STUDIES ON SOIL AMENDMENT STRATEGIES AND NEEM PRODUCTS FOR THE MANAGEMENT OF INSECT PESTS OF OKRA (Abelmoschus esculentus (L.) Moench). Nii - Arku Emmanuel Odai (Bsc. Hons.), Legon, Ghana. A thesis presented in partial fulfillment of the requirements for the degree of M. Phil. Entomology of the University of Ghana, Legon. Insect Science Programme* University of Ghana, Legon. July, 2001. * Joint interfaculty international Programme for thetraining o f entomologits in West Africa. Collaborating Departments: Zoology (Faculty o f Science) and Crop Science (Faculty o f Agriculture). University of Ghana http://ugspace.ug.edu.gh ,, 36824CS A S& 602 '05% DM University of Ghana http://ugspace.ug.edu.gh CONTENTS Page Declaration >v Dedication v List of Tables vii List of Abbreviations ix List of Plates x Abstract xi CHAPTER ONE 1 General introduction 1 CHAPTER TWO 5 2.0. Literature review 5 2.1. The Okra plant 5 2.1.1. Ecology of the plant 5 2.1.2. Importance in small - holding and commercial farming in Ghana 5 2.1.3. Importance in human diet 6 2.2. Okra production in Ghana 6 2.2.1. Production patterns and levels of okra production 9 2.2.2. Production constraints 12 2.2.3. Economics of okra production 16 2.2.4. Marketing constraints 16 2.3. Okra crop management practices 17 2.3.1. Current soil management practices 17 2.3.1.1. Use of inorganic fertilizers 17 2.3.1.2. Use of compost 18 2.4. Pest management in okra 19 2.4.1. Use of chemical insecticides 19 2.4.2. Use of botanical insecticides 21 2.5. Product application techniques for insect pest management 25 f University of Ghana http://ugspace.ug.edu.gh Table of content continued. Pa8e 2.5.1. Hydraulic energy nozzles 25 2.5.2. Spray coverage and distribution 26 2.5.3. Spray application 26 2.6. Integrated crop management in okra. 27 CHAPTER THREE - Experimental Work 29 3.0. Introduction - Studies on soil amendments and neem products for the management of insect pests of okra - 29 3.1. Materials and methods 30 3.1.1. Collection of neem seeds, drying and storage 30 3.1.2. Preparation of aqueous neem seed extract (ANSE) 30 3.1.3. Other insecticides 3 0 3.1.4. Site selection, land preparation and sowing 30 3.1.5. Treatments and their application, and experimental design 31 3.1.6. Data collected 32 3.1.6.1. Insects 32 3.1.6.2. Fruit damage 33 3.5.6.3. Fruit yield 33 3.1.6.4. Assessment of economic benefit 3 3 3.1.6.5. Data analysis 34 CHAPTER FOUR 35 4.0. Results 35 4.1. Insect fauna encountered on okra at Ashaiman 35 4.1.1. Effect of the different insecticide treatments on the major insect pests and beneficial insects encountered on okra during the sampling period 37 4.1.2. Relative abundance of major pests and beneficial insects observed under the various treatments at different growth stages of okra 41 4.2. Effects of the different treatments on growth and yield indices 46 4.2.1. Leaf damage 46 4.2.2. Plant height and girth 46 University of Ghana http://ugspace.ug.edu.gh Table of content continued. Page 4.2.3. Production of branches and functional leaves 48 4.2.4. Fruit damage 50 4.2.5. Percentage unmarketable fruits 52 4.2.6. Fruit dry matter and fresh fruit yield 52 4.2.7. Number of fruits produced per plant at harvest and weight of marketable fruits 55 4.3. Economics of production 57 4.3.1. Cost of production 57 4.3.2. Cost - benefit ratio and its monetary aspects 58 4.3.3. Marginal cost and benefit due to soil, and insecticide treatments alone 59 4.3.4. Marginal cost and benefit due to the combined effects of the treatments 60 CHAPTER FIVE 61 5.0. Discussion 61 CHAPTER SIX 76 6.0 Summary 76 6.1. Conclusions and Recommendations 77 References 78 Appendices 90 iii University of Ghana http://ugspace.ug.edu.gh DECLARATION I hereby declare that, except for references to other people’s work which have been duly cited, this work is the results of my own original research and that this dissertation has neither in whole or in part been presented for another degree elsewhere. Emmanuel Odai Nii -Arku (Student) Prof. K.Afreh - Nuamah (Principal Supervisor) University of Ghana Agricultural Research station, Kade. is / Dr. K. Ofos jlf-Budu (Co-Supervisor) University of Ghana Agricultural Research Station, Kade. (Co-Supervisor) Crop Science Department University of Ghana Legon - Accra. University of Ghana http://ugspace.ug.edu.gh DEDICATION I dedicate this thesis to my children, Champion Afotey Odai and Mathew Laryea Odai, my wife, Mary Amoadu, and my mother, Mary Abukweh Laryea, for their sacrifices during this course. I was away and denied you of my comfort, yet you prayed for me to endure all hardships to complete this programme. I say 1 would be forever grateful and God bless you! University of Ghana http://ugspace.ug.edu.gh LIST OF TABLES Tables page 1. Okra production in Ghana from 1970 - 1991 7 2. Production of okra in Ghana on regional bases 8 3. Asian vegetable production pattern and production levels in Ghana 11 4. Insect pests recorded on okra in Ghana 14 5. Major and minor insect pests of okra in Ghana and their damages 15 6. List of insects collected from okra plant during the sampling period at Ashaiman 35 7a. Effects of the different insecticide treatments on the major insect pests encountered on okra during the sampling period. 37 7b. Effects of the different insecticide treatments on the beneficial insects encountered on okra during the sampling period. 38 8a Relative abundance of major insect pests encountered on okra under the various treatments at pre - and post - flowering growth stages. 44 8b. Relative abundance of beneficial insects encountered on okra under the various treatments at pre - and post - flowering growth stages. 45 9. Effect of the different treatments on leaf damage in okra plant 46 10. Effect of the different treatments on plant height at flowering 47 11. Effect of the different treatments on plant girth development in okra plant 48 12. Effect of the different treatments on number of branches produced in okra 49 13. Effect of the different treatment on number of functional leaves produced in okra 49 14. Effect of the different treatments on number of fruits bored in okra 50 15. Effect on the different treatments on fruits dropped fruits dropped in okra 51 16. Effect of the different treatments on percentage unmarketable fruits produced in okra 52 17. Effect of the different treatments on fruit dry matter yield in okra 54 18. Effect of the different treatments on fruit yield in okra 54 University of Ghana http://ugspace.ug.edu.gh List of tables continued 19. Effect of the different treatments on number of fruits produced per plant at harvest in okra 56 20. Effect of the different treatments on weight of marketable fruits produced in okra. 56 21. Cost of the various operations involved in producing okra (ha) 57 22a. Cost - benefit ratio for the combined effects of soil and insecticide treatments 58 22b. Cost and benefits for the combined effects of soil and insecticide treatments use in okra 59 23a. Marginal cost and benefit for the soil treatments 59 23b. Marginal cost and benefit for the insecticide treatments 60 24. Marginal cost and benefit due to the combined effects of the various treatments in okra production 60 vii University of Ghana http://ugspace.ug.edu.gh ACKNOWLEDGEMENTS I wish to give thanks to the Lord, God Almighty for guarding and guiding me during the execution of this project. I am very grateful to Prof. Afreh-Nuamah, my Principal Supervisor for suggesting this topic and leading me into new direction for insect pest management. Drs. D. Obeng- Ofori and Ofosu-Budu, my co-supervisors, for their love, time, and constructive criticisms during the preparation of this thesis. I am also highly indebted to Dr. I. K. Ofori for his tremendous assistance and care during planning and analysis of this work. Special thanks also go Profs. Afreh-Nuamah and J. N. Ayertey for their financial support during this course, and also Dr. E. Owusu for his encouragement and guidance. My sincere thanks go to Mr. Ahia Clottey, a caring and loving friend, for the various forms of assistance and encouragement offered me throughout the course. Other friends, sympathisers, well-wishers and course mates are also acknowledged. I am also grateful to IDA, Ashaiman unit for allocating me a place for this project particularly, Mr. J. K. Antwi, the officer - in - charge. Special thanks also go to the SSIAP, and the soils division for their tremendous assistance, not forgetting of the farmers who participated in the project especially Messrs. Maxwell Owusu (Owuo) and Cephas. I am also grateful to my wife, Mary Amoadu, my children, Champion Afotey Odai and Mathews Laryea Odai, my parents and brothers for their moral support. Finally, I wish to thank Messrs. Asante, Vincent and Torgbor, all of the Crop Science Department of the University of Ghana for their various assistance during the preparation of this thesis. May God bless you all ! Amen!!. University of Ghana http://ugspace.ug.edu.gh LIST OF ABBREVIATIONS ha. Hectare mg. Milligram g- Gram Kg. Kilogram g/1- Grams per liter et al. And others cm. Centimeter t/ha. Tonnes per hectare r. h. Relative humidity °C. Degree celcius ml. Milliliter m. Meter LSD. Least Significant Difference GMT. Greenwich Mean Time ANOVA. Analysis of Variance ANSE. Aqueous neem seed extract 1/ha. Liters per hectare ix University of Ghana http://ugspace.ug.edu.gh LIST OF PLATES Plate Page Plate 1. Dysdercus superstitiosus (cotton stainer) 39 Plate 2. Anthonomus grandis (cotton boll weevil) 39 Plate 3. Podagrica uniformis (flea beetle) 40 Plate 4. Phenacoccus hirsutus (cotton mealy bug) 40 Plate 5. Rhinocoris rapax 42 Plate 6. . Aspavia brunnea 42 Plate 7. . Anoplocnemis curvipes 43 Plate 8. Larva of Earias insulana 43 X University of Ghana http://ugspace.ug.edu.gh ABSTRACT The effect of different soil amendment strategies, and neem products for the management of insect pests of okra was studied in the field at the Ashaiman irrigation project site. The insect pests encountered fell into seven orders belonging to twenty-three families. The important ones among these were Aphis gossypii (Glov.), Bemesia tabaci (Genn.), Dysdercus spp. Podagrica uniformis (Jac.), Heliothis armigera (Hb.) synonym Helicoverpa armigera (Hb,), Sylepta derogata (Fab.), Anthonomus grandis (Boh.) and Empoasca spp. Calidea spp. Pachnoda spp and Riptortus were also found attacking okra fruits in Ashaiman. The beneficial insects included Coccinella spp., Odonata spp. Cheilomenes vicinia (Muls.) and Rhinocoris rapax (L.). The neem products were less harmful to the beneficial insects and controlled homopteran pests better than the synthetic insecticide, dimethoate. Dimethoate was less effective in managing A. gossypii. and B. tabaci probably due to the development of resistance in these insects. In the field, the compost treatments improved plant vigour and enhanced their tolerance to pest attack than the sole chemical fertilizer, and gave significantly higher response in all yield indices studied. The sole fertilizer treated plants, however, performed better than the untreated control in fruit yield, damage, and vegetative yield indices studied. The combined effects of compost and aqueous neem seed extract (ANSE) at 50 g/1 enhanced okra resistance to insect pests attack, and improved yield and marginal benefit of over 100% the cost of production. ANSE was better than the formulated neem product, Neemazal at (2 ml/1), in managing the insect pests of okra, and compared favourably well with the synthetic insecticide, dimethoate 40% EC (75 ml/151). As a production package for okra, plants should be treated with compost prepared from cocoa husk, rice straw and poultry manure at (500 g/plant), ANSE (50 g/1) sprayed with cone nozzle is recommended. University of Ghana http://ugspace.ug.edu.gh CHAPTER ONE 1.0. GENERAL INTRODUCTION Okra (Abelmoschus esculentus) (L.) Moench, (Malvaceae) is also commonly referred to as okro or ladys fingers. The crop is of African origin and has spread to other parts of the world (Sinnadurai, 1992). However, it is extensively consumed in many other Tropical areas where it is grown mainly for domestic use (Rice el al., 1990). There are various varieties classified according to shape, colour, size, appearance as well as sliminess. The slimy cultivars such as ‘Asuntem’ red and white are preferred for soups and stew while the thin long cultivars which are less slimy such as Clemson spineless and Perkins long pod are used as salad (Sinnadurai, 1992), particularly the tender fruits when boiled or sliced and fried (Cobbley and Steele, 1976). Okra is one of the most important vegetables widely grown in Africa for its tender fruits and leaves (Ewete et al., 1980). The edible portion of the pod contains 2.0 - 2.2 % protein; 9.7 % carbohydrate; 0.2 % vitamin A (thiamin); and good source of minerals such as calcium, phosphorus and iron. (FAO, 1988; Margaret et al, 1989; and Norman, 1992) The young leaves are rich in protein (2.3 - 3.0 %) and vitamin B2 (Ewete et al., 1980; FAO, 1988). In West Africa, it is commonly mixed with fish, garden eggs and tomato as tasty salad. The crop is sometimes grown purposely for the seeds because of their high amounts of edible oil (Oyolu, 1983; FAO, 1988; Norman, 1992). Where there are good opportunities for sale, okra is among the most profitable tropically restricted agricultural products, which has found regular markets in the industrialised countries (Sigmund and Gustav, 1991). Consequently, the crop has currently gained high export potential and hence a source of foreign exchange to individuals and organisations in Ghana. However, in areas where okra is produced, the crop cannot be successfully grown without insecticide application. This is because every stage of the crop is vulnerable to insect pests attack. The crop is attacked by several insect pests and in Ghana, Critchley, (1997) observed 22 species of insect pests of 12 families in four orders attacking the okra plant in the Brong-Ahafo region alone. These include Aphis gossypii (Glov)., 1 University of Ghana http://ugspace.ug.edu.gh Earias biplaga (Wlk.) Podagrica unifomis Jac. P. sjostedti Jac., Sylepta derogata Butler, and Dysdercus superstitiosus (F.). Out of these, the Podagrica species are the most common and damaging in Ghana followed by Aphis gossypii, Dysdercus superstitosus and larvae of Spodoptera litoralis (Boisd.) and Earias biplaga (Norman, 1992; Obeng-Ofori, 1998). From a survey conducted as part of this studies, between August and September, 2000, in some vegetable growing areas in the Accra plains (Madina, Ashaiman, Kpone and Ningo), the most common insect pests of okra identified were Aphis gossypii followed by Bemisia tabaci (Genn.) and P. unifomis. Attack by these pests is reported to have denied farmers any harvest in the Tolon-Kumbungu district in Northern Ghana (Asante, 1978) and Kpone in the Tema district of the Greater - Accra Region (Udzu, 1993). As indicated earlier, most farmers rely mainly on synthetic insecticides for control of insect pests of okra. Cocktail mixtures of different pesticides sprayed at short intervals with inappropriate nozzles are used. This results in poor control of the pests. There are also adverse effects of these chemicals on the applicator, environment and consumers e.g. toxicity to beneficial and other non­ target organisms, pollution of the environment, tainting of produce, toxic residue levels in produce and poisoning of operators among others. These hazards coupled with their high costs, make the sole reliance on synthetic insecticides unsuitable for protecting the crop (Soliman and Bleih, 1994). Efforts to avert these adverse effects have created much interest in the search for an integrated approach, involving botanicals, efficient means of application and other agronomic practices as new tools to protect and increase the crop tolerance against insect pests. Neem (Azadirachta indicd) products have been used against the major pests of okra, A. gossypii, E. biplaga, P. uniformis and D. superstitiosus with mixed successes (Schmutterer, 1995). Emosairue and Ukeh, (1998) suggested that when these sprays are applied at higher concentrations (50 g/1 of water) and closer spray regimes, they may yield successful results as the synthetic insecticides. Okra has been observed to respond very well to high organic matter at the rate of 20 - 25 t/ha applied at least a fortnight before planting. Similarly, inorganic fertilizers also have positive effects on okra when applied at 250 - 300 kg/ha in the form of NPK 15-15-15 compound fertilizer (Norman, 1992). 