Information of www.infonet-biovision.org
Avocados
Avocados
Scientific name:
Persea americana
Family:
Laurales: Lauraceae
Local names:
Parachichi (Swahili)
Pests and Diseases:
Anthracnose  Avocado root rot  Cercospora fruit spot  Coconut bug  False codling moth  Fruit flies  Scab  Scales  Spider mites  Thrips 
General Information and Agronomic Aspects
Geographical Distribution of Avocado in Africa

The avocado is native to the Americas but grows well in Kenya. It is very nutritious with a high protein and oil content and is becoming increasingly important as an export crop.
The avocado oil is cholesterol free, of the monounsaturated type believed to protect against heart disease and certain kinds of cancers. The fruit is nearly sodium free, is rich in potassium dietary fibre and vitamin B6, C, D and E. It is eaten as fresh fruit, in salads, soups, ice cream, also used to make avocado oil, perfume and avocado paste.












Nutritive Value per 100 g of edible Portion
Raw or Cooked Avocado Food
Energy
(Calories / %Daily Value*)
Carbohydrates
(g / %DV)
Fat
(g / %DV)
Protein
(g / %DV)
Calcium
(g / %DV)
Phosphorus
(mg / %DV)
Iron
(mg / %DV)
Potassium
(mg / %DV)
Vitamin A
(I.U)
Vitamin C
(I.U)
Vitamin B 6
(I.U)
Vitamin B 12
(I.U)
Thiamine
(mg / %DV)
Riboflavin
(mg / %DV)
Ash
(g / %DV)
Avocado raw 160 / 8% 8.5 / 3% 14.7 / 23% 2.0 / 4% 12.0 / 1% 52.0 / 5% 0.5 / 3% 485 / 14% 146 IU / 3% 10.0 / 17% 0.3 / 13% 0.0 / 0% 0.1 / 4% 0.1 / 8% 1.6
*Percent Daily Values (DV) are based on a 2000 calorie diet. Your daily values may be higher or lower, depending on your calorie needs.


Climatic conditions, soil and water management
Depending on variety, avocado grows well from 0-2100 m above sea level (asl). The varieties 'Tonnage', 'Simmonds', 'Booth 7&8' are suited to lowland areas between 90 and 800 m asl. 'Hass' and 'Nabal' are suited to altitudes 800-2100 m asl. 'Fuerte' and 'Puebla' are suited to altitudes 1500-2100 m asl.

Avocado grows successfully on many types of soil provided they are deep, with good water holding capacity and free draining. Water logged or saline soils are unsuitable because avocado plants are sensitive to excessive soil moisture and high salinity. The optimum pH is 5.5-6.5. Temperatures between 16 and 24°C are good for growing avocados. Maximum temperature for avocado is 33°C. Above this temperature avocado fruits and trees can be damaged. High temperatures and direct sunshine can cause sunburn damage to exposed fruit. Avocado will not grow where frost can occur. An annual rainfall 1200 mm is optimal for good production. Water requirements are not less than 1000 mm/year. If supplementary water is required not more than 50 mm at a time may be applied. Climatic conditions with alternating dry and rainy seasons are best for avocados.

Varieties
  • 'Fuerte'. Hybrid of Guatemalan and Mexican races with thin skinned green-pebbled fruit of very good flavour. This variety has many lines with different shapes; the pear shaped fruit is preferred in the export market. Matures 6-8 months after flowering.
  • 'Haas'. Vigorous grower and bears medium-sized, rounded, rough-skinned, black fruits. Propagates well. Matures 8-9 months after flowering.
  • 'Nabal'. Bears fruit in alternate years. Its green fruits have a good flavour. Matures 8-9 months after flowering.
  • 'Puebla'. Spreading, dark green tree bearing deep purple to maroon round fruit. This variety is normally used as a rootstock. Matures 5-7 months after blossoming.
  • Others: 'Reed', 'Simmonds', 'Booth 7&8', 'Pinkerton', 'Bacon', 'Lula' and 'Taylor'

