– Mango is an evergreen fruit tree that can last up to 100 years. It has become an important domestic and export fruit for Kenya. It does well in coastal regions and other warm areas.
– Mangoes are eaten fresh or canned. The fresh ripe fruit are used for desserts, processed into jams and juice. Green mangoes are made into pickle and preserves. The tree is used for boat building and firewood. The bark is used for leather tanning and wall hangings. The wood can also be used for building.
- Soils: Relatively fertile, deep, well drained soils that are well aerated with a Ph 5.5-7.5
- Altitude: 0-1500m above sea level
- Temperature: Optimal growth occurs at 20-260C. The quality of the fruit decreases in very cold areas
- Rainfall/ Water requirements: At least 650mm per annum because the tree is very drought resistant due to well established root system. The plant does better on higher rainfall of around 1500mm per annum. To avoid shedding of flowers and fungal diseases, rains are not required at flowering.
Two types of mangoes are grown in Kenya, the local and the exotic or improved varieties. The latter are usually grafted on local mangoes and are grown for the export market. Most local varieties tend to have high fibre content, commonly referred to as “stringy” and this characteristic makes them unpopular for local consumption.
- The local varieties are Ngowe, Dodo, Boribo and Batawi
- The exotic varieties are Apples, Kent, Keit, Tommy atkins, Van Dyke, Haden, Sensation, Sabre, Sabine, Pafin, Maya, Kenstone and Gesine
|Variety||Marketing season||Fruit Size||Fruit colour||Flesh/ textures/sweetness|
|1. Ngowe||Early||Large & Long||Deep Yellow||– Excellent|
– Flesh quality
– Fibre free
|2. Boribo||Mid Season||Large & long but not as slender as Ngowe||Deep orange red||Fibre free|
|3. Apple||Late||Round||Rich Yellow and Red||Very sweet, fibre free|
|4. Batawi||Mid-season||Very large & round||Rich olive green to purple maroon colour||Good texture, little fibre & sweet|
|Variety||Marketing season||Fruit Size||Fruit colour||Flesh/ textures/sweetness|
|1. Tommy Atkins||Early||400-600gm||Red,||Deep Yellow flesh, Firm, very sweet & moderate fibre|
|2. Kent||Mid-season||450-800gm||Green/red/yellow||Soft, sweet & fibreless|
|3. Van Dyke||Mid –season||280-400gm||Red||Medium texture with scanty|
|4. Kensington||Mid-Season||250-300gm||Red/Yellow||Very Sweet, soft & fibreless|
|5. Haden||Early||450-680gm||Red/Yellow||Medium texture with scanty fibre|
The more preferred varieties for export include:-
- Tommy Atkins – Has long shelf life. Resistant to Anthracnose and Powdery mildews
- Ngowe – susceptible to Powderly mildews
- Haden – Can be Used as rootstock because of its good quality – medium to large size; very juicy, pleasant aroma
- Kent – Late maturing
- Apple – susceptible to Anthracnose and Powdery mildews
SOURCE OF PLANTING MATERIAL BY REGION
– Coast : KARI – MTWAPA, MATUGA, MSABAHA | GK PRISONS – MALINDI & SHIMO LA TEWA PRISONS’ FARM
– Eastern : KARI – Embu, Katumani | ATC Embu | GK Prison – Maranjau | • Kamiu horticultural nursery – HCDA registered
– Central : GK Prison – Gathigiriri(Mwea), Kamiti | KARI Thika
– Nairobi : GK Prison – Nairobi West Prison, Jamhuri Short sentence | Good Samaritan Nursery (Karen-Langata Road) | JKUAT
– R/VALLEY : KVDA – Tot, Eldoret | KARI Perkerra (Marigat)
– NYANZA : LBDA – Kisumu
Establishment of Mangoes
- Done by use of Seed or vegetative method
- Seed – before sowing, remove the husks & transplant soon after emergency
- Vegetative – through grafting
Methods of Grafting
– Grafting is done at pencil thickness stage
- Side Veneer
- Wedge grafting
- Top-working of old trees
• Plough the land thoroughly removing stems and roots, lay out the field by spacing the holes – 9m X 9m, 12m X 12m, 14m X 14m depending on the variety (smaller varieties like Ngowe can use the lower spacing) and amount of moisture available
• Dig holes 1-2months before planting. The size of the hole should be 60cm x 60cm x 60cm ( in wet areas) or – 1M x 1M x 1M(for dry areas) ; While digging the holes separate 1ft – top soil and 1ft – lower soil
• It is recommended to transplant the seedling at the onset of short rains
• Mix the top soil with 2 debes of well decomposed manure and return to the hole
• Plant the mango seed at the same soil level as that of the seedling when it was in the polybag/nursery(make sure you remove the poly tube before planting)
• Fertilizer – Add to each hole 60g of DAP (use 150g DAP if no manure is to be applied)
• Mulch, shade & water the seedlings after planting
• Continue watering the plants twice a week during the 1st six months. Reduce to once a week until one year after transplanting depending on the weather conditions
– Intercrop with low growing crops like legumes, vegetables , maize, cassava, etc
– Weeding –Ensure the orchard is weed free
– In mature trees, weed just a 2M strip along the rows and cut grass in the rest of the field
– Fertilizer Application – The following fertilizer regime should be followed:-
|Year||Manure & Fertilizer type (Quantity/ Tree)|
|Manure rates (10 kg debe)||DAP (g)||CAN (g)||NPK(g)|
|Long rains||Short rains||Long rains||Short rains||Long rains||Short rains|
|Above 6 years||3||2||200||200||200||200||200|
- For any mineral deficiencies apply foliar feeds for supplementation
– Remove all dead branches and twigs and all branches that have been attacked by pests and diseases.
