COCOA RESEARCH INSTITUTE OF GHANA (GHANA COCOA BOARD)

KOLA CULTIVATION IN GHANA Technical Bulletin No. 26

Dadzie M. A., Opoku S. Y., Akpertey A., Akrofi A., Lowor S., Assuah M.K. and Amoah F. M.

© Cocoa Research Institute of Ghana, 2013 All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the copy right holder, application for which should be addressed to the publisher. Such written permission must also be obtained before any part of this publication is stored in a retrieval system of any nature. Any person who does any unauthorized act in relation to this bulletin will be liable to criminal prosecution and claims for damages. For permission requests, please write to: Cocoa Research Institute of Ghana P.O. Box 8 New Tafo-Akim Eastern Region Ghana [email protected]

ISBN: 978 - 9988 -1- 8416 - 2 Printed in the Republic of Ghana by the Cocoa Research Institute of Ghana (CRIG) New Tafo-Akim

ACKNOWLEDGMENT

The authors of this manual wish to thank Drs. Boamah Adomako and Gilbert Anim-Kwapong for their useful suggestions and contribution towards the preparation of this manual. We also want to thank all Plant breeding staff of Cocoa Research Institute of Ghana especially the Kola team for their kind support and assistance.

LIST OF FIGURES Figure 1 Figure 1a Figure 1b Figure 1c Figure 1d Figure 2a Figure 2b Figure 2c Figure 3a Figure 3b Figure 3c Figure 4a Figure 4b Figure 4c Figure 4d Figure 4e Figure 4f Figure 4g Figure 4h Figure 5a Figure 5b Figure 5c Figure 6a Figure 6b Figure 7a Figure 7b

Two year old grafted plants producing pods Inflouresence covered with fine net Male flower (pollen donor) Pollinating female flower with pollen Pollinated flower covered with fine net Pre-treated nuts ready for sowing Sown kola nuts in a tray with cut surface facing upwards Covering of sown nuts with a thin layer of soil Germinated nuts ready for transplanting into polythene bags V-shape at the base of polythene bag serves as drainage hole Six month old potted kola seedlings Harvesting of appropriate scions for grafting exercise Wrapping of harvested scions in a moistened cotton wool to prevent dehydration Shaping of scion base into a wedge form Dissect rootstock to receive the prepared scion Insertion of a scion into a rootstock Tiring of the union (rootstock and scion) A complete graft Grafts covered with transparent polythene bags and arranged under shade to reduce transpiration Raising of cuttings in a propagation bin filled with rice husk and river sand in the ratio of 1:1 Covered bin after planting of cuttings Transfer of rooted cuttings from a propagation bin into a polythene bag Kola nuts destroyed by larvae of weevil Kola leaves damaged by grasshopper attack Covering of nuts in unlined basket to allow water to drain out Commencement of curing process for kola nuts prior to storage

4 5 5 6 6 7 7 8 9 9 10 12 12 12 12 13 13 13 13 14 14 15 20 20 24 24

CONTENTS 1.0 1.1 1.2 1.3

2.0 2.1 2.2 3.0 3.1 4.0 4.1 4.2 4.3

4.4 5.0 5.1 6.0

Introduction Importance and uses of Kola Growth and Botany of Kola Propagation methods 1.3.1 Choice of material for propagation 1.3.2 Sexual method 1.3.3 Germination of seed 1.3.4 Transfer of germinated nuts into polythene bags 1.3.5 Propagation by asexual methods 1.3.6 Grafting 1.3.7 Tips for successful grafting 1.3.8 Rooted cuttings 1.3.9 Budding 1.3.10 Advantages of using asexual propagation methods Site selection and land preparation Recommended soils for cultivation Land Preparation 2.2.1 Lining and pegging Field Planting Management of Transplant 3.1.1 Mulching and recommended rate for fertilizer application Kola pest and diseases Kola pest Control of kola pest Diseases of kola 4.3.1 Diseases of fresh kola nuts 4.3.2 Diseases of stored kola nuts Control of kola diseases Harvesting of kola Curing and storage of nuts References

