used for the management of foliar diseases like leaf spots, rust, Alternaria diseases and seed borne pathogens and defoliators like Spodoptera, leaf miner and sucking insects such as jassids, aphids and thrips. (iii) Barrier and trap crops should preferably be included in the cropping system for sustainability and compensation for losses in the main crop. Conclusion Neem and its products could be a economically viable alternative to synthetic pesticides and use of neem could form a important component in IPM of groundnut, and could be utilized on large scale under field conditions in the country. The IPM module developed by the NRCG was also verified on farmers field 15 each during Kharif 1999, 2000 and Considering the added advantages of IPM technology which gave control of major insect pests ranging from 24-46% and diseases from 28-48% and average increased in yield by 19%, and highest gross monetary return of Rs /ha as against farmers practice of Rs /ha. However, future areas of research include: (i) generation of more information on the effects of neem products on insect physiology and reproduction of insects and inhibitory effects of neem on the diseases of groundnut, (ii) multi-location testing of the findings and demonstrating the IPM package with neem products as major components to the farmers, and (iii) evaluation of the spectra activity of the species of neem from different agroecological zones of India for their efficacy against insects and diseases. 154 Natural Product Radiance Vol 3(3) May-June 2004

6 References 1. Anonymous, Annual Report, National Research Centre for Groundnut, Junagadh, Gujarat, 1988, 75 pp. 2. Chandramohan N and Sivaprakasam P, Evaluation of neem products against leaf miner Aproaerema modicella Dev., Neem Newslett, 1987, 4, Ghewande MP, Management of major foliar fungal diseases of groundnut (Arachis hypogaea L.) using aqueous neem leaf extract of neem (Azadirachta indica A. Juss). In Neem for the Management of Crop Diseases (ed. V. Mariappan) Associated Publishing Company, New Delhi, India, 1995, pp Ghewande MP, Desai S, Prem Narayan and Ingle AP, Integrated management of foliar diseases of groundnut (Arachis hypogaea L.) in India, Int J Pest Management, 1993, 39, Ghewande MP, Nandagopal V and Desai S, Insect Pest and diseases management using neem and their products in groundnut. In IPM Series Ed: S.S. Narwal et al, Department of Agronomy, Punjab Agriculture University, Punjab, Gold CS, Wightman JA, and Pimpert M, Mulching effect on termite scarification of drying groundnut pods, Int Arachis Newslett, 1989, 6, Jacobson M, The neem tree: natural resistance par excellence. In Natural Resistance of Plants to Insects: Role of Allelochemicals (eds. M.B. Green, and P.A.Hedin). American Chemical Society Symposium Series, 296, 1986, , ACS, Washington, DC. 8. Jotwani MG and Srivastav KP, Neem insecticide of the future II. Reaction against field pests, Pesticides, 1981, 15, Koul O, Azadiractin interaction with development of Spodoptera litura F., Indian J Exp Biol, 1968, 23, Nandagopal V, Studies on integrated pest management in groundnut in Saurashtra. Ph.D. thesis, Saurashtra University, Rajkot, India, 1992, Nandagopal V, Jaroli RK, Ramkumar and Reddy P S, Neem products: possible insecticide on the groundnut jassid Balclutha hortensis Lindb., Int Arachis Newslett, 1990, 8, Patel HK, Neem seed suspension A sure deterrent to hairy caterpillar Amsacta moorei S, Madras Agric J, 1968, 65, Rao DVR, Singh KN, Wightman JA and Rao GVR, Economic status of neem cake mulch for termite control in groundnut, Int Arachis Newslett, 1991, 9, Rao PT and Subramaniyan B, Effect of azadirachtin on Achaea janata Linn. and Spodoptera litura F. (Noctuidae:Lepidoptera), J Entomol Res, 1987, 11, Saxena RC, Insecticides from neem. In: Insecticides of Plant Origin (eds. J T Arnasan, J R Philogene and P Morand), American Chemical Society Symposium Series, 387, 1989, , ACS, Washington, DC. 16. Schmutterer H, Properties and potential of natural pesticide from the neem tree Azadirachta indica, Annual Rev Entomol, 1990, 35, Schmutterer H, Saxena RC and VonderHeyde J, Morphogenetic effects of partially purified fractions and methanolic extracts of neem seeds on the Mythimna seperata (Walker) and Cnaphalocrosis medinalis (Guenee), Zeitschrift fuer Zoologie und angewandte Entomologie, 1983, 95, Wightman JA and Amin PW, Groundnut pests and their control in the Semi-Arid Tropics, Trop Pest Management, 1988, 4, Zanno PR, Miura I, Nakanishi K and Elder DL, Structure of the insect phagorepellent azadirachtin, J Am Chem Soc, 1975, Preparation of neem leaf extract The neem leaf extract can be used for nursery and kitchen gardens against leaf eating caterpillars, grubs, locusts and grasshoppers. For 5 litres of water, 1 kg of green neem leaf is required. The leaves are soaked overnight in water. The next day the leaves are grounds and the extract is filtered for use ( Natural Product Radiance Vol 3(3) May-June