Avocado Pear

 

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 colour with smooth or warty skin depending on variety. The flesh of the fruit is yellow-green in colour 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.

https://plantvillage.org/topics/avocado/infos

 

Land Preparation in Avocado Cultivation: A thorough land preparation is important inn Avocado cultivation. Prepare the land by clearing off any weeds, dead trees and other material from previous crops. Give couple of ploughings and cross-harrowing to get the soil to fine tilth stage using local tractor or any other country plough.

 

Climate Requirement for Avocado Cultivation

Climate is one of major cultivation practices that influence the profitability in any crop. Commercial farming of Avocados requires cool and subtropical conditions with average daily temperatures between 18 °C and 25 °C. The temperature requirement may vary from one cultivar (variety) to another. However, all the cultivars require above 14°C. Avocados require high humid conditions during flowering and fruit set. The avocado trees should be protected from strong winds and hot dry winds as it may lead to breakage of branches or flowers and fruit drop. Avocados can be grown at an altitude of 2500 meters above sea level. A well evenly distributed annual rainfall of 1200 mm is desirable for avocado trees. Avocados are sensitive to frost conditions especially at flowering and fruit set stage. Water stress should be avoided at the time of flowering and fruit set.

 

Soil Requirement for Avocado Cultivation

Fertile soil is always desirable for any crop to obtain good yields and quality produce. If you are planning for commercial production of Avocados, a soil test is recommended to find out the chemical suitability of the soil and based on results; the required nutrients/micro-nutrients should be supplemented. The Avocado trees require fertile and well-drained soils with good aeration, ideally more than 1 meter deep. Only reddish brown, red and dark brown soils, particularly in the subsoil, are more suitable for Avocado cultivation. However, Avocado tress prefers medium sandy loam soils with a pH range of 5.5 to 6.5. Water logging conditions should be avoided and when it comes to soil texture, Avocado trees thrive best in soils with clay content between 20-40%. https://www.2lua.vn/article/avocado-cultivation-information-guide-5934cae7e49519f96e8b456c.html?hl=en

 

 

Varieties

There are three distinct races of avocados: Mexican, Guatemalan and West Indian. Some important commercial cultivars are hybrids of the various races.

The Mexican race is the coldest tolerant, while the West Indian type is most adapted to warmer climates. Fruits of the Mexican race are generally small with thin, smooth skins, while those of the Guatemalan race have skins that are thick, hard, brittle and warty. The West Indian type has shiny skin that is thin to medium in thickness.

‘Haas’ is a black-skinned, ovate cultivar whose fruit weighs 5 to 12 oz. It descends primarily from the Guatemalan race. This cultivar accounts for about 75% of the production in California, the main producing U.S. state. ‘Haas’ is also important in Mexico, the world’s largest avocado producer, and in Chile, the main foreign supplier to the United States. In Mexico, ‘Haas’ is harvested all year but the main season is from October to May. In Hawaii, ‘Haas’ has not produced high quality fruits.

‘Sharwil’ is a Mexican and Guatemalan cross and represents more than 57% of the commercial acreage in Hawaii. Its green-skinned fruits weigh 8 to 20 oz and mature in winter and spring. ‘Greengold’ and ‘Murashige’ are other green-skinned cultivars recommended by CTAHR for commercial planting.

‘Haas’, with black skin when ripe, is the most widely consumed avocado cultivar on the US mainland. Avocado consumption declines during fall and winter when there are less-desirable cultivars in the market. According to the California Avocado Commission, California growers received the highest price for ‘Haas’ (average of 40 cents per lb from 1980-1989) when compared to ‘Fuerte’ (23 cents per lb) and other cultivars that have green skin when ripe (17 cents per lb).

‘Sharwil’ avocados have small seeds and greenish-yellow flesh with a rich, nutty flavour. In Hawaii, many consider ‘Sharwil’ to be superior to California cultivars and believe it should be marketed as a gourmet item. ‘Sharwil’ has green skin when ripe, which is a problem where consumers rely on black skin as a sign of ripeness. It is the only Hawaii avocado authorized for shipment to Alaska and the US mainland in compliance with USDA/Animal and Plant Health Inspection Service (APHIS) requirements. Avocados destined for these markets are required to be packed in a fruit fly-proof, APHIS-approved and -inspected packinghouse.

Many consumers have trouble identifying ripe ready-to-eat avocados, especially green skinned cultivars. Stickers are now placed on ethylene gas-ripened avocados in retail outlets to help consumers select ripe fruits. http://www.extento.hawaii.edu/kbase/crop/crops/i_avocad.htm#VARIETIES

 

Method of soil preparation

The soil must be loosened as deep as possible before planting. In this case it will not be necessary to make large planting holes.

If the soil is very acid, heavy lime applications may be necessary. About two-thirds of the recommended agricultural lime must be distributed over the entire area 12 months before planting, mixed into the topsoil by disking and ploughed in as deep as possible.

Calcium (lime) moves very slowly in the soil, and should therefore be worked into the future root zone of the trees.

A cover crop can then be planted and ploughed in 6 months later to increase the organic-matter content of the soil.

The remaining lime and all the required phosphate must be applied and lightly worked in simultaneously. The trees are planted 3 months later.