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Kola Cultivation in Ghana

1.0 INTRODUCTION Kola (cola nitida) is a tropical cash crop in Africa that belongs to the family Sterculiaceae. The kola genus comprises of about 140 species (Onomo et al., 2006). Out of which 50 species have been described in West Africa by Adebola, (2003). In Ghana the crop is cultivated mainly in the Eastern, Volta, Ashanti, Brong Ahafo and the Western regions where it serves as the main livelihood of many farmers and traders. The major agronomic factors that limit kola production includes old age of trees, self and cross incompatibility of trees, partial and total sterility and inefficient natural pollination. The tree is also known to display long gestation period sometimes lasting over 10 years. Thus, the provision of improved planting materials is seen as a way of enhancing kola production. Research on the improvement of Kola productivity and utilization is one of the mandates of the Cocoa Research Institute of Ghana (CRIG), where remarkable achievements have been made in Kola research. Active Kola research began at CRIG in 1967-1968 with 272 seedlings raised from white kola nuts and 262 seedlings from red nuts (CRIG annual report 1967-1968). These introductions were made from Oyoko near Koforidua in the Eastern region of Ghana. Since that period, several other introductions have been made from the major Kola growing regions in Ghana into the gene bank at Tafo to enhance genetic variability needed for developing improved varieties. The most recent introductions were made in 2007 from scions and cuttings collected from farms in and around Ampeyo in the Volta region of Ghana. This manual highlights the importance and uses of kola and describes techniques used to propagate and cultivate kola. It has been written primarily for farmers and extension workers with the aim of enhancing production and improving yield. Simple low-cost methods and inputs are emphasized. 1

Kola Cultivation in Ghana

1.1 IMPORTANCE AND USES OF KOLA Commercial: Kola is an important cash crop for many West African countries including Ghana and Nigeria. It is estimated that Nigeria alone produces almost 70% of the world's kola nuts with an annual production estimated around 200,000 metric tonnes of fresh kola per year. Ghana, on the other hand, is also rated as a major kola producing country in West Africa, even though; annual production record is not available due to unregulated market. In the year 2006, producer price of Kola in Ghana was US $ 1123.01 per tonne (FAO, 2009). The crop is cultivated mainly in the Eastern, Volta, Ashanti, Brong Ahafo and Western regions of Ghana where it serves as the main livelihood of many farmers and traders. The nuts, aside local markets are also sold at African Shops and markets in international cities, like Washington D.C., Ridley Road Market in Dalson-London and Brixton Market in London. Medicinal: Kola nuts contain caffeine (2 to 3%) and smaller amounts of theobromine and kolanin, which dispel sleep, thirst and hunger and act as a stimulant and anti-depressant. It is also believed to reduce fatigue, aid digestion and work as an aphrodisiac. Furthermore, the nuts are often used to treat whooping cough and asthma. The caffeine present acts as a bronchodilator, expanding the bronchial air passages. It is masticatory. The nuts are nutritious and contain nearly 1% protein, 1.35% fats and 45% starch. More recently, kola nut and its extracts have become popular in Europe and North America as a natural or alternative medicine. It also has industrial usage for the production of drugs, soft drinks, candies, beverages, animal feed formulation, liquid soap and dyes. Cultural: The nuts have been described as sacred religious objects used in offering prayers during ancestral veneration. Kola is also used during 2

Kola Cultivation in Ghana

significant life events, such as naming ceremonies, weddings, funerals and traditional divination system called Obi divination which is an ancient practice that is currently enjoying increased growth within the United States and the Caribbean.

