From farm to fork: The A-Z of avocado farming

Avocado crispy egg toast by Chef Ali Mandhry.

For those interested in avocado farming always consider the market preference before selecting the variety to grow.

Avocado is a versatile fruit with different uses across the food and beauty industry. The Kenya Agricultural and Livestock Research Organisation (Kalro) says Kenya has more than 40 avocado varieties that can suit different agro-ecological zones. However, Hass and Fuerte are most common due exporter and processor preference of the two varieties. Other avocado varieties available include Keitt, Reed, Booth 8, Simmonds, Pinkerton, Nabal, Puebla, Tonnage, Ettinger, Hayes, G6 and G7. The varieties used as root stocks include Puebla, Fuerte, Duke, G6, and G7. For those interested in avocado farming consider the market preference before selecting the variety to grow.

Here are the guidelines to follow for optimal production.

1. Site selection

Select the right agro-ecological zones for avocado growing as the zone determines the soil type and rainfall amount and pattern. Avocados perform best in locations between 1,500 – 2,100m above sea level with 1,000mm of well distributed rainfall. This means the rain should spread throughout the year and not experience heavy down pour in some months. Heavy rains are destructive to an avocado orchard. The site should have well drained deep soil about 1m of topsoil and a pH of 5.5-6.5. Avoid sandy soils with low organic matter. Water-logged soils are detrimental to avocados and favour development of phytophthora root rots in your crop.

2. Spacing and Plant Population

The varieties we majorly grow are spaced out at 9 metres between rows and 9 metres between plants. This results in a plant population of 120 plants per hectare. Consider other orchard activities when laying out the field. For instance, will you need to lay out pipes to supplement rainfall? Will you use machines in the farm?

3. Nutrition Management

To avoid costly mistakes, carry out a soil test first before planting any crop. The test indicates the state of nutrients in your soil and recommendations are given against the nutritional requirements of the crop you want to plant. The test should give you the nutrients required and quantities needed for each. It goes further to recommend the fertiliser type and quantity. Regularly perform soil test for your orchard through the years.

Should you not have done a soil test, meet the following:

a.  A month before planting prepare holes 60 x 60 x 60cm (length x width x depth). Separate the top and sub-soils. Mix the top soil with 20kg (a debe) of well decomposed farm yard manure and 120 g of Double Superphosphate (46 per cent P2O5) with the top soil. This will be used to cover the seedlings when planting.

b. Planting- Carefully remove the plant from the container with the soil intact and place it in the centre of the hole and cover firmly with the mixture of top soil and farm yard manure. Make a basin around the seedling for holding water. Transplanting is more successful when carried out during the long rains either early morning or evening. Plant the seedlings at the same depth as it was in the nursery and water the plant immediately after planting. In hot areas, shade the seedlings after transplanting.

c. Use plenty of manure in the orchard throughout the growth of the trees.

Joel Mokaya tends to his hass avocado variety seedlings. [Sammy Omingo, Standard]

4. Irrigation

In areas where rainfall is not sufficient for growth of the fruit, plan for supplementary irrigation. Select micro-sprinklers as they are excellent precision irrigation tools that create a wetted pattern around the trees root zone. For the first five to six years, wet the ground a distance from the tree trunk equal to two feet times the age of the tree in years. For instance for a two-year-old tree wet 4 feet from the tree trunk (This indicates root spread of the tree as it grows). After six years, wet all the ground in the grove 24 inches deep or as deep as you find active feeding root fibres in your soil.

Since irrigation can make an avocado enterprise expensive, always irrigate the soil after checking different spots for soil moisture content with a soil auger for at least a depth of 24 inches. Advanced farmers can install automatic soil moisture metres that advise/ alert them when to water the orchard. Avoid surface irrigation methods like furrows and basin. They are undesirable and their comparative cost is high (water loss due to evaporation, use of too much water and labour required). In an avocado set up, farmers can consider use of portable underthrow sprinkler system. This is a normal sprinkler system that is shorter than the tree to ensure water does not travel a long distance through the tree leaves and branches but rather pours directly to the ground.

5. Mulching and weeding

Use of herbicides in avocado orchards is highly discouraged. Farmers are therefore advised to use pest/disease free mulch to keep weeds from growing. Mulching also reduces the need for irrigation by conserving soil moisture. Farmers can select mulches from dry grass, sawdust and plastic mulch sourced from agro-supply outlets near you. Select what best fits your pocket and environment.

Top tip: Keep your plantation weed free always.

6. Pollination

The type of avocado cultivars planted in an orchard will contribute to the expected yield. There are two types of avocado that flower at different times of the year (type A and type B). Mix both types in an orchard so that type A pollinates type B and vice visa. Avoid self-pollination in your orchard. One can install bee hives in an avocado orchard for bees to help with cross pollination.  Consult on the type as you purchase the seedlings. Type A varieties include Hass, Gwen, Lamb, Pinkerton, Reed, GEM and Harvest while Type B include Bacon, Ettinger, Fuerte, Sharwil, Sir Prize, Walter Hole and Zutano.

7. Intercropping and Pruning

Since avocados start bearing fruits three years after planting, farmers can plan to intercrop the trees with other annual crops like beans, peas, kales, cabbages, cowpeas and other crops preferably nitrogen fixing crops. Nitrogen is an important nutrient for avocados. Intercropping allows the farmer to generate revenue from the farm instead of getting nothing for the first three years.

Apical bud of young plants should be nipped to slow growth and lead to a compact tree. Lower branches that interfere with cultural activities including irrigation should be pruned. The canopy is pruned to a height of 5-8 metres to facilitate fruit picking. The avocado tree is susceptible to sunburn therefore practice moderate pruning only when necessary. Heavy pruning should only be carried out to reduce the size of the tree after 12 to 15 years of bearing. Farmers can also prune the larger tree roots by cultivating to a depth of 50 cm around the edge of the tree canopy.

8. Pests and Diseases

Most common pests that target the fruit are false codling moth, fruit flies, scales, thrips, spidermites and bugs. The most common diseases are scab, avocado root rot, anthracnose and cercospora fruit spot. With proper crop husbandry, you can keep pests and diseases at bay. For more info send me an email on [email protected]

 [Njoki Thuo – Mwakughu (BSc Agriculture, Egerton, MSc AICM, UoN]