2 University of Ghana http://ugspace.ug.edu.gh Compost is used to improve the physical conditions and fertility of the soil. It contributes in a major way to the diversity of soil organics and organisms that are critical to humus formation and to soil and plant health (Davis, 1982). The humus affect changes in the environment of the roots such as increase in water holding capacity and gas exchange among others, thereby enhancing plant metabolism (Flaig et al., 1977). Resource poor fanners usually grow okra without application of fertilizers and other soil amendments, rendering the crop more vulnerable to insect pests and diseases attack due to lack of vigour as a result of poor nutrient uptake. However, tolerance of okra to pests and diseases attack, and its performance could be increased by irrigating, manuring, or addition of fertilizer (NPK) and or decomposed organic matter. Such practices generally promote rapid growth and shorten the time that the susceptible stage of the crop would be available to pest attack, by providing the crop with greater tolerance and opportunity to compensate for insect damage (Jacob, 1990; Dent, 1991; Hugues and Philippe, 1992). Insect pests of okra such as P. uniformis, feeds on the leaf, and fruit surface; the fruit borer, Heliothis armigera (Hub.) seriously damage flower buds and bore into the fruit while the caterpillar of the spiny bollworm, Earias biplaga or E. insulana bore into flower buds, young shoots and petioles, and maturing fruits (Kaaya, 1990). These attacks reduce the quality and yields of okra, hence it is necessary that pesticides are distributed on and within the crop s canopy using appropriate nozzle to give adequate coverage of these localized niches of the pests for efficient protection. The use of soil amendments and neem products for any particular pest management in okra and the employment of an effective and efficient system for applying these botanicals would be paramount if yields and quality of produce are to be obtained and maintained. The main focus of this study is to evaluate integrated crop management strategies using neem products and soil amendment practices for reducing crop losses caused by insect pests of okra. The specific objectives for this study were therefore 1. To determine insect fauna associated with okra in the Accra plains and assess their damage. 2. To determine the effects of soil amendment practices on the incidence and damage of insect pests on growth and yield of okra. 3 University of Ghana http://ugspace.ug.edu.gh 3. To determine the most effective and efficient strategy for managing the insect pests. 4. To establish a cost benefit ratio for the different strategies used. 4 University of Ghana http://ugspace.ug.edu.gh CHAPTER TWO 2.0. LITERATURE REVIEW 2.1.THE OKRA PLANT Okra (Abelmoschus esculentus (L) Moench) , (Malvaceae) is an erect robust annual herb of up to two meters high. The leaves are large, alternate, and cordate and are divided into three to seven lobes with notched or toothed margins. The flowers are borne singly in the leaf axils on peduncles not more than 2.5 cm long with eight to ten very narrow, hairy bracteoles forming an epicalyx, which falls off before the fruit ripens (Kochhar, 1986). The flowers, which are yellow with brown centres, have shorter stamen and style (Messiaen, 1992). The fruits are long (10 - 30 cm), beaked, ridged, oblong hairy capsules, which dehisce longitudinally. The fruit’s colour ranges from light green, green and sometimes, red. When young, the fruits are mucilaginous and contains green or dark to black spherical but tuberculate seeds (Kochhar, 1986) with about 50 - 100 seeds per fruit (Messiaen, 1992). 2.1.2. Ecology of the plant Okra seeds germinate only in warm soils with temperature above 16 °C (Rice et al, 1990) and would not thrive where there is a continued cold spell (Kochhar, 1986). The crop grows quickly at high temperatures of 25 - 35 °C with a growth threshold temperature around 15 °C (Messiaen, 1992). It grows on a wide range of soils but well - drained, fertile soils with adequate organic material and reserves of the major elements are ideal (Rice et al, 1990) particularly in a moist, friable soil with a pH between 6.0 - 6.8 (Kochhar, 1986). Good crops have been raised from soils with pH 4.5 - 7.0 (Sinnadurai, 1992). 2.1.3. Importance in small - holder and commercial farming in Ghana In addition to the fruit being used as a vegetable, use is also made of the leaves, and stem. The leaves are used as spinach or fodder for goats, and the stem as fibre used domestically for tying firewood (Kemavor, 1977, Martin, 1982) and also as fuel wood (NARP, 1993). The high mucilage of the fruit helps to thicken soups and stews. The matured seeds are also roasted and ground as a coffee substitute in some West African countries (Martin, 1982). In the northern and upper Regions of Ghana, the fresh flower buds and leaves are also used in stews and soups (NARP, 1993). University of Ghana http://ugspace.ug.edu.gh In industry, a mucilaginous substance is prepared from the pod, which is used as plasma replacement or blood volume expander while mucilage from the stem and roots is used for clarifying sugar cane juice during jaggery manufacturing in India and for sizing paper in Malaysia and China. Also the matured pods and stems produce a fibre, which is used for textiles and paper making (Kochhar, 1986). 2.1.4. Importance in human diet The edible portion of the fruit contains 2.0 - 2.2 % protein; 9.7 % carbohydrate; 0.2 % Vitamin A (thiamin); and a good source of minerals such as calcium, phosphorus and iron (F.A.O., 1988; Margaret et al., 1989; Norman, 1992), as well as 1.0 % fibre; 0.2 % fats; 0.95 % ash, vitamins B and C and minerals especially iodine (Kochhar, 1986). The ripe seeds contain high amounts of edible oil (Oyolu, 1983) and the young leaves are also rich in protein (2.3 - 3.0%) and vitamin B2 (Ewete et al., 1980). 2.2. OKRA PRODUCTION IN GHANA In Ghana, okra is produced, sold and eaten in all the ten regions of the country. It is grown in mixed crop production system, often mixed with cassava, millet, groundnuts and other crops throughout Ghana in rainfed and small scale irrigation systems (small dams, dugouts/ponds, wells, etc. in Tamale, Bola, Bawku, Navrongo, Ada, Akumadan, Afife and Shai Hill). It is also grown as a sole crop in market gardens throughout Ghana and irrigated sites such as Ashaiman, Weija, Kpandu and Otsereko areas (NARP, 1993). Okra like other vegetables, has its production made up of 2 distinct components namely, a well paying market gardening section around the principal cities like Accra, Kumasi, Takoradi and Tamale, and a truck farming system where the crops are produced in distant places and transported in “Mummy” trucks to the cities (Sinnadurai, 1971). The local varieties commonly grown in Ghana include Labadi dwarf, Asontem red, Akatsi and Bawku red (Sinnadurai, 1992). In terms of production tonnage, Brong - Ahafo, Northern, Central, Greater Accra and Volta regions produce the bulk. (NARP, 1993). In Ghana, since 1974, there has been a dramatic fluctuation in land area under okra production from 51,000 ha to 7,300 ha in 1983. Similarly in terms of production tonnage, the total 6 University of Ghana http://ugspace.ug.edu.gh production from 1970 to 1991 followed a fluctuating trend, Table 1. On Regional basis, the production level and area under okra production is also indicated in Table 2. Table 1. Okra Production in Ghana from 1970 - 1991 Area under Production Year Production (‘ 000 Ha) Tonnage (‘ 000 MT) 1970 27.9 101.5 1971 27.9 101.6 1972 43.5 214.4 1973 34.4 170.7 1974 51.0 252.0 1975 32.4 159.5 1976 23.3 107.6 1977 23.2 111.0 1978 14.5 69.9 1979 19.9 97.2 1980 20.5 99.0 1981 8.6 40.4 1982 10.9 46.4 1983 7.3 20.2 1984 26.0 121.0 1985 21.0 102.0 1986 30.7 146.0 1987 27.4 138.9 1988 11.2 59.6 1989 28.0 146.5 1990 - - 1991 - - Source: NARP, 1993. 7 University of Ghana http://ugspace.ug.edu.gh Table 2. Production of okra in Ghana on a Regional Basis (Area in ‘lOOOITa and Tonnage in 1000 Mt) REGI ON Ashanti Brong Central Eastern Greater Northern Upper Upper Volta Western Ahafo Accra East West Ha 371 11629 685 - 1051 14010 - - 2537 - MT 1809 52710 3288 - 5348 68578 - - 1451 7 - - Ha 935 11000 1559 258 533 10000 8 8 3000 98 MT 4300 52100 7400 1200 2600 49200 50 50 1420 0 400 ~~ Ha 500 5000 1000 - 4000 2000 200 40 2000 60 MT 2900 23000 4500 - 2600 9900 900 200 9500 300 ~ Ha - - - - - - - - - - MT 4600 53200 7300 900 2700 50500 - - 1470 0 500 Source: NARP, 1993. 8 University of Ghana http://ugspace.ug.edu.gh 2.2.1. Production pattern and levels of okra production The plant begins to flower in about 40 days for early cultivars and 60 days for the late cultivars. The number of fruits produced by a plant varies from 8 to 22 depending on the cultivar. With good agronomic management and irrigation, okra plant will produce about 250 grams of fruit in a season but yield seldom exceeds 3,300 kg/ha. However under erratic rainfall, yields can be as low as 500 kg/ha though the crop can tolerate temporary drought conditions (Sinnadurai, 1992, and Critchley, 1997). Adelane (1986) reported that when okra is grown as an intercrop with maize, its yield is drastically reduced from an average of 9.4 fruits per plant in pure stand to 6.4 fruits per plant in intercropping. Messiaen (1992) also reported of yields of 7 -10 t/ha and 15 - 20 t/ha from the early and late maturing varieties respectively when grown as a sole crop and, harvesting spread over 60 - 80 days. In the Accra plains two varieties of okra are grown. These are the early (6 weeks) and late (8 weeks) varieties. The former is whitish in colour and drought resistant whereas the latter is greenish and drought susceptible. The 6 weeks variety is normally cultivated either in September, October or November while the 8 weeks Cultiver is grown in the months of February, March and April (Kemavor, 1977). From a survey conducted by F.A.O on some major crops grown in some regions of Ghana, it was reported that in the Navrongo and Bolgatanga districts of the Upper East region, okra is grown between the months October and April. However, in the Akumadan and Kumasi districts of the Ashanti region, okra is cultivated between the months Oct - April, and January - July, while in the Asamankese and Suhum districts of the Eastern Region, okra is produced between the months October - March and April - June. Considering the Greater Accra region, the production period for okra in the districts visited are Kakasunaka, May-September; Dahwenya, May - September (rainfall) and October - April (irrigated), Weija, May -September (rainfall) and October - April (irrigated) but in Accra and Ashaiman, okra is produced all year round (F.A.O, 1997). According to Boateng (1991) there are 3 seasons for producing okra in the Ashanti region. These are major and minor rainy seasons, and the dry season. In the major season, the Asuntem variety and the long duration types are grown while in the minor season the dwarf, short duration types, are cultivated. This is because the dwarf types are able to complete their cycle within the short rains hence no irrigation is required. However in the dry season, production takes place only in the low-lying areas, valley bottoms, where the 9 University of Ghana http://ugspace.ug.edu.gh water table is high. During this time, natural underground water is supplemented with water from wells. He also reported that the intensity of okra production decreases with the seasons hence yields in production tend to decrease with the rains in these areas of the region, Ejisu, Nkawere, Mankroso and Edujama. The National okra, and some Asian vegetable production patterns and levels under different growing conditions are in Table 3. 