1.2 GROWTH AND BOTANY OF KOLA Generally, the kola tree grows up to about 12m tall, although some exceeds 22.5m when it attains full maturity. The leaves are ovoid and pointed at both ends with a leathery texture. It produces a star-shaped fruit (pod) at maturity. Inside the fruit, about a dozen round or square seeds (nuts) are found. It develops buttress root system and has very dense foliage. Research has shown that, plantations established from seedlings takes between four to six years to flower whilst those established vegetatively, takes only 16 – 24 months to flower and subsequently produce pods (Figure. 1). Kola produces flowers just at the onset of rains thus, between (May and July in Ghana) on new inflorescence that develops from new flushes. The flower produced is either white or creamy usually with red markings at the base. These flowers are grouped as male and female. The male flower which contains pollen grains is usually smaller than the female flowers but similar in colour. Pollination of the female flower is usually by insects, which are attracted by a particular penetrating aroma of the flowers. Winds also account for a small percentage of natural pollination. Hand pollination is also done to improve nut set and contribute to yield increment. Kola takes between 100 - 140 days to develop mature pods after pollination. Note: Kola exhibits high degree of incompatibility and sterility characteristics which accounts for low pollination success that translates into low yields. It is therefore, important to collect compatible planting materials from CRIG for establishing kola farms. 3

Kola Cultivation in Ghana

Fig. 1 Two year old grafted kola plants producing pods.

1.3 PROPAGATION METHODS There are two main methods of propagation (sexual and asexual method) 1.3.1 Choice of material for propagation

In any of the methods, it is important to select outstanding mother trees for propagation. Select trees which are high yielding, resistant to diseases, early bearing and produce large nuts that are preferred by many consumers as the mother tree. 1.3.2 Sexual method This involves the use of seeds (red, pink or white coloured seeds) to raise new plants. Here, it is important to select about four most outstanding trees in the field that are cross compatible and also possess all the quality traits desired by consumers such as (large nuts, low astringency, and long shelf life). Label the best two as females (these should possess enough 4

Kola Cultivation in Ghana

female flowers on the inflorescence). The best trees are chosen as female in order to take advantage of maternal effect (potential transfer of maternal characteristics) onto off-springs. Select and cover potential female flowers with pollination net (fine net) to prevent unwanted pollen from landing on the stigma. Collect pollen from the male flowers of the selected male tree to pollinate the covered female flowers using a pair of forceps or pollination brush and then cover again with the pollination net. See figures 1a, 1b, 1c and 1d. Remember to label all the panicle that supports the flowers and indicate the source of pollen.

Fig 1a. Inflouresence covered with fine net Fig 1b. Male flower (pollen donor)

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Kola Cultivation in Ghana

Fig 1c. Pollinating female flower with pollen Fig 1d. Pollinated flower covered with fine net Note: Pollinated flowers take between 100-140 days to develop mature pods. Averagely each pod contains between 4-10 nuts with a mean nut weight ranging between 16-24 g. It is expected that young trees that will be raised from pollinated nuts will inherit the favourable traits of their parents through recombination of genes or gene introgression. It is therefore, advisable to use only selected seeds for propagation and not seeds collected from unselected trees in farmers' farm which may show sterility and incompatibility problems later in the plants life. Selected high yielding and compatible seedlings could be sourced at the Cocoa Research Institute of Ghana.

1.3.3 Germination of Seeds Kola germination is not uniform and usually takes between 60-80 days. Research at the Cocoa Research Institute of Ghana has shown that white coloured nuts usually germinate faster than pink and red nuts under the same conditions. Further studies also indicated that nut size does not influence germination. However, pre-germination treatments of nuts 6

Kola Cultivation in Ghana

before sowing have proved effective in kola germination at the Institute. These pre-treatment conditions include storing nuts in thinly wrapped banana leaves for 4 weeks to prevent drying and then greening them by gradual exposure to sunlight for up to 7 days before sowing. Further work at the institute also confirmed that removal of testa and cutting out of one third of the nut before sowing is also an effective pre-germination treatment. Pre treated nuts are sown in rectangular aluminium trays of dimension 61 cm x 35 cm x 12 cm filled with two thirds of top soil. During sowing, shallow straight line depressions are made in the soil and the pre -treated nuts (Figure. 2a) are placed dorso-ventrally in the soil with the cut portion facing upwards (Figure. 2b). The sown nuts are covered by spreading a thin layer of top soil over the nuts (Figure. 2c). This should be watered every three days to make water available for biochemical reactions to occur in the seed to break dormancy.

