GUIDE ON OGBONO PRODUCTION
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EXTENSION GUIDE ·.·.·-:.·. ~ PRODUCTION AND UTILIZATION OF 'OGBONO' (IRVINGIA GABONESIS)
Extension Bulletin No.
Produced and Distributed by:
ational Agri cultural Extension and Research Liaison Services Ahmadu Bello University P.M. B. 1067 Zaria. N igeria.
Published - - - Acknowledgement
The Authors w ish to acknowledge the following Institution who e varying contribution helped in the preparation of this bulletin:- Federal Uni ver ity of Tech nology (SAAT) Owerri ; Forestry Res. Institute; Nige rian Institute for Horticultural Research and Ministry of Agriculture, Anambra State.
Chris Chinaka (NAERLS J. C. Obiefuna (FUTO) Introduction lrvingia gabonensis, popularly known as 'ogbono' and commonly called ' African mango' or"wild mango", is an indig enous forest tree belonging to the group of plants classified as
" non timber forest products (NTEP). I n Nupe it is called
.. pekpeara"; '·Ogwi" in bini; ·'Agbono/ugiri depending on the va
riety in l gbo; " uyo" in Efik and " oro" (tree) " apon" (kern el) in
Yoruba. Tt belongs to the Irvingiaceae family of plants. The tree
attains a height of up to 30 meters and about 1.0 meter in girth
when fully developed. The leaves are simple and altern ate, up to
I 0 cm.long ~ i t h deciduous stipples up to 1 .2~m long·,. .w hi c ~ leaves encircling scares on the branchlets. Flowers are tiny, white to greenish and appear in clustered ax ially racemes. The flowers are very sweetly scented. The fruit is slightly flattened, ellipsoi.dal
drop with fibrous mesocarp and stony endocarp . . In the spec ies "gabonenesis ,. or Irving io. ·we II defined
intraspecific taxa have been recognized: thus there are: lrvingia
gabonensis var. gabonensis and ln ·ingia gahrmensis var excels a.
The pulp of the lrFingia gahonensis var exce/.\·a i ~ ~a i el to be
eaten although it i ~ biner and acrid with the fla vour of turpentine
and slightly slimy. On the other hand. the pu lp or the /. Cobonensis var gahonensis i ·sweet, mooth in the mouth and has brittle pul p. 1.1 Ecophysiology: The natural habitat of I. Gahonensis extends from Senegal to Sudan and South of Angola. The tree grow well in a variety of soil type ranging from sandy clay loam. to loamy clay soils w ith adequate rainfall of about 1000 mm per annum and abundant sun hine. In Nigeria. the tree i found grow ing between latitude 4. 15 " and 8.00°N of the equator especially along ·tream and the banks of rivers and in village homesteads.
The tree has adapted and now grows well even in the compara tively drier ecological zones of the northern edges of the derived savanna. Under natu_ral conditions, the plant bears fruits between
15-20 years but under improved management, especially when budded eedlings are planted. the vegetative pha~e i consider ably reduced and fruiting can start from 4- 5 year while eco nomic yield can be attained after 7- 8 years from planting. The ever expanding de forestation constitutes a major threat to the tree~ in the wild while the acti vities of fruit collectors. further com pound this negati ve impact on the natural regeneration of !n ·ingia tree!'> becai.tse the fruits are removed and thu~ not given a change to germin ate and grow into new tree.~!. These therefore call for the con.-c ious and planned establishment of ln •ingia plantations. 2.0 CULTIVATION PRACTICES: 2.1 Propagation:
'Ogbono' (irvingia gabonensis) is commonly propagated by seeds.
Increasing awareness have necessitated the development of propa gation procedures for the plant in order to enhance its popularity, economic potentials and continued and regular production intra dition al and future farming systems. In this regard; efforts are made at obtaining early flowering (and fruiting) through cultural management practices which include budding and 'topping'.
2.2 Nurs.ery: Although ground nur eries c.ould be .. used, polybag, basket or perforated tray nurseries are recommended. Movable nur ·eries e.g. polybag nurseries have the following ad vantage over ground nurseries:
i) They save labour co:t incurred during digging up for transplanting.
ii) There is reduced to no ri sk of transplanting shocks iii) There is space economy."
