Avocado

Avocado, Persea americana, is an evergreen tree in the family Lauraceae which grown for its nutritious fruit, the avocado. The avocado tree is large and dome shaped with oval or elliptical leaves arranged in a spiral on the tips of branches. The leaves have a red pigmentation when they first emerge and turn green as they mature. Avocado trees produce clusters of small, green-yellow flowers at the end of twigs and a large, fleshy, pear-shaped fruit with a single large seed. The fruits can be purple to green in color with smooth or warty skin depending on variety. The flesh of the fruit is yellow-green in color and has the consistency of butter. Each fruit contains one large seed. Avocado trees grown from seed can take 4-6 years to produce fruit whereas grafted plants may produce fruit within 1-2 years. The tree can reach a height of 20 m (65.6 ft) and originated in the rainforests of Central America.

Crop Details

Scientific Name: Persea americana

Common Name: avocado, alligator pear (En); aguacate, palta (Sp); parachichi (Sw)

The avocado is usually consumed fresh as a fruit or as an ingredient in salads or savory dishes. It has a markedly higher fat content than other fruits and is a staple in diets that have limited access to foods with high contents of monounsaturated fats. It is the main ingredient in guacamole, a popular Mexican dip. In Asia, avocados are used in desserts and dessert drinks.

Avocados are a source of vitamins C, E, K, and B6, as well as magnesium and potassium.

There are three horticultural races in which all avocado varieties are classified: Guatemalan, West Indian, and Mexican. However, many commercially interesting varieties are hybrids.

Some examples of Mexican race varieties are Zutano, Fuerte, Puebla, and Teague, while some examples of Guatemalan race varieties are Hass and Reed, among others. West Indian race varieties include Waldin, Hardy, and Simmonds.

Basic Requirements

Avocados thrive in subtropical or tropical climates but can also be grown successfully in cooler areas of the world. The optimum temperature for growing avocado is between 25 and 33°C (77-91.4°F) with moderate humidity levels. Once established, trees can tolerate temperatures down to around -2°C (28°F) with minimal damage but young trees will not tolerate freezing temperatures. Avocado requires a well draining, aerated soil and they produce a shallow root system which require a warm soil for efficient water and nutrient uptake. Although trees will tolerate low rainfall, irrigation, particularly during flowering and fruit set, will ensure high fruit yields.

Seeding

Avocados are commonly propagated from seeds but the seeds will not breed true due to type and this should be taken into consideration before planting. Clonal plants are obtained from budding and grafting from a parent tree to ensure the offspring are of the same high quality of the parent. In plantations, seeds can be sown directly in the soil. 2 to 3 seeds are usually sown and thinned later to leave the strongest seedling for grafting. Seeds may also be sown in containers and grown for 2 to 3 months before planting at the final site.

Avocado seedling should ideally be planted in the Spring when the soil has warmed through. Choose a location that receives full sun and has protection from the wind. The trees should be planted by digging a hole a little wider than the root ball and gently easing the tree into the hole. Slow release fertilizer can be added to the hole at planting but is not necessary. Care should be taken not to disturb the roots as much as possible and the hole should be carefully backfilled and the soil and tamped to prevent dislodging. Trees should be planted 4.5 to 6 m (15-20 ft) apart in rows spaced 6 m (20 ft) apart.

General Care and Maintenance

Newly planted young trees should be mulched after planting with several inches of straw or woodchips. Young trees will also benefit from staking which will help to prevent wind damage. Wood stakes should be driven into the ground outside the root ball allowing 2 stakes per tree. The tree should then be tied loosely to the stakes to provide support while it establishes.

Young trees should be irrigated and the root ball should not be allowed to dry out. Trees should be watered every few days. Water trees at and around the base to ensure the root ball is wetted. Trees are usually fertilized at around 4 weeks after planting. Add half a cup of urea every 4 to 6 weeks during the growing season. 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.

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. Prune 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.

Harvest

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.