Fig. 2a: Pre-treated nuts ready for sowing 7

Kola Cultivation in Ghana

Fig. 2b: Sown kola nuts in a tray with cut surface facing upwards

Fig. 2c: Covering of sown nuts with a thin layer of soil.

1.3.4 Transfer of germinated nuts into polythene bags

Germinated nuts are transferred with a ball of soil around its roots into a 13 cm x 10 cm polythene bag filled with good loamy top soil (Figure. 3a). The base of the polythene bag is cut to allow excess water to drain out after watering (Figure. 3b). The young seedlings are then arranged under a shade tree or a shed made of palm front or shade net (Figure. 3c). This will help reduce transpiration and water loss from the seedlings. They are then kept under shade for a period of six months with regular watering before transplanting them into the field.

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Kola Cultivation in Ghana

Fig. 3a: Germinated nuts ready for transplanting into polythene bags

Fig. 3b: V-shape at the base of polythene bags serve as drainage hole.

Fig. 3c: Six months old potted kola seedlings 1.3.5 Propagation by asexual methods Asexual propagation is based on the principle of direct transfer of traits from mother tree to offspring without any genetic modification. It is therefore, very important to evaluate and select the most outstanding trees that exhibit all the desired traits for propagation. Select about 2 or 3 high yielding trees with diverse genetic origin, that are early bearing with 9

Kola Cultivation in Ghana

good tree architecture and are also resistant to diseases as mother tree. Note: It is important to consider the age, condition and the time of harvesting the mother part which is used for propagation. This is because propagation success of matured part is low and also if the harvesting is done in a warm environment, there is a high possibility of water loss which will affect the success. The main methods under asexual propagation include grafting, cuttings and budding.

1.3.6 Grafting This involves the joining of a scion onto a rootstock with a polythene tape to form a union. Scions are semi-hardwood flushes (greenish brown in colour) harvested from the mother tree. Ideal scions for grafting should be between 10 cm - 20 cm long and should possess enough buds including an active apical bud which will develop into a new shoot. Harvesting of scions is done early in the morning or late in the evening with a pair of secateurs and then wrapped in cotton wool moistened with water to prevent scion dehydration. The scions are prepared by trimming the leaves around it. This is performed to reduce leaf area thereby minimizing water loss from transpiration. The detached end of the scion is shaped like a wedge with the aid of a knife. Rootstocks for the exercise are raised in a similar manner as described in section 1.3.2 and 1.3.3. However in this case, the seedlings (rootstocks) are grafted at six months with scions harvested from trees with desirable traits such as high yielding, disease resistance, large nut size and early bearing. Grafted plants are covered with small transparent polythene 10

Kola Cultivation in Ghana

sheets. This creates a humid environment around the leaves and helps reduce transpiration. The plants are finally arranged under shade and success checked after two months. Grafting tapes and transparent polythene covering on successful grafts are removed immediately. After six months, successful grafts would be ready for transplanting in the field. Grafting success depends on the age of rootstock and interaction between rootstock and scion. This declines with increasing age of scion and rootstock. Therefore semi hardwood scion and six months old rootstocks are most suitable for grafting.

1.3.7 Tips for successful grafting 1. Harvest appropriate scions (greenish brown) from the trees of interest. 2. Wrap harvested scions in a moistened cotton wool or an old newspaper to prevent dehydration 3. Put the wrapped scions in an empty box and transport them to the grafting site. 4. Clean up the stem of the seedling with cotton wool and then wipe the surface with 70 % w/v ethanol to sterilize it. 5. Prepare the scions with a knife by shaping the base into a wedge form. 6. Cut off the seedling at about 10 - 15 cm from the surface of the soil in the polythene bag. 7. Gently divide the cut surface into two (perpendicular to the surface) without going very deep. Thus, just about the size of the scion base. 8. Firmly press the scion into the rootstock and tire together with a grafting tape. 9. Cover each graft with a transparent polythene bag to create a humid environment around the graft and arrange grafts under shade. 10. Water the plants every 3 days. Ensure that water does not enter the graft union since it can cause rotting of the scion 11

Kola Cultivation in Ghana

11. Check for success ('take') two months after grafting and remove both the transparent polythene bags and the grafting tape. 12. Emergence of new shoot or out growth from the scion indicates successful grafting.