'Fuerte' is the main variety grown in Kenya. The variety 'Hass' is developing strongly, especially among small growers. These two varieties are grown for the export market. Other varieties ('Reed', 'Booth 8', 'Puebla', 'Pinkerton', 'Simmond', etc.) are grown but not exported (Mugambi, 2002)

Propagation and planting
Select healthy, egg sized seeds and plant them in boxes or seedbeds. Immediately after germination transplant the seedlings into 4 litre pots, tins or polythene bags. Water them regularly until they are pencil thick. Grafting should be carried out when the seedling reaches pencil thickness. Wedge grafting method is most successful. Grafting should be done at the point where rootstock is soft. The scion should be dormant at the time of grafting and should match the size of the stock. Wrap the grafting point thoroughly to exclude water from the union and to prevent it from drying out.


Land preparation
The fields should be cleaned by removing tree stumps, bushes and perennial weeds. Then the land should be mowed or cultivated.

Planting out
Generally a spacing for pure stands of avocadoes of 9m x9m will be suitable. Dig holes of 60cmx60cm by 60cm deep keeping the top soil and the sub soil separate. Mix the top soil with 1 bucket (20 litre) of well rotted manure or compost and 1-2 handfuls of Mijingu rock phosphate. Remove the plant from its pot keeping the root and soil structure intact (easiest if it has been properly wetted ahead of time) and plant out using only the topsoil mixture to fill the hole.
The subsoil may be used to make a basin around the tree. Water the seedlings immediately after planting if it is not in the rainy season. Shade the young plants with banana leaves or similar material after planting and when they are putting up a new flush. If planted in a windy area, a windbreak will be necessary to protect the plants from leaning to one side and to help prevent leaf shedding fruit drop and bruising.


Manuring
One avocado tree can yield 250-300 kg of fruit per harvest season. This causes a high demand on soil nutrients. To determine the right amount of manure to apply the soil should be tested annually, otherwise the following table can be used as a guide for organic farmers for manuring individual trees:
Age of tree (years) Nitrogen and potassium
Litres animal urine mixed 1:4 with water in split applications
Mijingu rock phosphate Additional potassium Ashes (handfuls) Manure or compost decomposed
1-3 8 500g - 15 Kg
4-5 16 900g - 15 Kg
6-7 30 1.4 Kg 1 30 Kg
8-9 46 1.4 Kg 2 30 Kg
10-14 60 (three 20 litre buckets/year, mixed with 12 buckets of water, divided into several applications) 2 Kg 4 30 Kg
15+ 80 (four 20 litre buckets/year mixed with 16 buckets of water, divided into several applications 2.5 Kg 8 30 Kg
Adapted from AIC advice for conventional farmers replacing conventional fertilisers with natural products to get the same amount of nutrients.


If chicken manure is available, it can be used instead of animal urine as follows, but spread on top of the soil far enough from the tree stem to avoid burning the stem:
Age of tree (years) Chicken manure Kg/tree/year Additional Mijingu Rock phosphate Additional potassium Ashes - (handfuls) Compost decomposed
1-3 1.5 150g - 15 Kg
4-5 3 300g - 15 Kg
6-7 6 450g 1 30 Kg
8-9 9 450g 2 30 Kg
10-14 12 800g 4 30 Kg
15+ 15 1 Kg 8 30 Kg



Trace elements: In spite of heavy applications of manures and compost, deficiencies may occur in avocado orchards. Usually these are seen as various degrees of discolouration. Accurate analysis can be made from plant analysis laboratories. The following list can be used as a guideline:
Mineral Symptom Control
Zinc Mottled leaves with light yellow areas between the veins and abnormal development of growing shoots Apply 250 g zinc sulphate for each year of age to a maximum of 4.5 kg/tree. The application should be done in a 60 cm circle around the tree
Manganese Progressive yellowing of the margins and interveinal parts of the leaves while the veins remain green Spray the young leaves with foliar spray of manganese sulphate
Iron Loss of green colour in leaves Apply 360 g iron chelate per tree in acid soils. In normal soils 250 g of iron sulphate in 10 l of water/per tree will correct iron deficiency
Chlorine High concentration of chlorine in the soil may cause leaf burn, also damage the root system Apply lime and compost to neutralise the chlorine.



