How to grow avocados for bumper harvest

Ugandan avocados are genetically diverse and are represented by a wide range of varieties differing in size, shape, colour and flavour.

The fruits can be round, oval, elongated, in pear-shape and generally have a bulging base that slightly spills into a neck with curved ends.  The skin also varies from green to dark purple, almost black and can be thick to thin textured and leathery to glossy.

Underneath the surface, the flesh is dense, dry, creamy, aqueous to fibrous, ranging in colour from pale green to yellow-green.

Ugandan avocados will exhibit varying flavour profiles depending on the variety and are commonly nutty and finely sweet.

This is according to Albert Kunihira, research and business development manager of Greening Uganda and Forestry Services, an organisation engaged in sensitising farmers in the country on how to grow avocado on commercial basis.

Varieties
Dr Ramathan Idd, an expert in vegetable and fruit breeding at the National Crops Resources Research Institute (NaCRRI) in Namulonge, explains that farmers in Uganda grow mainly five varieties and these include, hass variety which gives pear shaped to ovoid fruits, its skin is tough, leathery, dark purple to nearly black when ripe and pebbled. Because of its high demand in Europe, hass avocado is the most profitable and important cultivar of all the varieties.

Other varieties include reed, which gives round, medium to large fruits with skin slightly rough, medium thick pliable. The variety gives fresh cream coloured fruits with rich, faintly nutty flavour.
Bacon variety has fruits which are small to medium size, round ovoid, with smooth green to almost colourless flesh.

Fuertes are pear shaped and bare small to medium fruits. The skin is slightly rough to touch, with many small yellow dots.
Semil 34 contains oil, dry matter, and it has green leaves with organoleptic attributes  (aspects of food, water or other substances that create an individual experience via the senses—including taste, sight, smell, and touch).
Soils

Dr Iddi notes that although the avocado grows on a wide range of soils, it grows best on deep, well drained fertile soils of medium texture with a pH. range of 5.5 to 6.5.

Propagation
Albert Otim, who specialises in avocado breeding at NaCRRI, notes that avocado is propagated both by seed and preferably by grafted cuttings because avocado cuttings give faster results when used with fruiting starting as early as two years or less depending on how the farmer is managing the agronomy.
At NaCRRI his team has been breeding a number of varieties, six of which have been disseminated to farmers.

Other varieties are being worked on at NaCRRI and may be ready for release in two years’ time.
These are varieties which have been grafted to a local variety called Buke as the initial stem which is planted in the hole. Grafting is done in a nursery where mature seedlings of the land race variety is grafted to the preferred hybrid varieties. It takes six months for the seedlings to grow ready for planting.
The multiplication has been done by nursery operators in collaboration with the scientists and they are disseminated to farmers during the Seeds of Gold Farm Clinics across the country.

Seedlings
An acre requires 166 seedlings and the cost of a seedling is about Shs5,000 so the total cost of seedlings is Shs830,000. Bush clearing per acre ranges between Shs80,000 and Shs150,000. A farmer will spend about Shs24,000 to buy fertiliser which is applied at planting stage.

Planting
Otim contends that like any other tree plant, avocado occupies the ground for a long time. This therefore requires farmers to clear up the site meant for permanently sitting the avocado.
The layout can be in home garden or on a commercial basis and farmers are expected to open up the surface to create a hole of the same diameter as the seedling.

Process...Planting guide
Dig a hole about the same depth as the root ball making the width of the hole 2-3 times the size of the polybag in which the seedling was brought up.

Cut the polybag sleeve to separate it from the root ball and then gently place the seedling into the hole.
Fill the hole with soil, if it is already decomposed manure, a farmer may plant immediately but if not leave it to decompose for three months before planting.

Water the seedling to provide moisture needed for proper plant growth.
You can go ahead to mulch the seedling to help retain moisture in the ground.

Pests and diseases
According to Otim, root rot is the most common and dangerous disease which poses a challenge to farmers.  It affects the plant’s roots in poorly drained soils leading to withering of the tree. If not well managed it may lead to 100 per cent loss. Farmers are expected to manage it right at the time of planting to ensure that the grafted root is planted protruding above the soil surface.

Other diseases include anthracnose and powdery mildew, a fungal disease that affects the flowers of plant leading to abortion meaning fruiting will be affected. These, if not well managed, lead to 80 per cent yield loss.

The pests include mealy burg which sucks the plant’s sap and chlorophyll from the leaves by means of their piercing sucking mouth and this affects the growth of the plant.
The other is thrips which are minute, slender insects with fringed wings which do the same damage as mealy burgs.

Fruit flies are also a challenge they lay their eggs on the leaves of the plant thereby defoliating the leaves which causes stunting and leading to yield loss.

Farmers are expected to manage them by planting grafted plants which are able to resist the pests and diseases.

It is advisable to spray the plants with ridomil pesticide to clear the pests off the plant’s leaves.
Methods such as intercropping, mulching at appropriate periods and application of manure are good because they improve nutrition of the crop.

Harvesting
Avocado is unique in the way it ripens. It matures on the tree but does not ripen until it’s picked so some experience is required to determine when an avocado is sufficiently mature for harvesting.
Generally the skin colour becomes more yellowish, green or purple and the surface shine becomes dull in appearance.
Farmers can harvest the ready fruits by hand, using picking poles or ladders.
Avoid picking during wet weather as fruits are more susceptible to skin damage and fungal infection.

Market
The fruits are commonly sold in local markets and are highly favoured for their rich flavours, but there is also a movement throughout the country towards increased cultivation for export. Dutch wholesalers have established relationships with Ugandan growers to cultivate and export more well-known avocado varieties to Europe.

Famers can sell avocado surplus to fresh fruit markets in Kampala and other towns or even in supermarkets grocery stalls.

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