10 University of Ghana http://ugspace.ug.edu.gh Table 3 Asian Vegetable Production Patterns and Production Levels in Ghana VEGETABLE Yield Yield, Potential Time of Planting Time of Harvesting Gestation W ater Plant Population Rainfed Irrigated Yield, North South North South Period requirement ( ‘ 000)Plts/Ha (T/HA) (T/HA) Rainfed (T/HA) (Days) (mm) Cabbage 12.5 25 18,75 Dec/Jan Dec/Jan Feb/Mar Feb/Mar 90 1500-2000 30000-55000 Carrots S 30 20 Dec/Jan Feb/Mar 90 600-1000 450000 Garden eggs S 22 15 April/May July/Aug 90 1000-2000 31000 Lettuce 5 15 10 Dec/Jan Feb/ Mar 60 1500-2000 150000 Melon (Agusi) 12 55 27.5 Okra 8 15 12.5 April/May April/May June/July June/July 60 35000 Pepper 15 22.5 20 July -do- Aug/Sept -do- 90 600-1500 35000-40000 Pumpking 8 10 10 April/May June/July leaves Talinum leaves June/July 60 1000-2000 Source: PPMED,2001 University of Ghana http://ugspace.ug.edu.gh 2.2.2. Production constraints In Ghana, low yields in okra are attributed to several production constraints among which low soil fertility, and damage caused by insect pests are most critical (Hayase, 2001). Damage caused by insect pests has been reported as the major constraint ( Sinnadurai, 1971; Critchley, 1997). Tindal (1965) reported of okra being attacked by several insect species in Ghana. These include Sylepta derogata (F.), Dysdercus superstitiosus (F), Aphis gossypii (Glov.) and Podagrica uniformis (Jac.). Critchley (1997) reported of 22 insect pests from 12 families in four orders (Coleoptera, Hemiptera, Lepidoptera and Orthoptera) attacking okra in Brong-Ahafo region of Ghana. Of these, the most important are the flea beetles, Podagrica uniformis Jacoby and P. sjostedti Jacoby, followed by aphids, A. gossypii Glover, cotton stainers, Dysdercus superstitiosus (Fab) and Lepidopteran caterpillars, Sylepta derogata (Fab.) and Heliothis armigera (Hub.). The blister beetle, Mylabris spp., feeds on the flowers, reducing the number of fruits formed, while both adults and nymphs of A. gossypii suck sap from young leaves and buds, thus reducing the efficiency of the leaves. Nymphs and adults Leaf hoppers, Empoasca spp., attack leaves and cause their edges to curl down and become chlorotic. The leaf-footed bug, Anoplocnemis curvipes (Fab.) (both nymphs and adults), attacks new shoots and developing fruits to cause distortion of leaves and poor development of fruits, and their attack is similar to that of the coreid bug, Riptortus tenuicorinis Dali. The shield bug, Halomorpha annulinornis Sign., and the green stink bug, Nezera viridula (L), both attack developing pods and suck sap from leaves causing local necrosis. The adults and nymphs of the cotton Stainer, Dysdercus superstitiosus (Fab.), pierce and suck pods which then shrivel, and cause reduction in seed viability. However, the larvae of Anomis flava (Fab.) feed on the leaves causing severe defoliation, while adult crickets, Oecanthus spp., attack and bite a pear-shaped hole in the leaf. The leaf roller, Sylepta derogata (Fab.), attacks the leaves, which they cover in webbing as the leaves curl and droop. (Asante, (1978) observed that A gossypii Glov. (Aphididae) was most prevalent and occured in small colonies, mostly confined to the under surface of leaves, sucking sap, and causing appreciable damage. However, the cotton whitefly, Bemisia tabaci Genn. (Aleyroidae) occured in low numbers and suck sap from the underside of leaves. He also observed Prodenia litura (F.) 12 University of Ghana http://ugspace.ug.edu.gh (Noctuidae) on old plants feeding on the upper side of young leaves causing appreciable damage, similar to that of Aegocera rectilinea Bdv. (Noctuidae). P. uniformis was found feeding on the fruits and flowers, and are responsible for virus - induced mosaic in okra (Lana et al., 1974). Tables 4 and 5 present some of the important insect pests that attack the crop in Ghana. However, the constraints vary based on the production area. For example in the Anlo-District of the Volta region, lack of extension services, pest infestation and high cost of seeds are the major constraints facing the okra industry (Gilbert, 1990). However, in the Akatsi district, okra production has been limited also by lack of extension officers to educate fanners in farm management practices like fertilizer and insecticide application, harvesting time and frequency in order to increase yield (Paul, 1991). An F.A.O survey in some okra producing areas in Ghana recorded the following: In the Upper East region, Bolgatanga and Navrongo district, access to quality seed, fluctuations in market prices, low soil fertility, insect pests and diseases were the major problem hindering okra production. But, in the Bongo district also of the Upper East region, the problem was rather related to limited arable land area, lack of money to buy inputs and post-harvest storage. In the Ashanti region, however, okra production was found to be hampered by fluctuation in market prices, lack of good roads, pests and diseases attack. In the Asamankese district of the Eastern region, lack of quality seeds, good farming land, money to buy agro - chemicals, and price fluctuation were noted whilst Vegetables farmers in Dodowa, Kakasunaka, Dohwenya, Weija and Accra of the Greater Accra region complained of root knot nematodes, lack of quality seeds, insect pests and diseases, erratic rainfall, limited access to credit for inputs and labour, poor access to land, insect pest resistance, lack of water pumping machines and abuse of pesticide (F.A.O, 1997). Research has had little impact on the production of okra in Ghana. This is because only limited research findings have been available to farmers. Consequently there has been little adoption of okra production technology by farmers. Even though technological interventions in seed quality, fruit maturity and quality indices as well as post harvest loss control are available. Other bottlenecks are high cost of agrochemicals and or methods for pest and diseases control (NARP, 1993), and presence of soil born diseases and inadequate nutrient management practices. (Ofosu- Budu etal., 1998). 13 University of Ghana http://ugspace.ug.edu.gh Table 4 . Insect pests recorded on okra in Ghana Insect pest____________________ Order Family Anomisflava F. Lepidoptera Noctuidae Lagria cuprina Thoms. Coleoptera Lagriidae Podagrica uniformis Jac. Coleoptera Chrysomelidae Ootheca mutabilis Sahl. Coleoptera Chrysomelidae Podagrica sjostedtis Jac. Coleoptera Chrysomelidae Chasmina Camilla Druce. Lepidoptera Noctuidae Comsophila flava Druce. Lepidoptera Noctuidae Lagria villosa F. Coleoptera Lagriidae Mylabris temporalis Wellem. Coleoptera Meloidae Mylabris adbominalis Coleoptera Meloidae Labidognatha sp Coleoptera Scolytidae Aphis gossypii Glov. Homoptera Aphididae Bemisia tabaci Genn. Homoptera Aleyroididae Locris maculata F. Homoptera Cercopidae Dysdercus superstitiosus F. Hemiptera Pyrrhocoridae Sylepta derogata (F.) Lepidoptera Pyrelidae Prodenia litura (F.) Lepidoptera Noctuidae Aegocera rectilinea Bdv. Lepidoptera Noctuidae Plutella maculipennis (curtis) Lepidoptera Noctuidae Source: (Forsyth, 1962; Gupta, 1971; Asante, 1978). 14 University of Ghana http://ugspace.ug.edu.gh Table 5. Major and minor inspect pests of okra in Ghana and their damage Common Name Scientific Name Parts Attacked Major pest Flea beetle Podagrica uniformis Jac. Roots and leaves White fly Bemisia tabaci Genn. Leaves American bollworm Heliothis armigera Hub. Flower and pods Cotton aphids Aphids gossypii Glov. Leaves Minor pests Weevils Coryssopus fulvescens F. Stems and roots Mecysolbus crassirostris F. Stems and growing shoots Leaf beetle Ootheca mutabilis (Salhlberg) Leaves Long-jointed beetle Lagrica cuprina (Thoms.) Leaves L. vilosa F. Leaves Jassids Empoasca spp Leaves Semi-looper Anomis (cosmophilla) flava (F.) Leaves Noctuid Moths Chasmina Camilla (Meyr) Leaves Leaf roller Sylepta derogata (F) Leaves and pod Seed bug Oxycaraenus spp Developing seed Stink or Shield bug Nezera viridula (L) Pods Cotton stainer Dysdercus superstitiosus (L) Slender stems, pods Diamond-back Plutella maculipennis (L) Leaves Root Knot Meloidogyne spp Roots Nematode Source: Anon (2000). 15 University of Ghana http://ugspace.ug.edu.gh 2.2.3. Economics of okra production The viability of okra production as an enterprise varies according to the location, the season and the management practices adopted. In the coastal savanna zone, it has been estimated that about 250.2% returns on investment can be realised on a hectare of okra while in the forest zone, a return on investment of 231.3% is achieved on one hectare of okra under proper soil and pest management practices (PPMED, 2001). Returns from okra production can further be increased by using more labour especially for applying fertilizers, spraying insecticides, weeding and harvesting the crop (Kemavor, 1977). Gilbert, (1990) reported that applying fertilizer and pesticides makes okra production a profitable enterprise with over 100% return on investment at the Anlo district. In an earlier work, Obeng-Ofori (1982) reported of over 100% returns from okra production per hectare when 2.0g Furadan 5G was applied per plant with a cost - potential benefit ratio of less than one. However, Sackey (1999) reported that the use of aqueous neem seed extract applied at 50g/litre of water for the management of insect pests of okra yielded over 153% returns on the investment while the untreated control which yielded a loss of 12%. Ofosu- Budu (in-press) has recently recorded over 200% turnover on okra grown in compost at Asamankese in the Eastern Region. Consequently, he commended okra production in this area as a viable enterprise especially when the crop is grown in compost. 2.2.4. Marketing constraints Marketing of okra in Ghana is saddled with a lot of problems, which hamper the development of the okra industry. Storage of fresh vegetables like okra is limited, and often during peak harvests, market prices drop. In other situations, access to the market is a constraint due to either poor state of secondary roads or lack of transport (FAO, 1997). Vegetable characteristics such as size, shape or tenderness like any other foodstuff in the country lack standardization. For example, only departmental stores and kiosks use scales for weighing the okra. This makes it difficult to formulate policy on their prices. The perishable nature of okra is also a menace to its farmers. Poor processing and storage facilities, lack of marketing finances, grading and standardization are also key constraints to okra marketing in Ghana. Poor marketing information system, which also hinders proper allocation of resources in vegetable production, leads to poor distribution of the vegetable (Tarimo, 1977; Boateng, 1991; FAO, 1997). 16 University of Ghana http://ugspace.ug.edu.gh 2.3. OKRA CROP MANAGEMENT PRACTICES The current management practices in okra take the form of an integration of several cultural, chemical and soil factors. 2.3.1. Current soil management practices Currently okra farmers in Ghana manage their soils with both inorganic and organic fertilizers with the view to increasing yield of the crop. The use of these as nutrient sources for vegetables have been widely investigated (Sinnadurai, 1992; Norman, 1992). 2.3.1. l.Use o f inorganic fertilizers These are chemical substances that are applied to soil to increase crop yields by providing one or more of the elements that are essential plant nutrients. They increase yield and promote plant's growth by supplying more plant nutrients than organic manures in the cycle of growth and decay. Consequently with good farming practices, much of the extra plant nutrients that are bought can be maintained in circulation, thereby raising cropping potential or fertility of the land. In addition, fertilizers lessen the cost of production per tonne since they raise yields without a correspondingly large increase in total costs per hectare (Cooke, 1982). In the Near East, selected agricultural practices for vegetable cultivation which also aims to manage insect pests at reduced pesticide application by farmers include balanced fertilization to address nutritional deficiencies, and irrigation to prevent water stress (Anon, 2000). All these stimulate plant growth, and enhance the plant resistance to, or tolerance of, pests and diseases. This practice has proved very successful and has now become an important component of Integrated Pest Management (IPM) strategies for vegetable production (Lebeek and Lenteren, 1992). Cultivated crops are weakened by poor nourishment, and even if they show no deficiency symptoms such as chlorosis, stunting, leaf or fruit fall, they tend to be more prone to significant pests damage because the plants lack vigour. Vigorous plants are well - fed and regularly watered, hence are able to replace the sap sucked up by aphids, and are strong enough to develop new shoots and leaves. Chemical fertilizers speed up plant growth and increase yields, however, they often cover plant resistance and make them more attractive to pests. Consequently, farmers who feed their crops exclusively on chemical fertilizers, and on nitrogenous fertilizers in particular have to use pesticides in order to compensate for the low resistance of their crops. On 17 University of Ghana http://ugspace.ug.edu.gh the other hand, crops grown on organic materials like compost or manures, obtain a range of nutrients that they need to thrive and withstand the attacks of microorganisms and insect pests (Hugues and Philippe, 1992). Davis (1982) reported that the positive effect of mineral fertilizers depends upon well-regulated humus husbandry. Consequently, the growth of crops and therefore the yield of harvests depend upon the soil physical and mechanical properties as well as the inorganic and organic soil matter. Jacob (1990) reported that a well-timed and adequate application of fertilizer treatment promotes early and fast development of the crop, enabling it to recover more easily from insect pests attack. He indicated also that well nourished plants are more tolerant to attacks by various diseases and pests, and because of their vigorous growth, they recover better from any injuries suffered. 2.3.1.2. Use o f compost Compost as a component of organic farming involves the return of organic matter to the soil. It involves adding only products in their naturally occurring states to the soil. Some organic farming systems have produced good yields through increasing plant tolerance to insect pests and diseases, (Cooke, 1982). Muchena (1991) reported that majority of small-scale vegetable farmers in Zimbabwe use kraal manure, poultry manure and compost in the nursery and at planting for fertilizing and controlling insect and diseases. He stated further that a research is needed to make this improved practice cost effective and attractive to the financial resource poor farmers. Keya, (1978) reported that in East Africa, a growing potential source of organic materials (compost) and pretreated dried sewage is being used in vegetable farms in Nairobi with promising results, whilst in Tanzania, the productivity of vegetables is increased by using compost, lime and N.P.K. fertilizer. The compost increases the pH, changeable Ca, K and Mg, (Le Mare, 1972). The U.S. department of Agriculture observed that in Maryland, vegetable seedlings produced with compost were of better quality, had more developed root systems, and were transplanted with lower mortality and matured earlier than those grown only with inorganic fertilizer. Consequently through the proper use of compost, it is possible to grow wide variety of both horticultural and vegetable crops (Parr et al., 1982). Compost contributes in a major way to the diversity of soil organic matter and living organisms critical to humus formation and to soil and plant health (Davis, 1982). 