Pruning
Initial pruning may be done to give the tree a good shape. Otherwise pruning is limited to the removal of dead wood and parasitic plants.
  • Remove all sucker and dead branches from main trunk branches.
  • Prune canopy to keep the tree to a height of 5-8 m and for ease of picking. The tree is very susceptible to sunburn, therefore pruning should be minimised.
  • Prun the larger tree roots by cultivating to a depth of 50 cm around the edge of the tree canopy

The area around the tree should be kept clean by weeding and removal of all fallen fruits.


Harvesting
Harvesting starts at 3-4 years from planting but a good yield is obtained from the 6th year onwards. It is not easy to tell when the fruits are ready for harvesting unless they are of the varieties that change colour at maturity. Harvest a sample and keep at room temperature. If they soften within 7-10 days without shrivelling then the fruit of that age are ready for harvesting.

Fresh Quality Specifications for the market in Kenya
The following specifications constitute raw material purchasing requirements.

© S. Kahumbu, Kenya

Information on Pests
Insect pests are not serious constraints to avocado production at present.
The most common insect pests attacking avocados are:

Information on Diseases
Information Source Links
  • CAB International (2005). Crop Protection Compendium, 2005 edition. Wallingford, UK www.cabi.org
  • De Villiers, E. A. (1990). Avocado Pest in South Africa. In Framing in South Africa. Avocado. Institute for Tropical and Subtropical Crops. Published by ARC.
  • Griesbach, J (2005). Avocado Growing in Kenya. World Agroforestry Centre, Nairobi, Kenya. ISBN: 92 9059 173 0. www.worldagroforestrycentre.org
  • Griesbach, J. (1992). A Guide to Propagation and Cultivation of Fruit Trees in Kenya. Schriftenreihe No. 230, Eschborn / Germany: GTZ. ISBN: 3-88085-482-3
  • HCDA. (1996). Avocados. Export Crop Bulletin: No 2 June 1996.
  • ICIPE (2006). A Field Guide to the Management of Economically Important Tephritid Fruit Flies in Africa. The International Centre of Insect Physiology and Ecology. ISBN: 92-9064-179-7.
  • KENYAWEB HORTICULTURE. Fruits- Avocado.
  • Mugambi, D.M. (2001). Market Status of Avocado and Associated Products in Kenya. RELMA Working Paper No. 12. RELMA, Nairobi, Kenya.
  • Muigai, J.K. and Mwaura, F.M. (2005). Preparation and Use of Avocado Oil and Its Products. Chapter 16 in Organic Resource Management in Kenya Perspectives and Guidelines. 2005. Forum for Organic Resource Management and Agricultural Technologies (FORMAT).
  • National Horticultural Research Station, Thika (1984). Horticultural Crops Protection Handbook. Ministry of Agriculture & Livestock Development, Kenya.
  • Nutrition Data www.nutritiondata.com.
  • PIP Pesticides Initiative Programme (PIP) with collaboration of NRI. Crop production protocol Avocado (2011). www.coleacp.org/pip
  • Protrade. Avocados. Export Manual Tropical Fruits and Vegetables.
  • Tree Crop Propagation and Management (2000). A farmer Trainer Training Manual. Integration of Tree Crops into Farming Systems Project- GTZ, Ministry of Agriculture and Rural Development) MoARD.
Contact Information
  • Corner Shop, Nairobi [email protected]
  • Food Network East Africa Ltd: info@organic.co.ke +254 721 100 001
  • Green Dreams. admin@organic.co.ke +254 721 100 001
  • Kalimoni Greens. kalimonigreens@gmail,com +254 722 509 829
  • Karen Provision Stores, Nairobi. [email protected] +254 20885552
  • Muthaiga Green Grocers, Nairobi
  • Nakumatt Supermarket. [email protected] +254 20551809
  • National Horticultural Research Centre, KARI, Thika. [email protected]. +2546721281
  • Zuchinni Green Grocers, Nairobi. +254 204448240
Information of www.infonet-biovision.org