Pictorial illustration of grafting stages after harvesting of scions. (see Fig 4 a -4 h)

Fig. 4 a: Harvesting of appropriate Fig. 4 b : Wrapping of harvested scions for grafting exercise scions in a moistened cotton wool to prevent dehydration

Fig. 4 c : Shaping of scion base into a wedge form

Fig. 4 d : Dissecting rootstock to receive the prepared scion 12

Kola Cultivation in Ghana

Fig. 4 e: Insertion of a scion into a rootstock

Fig. 4 f : Tiring of the union (rootstock and scion).

Fig. 4 g: A complete graft

Fig. 4 h: Grafts covered with transparent polythene bags and arranged under shade to reduce transpiration.

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Kola Cultivation in Ghana

1.3.8 Rooted Cuttings Propagation by rooted cuttings involves the use of semi hard wood to develop new plants. Rooted cuttings are harvested in a similar manner like scions harvested for grafting. However, in this case, the cuttings are dressed differently (i.e. removal of leaves from the cutting except two or three leaves close to the apical bud are left and also the detached end of the cutting is not dressed) and are planted directly into propagation structures (wooden boxes, bins, aluminium trays or propagators) filled with rooting medium. Rooting medium used is either a mixture of river sand and rice husk in a ratio of 1:1 or river sand and rotten palm fibre in the same ratio or only loamy soil (Figure. 5a). Cover medium after sowing if propagation bin is used (Figure. 5b). The entire medium and cuttings are then kept under shade. Cuttings are then watered every 2-3 days. Root development is inspected from 2-3 months. After roots have developed, transfer cuttings into polythene bags filled with top soil (Figure. 5c) just as described in propagation by seed.

Fig. 5 b: Covered bin after planting of cuttings

Fig. 5 a: Raising of cuttings in a propagation bin filled with rice husk and river sand in the ratio of 1:1

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Kola Cultivation in Ghana

Fig. 5 c: Transfer of rooted cuttings from a propagation bin into a polythene bag 1.3.9 Budding Budding involves the joining of a bud onto a seedling. The new bud introduced then takes over growth from the previous shoot and develops into a new shoot. The old shoot is removed two weeks after budding to prevent apical dominance. Budding in kola has not been very successful compared with grafting. This needs further investigation. Even when it is successful it takes quite some time to develop into a shoot. It is therefore not very convenient to propagate kola by this means. 1.3.10 Advantages of using asexual propagation methods

1. 2. 3. 4.

It allows desirable traits of mother tree to be maintained. It allows reduction in the normal gestation cycle of the plant compared to seedlings raised from nuts / seeds. It provides uniform growth of the plants. It also makes harvesting easy since it prevents trees from growing so tall and huge.

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Kola Cultivation in Ghana

SITE SELECTION AND LAND

2.0 PREPARATION FOR CULTIVATION Kola is a tree of the tropical rainforest which requires a hot humid climate, but can withstand a dry season on sites with a high ground water level. Therefore, it may be cultivated in drier areas where ground water is available. Although, it is a lowland forest tree, it has also been found to do well at altitudes above 300 m on deep, rich soils under heavy and evenly distributed rainfall. Mean annual temperature requirement ranges between 26 °C - 35°C and mean annual rainfall requirement also ranges from 1200 mm – 1800 mm. It is therefore, important to consider the above requirement during site selection for Kola establishment. SOILS FOR 2.1 RECOMMENDED CULTIVATION

Soils of varying fertility levels can be exploited for kola cultivation in Ghana. These soils are scattered all over Ghana but are mostly concentrated in Eastern, Ashanti, Brong Ahafo, Volta and Western regions of Ghana. Even though Kola does well on a wide range of soils; it does not do well on clayey and marshy soils or waterlogged soils. In the event of flooding create drainage paths to allow free drainage of water.

