Introduction
Mangoes account for approximately fifty percent of all tropical fruits produced worldwide. The Food and Agriculture Organization of the United Nations estimates worldwide production of mangoes at more than 23 million tons in 2001.With 12 million tons produced annually (2002-3 data), India accounts for almost half of the world production, followed by China (3 million tons), Pakistan (2.25 million tons), Mexico (1.5 million tons) and Thailand (1.35 million tons). The aggregate production of 10 countries is responsible for roughly 80% of the entire world mango production.
In Uganda, the production of mangoes is improving steadily especially as a result of the improvement in the export market and growth of the food processing subsector. For example Britannia food processing plant requires more than 4000 tonnes of mangoes annually. “We need at least 5,000 tonnes of mangoes annually. However, we get only 800 tonnes. We need 4,000 more tonnes. Uganda has the potential to grow more mangoes but it has not been exploited," said Sridharan Stidar, the marketing general manager.
The horticulture research program is dedicated to provide all the technical support required to promote this enterprise. In light of this, the program has a department for production of clean and improved planting material for the farmers and also provide training on production aspects. The varieties available include Alphonso, Kent (dodo), Glenn, Bire, Palvin, Boribo, Tommy and atikin. Below is a production manual to guide anyone interested in mango production to ensure food security and poverty reduction through income generation.
Management in the field
Remove binding tape a month after transplanting.
Remove shoots which grow below the graft union.
Weeding
Ring weed around the trees and slash the rest of the orchard. At the young stage of the crop, intercrop with lowly growing crops like beans, ground nuts. Keep the mango trees and the intercrop weed free.
Manure application
This is important for:
Faster growth, helps to fend off some diseases and other stresses, builds productive capacity
Mulching
Mulch the plants immediately after transplanting. Add more mulch especially after every weeding and manure application.
Irrigation
Irrigate young trees during dry periods. Irrigate immediately after fruit set. As a rule of thumb, young trees should be irrigated every 2 weeks.
Farmers can irrigate by filling jerrycans with water and perforating them at the bottom and in the lids. A jerrycan is placed near the stem of each plant.
Pruning
Pruning is also done at a young stage of trees at the height of 0.5m-1m above the ground. Pruning off the excessive shaded branches removes leaves that do not photosynthesize.
Harvesting
Grafted trees will begin to produce in the 2nd-3rd year after establishment. Time from flowering to maturity is only 100-150 days depending on variety.
Yield
Yield of 8-16 tons/ha can be obtained depending on management, variety and age of orchard.
Diseases
The major diseases of mangoes of economic importance in Uganda are:
a) Anthracnose
Caused by a fungus Glomerall cingulata. The disease causes serious losses to young shots, flowers and fruits under favourable climatic conditions of high humidity, frequent rains and temperatures of 24-34 degrees centigrade. It also affects fruits during storage. The disease produces leaf spots, blossom blight, withering tip; twig blight, fruit cracking and rot symptoms. Black spots develop on panicles as well as on fruits. It is common to find mummified young fruits on dead inflorescence stock. Fruits infected at mature stage carry the fungus into storage and cause considerable loss during storage, transit and marketing.
Control
The diseased twigs therefore should be pruned and burnt along with fallen leaves for reducing inoculum.
To reduce flower infection apply the first spray when panicles first appear, after observing the presence of the disease. Copper oxychloride WP used at the rate of 300g/L of water is effective. The first spray to be applied three weeks after fruit set when the fruits are pea size. Other fungicides are Ridomil, Dithane, and Antracol.
b) Powdery mildew
The characteristic symptom of the disease is the white superficial powdery fungal growth on leaves, stalks of pinnacles, flowers and young fruits. The affected flowers and fruits
drop pre-maturely reducing the crop load considerably or might even prevent fruit set.
Rains or mists accompanied by cooler night during flowering are conducive environments for disease spread.
If fruits are set, the diseased area becomes cracked. Cork-like tissue is formed and the fruits drop at pea size. Young leaves when infected develop white patches and later become curled and distorted.
Control
Use Ridomil and Antracol. Spraying can start at bud break and repeated after 2 to 3 weeks depending on weather conditions until fruit set. However, it is better to monitor weekly and spray at the first sign of the disease. Once young tissue has hardened it is no longer susceptible and spraying can be stopped.
Pests
a) Fruit fly
The female punctures the outer wall of the mature fruits with the help of ovipositor and inserts eggs in small clusters inside the mesocarp of mature fruits. After hatching, the larva feeds on the pulp of fruit, which appears normal from outside, but drops down finally. The mature maggots fall down into the soil for pupation. Some fruits may remain hanging on the tree and ripen prematurely. When such fruits are harvested and cut open, maggots of the fruit fly are seen and the flesh is damaged.
Control
Collection and proper disposal of infested and dropped fruits
Home gardens require three sprays of suitable insecticide e.g salut, 7 weeks and 3 weeks before picking
b) Mango seed weevil
It is a serious pest hampering export of Ugandan mangoes. The female lays eggs on the epicarp of partially developed fruits or under the rind of ripening fruit. Newly emerged grubs bore through the pulp, feed on seed coat and later cause damage to cotyledons. Pupation takes place inside the seed, discoloration of the pulp adjacent to the affected portion has been observed.
Control
A combination of removal of fallen fruits, trash and spot spray application of salut up to a meter round the stem greatly reduces the weevil population.
Destroying the affected fruits and exposing the hibernating weevils by digging the soil
Spraying the tree with an insecticide
It is a quarantine pest and therefore, great care must be taken to avoid its entry into other countries where mangoes are exported.