– Remove intertwining branches that prevent light penetration and air circulation.
– Remove all branches that fall below 1 meter from the ground level
– Pruning is best done immediately after harvesting the last fruits and before flowering to give an allowance for wounds to heal.
– Cap the tree at 1m height in 1st year to produce a spreading framework of branches; In the following year, select 4-5 well spaced branches and let grow. Prune off the rest
– This is done to induce off-season crop.
– It is done in two ways: –
- Spray with Potassium Nitrate 30-40gm per tree when the crop is dormant.
- Culturally – deprive the plant water for 1-2 months to induce stress and then irrigate the plant regularly.
– In the first year remove all the flowers. This is because the stem is weak and cannot support the fruits.
– Allowing fruits in the first year leads to lower yields in subsequent years
Pest and Disease Control
Mango Seed Weevil (sternochetus mangiferae)
Diagnosis / Symptoms
- The adult is dark brownish with pale patches, 1cm long, a curved snout and black eyes
- The larva is small , white and legless with brown head and can be seen inside the husk
- Partly eaten embryo inside of the husk
- The adults emerge from the ripening fruit by tunneling through the fruit
- Mango seeds damaged/destroyed by the weevil larvae have no external signs of damage to the fruit.
- Attacked fruits fall off prematurely but most times not.
- Plant less susceptible varieties like Ngowe or Boribo
- Collect all fallen fruits and destroy them either by burning or burying.
- Spray weekly with Malathion, Dimethoate, Sumicidin, Marshal 25EC from flowering until the fruits are 1 inch in diameter
- Paint the trunk with white paint mixed with dusburn or Malathion during the flowering stage to prevent the adult weevil from climbing tree from their hibernation site
Mango White Scales (aulacaspis cinnamoni)
- Appear as reddish brown legless and wingless insects 1mm long
- They make flat or circular white scales/clusters with 3 ridges on the body
- Adults come out of the scales as dark yellow with black eyes
- Due to sucking by the pest infested spots on fruit skin turn yellow and become depressed making fruits less attractive and difficult to market.
- Spray diazinon 60EC plus white oil.
Red Banded Thrips (selenothrips rubrocinctus)
Attacks only young seedlings in the nursery
- Lower leaf surface is darkly stained, rusty appearance, with curled edges of leaves and numerous shiny black spots of excreta.
- Spray sumithion 50EC or fenitrothion
Mango Fruit Fly
- Premature ripening of fruit.
- Flesh under the skin (which is the egg laying site) becomes liquid due to secondary infection. – Widespread fruit dropping
- Collect all fallen fruit put them in a drum of water with 1 inch of oil for 2 weeks
- Burn them.
- Bury them deep in the soil(2 ft)
- Put them in tied plastic bags and expose them to the heat of the sun for a few days until the fruit is rotten and all the maggots in the bag are dead.
- Spray trees with any of the following; Malathion or Dimethoate or labaycid
- Control is enhanced if the insecticide is mixed with an attractant/bait like molasses or sugars Other commercial baits such as nulure, buninal, solbait, GF120(Success). These baits are normally applied 1 m square spot on the canopy of each fruit tree on a weekly basis starting from when the fruits are 1 cm in size till the end of harvest
- The adult lays eggs on tender leaves. Occurrence of “pimples” becomes necrotic and the leaves may drop
- Apply Malathion, Dimethoate mixed with white oil
- The concentration of the white oil should not exceed 2 percent i.e. 400ml for 20 liters of water. Higher concentrations are poisonous. Avoid application during hot periods of the day.
Mango Powdery Mildew (Oidium mangiferae)
- Infected flowers, flower stalk, young fruits and leaves are coated with white powdery growth of the fungus.
- Attacked fruits turn brown and shed prematurely.
- Fruits fail to set if whole blossom is infected
- It is common in cool and cloudy weather
- Spray Dinocarp from flowering to fruit formation stage at 2 weeks interval
- Spray Benlate before flowering and again 3 weeks later
- Culturally, avoid arranging seedlings in a nursery densely and prune tree canopy for improved air circulation.