18 University of Ghana http://ugspace.ug.edu.gh Organic matter when broken down into humus has direct and indirect effects on growth and yield of crops. The humic substances (mainly higher molecular weight parts) affect changes in the environment of the roots by changing physical and chemical properties like water holding capacity, gas exchange and others which lead to better growth of the crop, resulting in yield increases. The low molecular weight organic compounds from the compost results in increased plant metabolism. Phenolic compounds formed by lignin degradation or microbial syntheses are responsible for the resistance of crops to frost, drought, pests and diseases, (Flaig et al., 1977). The application of organic matter or inorganic fertilizers alone gave unsatisfactory results in numerous vegetable experiments, but by combining both treatments, yield increases of up to 100 % were obtained, (Jacob, 1990). Noah (1998) also reported from his work on the effect of compost in nutrient uptake, fruit yield and yield component, fruit quality and disease incidence in tomato that no significant difference occurred among compost related treatments on marketable fruit yield and nutrient uptake but were significantly different from the untreated control and sole fertilizer treatments. On the effects of compost on yields, and vigour in cabbage, Brassica oleracea, var capitata, Ofosu - Budu (unpublished) reported that plants grown in compost yielded heavier heads of at least l.Okg/plant, grew vigorously and had more greener leaves compared to the fertilizer and the control treatments. Also according to Ofosu - Budu, (unpublished) significant yield increase was realized when tomato seedlings were raised in compost and transplanted to the field at flower initiation under semi - deciduous forest condition. Consequently, by increasing the organic matter content of the growing medium and by improving soil moisture through irrigation, the number of infected plants was reduced and higher yields were produced in vegetables. 2.4. PEST MANAGEMENT IN OKRA 2.4.1. Use of chemical pesticides Insect pest are responsible for reducing productivity and gross output in agriculture consequently losses due to these pests must be eliminated in order to increase yields (Hill, 1987). To achieve higher productivity, okra farmers have depended heavily on the use of synthetic insecticides to combat insect pest, diseases and nematodes. David (1964) reported that Thiometon at 0.1% applied twice at fortnight interval to one-month-old plants effectively controlled the leaf hopper, Empoasca devastans D. (Homoptera: Cicadellidae). Yazdani (1971) also found that four 19 University of Ghana http://ugspace.ug.edu.gh organophosphates, demeton, phosphamidon, diazinon and parathion were very efficient at 0.02% concentration for the control of the spotted bollworm, Earias fabia Stoll. (Lepidoptera: Noctuidae) which caused considerable economic losses to cotton and okra in Tanzania. Rivivasan and Gowder (1973) indicated that spraying endosulfan 0.7 % or sevimol 0.01% three times controlled aphids, leafhoppers and fruit borers, which are serious pest of okra. Dipel (Bacillus thuringiensis var. thuringensis Berliner) when applied at the rate of 0.56 - 1.12 kg/ha was suitable alternative for the control of Lepidopterous larvae associated when okra is grown for leaves and fruits (Taylor, 1974). According to Obeng-Ofori (1982), okra treated with 2g Furadan 5G per plant was protected against insect pests and parasitic nematodes, and resulted in higher yields. In Nigeria, Egwantu (1982) also reported from field trials that Furadan performed better in reducing infestation of okra plants by Podagrica uniformis and P. sjostedti than carbaryl, formetenate and phosmet, and resulted in higher yields. Letchnimanane and Paramasivan (1974) also reported that dusts of 0.1% DDT, l%carbaryl, 5% fenithrothion, 1% Trichlorophan and 1% parathionmethyl gave better control of the jassid, Empoasca devastans (D.) on okra. Phosphin 24.E.C applied at 10ml /5 litres of water; Aldrex 40 applied at 1 lmls/51itres of water; Gadona 24 E.C at 20ml/51itres of water have been used successfully against okra pest. (Hill, 1987). Metcalf (1991) reported that insect pest of okra such as Heliothis armigera (Hub.); Anthonomus grandis Boh. and Aphis gossypii Glov. could be controlled effectively using 10% DDT. applied at 10 - 15 15kg/ha plus BHC containing 3% X - isomer. Tindal (1965) also reported that the use of DDT, BHC or malathion could effectively control leaf feeding beetles and weevils in okra when applied in an effectient manner. Udzu (1993) also reported from his survey on chemical insecticides used in okra production in the Assin manpong and Tema in the Central and Greater Accra Regions of Ghana respectively that the farmers use insecticide like Cymbush, Dimethoate, Karate and Furadan to control okra insect pests on their farms. Also from his work on the control of insect pest of okra at Legon, he recommended perfekthion at lOml/litre of water applied using knapsack sprayer as more effective and efficient in controlling insect pest of okra than Furadan at 2g/plant. The perfekthion treated plants had the lowest number of damaged leaves, flower and fruit drops, and produced heavier and many undamaged fruits. Pesticide use has therefore been the main method for controlling pests of vegetables including okra. 20 University of Ghana http://ugspace.ug.edu.gh The heavy reliance on synthetic insecticides for the control of insect pests in okra is likely to create problems such as environmental pollution and insecticide resistance in most of the insect pests. It is therefore about time to try other control measures that would be environmental and user friendly. 2.4.2. Use of botanical insecticides Limonoids are bitter tetranortriterpenes found predominantly in plants belonging to the families Miliaceae and Rutaceae (Champagne, et al., 1989), which account for the plants' insecticidal activity. The major compound in neem is azadirachtin and it is known to have adverse effects on more than 200 insect species (Butterworth and Morgan, 1971). Neem seed extracts have exhibited antifeedant activity against several insect orders, including Orthoptera (Attri, 1975), Coleoptera (Sarademma et al., 1977), Lepidoptera (Warthen et al., 1978) and Diptera (Kareem et al, 1974). The compound responsible for these activities is azadirachtin, a terpenoid that Butterworth and Morgan (1971) isolated from neem seed (Sanaa, 1992). They reported that even at concentrations as low as 40 ug per litre of water, the compound prevented Schistocerca gregaria Forskal from feeding. Redknap (1991) reported of an antifeedant effect of aqueous neem seed extract against the flea beetles, Podagrica sjostedti and P. uniformis. Siddig (1981) also recorded similar effects of neem seed and leaf water extracts on P. puncticollis. In the laboratory neem has demonstrated its potency against several insects. Amason et al., (1985) reported from laboratory tests of neem products on the corn borer (Ostrinea nubilalis) larvae that 10 ppm azadirachtin produced 100% mortality, 90% mortality at lppm and 0.1 ppm showed no effect. However, the adults that later emerged had grossly altered sex rations (more males than females) with the few females laying few eggs at later periods. Recent laboratory research on the desert locust indicated that neem oil causes 'solitarization' of gregarious locust nymphs. This is because after exposure to doses equal to 2.5 litres per hectare, the juveniles fail to form the massive, moving, marauding plagues that destroys crops and trees (Schmutterer and Freres, 1990). From a laboratory test on NeemAzal, a neem product of TRIFOLI, at 3% and 5% v/v concentrations against the cocoa capsid, Sahlbergella singularis (Hagl.), the 5% concentration proved very effective causing 95 % mortility compared to 90 % at 3 % concentration. Besides, the number of feeding lesions and exuviae (moulted skin) at both concentrations were much lower on the treated capsids than capsids in the control. This indicates 21 University of Ghana http://ugspace.ug.edu.gh the chemical's inhibition on feeding and reproduction (Adu-Acheampong and Padi, 1999). Obeng-Ofori et al, (1997) evaluating the effects of neem seed water extracts in the laboratory on the oviposition and development of fruit fly, Ceratitis capitata (Wiedemann) infesting citrus at the Agricultural Research stations, Kade, reported that neem powder sprayed at 20%, 25% and 30% wt/vol. concentration significantly reduced oviposition and larval development. Neem products have proved to be effective against insect pests of okra and other malvaceous plants. Patience (1994) compared aqueous extracts of neem seed with karate 2.5 E.C for the control of insect pests on okra at the Ashaiman Irrigation site. She reported that neem seed powder at 30 g/1 of water although showed some control was not as effective as the karate 2.5 E.C in protecting the crop against insect pests, and therefore recommended an increase in the concentration of the neem extract. This observation was confirmed by Emosairue and Ukeh (1998) also working on water extract of neem seed powder in Nigeria and reported that at 50 g/1 the aqueous extract was as effective as the synthetic insecticide, cymbush, in protecting okra against insect pests. Sackey (1999) reported from a field trial of aqueous neem seed extract on insect fauna of okra at the University farms, Legon, that the neem seed extracts at 50 g/1 and 75 g/1 were equally effective as the synthetic insecticide, actellic 25 EC., at 2 ml/1, in controlling the insect pests. He also recorded a better fruit yield of okra from the 50 g/1 and 75 g/1 neem treatments than the 100 g/1 treatment and consequently recommended the50 g/1 as an alternative for okra insect pests control. Okra plants treated with a methanolic neem kernel extract at 1 % to 4 % concentrations reduced the damage caused by P. uniformis than the untreated plants (Adhikary, 1984). Dreyer (1986) confirmed the antifeedant effect of weekly applications of aqueous neemseed extract at 50 g/1 against P. unifomis, and reported of similar effect against the occasional pest, Sylepta derogata., and the onion thrips, Thrips tabaci (Freisewinkel,1989). Taylor (1974) reported that Dipel (Bacillus thuringensis var thuringensis Berliner) applied at the rate of 0.56 - 1.12kg per hectare was a suitable alternative for the control of Lepidopterous larvae associated with okra grown for leaves and fruits while Irvine (1964) stated that early sowing of okra seeds would reduce the attack by the cotton Stainer, Dysdercus spp, Schmutterer (1995) also reported in the Dominican Republic that water extracts of neem seed proved effective against Aphis gossypii on cucumber and okra, and against Lipaphis erysimi (Scop.) on cabbage as direct contact sprays. However, when applied in a systemic manner, neem has little effect on aphids because aphids feed only on the phloem tissues where neem materials least accumulate. 22 University of Ghana http://ugspace.ug.edu.gh Various neem extracts are effective against over 200 insect species including many that are resistant to or inherently difficult to control with conventional insecticides. These include the sweet potato whitefly, green peach aphid, western floral thrips, diamond back moth and several leaf miners (Anon, 1992). Saxena (1990) reported that Neem cake after oil extraction successfully controlled brown plant hoppers and other pests of rice in the Phillippines. Similarly, five applications of a 25% neem oil emulsion sprayed with an ultra - low volume applicator protected rice against the increasing severe scourage caused by the plant hoppers. Neem showed considerable potential for controlling pests of stored products with repellency being the primary importance. This is because jute sacks treated with neem oil or other neem extracts prevented pests particularly weevils (Sitophilus species.) and flour beetles (Tribolium species.) from penetrating for several months. (Anon, 1992). Zehrer (1984) also reported that Neem oil offered an extremely effective and cheap protection for stored beans, cowpeas and other legumes as it keeps them free from bruchid beetle infestation for at least six months, regardless of whether the beans were infected before treatment or not. NeemaAzal-T (a liquid formulation containing 5% Azadiracltin) was'found to be effective against Sitophilus oryzae in stored rice in Egypt especially when applied as bag surface treatment (EL - Lakwah and Abdel - Latif, 1998 ). Neem seed extract when sprayed against the birch leaf miner, Fenusa pusilla, performed as well as the registered commercial pesticide, Diazinon. However, It was slow acting, and the insects continued to damage the trees before they died. When applied to the soil, neem compounds are absorbed by the roots and translocated to the crop's leaves so that leaf miners munching on the leaves get their moulting - hormone jammed, trapped fatally in their own juvenile skins (Anon, 1992). A commercial neem seed extract formulation (Margosan - O) produced 100 % kill at very low concentration 90.2 1/ha.) against the Gypsy moth, and after 25 days of application, larvae shrivelled, stopped feeding and died, (Anon, 1992). A wide range of aqueous neem concentrations ( 5 - 50 g of seed powder per litre of water ) have been quoted as being effective in reducing pest damage in vegetable field trials (Dreyer, 1987; Ruscoe, 1972; Asari and Nair, 1972; Cobbinah and Osei-Owusu, 1988). However, at 75 g/1, the 23 University of Ghana http://ugspace.ug.edu.gh neem seed water extract significantly promoted vegetative growth in garden eggs than Karate and Bacillus thuringiensis (Biobit) preparations, and delayed flower initiation. (Ofosu-Budu, et al., 1998). Afreh-Nuamah et al., (1993) reported from a field evaluation of two bio pesticides (Neem and Garlic seed water extracts) against the standard insecticide, (Karate 25EC - Lambdacyhathrin, a pyrethroid) on lepidopterous pest of egg plant in Ghana that Neem at 50 g/1 (7 kg/ha) and the Karate treatments reduced fruit damage from 26.1 to 11.8 % and 26.1 to 10 %, respectively. They also indicated that among the three concentrations of neem seed water