If polybag nurseri es are to be used. polybags not ~ma ll c r th an
ISmm gauge, 12cm diameter and 25 em deep are recommended. This should be filled with top soi l up to at least 14 em from the base. The top IOcm should be filled with sa w du t (Fig. I ).
Fig. I : Polybag nursery
Tree-ripened fruits (that have fallen by themselves) are elected.
It is advi ed not to germinate fruits that have been plucked from the tree. eed extracuon is by carefully cu tting out completel y the fleshy pericarp (pulpl. and was hing the nut using sand and water. Allo\ving the pulp to rot naturally and washing in \.vatcr reduce:- the germinal ion percentage b) about :wec. Dr) the nu t:-. in a shade for one or two days. Prolonged drying for more than a week rc~ ult s in decrea~ed seed vi abilit) . Avo1cl ~un drying. Pl ant seed~ within two or three days after ex traction. To avoid the incidence of damping-off treat seeds with Ben late or other potent fungicides before sowing. After sowing, move the poly bags to a shade and arrange in 10 x 100 or 20 x 50. Water daily. Avoid over-watering to prevent water logging and damping off disease.
Apply fertilizer when nutrient deficiency symptoms e.g. chloro is ar~ noted. Apply water soluble fertilizer, NPK dissolved in water from time to time. I kg NPK may be applied in about 6 doses for
2000 eedling . Germination starts 3 weeks after planting and may continue for another 4 weeks.
2.3 Budding: I 0- 12 months after germination, the eedling are ready for budding. Budding is done at about 15- 20 em height u ing the inverted " T" cut. Rootstocks to be bud ded should not be less than 0.5cm in diameter at a height of !Scm from the soil surface. Obtain budwood from healthy mature flow ering trees. It is recommended to bud during the rainy season. 2.4 Land Preparation: Land preparation for field planting is done between ovemher and March. The operation involved include: clearing, fel lin g of un wanted trees. cross-cut ting. packi ng and burning. A rter bu rning. marking ou t or the planting ite follow. The spacing of 7m x 7m is recommended.
7 This gives a population of about 200 stands in a hectare. After marking out. dig planting hole 60 em x 60 em x 45 em. Fill the holes with well decomposed organic mater and top oil two weeks before transplanting. Do not put inorganic ferti lizer into planting holes at transplanting of seed lings. This may be harmful to the young eedlings.
2.5 Field Establishment: I 0-12 months after bud- ding, seed lings are ready for transp lanting. Thus seedlings are ready for field planting 20-24 months after sowing in the nurs ery ... Tran. planting i. done in the early pa~·t of the· rainy season as soon a the rains stabilize- i.e. May- June in the rain forest zones: and June- July in the savanna. Seedl ings should be tran ~ planted with the ball or earth around the root of the plant. If budded seedlings are planted, regularly check and prune off al l
~ide <.: hoot' from the stock.
2.6 Fertilizer Recommendation: Fertilizer applica- tion starts one year after l'ield establi..,hmcnt. II' the planting holes were well prepared (with well decomposed organic matter and top .... oil ). no chemical rcniliter i ~ required in th e fir:t year or es tablishment. Within the next year ( 1-4 years after planting) and if the soil is fai rly rich to rich, an application of 0.25kg/stand or
NPK ( 15: 15: 15; I 0: I 0:20 or NPK M g 12: 12: 17:2) or any other
compound fertilizer having NPK may be applied. Fertilizer ap
plication hould be done during the rainy season. I f however the
soil is poor, the dosage could be increased to 0.5kg/stand. The
plants are ri ng weeded before broadca Ling the fertilizer aro un ~
each stand once a year.
2.7 Topping: This is a management practice whereby
all the growing shoots of the plant are shaped by clipping (prunning or training). In lrvingia, this i . a '"tam·ing" process. In the tradi tional system regular bush burning and farming activities take care of"topping". Topping has the following advan tages: a) It gives the tree the des ired shape - " dome" instead of the
conical shape that the tree is naturally prone to. b) lt e.x po ~e~ more l eave~ to ~u nli gh t thereby en hancing ph0- tosynthesis and facilitating more fruit formati on. c) It encourages early flowering d) It controls the height or the plant.
Between the seco nd and thi rd ye ar. and towa rd ~ the end or the rains. do the first topping (prunning). Thi ~ i: achieved by cutting back all the growing shoots. Repeat this yearly for the nex t 3 - 4 years.