2.2

LAND PREPARATION

After clearing the appropriate sites for establishment, it is advisable to gather all slashed weeds. This will allow easy movement in and around the field. Do not burn the collected weeds. Allow it to decompose on the plot to increase the organic matter content of the soil. Burning destroys some important trace elements such as nickel, copper, boron, selenium, vanadium and chromium. It destroys organic matter content and act as a pre-disposing factor to leaching and erosion. 16

Kola Cultivation in Ghana

2.2.1 Lining and Pegging Implementation of appropriate (recommended) plant spacing is a vital requirement for crop growth and yield. It is therefore, prudent to use the recommended spacing to maximize yield. Kola flowers mostly at the peripheries of the crown or canopy. Research has shown that close spacing causes canopies to merge in a relatively short time which affects yield significantly because intensity of flowering drops, so it is advisable not to plant closely and anyhow. The recommended spacing for kola is 9.0 m x 9.0 m. This translates into 123 plants to a hectare plot. After estimating the required number of plants per plot; prepare pegs for lining and pegging. Pegs are normally prepared from Gliricidia sepium branches. These branches are cut into equal lengths of about 1 m with one sharpened end. Measure the appropriate plant spacing with a measuring tape and place the pegs at each marked site. Mark out spaces between any two adjacent plants and plant temporary shade since early establishment requires some amount of shade. Plantain or Gliricidia could be used for this purpose. If plantain is used, then about three plantain suckers should be planted at 2.5 m x 2.5 m in between any two adjacent plant stands to provide the needed shade for good establishment. Plantain is usually preferred since it could be consumed or sold for revenue.

3.0

FIELD PLANTING

Dig out holes of dimension (20 cm x 30 cm) at the marked sites (big enough to receive the seedling or rootstock with a ball of soil in the black polythene bag). Carefully remove the black polythene without disturbing the ball of soil and the roots. Plant gently in the holes and cover the hole with the dug soil and press firmly. Watering of the plants should be done in the evening to avoid excessive evaporation of water during the day. 17

Kola Cultivation in Ghana

3.1

MANAGEMENT OF TRANSPLANTS

Good agronomic and cultural practices after planting will ensure good field establishment and yield. Studies have shown that kola responds well to initial fertilizer application. Therefore, early fertilizer application will enhance growth. This is usually done six months after planting in the field. It is also advisable to plant food crops such as cocoyam, maize and legumes as intercrops to maximize land use. It is appropriate to weed the field 3 - 4 times each year for juvenile farms and 1 - 2 times for matured farms. This practice will reduce the pressure on nutrients in the soil and also prevent the build up of pest. 3.1.1 Mulching and recommended rate for fertilizer application

Mulching is recommended during the early years of planting in the field. This could be done with rice husk, pureria and other legumes to help conserve water in the soil during the dry season. Even though mulching is important, it may attract termites therefore, it is necessary to put in place measures to control termites when necessary. This involves the use of a recommended termiticide solution such as Bora-care, Orange oil, Borrada D and Cyper TC to drench the soil around the plants at a recommended rate. Since young kola responds well to fertilizer, it is recommended that NPK is applied in the form of: a. Sulphate of ammonia at a rate of 120-150kg/ha/year. b. Triple Superphosphate at a rate of 100-120 kg/ha/year. c. Muriate of potash at a rate of 100-120kg/ha/year. This will ensure good establishment of the plants and facilitate rapid growth. 18