extract tested, (25 g/1, 50 g/1 and 75 g/1), the performance of the 50 g/1 was significantly similar to the Karate treatment during the major rainy season. However, in the minor season, the 75 g/1 compared favourably well to the karate insecticide. In onions, Fagoonee and Toory (1984) reported that 5 % aqueous extract of neem leaf gave effective control of the leaf miner, Lean’s trifolii, and that treated plots yielded four to six times higher than the control plots. Saxena and Batis (1982) indicated that egg-laying ability of Amrasca devastans on cotton treated with neem oil was significantly reduced. However in Taiwan, for reasons unknown, Klemm and Schmutterer (1993) and Schmutterer (1995) indicated that Plutella xylostella preferred neem treated cabbage to the untreated since very high numbers of eggs were laid on the treated than the untreated. In India, experiments have proved the repellent effects of aqueous neem seed extract (10 g/1) against Empoasca spp., Aphis gossypii and Epilachna beetles on brinjal. Asari and Nair (1972) reported that neem performed better in post treatment counts showing immediate repellency. Consequently damage caused by the Colorado potato beetle, Leptinotarsa decemlineata, was significantly reduced by weekly application of ethanol extract of neem seeds (Reed and Reed, 1985). When exposed to sunlight, neem products degrade and lose their activity. Topically, the crude extract remains active for only eight days when exposed to the sun’s ultra violet rays. Neem products although natural, can produce some deletarious effects. Jacobson (1989) reported that cabbage when treated with neem, produced medium sized heads whereas in tomato, growth and yield were reduced. Tanzubil (1991) reported from Northern Ghana that aqueous extract of neem seeds or leaves reduced the incidence of Megalurothrip sjostedti infesting cowpeas and increased yields significantly. Eziah (1999) reported from a field trial on the evaluation of aqueous extracts of Jatropha curcas (40 g/1), Jatropha seed oil (4 ml/1), aqueous neem seed extract (75 g/1) and 24 University of Ghana http://ugspace.ug.edu.gh cymethoate (2 ml/1) for the control of insect pests complex of aubergine that the plant products compared favourably with the synthetic insecticide in controlling most of the major insect pests (Aphis gossypii, Selepa docilis and Urentius hystericellus). Osterman (1992) also reported from a field trial that weekly applications of aqueous neem seed extract (50 g/1) drastically reduced the damage caused by Heliothis amigera to tomato compared to aqueous extract of neem leaf and neem powder. The treatment was also superior to deltamethrin, and increased marketable fruit yield considerably. Similarly, weekly applications of aqueous extract of neem seed (50 g/1) and 1.5% neem oil when compared with two different insecticide combinations against Bemisia tabaci, the two neem treatments kept the population levels of B, tabaci very low compared to the synthetic insecticide, (Sierra, 1992, and Schmutterer, 1993). The extent of pest control achieved by any of the above methods would depend on the efficiency and efficacy of the product, its application (distribution) and coverage of the taraget. Consequently it is always important to choose a nozzle that would help achieve these objectives. 2.5. PRODUCT APPLICATION TECHNIQUES FOR INSECT PESTS MANAGEMENT Nozzles are the means by which plant protection agents are applied to their targets and the success of any plant protection measure depends on the quality of the product, its distribution and coverage and correct timing of application (Basel, 1985, Norman, 1986). 2.5.1. Hydraulic Energy Nozzles A nozzle is any device through which spray liquid is emitted, broken up into droplets and dispersed at least over a short distance, (Mathews, 1984). A hydraulic energy nozzle is that type in which pressure generated by liquid with sufficient velocity energy breaks a thin sheet of liquid into droplets of different sizes (Dent, 1990). Four different types of hydraulic energy nozzles have been identified (Mathews, 1984, and Anon, 1991). (a) Polyjet, Flood or Impact nozzle: This is probably the most popular nozzle used with a knapsack sprayer. It produces a fan shaped spray partern. There is usually more spray deposited at the edges of the fan (spray horns) with wider swath width. 25 University of Ghana http://ugspace.ug.edu.gh (b) Cone Nozzles: (i) Hollow Cone. In this, liquid is forced through a slot to impact a swirl to the spray cloud, which produces a hollow cone shape (ii) Solid cone. This pattern is produced by passing the liquid centrally through the nozzle to fill the air core, giving a narrow display of spray. (c) Variable cone nozzle: In this, the swirl chamber depth can be adjusted to produce sprays ranging from solid stream to a fine mist. It has two or more holes. Cone nozzles are used widely for spraying foliage because their droplets approach leaves from more directions than in the single plane produced by a flat fan or polyjet nozzles. (d) Fan nozzles: In this, liquid is forced through an ecliptical hole producing a fan jet with tapered edges. The random integration of the spray sheet from the nozzle produces a wide range of droplets spectrum. It is recommended for general applications particularly spraying flat surfaces such as the soil. Anon (1991) indicated that where a single cone nozzle was used and not a boom, the effective spray width was small and for convenience, operators frequently used flood or polyjet nozzle to obtain wider swath. However, this technique was not recommended for fungicide or insecticide applications where droplet size and distribution are critical. 2.5.2. Spray coverage and distribution When sprays are applied at high volume (HV), the aim is to achieve complete coverage of the crop. However with discrete droplets, the pesticide applicator needs to know the droplets density required and the distribution of the droplets on the target. Microvariations in droplets have little or no effect on the control especially when systematic or translocate insecticides are used, hence control of mobile pest like jassids can be achieved without complete coverage but uniform coverage is required for the control of scale insects and leaf miners (Mathews, 1988 ). 2.5.3. Spray Application Successful spraying depends on thorough coverage of the target with evenly distributed individual droplets, and for good biological efficiency, an application that would yield not less than 20 droplets per cm2 on the target is recommended (Basel, 1985). According to Norman (1986) the technique by which plant protection agents are applied, are so important for successful 26 University of Ghana http://ugspace.ug.edu.gh plant protection as the product itself, and as decisive as the timing of it's application. Hence the success of any plant-protection measure depends on the quality of the product, it's distribution and coverage, and correct timing. Evaluating four different spray nozzles on a cowpea variety “Asontem” at the University of Ghana research station, Kade, Afreh-Nuamah (1991) reported that for each of the insecticides (Cymbush and Karate) the cone nozzle gave better spray coverage and distribution at all stages of the plant growth than the polyjet on the Technoma Knapsack sprayer. However, when the electrodyne sprayer was used, greater efficiency was achieved because of electrical charges it imparts to the spray droplets. 2.6. INTEGRATED CROP MANAGEMENT IN OKRA The combination of the various chemical and soil amendment practices and cultural methods in managing okra varies from place to place in Ghana. This holistic approach, which aims at improving the performance and yield of the crop, helps to decrease pest populations to levels that would not cause economic damage and also enhances the vigour of the crop. In Ghana, at Asempaneye, a suburb of Kumasi in the Ashanti Region, okra farmers grow their crops in compost and sprayed neem seed extracts against insect pests. They gained over 200% increase in fruit yield and a corresponding higher fruit weight compared to those grown using conventional farmer practice (fertilizer application). Also in farms where integrated crop pest management practices were carried out (timing insecticide application, regular weed control and using methods that enhance plant nutrition), populations of natural enemies were far higher than that of insect pests (Antwi et al., 1999). From a survey on integrated pest management (IPM) in some regions of Ghana, FAO (1997) reported that at Dawhenya irrigation project site in Greater Accra Region, vegetable growers use organic manure and fertilizers in an attempt to improve soil fertility and to increase yield. Such farmers carry out four pesticide applications in a cropping season to fight insect pest with the view to complementing the effects of the soil amendment practice to enhance yield in okra. However, at Ekoso in the Asamankese district of the Eastern Region, okra growers use chemical fertilizers to grow the crop. Besides, every year, different locations are used (crop rotation) for the crop with the view to evade nematode and insect pest attack. Pesticides such as Karate 2.5 EC and Cymbush are sprayed using knapsack sprayers to 27 University of Ghana http://ugspace.ug.edu.gh control the most rampant insect pest Prodagrica spp. These practices help to increase the yield of okra. At Kasoa in the Central Region, okra farmers intercropped okra with pepper, and maize. In the field, chemical fertilizers are applied at 2 weeks and 40 days after seedling emergence. To prevent the development of resistance to insecticides, the farmers use a mixture of Biobate and Karate to protect their crop and reap higher yields with less damage from insect pests. At Akumadan in the Ashanti Region, okra farmers grow the crop using manures for fertilizing the crop and where funds are available, at flowering, side dressing is done with N.P.K. fertilizer in holes. Two insecticide products are mixed and used to protect the crop with 4 - 8 applications made in a season using knapsack sprayers. However, in Kumasi, the farmers use Dipel mixed with Karate and Dipel alone to control beetles and Lepidterous pests to obtain higher yields. In the Near East, high rates of nematode infestation in okra is controlled using fumigants such as DD and 1,3 - dichloropropene applied a week before sowing of seeds. Weeds are controlled manually by hoeing four times at fortnight intervals and the farm irrigated to field capacity a week after (Lebeek and Lenteren, 1992). However, in Tunisia, okra farmers grow the crop using poultry manure with three irrgations in a week. These farmers also manage soil borne pathogenes that survive on debris in the soil, Botris cinerea and Colletotrichum coccodes, which account for over 32% fruit yield reduction by practicing crop rotation every two to three years (Davis, 1982). In Western Nigeria, during the dry season, okra farmers manage their crop by regular watering to ensure good yields. Also since insect pests greatly reduce seed production, they are managed by prompt harvesting of the matured fruits 30 days after flowering. The fruits are then opened immediately in the sun to avoid attack by the larvae of Heliothis armigera on the soft ripe seed. Consequently, seed losses through dehiscence are also avoided (Ewete et al., 1980). In the case of diseases, the yellow vein mosaic is a serious virus disease and often causes total crop failure. Okra farmers manage this situation by removing and burning affected plants, while those in the vicinity of such affected plants are supplied with additional fertilizer and watered regulary. For Fusarium wilt, the farmers uproot and burn affected plants, weed the farm and reduce water supply to the field (Oyolu, 1983). 28 University of Ghana http://ugspace.ug.edu.gh CHAPTER THREE-EXPERIMENTAL WORK STUDIES ON SOIL AMENDMENTS, AND NEEM PRODUCTS FOR THE MANAGEMENT OF INSECT PESTS OF OKRA 3.0. INTRODUCTION Insect pests and poor soil fertility have been the major constraints to successful okra production in Ghana. Potential farmers grow the crop by applying chemical fertilizers to promote yield increases. However, continual use of these fertilizers renders the soil unproductive due to excessive accumulation of salts (Davis, 1982). Resource poor farmers grow the crop without the application of any soil nutrient. Consequently, the tolerance of the crop to insect pests and diseases, as well as its yield becomes drastically reduced. Yield from fertilizer treated vegetables are often low unless the nutrients are replenished at the reproductive stage of the crop (Grimes and Clark, 1963), thus increasing the cost of production. Compost is easy to prepare and hence comparatively cheap. It contains both major and minor nutrients and when applied to vegetables, they obtain a wide range of nutrients, which enable them to thrive and withstand attacks from diseases and insect pests (Hugues and Philippe, 1992) and thus increase their yields. This potential of compost to pest management has not been realised by most vegetable growers. Aqueous neem seed extracts (ANSE) have been reported to control over 200 insect species including those that have been resistant to or inherently difficult to control with conventional insecticides (Schmutterer, 1995). Consequently when the effects of neem are complemented with agronomic practices that will enhance plant tolerance, the devastitating effects of insect pests on okra could be reduced and yield drastically increased. It has therefore become necessary to investigate compost and neem products on the performance of okra. 29 University of Ghana http://ugspace.ug.edu.gh 3.1. MATERIALS AND METHODS 3.1.1. Collection of neem seeds, drying and storage Ripe neem seeds were collected from neem trees at Klagon, Lashibi near Ashaiman. The seeds were depulped in water and dried on tarpaulin sheets in a shade for 14 days at room temperature (28 + 2 °C). This was to prevent deterioration and germination of the seeds. The dried seeds were stored in sacks in a room and used when needed. 3.1.2. Preparation of aqueous neem seed extract Neem seeds were milled for 5 minutes using a high - speed blender (Electodee, model 13452E, Volume - 750 ml.). The powdered seed was weighed and dissolved in sufficient water at the rate of 50 g/1 for 24 hours to ensure adequate infusion. The mixture was sieved using a 0.5 mm sieve, the residue was discarded and the filtrate used for the spraying. 