2.8 Interplanting: Within the first five years of field life and until the lrvingia closes up all the elbow spaces", food crop - yam , cassava, Cocoyam, and vegetable can be planted within the lrvingia stands. Ginger will grow well panted under lrvingia. Spreading crops especially sweet potato is highly rec ommended as interplant becau e apart from the edible ·weet po tato roots. the sweet potato will al o serve a a soil cover to check e to:iio n and to co ntro l w eed growth. Al full cover of lrv in8 ia , only crop. like ginger, Cocoyam and . weer potato w hi c ~ are shac:le tolerant can be interplanted with lrvingia .
2.9 Irrigation: Seedl ings transplanted in May/June or June/July depending on location, may be adversely affected by the fo llt'~ w in g di·y -;ea~o n (. ov-March) esrec iall y if the dry sca
-;o n co m e~ earl y and ex tends to March - April of the foll owin g year. During this ti me. it is recommended to mu lch round the
"tand ... with gra~~ and suppl ) 20-25 li t re~ or water per tree per '-"Cek . Th io., \v iii enhance : urvival rate and ea rl y producti vit y.
10 2.10 ' Beating up' (Replacement of Dead Plants):
Plants that fail to survive, should be replaced the next rainy season. This practice should continue until all the miss ing stands are fi ll ed up. Before repl anting, the dead plants and . the planting holes should be properly checked.to find out the cause of the death. [f the death is cau ed by a di sease or pest, adequate me·asures should be taken to 'clean up' the planting site and planting materi al before and after replanting.
3.0 PLANT PROTECTION:
3.1 Diseases: Most of the di sease of lrving ia are nursery diseases. These include: a) Damping off: lrvin.gia is susceptible to damping off disease cau ed by two fungi"- Pythium :pp. And PhyTophtoro spp. Seri ou damping off e. peciall y when germinated in unsterized soils is a very common feature. The seedli ngs remain susceptible till the cotylendons drop 3 -4 weeks aft er pl anting (w II of water. E ffic ient treatment requires complete wetting of af fected part.. Dithane M -45 or Furadan could eq ually be used only on seedlings infected after the coty lendons had opened and the first 2 lea ves appear light green in colour. b) Leaf spots: there are two types of leaf spots- (i) Chl orotic to necrotic spots caused by two fungi- Rhiz.octonia spp and Collectrotirichum spp; and (ii) Re dd is h purp le spots caused by Rhiznctonia spp. These are controlled as sta~ed for damping off. 3.2 Pests (a) Insects pests: Young seed lings are attac ked by grasshop pers, caterpillar , sca le insects etc. Leaf miners and fruit borers occasional ly attack mature plants. These pests are controlled by spraying monthly wirh any bro~1cl ~ p ectru !T! in~ectic i cle l ike Ultrac icle. Gamal in 20. Rh ona lin 20EC. M ocap I 0 G etc. Purple blotches on leaves of ln •ingio gobonensis var cxcclsa delays on se t or fruits. T liis is caused hy unarmoured -;calc insects. The control equally is by :praying month ly with any poten t insec ti cide. I -, (b) Rodents:- Rodent can attack newly transplanted stand of [rvingia and destroy them. Bai ting w ith rodenticides (e.g. Chlorophacinone) is a recommended control measure, otherwise, setting of traps could keep off rodents from newly established field . (c) Epiphytes: The mist letoe .( Visum spp) is a green parasitic shrub which grow attached to trees in a ball like bush. In Irvingia, l ike other fruit trees (Citru ·, kola etc.), this parasitic plant ystem atically _k ills the host plant from branch to branch until the entire plant dies. _The control is by physical ly removing and bur~ ing the· weed or by cutting off the affected branch. (d) Weed control: In the fir t 2 years of field establishment. it is recommended to ring weed I meter from the base of the plant . In situations where the trees have been interplanted with food crop. , the entire field hould be clean weeded as the need arises but at least twice a year. If the field i not intercropped with food crops. slash the inter row (as the need ari es) to keep clown weeds. (e) Fire Tracing: Bush fire which i!