Kola Cultivation in Ghana

4.0

KOLA PEST AND DISEASES

4.1. Kola pest Kola cultivation is mainly confronted with pest and disease problems at various stages in the development of the crop until the nuts get to the consumer. Kola pest can be grouped into major and minor depending on the level of damage they cause. The major pest are the kola weevils (Balanogastris kolae, Desbr. and Sophrorhinus spp); the stem borer (Phosphorus virescens Olivier); the fruit fly (Ceratitis colae Silv); the pod borer (Characoma stictigrapta Hmps); the leaf roller (Sylepta spp) and the defoliator ( Anomis leona Schuas). The kola weevil, B. kolae and Sylepta. spp are the most destructive insect pest of kola nuts, (figure 6a). They are field-to-store pests. Most kola trees in Africa are believed to be infested and the percentage infestation ranges from 30 - 100% (Daramola et al. 1973). Other pests such as the grasshoppers, psyllids and defoliators also attack the plants at both juvenile and matured stage by destroying the leaves. Figure 6b

Figure 6b: kola leaves damaged by grasshopper attack (punched holes in leaves)

Figure 6a: kola nuts destroyed by larvae of the kola weevil 19

Kola Cultivation in Ghana

4.2 Control of kola pest The major control measure outlined for majority of kola pest is the cultural methods since the use of pesticides are discouraged because kola nuts are consumed in its raw state without further processing, therefore, pesticide application may pose serious health issues to consumers. Cultural practices recommended include prompt removal of fallen and hanging matured pods, prompt and regular harvesting of matured pods, regular removal of dead pods, regular weeding and keeping of clean farm sanitation has been observed to reduce weevil damage by 35.4% (Idowu and Ojelade, 1995). Other effective cultural practice includes the destruction and proper disposal of all debris from the nut. Physical removal of adult weevil from crevices and bottom of storage baskets also help to reduce the incidence of weevils since they exhibit positive geotaxis. Ojo (1981) reported that larvae of Phosphorous viriscens which creates tunnel in kola stems could be controlled effectively by poking the larvae with a long wire or removal of the stem containing the larvae. Further practices such as dehusking of pods far away from kola groves and burying of pod husk which may harbor larvae, help reduce pod borer Characoma stictigrapta population. 4.3 Diseases of kola Major diseases of kola are caused by fungus, this pose serious threat to kola production. An example of such disease is the root rot diseases caused by Armillaria mellea and Formes noxius. This disease causes extensive damage to the roots of the kola tree making it impossible to perform it core functions such as nutrient and water uptake.

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Kola Cultivation in Ghana

4.3.1 Diseases of fresh kola nuts Kola nut disease are classified into three main categories as fresh rot, dry rot and internal rot Fresh rot disease of kola is caused by the fungus Fusarium moniliforme. This fungus produces colonies of fungal hyphae which develop on the testa of the kola nuts followed by development of yellow patches on the older lesions. It affects both harvested and unharvested nuts. The dry rot is caused by Fusarium solani. Its damage is characterized by the development of grayish powdery crusts on the kola nut cotyledons. The affected areas eventually turn black and hard. Infection often starts from the outside and spreads inwards. Dry rot is a field-to-store disease affecting the fresh harvested kola nuts and stored nuts. Internal rot disease of kola is also caused by Fusarium solani. In this instance, the outside of the cotyledon looks healthy whilst the inside is characterized by grey rot. 4.3.2 Diseases of stored kola nuts Three main diseases affect kola nut storage. These are Black rot, Dry rot and Grey mould disease. Black rot is caused by Botryodiplodia theobromae whilst dry rot and Grey mould are caused by Fusarium solani and Boytritis sp respectively. Black rot appears as spot over the outer surface of the nut, causing infected portions to turn charcoal black and hard. It may also be characterized by brownish black spots on the surface of the nut. Grey mould is a fungal disease which spreads rapidly from nut to nut during storage. It is also characterized by greyish lesions and powdery mycelia which covers the nut

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Kola Cultivation in Ghana

4.4 Control of kola diseases An effective way of controlling major kola disease such as the root rot, involves a complete removal of the tree from the field. In the case of the nut diseases, it is advisable to adhere to good sanitation practices. Again the use of hydrogen gas and some plant extracts is also an effective way of controlling storage fungi. Agbeniyi et al. (2000) reported that soaking of the nuts in 1% sodium hypo chloride solution (Milton solution) immediately after skinning the nut also minimizes microbial infection. Furthermore, the use of botanicals such as Ocimum gratissimum and Azadirachta indica leaf extracts protect the nuts against storage pathogens