3.1.3.Other insecticides Other insecticides used were dimethoate 40 EC and neemazal T/S. Dimethoate: 0 ,0 - dimethyl- S-methyl carbamoyl (methyl) phosphorodithioate, is an organophosphorus insecticide with systemic and contact action against a wide range of insects attacking various crops particularly sap sucking insects. It was applied at the manufacture’s recommendation of 75 ml/ 151itres of water. NeemAzal T/S on the other hand is an emulsifiable concentrate (EC) of Azadirachtin supplied by EID Parry and Trifolio - M- GmbH, Germany. It contains 10,000 ppm Azadirachtin and over 60 other limonoids. It has a wide range of activity (antifeedancy, repellency, oviposition deterrent, growth regulation etc.) against a broad spectrum of insect pests of crops. It was applied at the manufacture’s recommended rate of 2 ml/litre of water (ie. 30 ml/151iters of water). 3.1.4.Site selection, Land preparation and sowing The Ashaiman Irrigation site was chosen for the project since water for irrigation is readily available and Ashaiman is one of the major vegetable growing areas in the Greater Accra region of Ghana, supplying Tema and Accra with fresh vegetables. Most vegetable farmers in the area 30 University of Ghana http://ugspace.ug.edu.gh also grow okra. The soil is clayey and an example of Akuse soil series, a Dystric Vertisol (FAO/UNESCO classification). The slope of the land is almost flat (Terrace land), drains slowly and floods easily. The texture is clay loam with the following properties: pH = 7.6, organic content = 1.18, total nitrogen = 0.09%, C/N ratio = 13.1, available P (ppm) = 18.1, CEC = 25.1, and changeable cations: Ca = 7.86, Mg = 5. 22. K= =0.61, Na = 0.37 (Koei, 1997). A land of 18 x 144 m was ploughed and harrowed to a fine tilth. The field was lined and pegged at 35 x 17.5 m per block. Four blocks were laid across the gradient of the land with lm distance between adjacent blocks to offset any variation in soil moisture and fertility. Within a block, 28 small cells of size 2.7 x 3.6 m each were demarcated with a lm distance between adjacent cells to prevent spray drift. Within each cell, lining and pegging was done at a spacing of 90 x 60 cm. 3.1.5.Treatments and their application, and experimental design Owing to the clayey nature of the soil, the field was irrigated to field capacity and sowing was done the following day. The okra variety used was Labadi dwarf and this was sown at the rate of three seeds per hole. A split - plot design was used with NPK 15-15-15 fertilizer (20 g/plant), compost (500 g/plant), compost plus fertilizer (250 g/plant and 10 g/plant respectively) and no soil treatment (control) as main plots treatments. Insecticides namely - aqueous neem seed extract, (ANSE), Neemazal, and dimethoate as well as no spray (control) constitute the sub-plot treatments, and were applied using a Green cone hydraulic energy nozzle fitted on the PB- 16 knapsack sprayer. The compost was prepared from cocoa husk, poultry manure and rice husk, and was supplied by Dr. Ofosu - Budu of the University of Ghana Agricultural Research Station, Kade. Treatments were combined in a factorial manner per block. One week after emergence, the compost treatment was applied around the base of the seedlings, and a week later the fertilizer was applied 5 cm from the stem of the seedlings to prevent scorching of their tender roots. The compost was immediately covered with soil to form ridges and furrows created for irrigation. Spraying was done on weekly schedule using the Green cone nozzle and the insecticides at their recommended dosages in turn. Seedlings were thinned two weeks after emergence to one plant per hill. All insecticide treatments were carried out using the knapsack sprayer (Model PB - 16 from Malaysia) with the water as a diluent. Each insecticide treatment was applied fortnightly from November 2000 through to February, 2001. Cultural 31 University of Ghana http://ugspace.ug.edu.gh practices, weeding and irrigation, were done by local vegetable growers in Ashaiman who participated in the project. Weeding was done when necessary and the field irrigated at weekly intervals to field capacity. In each block, both main-plot and sub plot treatments were assigned randomly. Within a cell in each block, there were four rows of seven plants each, and the middle 2 rows were used as a sampling area, leaving a border row of one plant. Consequently, 10 plants were taken as reading units. Farmers participated in the project because Ashaiman is one of the major vegetable growing areas in the Greater Accra region and the farmers in this area grow okra throughout the year using chemical fertilizers only. Also the farmers always use synthetic insecticides to protect their crops without any agronomic practices that could help manage their pest problems. Consequently, the farmers' participation was to indirectly influence their practices and to expose them to sustainable okra production practices. 3.1.6. Data collected. Plant height was assessed fortnightly using a meter rule. Height was taken from the soil surface to the terminal bud and the average for each of the 10 plants was calculated for each cell (small plot, 2.7 x 3.6 m in a block). Plant girth was taken at 10 cm from the soil surface and the average recorded. Number of functional leaves was also counted for the 10 plants and the average recorded (Functional leaves are green leaves with less than 50 % area damaged). Insect damage to leaves was assessed by determining the proportion of leaf area damaged for the three topmost fully flexed leaves and then rated using a five-point scale (1 = no damage; 2 = 1 -20 % damage; 3 = 21 - 50 % damage; 4 = 51 - 75 % damage; 5 = > 75 % damage). 3.1.6.1. Insects. The number and type of insects were assessed by sampling the insects using sweep net, and water traps (detergent, omo, in water solution) weekly. Sweeping was done at a rate of 1 sweep per step and 10 sweeps per cell in east - west direction. During sampling, 2 minutes was spent per reading unit in a cell and the number and kinds of insects found on a plant recorded. Sampling started from 6 am (0600. GMT), and ended 9am (0900. GMT). The immature stages found were cultured in the laboratory until the adults emerged. The water traps were arranged per cell and were inspected early mornings at weekly intervals, and the captured insects were sieved and 32 University of Ghana http://ugspace.ug.edu.gh counted. The insects were soaked in 70% alcohol for 24 hours after which they were spread on tissue papers for another 24 hours to absorb the alcohol and then pinned. Insects caught were then identified by examining their features using identification keys under a stereo zoom binocular microscope (Zeiss, Stemi 1000). Spraying started three weeks after emergence by which time pest damage was becoming pronounced. 3.1.6.2. Fruit damage. The harvested fruits were separated into marketable and unmarketable portions and the percentage unmarketable fruit per treatment was calculated as No. of unmarketable fruits X 100 Total No. of fruits The number of fruits bored by fruit borers was also recorded. Dry matter yield of fruit was determined by randomly selecting five fruits from each plot. The fruits were weighed, enclosed in a paper bag and dried in an oven to a constant temperature at 105 °C for 12 hours (Berrie et al., 1987). The moisture content and the dry weight were recorded. The dry matter was calculated as mean fruit fresh weight - mean fruit moisture content. 3.1.6.3. Fruit yield. At flowering, and post-flowering periods, the number of fruits dropped due to D. Superstitiosus attack was counted per treatment. Harvesting was done every other day (i.e. at 3 days interval) and fruit yield per treatment was determined by harvesting matured fruits (i.e. fruits produced 6 days after flower opening) (Ewete et al., 1980) into well-labeled polybags. The polybags were taken to the laboratory, and by means of electronic scale, the average fruit weight was determined. Yield in tonnes per hactre (t/ha) of fruits obtained from each plot was calculated based on plot size, plant spacing and mean yield per plant. Other yield components such as number of fruits per plant per harvest, weight of marketable fruits as well as number of branches per plant were also recorded. 33 University of Ghana http://ugspace.ug.edu.gh 3.1.6.4. Assessment o f economic benefits. The economics of production was determined by assessing the costs associated with the use of the various nutrient sources. These were calculated by determining the cost of the soil nutrients on per - hectare basis. That due to pesticide application based on the cost of the pesticides was also determined. The total value of the harvested fruits was determined based on the prevailing price of $, 2000.00 per kilo. All costs of labour, land cultivation, maintenance of experimental site, seed were similar for all treatments and their values adjusted on per hectare basis from the research plots. Marginal cost and benefit were calculated as the difference between costs and benefits of treatments and their controls respectively. 3.1.7. Data analysis. All count data on insect pests and yield indices were transformed by the square root transformation, that is A (x + 0.5) to take care of zero figures before the variances were analysed. Where significant differences were observed, means were separated using the Least Significant Difference (LSD) test. Data in percentages were also transformed using the arc sine. 34 University of Ghana http://ugspace.ug.edu.gh CHAPTER FOUR 4.0. RESULTS 4.1. INSECT FAUNA ENCOUNTERED ON OKRA AT ASHAIMAN. The lists of insects encountered during the sampling period from the field work, are shown in Table 6. The insects fall within the orders Coleoptera, Heteroptera, Lepidoptera, Homoptera, Diptera, Orthoptera, Odonata, and Hymenoptera. Different stages attack various parts of the crop causing varying degrees of damage. The dominant order was Coleoptera followed by Heteroptera, and Diptera being the least. Among these, the major insect pests were classified based on the degree of their damage and their population levels. Those found included the cotton aphids, Aphis gossypii Glov., the cotton mealy bug, Phenacoccus hirsutus Green., white flies, Bemisia tabaci Genn., the flea beetle, Podagrica uniformis Jac.,the cotton Stainer, Dysdercus superstitiosus (F.). The beneficial insects were Crematogaster spp., Brachyplatus spp., the lady bird beetle, Epilachna spp., Cheilomenes vicinia Muls., Cheilomenes lunata F., Odonata spp., and Rhinocoris rapax (L,). Other insect pests found to cause little damage were considered to be minor pests. Table 6. List of insects collected from okra plant during the sampling period at Ashaiman. Insect Order Family Activity Podagrica uniformis Jac. Coleoptera Halticidae Adult feeds on leaves Anthonomus grandis Boh. Coleoptera Curculionidae Adults feed on flower buds Sphaerocoris spp. Coleoptera Scutelleridae Feeds on leaves Epicauta abovittata Gestro. Coleoptera Meloidae Adults feed on leaves Colaspis flvida Lefevre Coleoptera Chrysomelidae Adults feed on leaves Mylabris spp. Coleoptera Meloidae Adults feed on leaves Coryna spp. Coleoptera Meloidae Adults feed on flower pollen Podagrica sjostedti Jac. Coleoptera Halticidae 99 Lagria cuprina Thoms. Coleoptera Lagriidae Feeds on flower buds Aspidomorpha spp. Coleoptera Chysomelidae Adults Feeds on leaves Pachnoda spp. Coleoptera Cetoniidae Adults Feeds on fruits Epilachna spp. Coleoptera Coccinelidae Feeds on leaves Brachyplatus spp. Coleoptera Coccinelidae 99 Cheilomenes vicinia Muls. Coleoptera Coccinelidae 99 Cheilomenes lunata F. Coleoptera Coccinelidae 99 Podagriac bowringi Baly. Coloeptera Halticidae Adults feed on leaves Lagria villosa F. Coloeptera Lagriidae Feed on flower buds Gasteroclisus rhomboidalis Coloeptera Curculionidae Feeds on flower buds Boh. Diopsis thoracica Westw. Diptera Diopsidae Larva feeds on flower 35 University of Ghana http://ugspace.ug.edu.gh Riptortus dentipes Dali. Dysdercus superstitiosus (F.) Aspavia brunnea (Hust.) Aspavia ingense (F.) Nezera viridula (L.) Chinavia acuta (L.) AnopJecnemis curvipes Fab. Oxycaraenus spp. Dysdercus fasciatus Sign. Anthocoris spp. Acanthomia horrida Germ. Calidea dregii Germar. Graptostethus spp. Acanthocoris spp. Rhinocoris rapax (L.) Aphis gossypii Glov. Phenacoccus hirsutus Green. Bemisia tabaci (Genn.) Empoasca spp. Crematogaster spp. Heliothis armigera Hb. Sylepta derogata ( F.) Earias insulana Boisd. Anomis flava (F.) Selepa docilis Butler Odonata spp. Brachytrupes membranasus Drury. Atractomorpha acutipennis Guerin. Zonocerus variagatus (L.) Trilophidia spp. Eulioptera reticulata Pagge Acisoma spp. Urenthis spp. Hemiptera Coreidae Heteroptera Pyrrhocoridae Heteroptera Pentatomidae Heteroptera Pentatomidae Heteroptera Pentatomidae Heteroptera Pentatomidae Heteroptera Coreidae Heteroptera Lygaeidae Heteroptera Pyrrhocoridae Heteroptera Coreidae Heteroptera Coreidae Heteroptera Pentatomidae Heteroptera Pyrrhocoridae Heteroptera Pentatomidae Heteroptera Reduvidae Homoptera Aphididae Homoptera Pseudococcidae Homoptera Aleyroidae Homoptera Cicadellidae Hymenoptera Formicidae Lepidoptera Noctuidae Lepidoptera Pyralidae Lepidoptera Noctuidae Lepidoptera Noctuidae Lepidoptera Noctuidae Odonata Orthoptera Gryllidae Orthoptera Pyrgomorphidae Orthoptera Pyrgomorphidae Orthoptera Acrididae Orthoptera Gryllidae Orthoptera Gryllidae Orthoptera Gryllidae Suck sap from fruits Adults and nymphs suck sap from fruits Suck sap fromterminal buds 99 )} Suck sap from terminal and flower buds Suck sap from fruits Suck sap from flower buds Suck sap from fruits Adults suck sap from fruits Suck sap from flower buds Suck sap from fruits and flower buds Suck sap from fruits 99 Feeds on other bugs and coleoptera Suck sap from under side of older leaves Suck sap from leaves and tender shoots Suck sap from under side of older leaves Suck sap from under side of older leaves Attend mealybugs and aphids Larvae feed and bore into fruit Larva rolls leaves and feed on leaf lamina Larva feeds on leaves Larva feeds on leaves Larva feeds on leaves Feeds on other insects Feeds on leaves 99 Feeds on leaves 99 Feeds on leaves Feeds on leaves Feeds on leaves 36 University of Ghana http://ugspace.ug.edu.gh 4.1.1. Effects of the various insecticide treatments on the major insect pests and beneficial insects observed on okra during the sampling period. Table 7a shows the effect of the insecticide treatments on the major insect pests observed in the field during the experiment. The numbers of Aphis gossypii Glove, and Bemesia tabaci Genn. recorded were significantly (P<0.01) higher under the dimethoate treatment compared to the neem treated plots, with Sylepta derogata (F.) being the least recorded insect (appendix 1). Under the neem products, the ANSE treatment recorded significantly (P< 0.01) lesser number of the major pests relative to the neemazal and the control treatments. However, the overall performance of the ANSE in the control of the major pests was not significantly (P < 0.01) different from that of the dimethoate. Table 7a: Effects of the different insecticide treatments on the major insect pests Mean (±) Number of Insects____________________________ Insect pest____________________ ANSE_________ Neemazal_____ Dimethoate Control Aphis gossypii Glov. 25.80d± 1.2 106.20c ±0.9 135.03b ±1.3 168.10a ± 1.1 Bemisia tabaci Genn. 34.28d ± 0.6 108.35c ± 1.1 139.03b ± 0.6 167.53a ±0.8 Empoasca spp. 29.65c ± 1.4 77.65b ± 1.7 15.60d ± 0.8 97.22a ±1.1 Phenacoccus hirsutus Green. 