Attacks all tender parts of fruit and severe on the flowers, young fruits and leaves
- Black spots seen on fruits, flowers and leaves
- Excessive flower and fruit drop
- The black spots on fruits develop into depressions and the skin cracks and turns into black rots and penetrates into the flesh
- All dead twigs and leaves should be removed and destroyed
- Spray with any of the following; Antracol, Kocide DF before and after flowering
- Plant less susceptible varieties e.g. Tommy Atkins
– Local varieties starts bearing at age 4-7 years while the grafted varieties take 2-3 years.
– The yields increase with age and trees reach optimal bearing at 8 years, reaching full maturity at 20years.
– The fruit takes 5 months from blossoming to ripening. Maturity of the fruit is determined by change in skin colour, shape, texture and flavor of the fruit.
– When harvesting, to avoid damage the fruit should be handled gently both at picking and post harvest handling (for tall trees it is advisable to use a ladder and avoid pulling the fruit from the tree)
– Cut the fruit with 5 cm of stalk.
– Harvesting seasons are different for different varieties in Kenya as shown in the table below:-
|Mangoes harvesting seasons in Kenya|
Maturity indicators for mangoes (when to pick mangoes)
- Shoulder development
A fully-grown mango should have outgrown shoulders (fullness of the chicks) shown by formation of a depression at the stem end (where fruit attaches to the stem) firm and green.
- Skin colouring
Ripe mangoes skin colour change from dark green to yellow in some cultivars e.g. Haden.
NB: in some cultivars e.g. Sensation the red/purple colour skin is not a dependable maturity index.
- Colour of the flesh
Colour changes from greenish yellow to yellow to orange. Slice the fruit to observe.
- Hardening of the mango-stone
The hardening of the stone is a good sign of maturity. Cut fruit to observe.
- Specific gravity
This is done using the ‘float test’. Ripe mangoes sink immediately and hence not suitable for export. Fruits that float just beneath the surface of the water or sink slowly to the bottom are suitable for export. Immature fruits not ready to be harvested for export float with about one tenth of their volume above water.
NB: a few mangoes from semi-arid areas have high specific gravity and even immature ones will sink. Modify the test by adding about 1 kg of salt to every 100 litres of water.
- Ripening period
Fruits in mature green stage take about 7 days to ripen fully under natural conditions. They don’t shrivel but develop full flesh Colour and flavour. If fruits ripen (soften) before the 7 days are over then they are not fit for export market – they are over mature and fit for local market. If they do not soften by the end of the seven days, they are immature and hence not yet. Ready for harvest
Maturity is also based on a standard of 13 percent dry matter content.
- Brix value
A brix value of 8-9 percent – the mango is ready to be picked for export. Locally sold mangoes can be harvested at a brix value of 10 percent.
A brix value is taken using a refractometer reading
The local varieties yield 200-500 fruits per tree per year whereas the grafted varieties yield 1000 fruits per tree per year (15 tons/ha).
The table below shows expected yields of mango trees by age:-
|Year||Yield per tree (tons)||Yield per Ha (70 trees/ha)|
|7th and above||214||15000|
POST HARVEST MANAGEMENT
Post harvest minimum requirements for export market
- The Fruit
For export cut the stalk to 2cm. the fruit should be intact, firm and fresh in appearance. Fruits affected by rotting or deterioration are excluded.
Fruits should be clean (practically clean from any foreign material, free from black stains or traits, free from marked bruising.)
- Post harvest treatment
Mangoes are submerged in hot water at 550C to kill latent fungal infection developed in the field except Tommy atkins which cannot withstand higher temperatures of 500C.
Size is determined by the weight of the fruit which is consumer driven. This determines the no. of mango pieces a 5Kg carton carries e.g. size 12, 10, 9
The contents of the package must be uniform and contain only mangoes of the same origin, variety, quality and size. The visible part of the content must represent the entire content.
Use clean material and of high quality that can withstand transportation to the final market destination. Pack in single layers in boxes with plenty of wood wool or tissue lining.
Each package must bear the following particulars; Identification, packers names and address of official dispatcher, produce name and variety, origin of the produce, indicate country of origin and optionally district where it is grown.
There are two main market destination for fresh mangoes, the local and export market
- Export market
Consumes 1 percent of mangoes produced in Kenya.
Kenya Mangoes fetch better prices in Europe and Middle East between November and December where there is less competition
- Local market
Consume 99 percent of mangoes produced in Kenya (50 percent consumed at farm level, 49 percent sold for local consumption).
Major outlets for fresh fruits are urban centers, processing industries ( e.g. Milly Fruit Industries, Kevian Foods), hotels, schools and the Armed Forces
– Mangoes grown in Coast and other hot areas are sweeter than those grown in colder regions.
– Varieties that are fibre free are more preferred in the market