5.0

HARVESTING

Kola nuts can be harvested by hand directly from the tree branch with a machete. At maturity, the fruit is inconspicuously brown and changes colour from deep green to paler tint. Special equipment such as the mistletoe pruner could be used to harvest kola pods that are high in the branches. Ideally harvesting should be carried out before the pods begin to split open. This could be done once or twice in a month during the peak season, usually between October and December. All harvested pods should be collected onto a clean platform and break. The testa covering the nuts could be removed by soaking it in water or burying it in moist sand or subjecting it to lightly watered heaps for 24 hours. The nuts are then washed to remove testa completely. 5.1 Curing and storage of nuts Curing refers to treatment performed to increase the shelf life of the nuts after pods are broken.

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Kola Cultivation in Ghana

The treatment can either be conventional or nonconventional. Conventional involves drying of peeled nuts in ovens at constant temperature of about 32°C to remove moisture from the nuts. This method is not very common compared to the non conventional method. In the non conventional method, skinned nuts are placed in unlined basket with the top covered in banana leaves (Figure. 7a) to allow the nuts to sit for about 3 days in the basket to enable water loss from the nuts. After the third day, a new basket is lined with fresh banana leaves and the nuts are transferred into it (Figure. 7b). The basket is then covered with banana leaves and stirred periodically to avoid excessive heat build up during this curing process which last for approximately 3 weeks. Another curing method involves the removal of the testa around the nuts and subjecting the nuts to direct sun light for four weeks at ambient day temperature of 32ºC in wooden trays. Cured nuts could now be stored on mats or trays in a cool dry place.

Fig 7a. Covering of nuts in unlined basket to allow water to drain out

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Fig 7b. Commencement of curing process for kola nuts prior to storage

Kola Cultivation in Ghana

6.0

REFERENCES

Adebola, P.O., 2003. Genetic characterization and biosystematic studies in the genus colaschott and endlicher. Ph.D. Thesis, Submitted to the University of Ibadan, Ibadan, Nigeria, pp: 203. Adebona, A.C., 1992. Biotechnology of Kola Improvement In: Thotappilly, L.M., D.R. Monti, M. Raj and A.W. Moore, (Eds.), Biotechnology: Enhancing Research on Tropical Crops in Africa. CTA/IITA. Co-Publication. IITA, Ibadan, Nigeria, pp: 376. FAO, 2009. Food and Agriculture Organization of the United Nations. Retrieved form: http://faostat.fao. org. Agbeniyi, S.O., A.H. Otuoye and A.R. Adedeji, 2000.Mycoflora Associated with Post Harvest Processing stages of kolanuts (Cola nitida vent schott and Endlicher). The J. Food Technol. In Africa, 5(4): 129-131. Daramola, A.M., 1973. The bionomics of kola weevils Sophrorhinus spp. (Coleoptera: Curculionidae). Ph. D. Thesis. University of Ibadan, Nigeria, pp: 325. Idowu, O.L. and K.T.M. Ojelade, 1995. Effects of timeliness of kola pod harvesting on weevil infestation in the field. Ann. Rep. CRIN, pp: 28-30. Lovejoy P.E. (1980). Kola in the History of West Africa (La kola dans l'histoire de l'Afrique occidentale) Cahiers d'Études Africaines, Vol. 20, Cahier 77/78, pp. 97-134. Ojo, A., 1981. Investigations into the control of the kola stem borer P. virescens Oliver (Cerambycidae: Coleoptera) in Western Nigeria. Turrialba, 31(3): 1. 24

Kola Cultivation in Ghana

Onomo, P.F., N. Niemenak and D.O. Ndoumou, 2006. Isoenzyme variability of three Cola (Cola acuminate (Pal de Beauv, Schott and Endlicher), Cola nitida ((Vent) Schott and Endlicher) and Cola anomala (Schott and Endlicher) germplasm in Cameroon. Pak. J. Biol. Sci., 9(3): 391-397.

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