39.98c ± 1.1 93.20b ± 0.4 9.95d± 1.5 105.73a ±0.6 Heliothis armigera (Hb.) 26.50c ±2.0 60.85b ±0.8 8.45d ± 0.2 89.43a ± 0.2 Dysdercus spp. 8.73c ± 1.6 31.08b ± 1.5 14.35d ±1.1 43.25a ±0.8 Anthonomus grandis Boh. 29.45c ± 0.4 65.75b ± 0.2 1 l.OOd ± 1.4 90.78a ±0.4 Sylepta derogata (F.) 29.68c ± 0.3 53.78b ±0.8 5.85d ±1.2 66.88a ± 1.5 Podagrica uniformis Jac. 12.55c+ 2.1 45.30b ±0.6 10.00c ±0.3 78.13a ± 1.6 Mean 29.29c 71.35b 38.81c 100.78a LSD —10.02; Means followed by the same letter in a row are not significantly different (P > 0.01) 37 University of Ghana http://ugspace.ug.edu.gh Table 7b shows the effect of the different insecticide treatments on the beneficial insects encountered during the experiment. The dimethoate treatment recorded significantly (P < 0.01) the least number of all the beneficial insects compared to the other treatments (appendix 2). The control (no spray), however, recorded significantly (P < 0.01) the highest number of each beneficial insect collected. Generally, the effects of the botanical insecticides, ANSE and neemazal, on the beneficial insects were not significantly (P <0.01) different. However, they differed significantly from the synthetic insecticide, dimethoate. Table 7b. Effects of the different insecticide treatments on the beneficial insects. Beneficial insects Mean (±) Number of Insects ANSE NeemAzal Dimethoate Control Cheilomenes vicinia Muls 16.75b ± 1.3 12.70c ± 1.4 1.43d ±0.2 39.68a ±0.5 Cheilomenes lunatus (F.) 30.35b ±0.5 34.13b ±0.6 0.78c ±0.1 46.93a ±1.1 Rhinocoris spp. 14.05c ± 1.1 18.48b ±0.5 0.83d ± 0.4 37.45a±.1.3 Rhinocoris rapax (L.) 21.43b ± 1.8 32.55a ± 0.8 0.98c ±0.1 32.60a ±0.5 Coccinella spp. 27.95b ±0.9 30.23b ± 1.7 1.05c ±0.1 37.68a ±0.7 Odonata spp. 24.48b ± 1.7 30.78a ± 1.8 1.20c ±0.3 32.83a ± 1.2 Bachyplatus spp. 24.68b ±0.3 25.65b ±0.2 1.13c ± 0.1 32.13a ±0.4 Mean 22.81b 24.36b 1.05c 37.04a LSD = 3.91. Means followed by the same letter in a row are not significantly different (P > 0.01) 38 University of Ghana http://ugspace.ug.edu.gh Plate 1. Dysdercus superstitiosus (Major pest) Plate 2. Anthonomus grandis (Major pest) 39 University of Ghana http://ugspace.ug.edu.gh Plate 4. Phenacoccus hirsutus (Major pest) 40 University of Ghana http://ugspace.ug.edu.gh 4.1.2. Relative abundance of major pests and beneficial insects encountered at pre- and post- flowering growth stages of okra. Tables 8a and 8b show a summary of major pests and beneficial insects encountered at pre- and post- flowering growth stages of okra under the various treatments. A week after seedling emergence, the cotton aphid, Aphis gossypii Glove, was the first to be observed on the compost treated plants and then on the sole fertilizer teated plants. Later they appeared in each of the soil amendment treatments irrespective of the insecticide applied. In the control, no soil amendment treatment, infested plants sprayed with any of the test insecticides showed no improvement in their stuntedness and distorted leaves except those treated with ANSE. The yields of such affected plants were virtually reduced to zero. During the 2nd and 3rd weeks after seedling emergence, Podagrica uniformis Jac. Bemisia tabaci Genn., Empoasca spp. and Phenacoccus hirsutus Germ, appeared and were randomly distributed in the field. Attack by these pests caused severe wilting of leaves particularly in the control (no soil treatment) plots where no pesticide was applied. However, the compost, and inorganic fertilizer treated plants appeared healthy with those grown in compost developing broader and greener leaves. After flowering, the infestation levels of the major pests were not much different from that at pre- flowering. Fruit damage and flower drop were also very low in the compost treated plants compared to those in the sole fertilizer and the control (no soil amendment) treatments. Dysdercus superstitiosus Fab. and Heliothis armigera (Hb.) were virtually absent at the pre- flowering stage and appeared only after flowering. The D. superstitiosus sucked sap from young and matured fruits and caused heavy fruit drop in plants grown without any soil amendment. However, its attack in the ANSE and dimethoate sprayed plots were quite low for each soil treatment. Predators like the Coccinelid beetles and the Cheilomenes species were the first to be observed during the 2nd week after seedling emergence and they fed on the aphids at the underside of the leaves. These beneficial insects occurred abundantly on the compost treated plants compared to the other soil treatments. Other beneficial insects such as Odonata and Rhinocoris species appeared later after the 4th week, but Rhinocoris rapax in particular, appeared after fruit setting and were found feeding on the Pentatomid pests, Aspavia and Nezera species. The number of beneficial insects was quite low on the dimethoate treated plants irrespective of the soil treatment. Both insect pests and beneficial insects occurred abundantly on the compost treated plants than those in the sole fertilizer and the control plots. However, such compost treated plants 41 University of Ghana http://ugspace.ug.edu.gh grew healthily, vigorously and produced succulent fruit and vegetative parts, and yielded higher. They were also less damaged particularly when sprayed with ANSE or dimethoate. Other insects listed in Table 6 were not considered serious pests of okra in Ghana due to the lesser damage they inflicted on the crop. Plate 5 shows one of the beneficial insects while plates 6 - 8 depict some of the minor insect pests encountered during the experiment. Plate 6. Aspavia brunnae (Minor pest) 42 University of Ghana http://ugspace.ug.edu.gh Plate 7. Anoplocnemis curvupis (Minor pest) Plate 8. Larva of Earias insulana (Minor pest) 43 University of Ghana http://ugspace.ug.edu.gh Table lOa.Incidence o f major insect pests encountered on okra under the various treatments at pre- and post- flowering growth stages Major insect pests Compost Compost + Fertilizer Dimethoate ANSE Neemazal Control Dimethoate ANSE Neemazal Control PRE- POST PRE- POST PRE- POST PRE- POST PRE- POST PRE- POST PRE- POST PRE- POST Aphis gossypii Glove. * * * * * * + + + * * * * * * * * * * * * * * * * * * + + + + * * * * * * * * * * * * Podagrica uniformis Jac. + + + + + * * * * * * * * + + + + + * * * * * * * * Sylepta derogata (F.) + + + + + + * * * * * * + + + + + + * * * * * * Dysdercus superstitiosus (F.) NIL NIL + + NIL * * NIL * * NIL + + NIL + + NIL * * NIL * * Phenaeocus hirsutus Green. + + + + + + + * * * * * * + + + + + + + * , * * ♦ * * * Heliothis armigera (Hb.) NIL + + NIL + + NIL * NIL * NIL + + NIL + + NIL * NIL * Bermisia tabaci Genn. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Empoasca spp. + + + + + + + * * * * * * * * * * + + * * * * * * * * Anthonomus grandis Boh. + + + + + + + * * * * * * + + + + + + * * * * * * * * Fertilizer Control Dimethoate ANSE Neemazal Control Dimethoate ANSE Neemazal Control Major insect pests PRE- | POST PRE- | POST PRE- POST PRE- | POST PRE- | POST PRE- ! POST PRE- | POST PRE- POST Aphis gossypii Glove. * * * * * * + + + * * * * * * * * * * * * * * * * + + + + * * * * * * * * Podagrica uniformis Jac. + + + + + * * * * * * * * + + + + * * * * Sylepta derogata (F.) + NIL + + + + * * * * + NIL + + + + * * * * Dysdercus superstitiosus (F.) NIL + + NIL + + NIL * * NIL * * NIL + NIL + NIL * NIL + + Phenacocus hirsutus Green. + + + + * * * * * * * + + + + * * * * * * Heliothis armigera (Hb.) NIL + + NIL + + NIL * NIL * * NIL + NIL + NIL * NIL * Bermisia tabaci Genn. * * * * * * ++ + + * * * * * * * * * * * * * * * * + + + + * * * * * * * * Empoasca spp. + + + + + + * * * * * * + + + + + + * * * * * * Anthonomus grandis Boh. + + + + + * * * * * * + + + + + + + + + + * Incidence key : * *•* : Very high infestation ( 80 or more insects/ sampling ) * * : High infestation (5 0 -7 9 insects/ sampling ) * : Medium infestation ( 30- 49 insects/ sampling ) ++ : Low infestation (29 - 10 insects/ sampling ) + : Very low infestation (1 -9 insects/ sampling) NIL : Not encoutered University of Ghana http://ugspace.ug.edu.gh Table 10b. Incidence o f beneficial insects encountered on okra under the various treatments at pre- and post- flowering growth stages Compost Compost + Fertilizer Dimethoate ANSE Neemazal Control Dimethoate ANSE Neemazal Control Beneficial insects PRE- POST PRE- POST PRE- POST PRE- POST PRE- POST PRE- POST PRE- POST PRE- POST Coccinella spp. NIL + * * * * * * * * * NIL NIL * * * * * * * * * * * Brachylplatns testudionigra D. + + * * * + + * * NIL NIL * * * ♦ * * * Cheilomenes vicinia Muls. + * * * * * * * * * * * + NIL * * * * * * * * * * * * Cheilomenes lunata (F.) + + * * * * * * * * * * * * NIL + * * * * * * * * * * * * Rhinocoris rapax (L.) NIL + NIL * NIL * NIL * * NIL + NIL * * NIL ♦ * NIL * * Rhinocoris spp. + + + + * * * * * * * + + * * * * * * * * * * * * Odonata spp. + + + + + + * * * * + + * * * * * * Fertilizer Control Dimethoate ANSE Neemazal Control Dimethoate ANSE Neemazal Control Beneficial insects PRE POST PRE- | POST PRE- | POST PRE- | POST PRE- | POST PRE- POST PRE- POST PRE- POST Coccinella spp. NIL NIL * * * * * * * * * * NIL NIL * * * * * * Brachylplatus testudionigra D. NIL + * * * + + * * NIL NIL + + + + + + * + + + + Cheilomenes -vicinia Muls. + + * * * * * * * * * * * * + + * * * * + + + + Cheilomenes lunata (F.) + + * * * * * *. * * * * * + + * * .* * * + + Rhinocoris rapax (L.) NIL + NIL * NIL * * NIL * * NIL + NIL + + NIL * NIL + + Rhinocoris spp. + -f * * * * * * * * * * * * + + * * * * + + + + Odonata spp. + NIL ++ * * + + + + * + NIL + + + + + + + + + + Incidence key : * * * : Very high infestation ( 80 or more insects/ sampling ) * * : High infestation (5 0 -7 9 insects/ sampling ) * : Medium infestation ( 30- 49 insects/ sampling ) ++ : Low infestation (29-10 insects/ sampling ) + : Very low infestation (1 - 9 insects/sampling) NIL : Not encountered University of Ghana http://ugspace.ug.edu.gh 4.2. EFFECTS OF THE DIFFERENT TREATMENTS ON GROWTH AND YIELD INDICES. 4. 2.1. Leaf damage Table 9 shows the percentage leaf area damage caused by various phytophagous insect pests per treatment. For the soil treatments, the untreated control plants had their leaves significantly (P< 0.05) damaged than the treated (appendix 3). However, leaf damage between the treated soils was not significant different (P > 0.05). Significant differences, however, occurred between the insecticide treatments. The untreated control (no spray) plants were significantly (P < 0.05) heavily damaged compared to the treated plants. Significant interaction also occurred between the soil and insecticide treatments. Table 9. Effect of the different treatments on leaf damage in okra plant (%) Soil treatment Mean (± SE) Percentage leaf damage (ST) ANSE NeemAzal Dimethoate Control Mean Compost 11.3 ±0.51 18.8 ±0.22 10.0 ±0.31 32.3 ± 0.36 17.8 Fertilizer (NPK) 15.0 ±0.38 20.0 ±0.19 10.0 ±0.41 32.8 ± 0.47 19.4 Compost + Fertilizer 13.8 ±0.18 22.5 ± 0.35 10.0 ±0.39 31.8 ±0.37 19.2 Control ' 12.5 ±0.41 22.5 ± 0.29 11.3 ±0.48 39.6 ±0.39 20.3 Mean 13.1 20.9 10.6 32.2 LSD (P =0.05) ; Soil treatment (ST) = (2.4)NS ; Insecticides** = 2.2; ST X insecticide* = 4.2 ; NS = Not significant. ANSE = Aqueous neem seed extract. * = significant at P < 0.05; ** = significant at P < 0.01 4.2.2. Plant height and girth. The height and girth of plants are shown (Tables 10 and 11). For the soil treatments, the compost treatments, produced the tallest and vigorous plants at flowering, and were not significantly (P > 0.05) different. They, however, differed significantly from the control, which produced the shortest plants at flowering. All the insecticide treatments were not significantly (P > 0.05) 46 University of Ghana http://ugspace.ug.edu.gh different from each other but were significantly (P <0.01) different from the control (no spray) (appendix 4). The aqueous neem seed extract (ANSE) produced the tallest plants. However, significant interactions occurred between the soil and insecticide treatments. The compost + fertilizer treated plants when sprayed with dimethoate, produced the tallest plants at flowering while the control (no soil treatment) plants which is also not protected (no insecticide spray) produced the shortest and less vigorous plants. With the plant girth, highly significant differences occurred among the soil treatments. Girth of sole compost and compost + fertilizer treated plants were not significantly (P > 0.05) different. These treatments produced the healthiest and thickest plants while the control (no soil treatment) produced the weakest and thinnest plants (5.00). All the treated soils were significantly (P < 0.01) different from the control (appendix 5). Significant differences also occurred among the insecticides. The dimethoate treated plants produced the largest girth (5.75) compared to the control (no spray). Interactions between soil and insecticide treatments produced thicker and healthier plants. The compost j+ fertilizer treated plants when treated with dimethoate produced the thickest plants while the urpprayed control (no soil treatment) produced the thinnest plants Table 10. Effect of the different treatments on height of okra plant at flowering (cm ). Soil treatment Mean (± SE) Plant height at flowering (ST) ANSE NeemAzal Dimethoate Control Mean Compost 59.74 ± 0.45 60.59 + 0.19 59.14 ±0.34 56.38 ± 0.40 58.96 Fertilizer (NPK ) 56.65 ± 0.38 52.51 ±0.31 51.69 ±0.33 51.28 ±0.25 53.03 Compost + Fertilizer 62.94 ± 0.47 60.66 ±0.41 63.59 ± 0.27 60.06 ±0.14 61.81 Control 54.45 ± 0.22 54.75 ±0.37 55.70 ±0.31 49.96 ± 0.34 53.72 Mean 58.44 57.13 57.53 54.42 LSD (P =0.05) ; Soil treatment** (ST) = 2.94; Insecticides** = 1.32; ST X insecticide* = 3.55; NS - Not significant. ANSE = Aqueous neem seed extract. * = significant