-> a regular future during the dry season can des troy a newly es tablished Irvinxio field. It i!'> recommended to cut a fire trace 6 111etcrs wide round th e pl anta ti on during the dry sea on to create a fire corndor round the plan- 13 tation each dry season. 4. HARVESTING AND UTILIZATION: Fresh 'Ogbono' comes into market between June and Augu t and is mo t scarce between March and April. The two varieties of lrvingia have different flowering/fruiting cycle . thus: Variety Flo\\ering Fruiting I. Nov. -l'vbrch Apil - July · CalXJ11eJISis v~.·· ~abonensis ·. and and June Sepl - Cl:t. II. Gabonensis var. e.xce/sa Sept.-O::t. Dxen-rer-Mlrch When ln · in~io fruib mature. the y fall to the ground and are col- lected for processing. M ature fruits can equally be plucked manu- ized annual event in areas where lrviuoia,., 2.~ row: in the wild on commercial lands. I-I 4.1 Processing: After picking, the fruits are heaped and the pulp (mesocarp) is allowed to ferment for about 7 - 10 days. Thereafter, the seeds are washed off with water and at times with some sand. In fre hly harvested lrvingia, the pu lp can be manuall y removed with sharp kn ives to. extract the eed . The pulp so removed could be processed into other products while the seeds are dried in the sun or by fire. After drying the seed are split into two flat white co t y l edo~s (kernels) and further dried before marketing. The seeds may be stored in a calabashes, pots or sacs at room ten:perature for upward of 6- 8 f!lOnth s.· ..The ~e rn el s (cotyle dons) are the Jrvingia of commerce. An average kernel yield of 25 kg/stand of lrvingia is con sidered good. Kernel yields could be up to 30-35 kg/plant in good years and could go as low as below 20kg in bad fruit in g year . 4.2. Utilization The kernels of ln ·ingia contain 54-67o/c of fa tly matter. Thus /n •inglo can class ify as an oi l crop. The kerne l serves as condiments used in thickening and flavouring ~o up s . The more the ground kernel '·draws·· in soup. the mon: accept able it is. Thu , lrvingia gahonensis var. excelsa wh ich ··draw:-.· · 15 more than the var. gabonensis is more acceptable in soup mak- mg. The fresh fruit of the I. Gabonensis var. gabonensis is sweet and ed ible, and is suitable in the manu fac ture of jams, jellies and fruit JUtces. The pulp of the var. excel sa is bitter and inedible. The kern el of lrvingia is u ed in making a fatty paste ca lled ·'ctika··. Thi is the principal ingredient in the making of " Gabon chocolate'' or " Dika bread". Thus the lrvingia fruit is often called " Dika nut... The pulp :,erves as li vestock feeding materia ls When fully dried, the kernel . hell. are good firing materials. The bark of the tree is bitter and is added to palmwine as a preservative. In traditional re ligion , orne tribes use the plit shells of the fruit in divination; gi ving a favourable omen if one falls flat and the other cover ~i-de ur. The '-VOod i~ pale brown. very hard . fi.nc grained and immune to termites. It i!'> u~ed in building canoes from the trunk: Pes tles for yam mortms: house posts etc. The tree is useful for allore~tation and erosion control. References I. Eze, 1.0.1. and J. C. Okafor (1984). " How to grow se lected fruit trees". Ministry of Agriculture, Anambra State, Enugu. Information Series Booklet No.4. 2. FUTO (Federa l University of Technology, Owerri) 1986. Annu_al Res. Report. 3. -do- 1987. Annual Report. 4. -FUTO (Fed. Universi ty of Tech. Owerri) 1988. School of Agric. And Agric. Technology: Production Guide No. I . Cultivation of Agbono- (! rvingia gabonensis). 5. Nielsen, M .S. ( 1965). Introduction to the flowering Plants of West Africa. University of London Press Ltd. London. E.C.4. 6. Okafor, J. C. ( 1980) " Edible Indigenous Woody Pl ants in the Rural Economy of the Nigerian Forest Zone". An In vited paper presented for NAB Workshop on State of Knowltuge ur the Nigerian Rain rure~L Ecu:-.y:-.lc ln. Fure:-.1 Ecol. Mgt. 5. 7. Okafor. J. C. , and I. C. Okolo ( 1974). Potentials or ~ ome Indigenous Fruit Trees in igeria. In: Proc. Of the 5'11 Ann . Conf. or Fore!-.try A:-.:-.n. or Igena. Ju:-. 1-6 Dec. 197-L 17 ..