at P < 0.05; ** = significant at P < 0.01 47 University of Ghana http://ugspace.ug.edu.gh Table 11. Effect of the different treatments on girth development in okra plant (cm) Soil treatment Mean (± SE) Girth of plant (S T) ANSE NeemAzal Dimethoate Control______, Mean Compost 5.74 ±0.25 5.78 ± 0.28 5.92 ± 0.74 5.98 ± 0.84 5.86 Fertilizer (NPK) 5.49 ±0.69 4.90 ±0.88 5.34 ±0.68 5.43 ± 0.54 5.29 Compost + Fertilizer 6.12 ±0.95 6.00 ± 0.35 6.47 ± 0.55 5.81 ±0.81 6.10 Control 5.06 ±0.65 5.37 ± 0.46 5.27 ± 0.48 4.93 ± 0.65 5.00 Mean ± SE 5.53 5.51 5.75 5.54 LSD (P =0.05); Soil treatment** (ST) = 0.24; Insecticides* = 0.17 ST X insecticide** = 0.36; NS = Not significant ANSE = Aqueous neem seed extract * = significant at P < 0.05; ** = significant at P < 0.0 4.2.3. Production of branches and functional leaves. The number of branches and functional leaves produced per treatment, and their interactions are shown (Tables 12 and 13). Highly significant (P < 0.01) difference occurred within individual soil, and insecticide, treatments. Considering the soil treatments, the compost treated plants produced significantly higher number of branches, while the control produced the least number of branches. Among the insecticides, the untreated control (no spray) plots also significantly produced the highest number of branches (appendix 6). Plants sprayed with neemazal produced the least number of branches. Interaction between soil and insecticide treatments produced significantly (P < 0.05) lower number of branches compared to the untreated control. Plants on the control (no soil treatment) plots when sprayed with dimethoate produced the least number of branches while the unsprayed compost + fertilizer treated plants produced the highest number of branches. Considering functional leaves, highly significant (P <0.01) differences occurred among the soil treatments (appendix 7). The compost treated plants produced the highest number of functional leaves. Significant differences also occurred among the insecticide treatments. The ANSE 48 University of Ghana http://ugspace.ug.edu.gh protected plants produced the highest number of functional leaves but were not significantly (P > 0.01) different from those sprayed with dimethoate. Significant differences, however, occurred in the soil - insecticide interactions. The compost treated plants when sprayed with dimethoate produced high numbers of functional leaves relative to plants in the unsprayed control (no soil treatment) treatment. Table 12. Effect of treatments on number of branches produced in okra. Soil treatment Mean (± SE) Number of branches produced (ST) ANSE NeemAzal Dimethoate Control Mean Compost 15.16± 0.56 11.84± 0.73 15.60 ±0.21 18.55± 0.15 15.29 Fertilizer (NPK) 12.25± 0.59 11.56 ±0.35 14.28± 0.26 14.35±0.73 13.11 Compost + 14.31+0.11 12.94±0.98 15.05 ±0.15 18.71± 0.57 15.50 Fertilizer Control 6.44 ± 0.78 8.11± 0.78 6.10± 0.25 6.38± 0.35 6.76 Mean 12.04 11.11 13.01 14.50 LSD (P =0.05); Soil treatment** (ST) = 1.28; Insecticides** = 0.76; ST X Insecticide** =1.74; NS = Not significant. ANSE = Aqueous neem seed extract * = significant at P < 0.05; ** = significant at P < 0.01 Table 13. Effect of treatments on number of functional leaves produced in okra. boil treatment Mean (± SE) Number of functional leaves produced (ST) ANSE NeemAzal Dimethoate Control Mean Compost 18.33 + 0.25 12.50 ±0.22 16.99 ±0.26 11.56 ±0.29 14.84 Fertilizer (NPK) 13.89 ±0.35 11.65 ±0.31 13.45 ±0.22 10.23 ± 0.34 12.30 Compost + 18.46 ±0.14 11.86 ± 0.15 18.78 ±0.17 12.19 ±0.21 15.32 Fertilizer Control 10.21 ±0.27 9.25 ±0.19 10.59 ±0.16 6.50 ±0.13 9.14 Mean 15.22 11.32 14.95 10 12 LSD (P =0.05); Soil treatment** (ST) = 2.42; Insecticides**=1.17;. ST X insecticide* = 3.00; NS = Not significant. ANSE = Aqueous neem seed extract * = significant at P < 0.05; ** = significant at P < 0.01 49 University of Ghana http://ugspace.ug.edu.gh 4.2.4. Fruit damage Tables 14 and 15 show the number of insect bored fruits and the fruits dropped due to insect pests per treatment respectively. Highly significant differences occurred among the soil amendment treatments. The compost treatments produced significantly (P < 0.05) higher numbers of bored fruits than the other soil treatments (appendix 8). Significant differences were also observed among the insecticide treatments. The control (no spray) produced the highest number of bored fruits while the aqueous neem seed extract (ANSE) produced the least bored fruits (8.88). The number of fruits dropped also showed significant differences among the soil treatments. The compost treated plants significantly (P <0.01) reduced the number of fruit drop than the other soil treatments (appendix 9). The highest number of fruits dropped was in the plots of the unsprayed plants (control) while the dimethoate treatment significantly (P < 0.05) had the number of fruit dropped reduced. There was also significant difference between treatment interactions (P > 0.05) in the number of fruits dropped. The highest number of fruit drop was recorded within the control (no soil treatment) - control (no spray) interaction, whilst the least number of fruit drop was achieved in compost treated plants sprayed with ANSE (Table 15). Table 14. Effect of treatments on number of bored fruits on okra plant. Soil treatment Mean (± SE) Number of bored fruits (ST) ANSE NeemAzal Dimethoate Control Mean Compost 9.00 ± 0.23 10.2510.25 9.5010.65 27.1210.89 13.97 Fertilizer (NPK) 7.62±0.56 10.38 10.36 7.8710.66 28.7510.98 13.66 Compost + Fertilizer 10.1310.84 15.3810.14 9.8810.74 34.5010.36 17.47 Control 8.7510.86 11.8810.74 12.1310.54 10.8810.81 10.91 Mean 8.88 11.97 9.85 25.31 LSD (P =0.05); Soil treatment** (ST) = 1.48; Insecticides** = 2.14; ST X insecticide = NS; NS = Not significant. ANSE = Aqueous neem seed extract. * = significant at P < 0.05; ** = significant at P < 0.01 50 University of Ghana http://ugspace.ug.edu.gh Table 15. Effect of treatments on number of fruits dropped in okra. Soil treatment 'Mean (± SF.t Number of fruits dropped (ST) ANSE NeemAzal Dimethoate Control Mean Compost 6.62+0.63 12,50+ 0.45 10.38+0.87 24.37± 0.93 13.47 Fertilizer (NPK) 11.38±0.85 13.13 0.24 10.500.79 23.87 0.23 17.34 Compost + Fertilizer 9!88±0.66 17.00 ±0.35 11.38± 0.81 31.12± 0.94 14.72 Control 18.00± 0.11 30.75± 0.69 16.25 +0.44 47.38±0.36 28.09 Mean 11.47 18.34 12.13 31.69 LSD (P =0.05); Soil treatment** (ST) = 2.73; Insecticides** = 2.58; ST X insecticide** = 5.06; NS = Not significant. ANSE = Aqueous neem seed extract. * = significant at P < 0.05; ** = significant at P < 0.01 4.2.5. Percentage unmarketable fruits High significant (P < 0.01) differences were observed among the insecticide treatments. The no insecticide treated plants produced the highest percentage of unmarketable fruits, but that for the dimethoate and aqueous neem seed extract treatments were not significantly different (P > 0.01). Interactions between soil and insecticide treatments produced vigorous plants and significantly (P < 0.05) reduced the percentage of unmarketable fruits produced (appendix 10). However, the control (no soil treatment) plants when sprayed with dimethoate produced the least unmarketable fruits. Irrespective of the soil treatment, dimethoate and ANSE application produced the least unmarketable fruits (Table 16). 51 University of Ghana http://ugspace.ug.edu.gh Table 16. Effect of treatments on unmarketable fruits produced in okra (%) Soil treatment Mean (± SE) Percentage unmarketable fruits__________ (ST)___________ ANSE_______ NeemAzal Dimethoate Control Mean Compost 10.22+0.39 26.41±0.77 12.81 ±0.73 32.95 ±0.44 20.60 Fertilizer (NPK) 15.21± 0.95 24.66 ± 0.66 10.64± 0.33 31.89 ±0.22 20.60 Compost + Fertilizer 9.15 ±0.22 20.99 ± 0.36 10.66±1.52 30.80 ± 0.54 17.90 Control 9.47±0,29 25.17 ± 1.22 7.15± 0.31 34.28± 025 19.02 Mean 11.02 24.31 10.32 32.48 LSD (P =0.05); Soil treatment (ST) = (2.69) NS; Insecticides** = 2.09; ST X insecticide* = 4.23; NS = Not significant ANSE = Aqueous neem seed extract * = significant at P < 0.05; ** = significant at P < 0.01 4.2.6. Fruit dry matter yield and fresh fruit yield. The fruit dry matter and fresh fruit yields per treatment, and that due to treatment interactions are shown in Tables 17 and 18. The soil, and insecticide treatments showed highly significant (P < 0.01) differences (appendix 11). For the soil treatments, compost treated plants produced significantly (P <0.01) higher fruit dry matter compared to the other soil treatments whilst with the insecticide treatments, dimethoate produced the highest diy matter and neemazal, the least. Treatment interactions also showed significant differences. Compost treated plants when sprayed with dimethoate or ANSE produced significantly higher fruit dry matter than those plants in unsprayed - no soil treated plots. High significant differences in fresh fruit yield were observed among the soil, and insecticide treatments (appendix 1). Among the soil treatments, the compost treated plants produced larger number of fresh fruits, but fresh fruit yield for the fertilizer alone, and the compost + fertilizer teratments were not significantly (P < 0.05) different. Among the insecticide treatments, plants sprayed with dimethoate produced the highest number of fresh fruit. The aqueous neem seed 52 University of Ghana http://ugspace.ug.edu.gh outyielded the control. Interaction between soil and insecticide treatments showed significant differences in fruit yield. Compost treated plants when sprayed with dimethoate or ANSE produced higher number of fresh fruits than the unsprayed plants grown in compost. 53 University of Ghana http://ugspace.ug.edu.gh Table 17. Effect of treatments on fruit dry matter yield in okra (g). Soil treatment Mean (± SE) Dry matter yield (ST) ANSE NeemAzal Dimethoate Control Mean Compost 4.51 ±0.68 4.17 ±0.87 4.89 ±0.49 4.45 ±0.85 4.51 Fertilizer (NPK) 3.20 +0.69 3.13 ±0.72 3.41 ±0.69 3.72 ±0.57 3.37 Compost + Fertilizer 3.96 ±0.28 3.95 ±0.39 4.37 ±0.53 3.99 ±0.51 4.07 Control 1.90 ±0.57 2.08 ±0.99 2.24 ±0.83 1.67 ±0.31 1.97 Mean 3.39 3.33 3.73 3.46 LSD (P = 0.05); Soil treatment** (ST) = 0.26; Insecticides** = 0.18; = Not significant. ANSE = Aqueous neem seed extract * = significant at P < 0.05; ** = significant at P < 0.01 ST X insecticide*1=0.39; NS Table 18. Effect of treatments on fruit yield in okra (t/ha). Soil treatment Mean (± SE) Fruit yield (ST) ANSE NeemAzal Dimethoate Control Mean Compost 2.07 ±0.25 1.84 ±0.67 3.60± 0.39 0.53 ±0.27 2.01 Fertilizer (NPK) 1.64 ±0.87 1.40 ± 1.87 2.45± 0.29 0.38 ± 0.73 1.47 Compost + Fertilizer 2.17±0.97 1.47± 0.91 3.04± 0.68 0.42±0.77 1.78 Control 0.73± 0.83 0.57± 0.45 1.41 ±1.91 0.09 ± 0.88 0.70 Mean 1.65 1.32 2.63 0.35 LSD (P =0.05) ; Soil treatment** (ST) = 0.12; Insecticides** = 0.15 ST X insecticide** = 0.28 NS = Not significant ANSE = Aqueous neem seed extract * = significant at P < 0.05; ** = significant at P < 0.01 54 University of Ghana http://ugspace.ug.edu.gh 4.2.7. Number of fruits produced per plant at harvest and weight of marketable fruits. Tables 19 and 20 respectively show the number of fruits per plant at a harvest and weight of marketable friuts for each treatment. Significant differences occurred among the soil, and insecticide treatments. Under the soil treatments, the compost treated plants produced significantly (P < 0.05) higher number of fruits per plant at a harvest (appendix 13). Among the insecticide treatments, dimethoate treated plants produced the highest number of fruit per plant. The number of fruits from the neemazal treatment was not significantly different from the control (P > 0.05). Significant interactions occurred between soil and insecticide treatments. The compost treated plants when sprayed with dimethoate produced the highest number of fruits but were not significantly (P < 0.05) different from those sprayed with ANSE. Significant differences in marketable fruit weights were observed for both the soil treatments, and the insecticide treatments (appendix 14). Among the soil treatments, the compost treated plants produced the heaviest marketable fruits and were significantly (P > 0.01) different from those produced by the sole fertilizer and the untreated control. Similarly, the dimethoate treated plants produced significantly (P < 0.01) heavier marketable fruits than the neem products. However, between the neem products, ANSE sprayed plants produced significantly heavier fruits than those treated with neemazal. No significant interactions occurred between the soil and insecticide treatments. 55 University of Ghana http://ugspace.ug.edu.gh Table 19. Effect of treatments on number of fruit produced per plant at harvest in okra. ___________________________ Soil treatment Mean (± SE) Number of fruits produced per plant at harvest (ST) ANSE NeemAzal Dimethoate Control Mean Compost 3.84 ± 0.24 3.05 ± 0.58 5.06 ± 0.57 3.41± 0.69 3.84 Fertilizer (NPK) 3.21±1.25 2.95± 0.28 3.21± 0.22 2.11± 0.28 2.87 Compost + 3.84+ 0.58 3.16 ±0.84 4.90 ± 0.29 3.11± 1.23 3.75 Fertilizer Control 2.11 ±1.23 2.00 ±1.50 2.99 ±1.29 1.31 ±1.39 2.10 Mean 3.25 2.79 4.04 2.48 LSD (P =0.05); Soil treatment** (ST) = 0.46; Insecticides** = 0.32; ST X insecticide* = 0.69; NS = Not significant ANSE = Aqueous neem seed extract * = significant at P < 0.05; ** = significant at P < 0.01 Table 20. Effect of treatments on weight of marketable fruits produced in okra(g). Soil treatment Mean (± SE) Weight of marketable fruits (ST) ANSE NeemAzal Dimethoate Control Mean Compost 31.59 ± 1.38 28.62±1.47 35.26 ±1.69 28.60 ± 0.97 31.02 Fertilizer (NPK) 29.91±0.58 28.19 ±0.86 33.45 ±8.39 26.74 ±1.68 29.57 Compost + Fertilizer 30.20+1.69 30.51 ±1.82 33.14±1.37 29.29±1.59 30.78 Control 24.73±1.36 22.11±1.97 25.36±1.38 20.40±0.87 23.15 Mean 29.10 27.36 . 31.80 26.26 LSD (P =0.05) ; Soil treatment** (ST) = 1.30; Insecticides** = 1.34; ST X insecticide = NS; NS = Not significant ANSE = Aqueous neem seed extract *= significant at P < 0.05; ** = significant at P < 0.01 56 University of Ghana http://ugspace.ug.edu.gh 4.3. ECONOMICS OF PRODUCTION 4.3.1. Cost of production. Table 21 shows the cost and their proportions for the various operations involved in producing okra in Ashaiman. The synthetic insecticides recorded the highest cost followed by land preparation with labour applying sole compost and sole fertilizer being the lowest. In terms of proportion of individual activities on cost of production, the synthetic insecticides form the highest percentage followed by land preparation. Table 21. Cost of the various operations in okra production (ha) Activities_________________________________________Cost (