If soil samples have not been taken early enough to proceed as described, two thirds of the lime must be mixed with the soil and ploughed in deeply. Phosphate and the rest of the lime should then be distributed and worked into the soil lightly. If large quantities of lime are required, this must be applied at least 3 months before planting (as described), thoroughly mixed with the soil and then worked in deeply.

If the soil depth is inadequate but still acceptable, it is recommended to make ridges of approximately 0,5 m high and about 3 m wide. The trees are then planted on these ridges.

It is important not to fertilise recently-planted trees too soon. The trees must first become well established and start to grow vigorously before any fertiliser is applied. In most cases it would be advisable to wait a year. These applications must be very light. The fertiliser must be applied evenly and should not come into contact with the stem of the tree. Immediate irrigation is required.

 

Layout of orchard

An avocado orchard should be profitable within 7 to 10 years.

There are 3 patterns according to which trees can be arranged in an orchard:

• Rectangular (which leads to hedge-type tree rows)
• Square (which leads to a change of direction when thinning diagonally)
• Diamond-shaped (which also results in a change of direction of tree rows with every thinning).

If trees are spaced in such a way that no thinning will be necessary during the lifespan of the orchard, only slightly more than 50 % of the land is utilised. Effective land use therefore, means that the trees are initially spaced close together, to be thinned systematically and selectively at a later stage.

There is, however, no proof that any specific layout is the best. The choice of planting distance and the pattern of planting depends on the following factors:

• Cultivar
• Location of orchard (e.g. north or east facing)
• Soil type and depth
• Expected short and long-term production
• Access for machinery, depending on orchard practices
• Thinning practices.

The final decision must be based on economic principles, because each of the aspects mentioned has an influence on the ultimate economic value of an orchard.

 

Planting distance and planting pattern

The choice of a planting pattern (rectangular pattern discussed here) depends on the management practices followed.

Early yields are maximised by planting trees close together in the row.

Hedge-type tree rows are more suitable for installing a permanent irrigation system.

Where implements are constantly used in orchards, the hedge-type layout is more suitable because access to the orchard is possible for a longer period of time than it is in a square layout. Traffic is also always moving in the same direction in such an orchard—an important point in orchards planted on a slope.

The hedge-type tree-row layout minimises the effects of the loss of branches and trees in a row.

 

Inter-row spacing

Economic considerations and access for implements determine inter-row spacing of trees. Final distances of less than 10 m will necessitate thinning before the orchard is 10 years old. High-density plantings can therefore be planted at less than half the “final” distance on the understanding that trees in the semi-permanent rows are removed timeously.

 

Planting and early care

• Avocado trees bought from a nursery should already have been hardened off.
• Plant the trees as soon as possible; if kept too long they may become root-bound or suffer from nutrient deficiencies.
• Do not place the trees in the sun because the containers will become hot and the roots could be burnt even before planting.
• Support the young trees with sturdy props as soon as possible after planting. Make sure that the stems are whitewashed.
• Remove the nursery tags and surplus graft strips after planting to prevent girdling.

 

Planting hole

If the soil has been well prepared, big planting holes are unnecessary.

If it is not possible to prepare the soil properly, a planting hole of 1 x 1 x 1 m should be made.

A well-prepared orchard does not require extra fertiliser in the holes. The addition of especially poultry manure could easily burn the roots.

Plant the trees to the same depth that they were in the planting bag.

The trees should preferably be planted in a slightly-raised position so that water cannot collect in the basin.

 

Irrigation

Young trees must be irrigated to ensure a uniform stand.

Over irrigation is just as harmful as too little water.

Examine the soil moisture content of the subsoil regularly to prevent over irrigation.

Avocados are sensitive to moisture stress. In the nursery the trees would have been accustomed to regular water applications and still have a limited root system as a result of the small bag. It is therefore essential that the water reaches the limited and shallow root system.

A small basin around the tree will ensure that the roots get enough water.

Apply frequent light irrigations: 50 l/tree/week and 100 l as soon as the subsoil starts drying out, and then resume watering at 50 l/week/tree.

 

Shade

Where hardening off has been inadequate (in the nursery) temporary shade should be provided.

Remember to whitewash the stems.

Erect a frame covered with grass or shade netting over the trees to protect the leaves. Remove the frame as soon as the leaves penetrate the grass because then they have become hardened off and need no further protection.

Structures erected to protect the trees against animals, also provide shade.

 

Protection against animals

Trees are often damaged by wild animals at night. A screen that will keep the animals out can be made by covering poles with chicken wire and building a tent-like structure around the trees.

Termite control will be necessary during droughts.

 

Cover crops

During the early years of an orchard a cover crop will protect and maintain the soil until the trees start providing shade.

A cover crop must not, however, compete with the trees and must be restricted to the strips between the tree rows.

The drip area of the tree must be free of grass and other weeds and, if possible, this area should be covered with an organic mulch.

Plastic covers are suitable for young trees, but irrigation management must then be very effective and accurate to prevent overirrigation. http://www.daff.gov.za/docs/Infopaks/avocado.htm

 

Fertilizer Application

Nitrogen requirements are the main consideration. Nitrogen applications are best applied before the mid-summer flush. Very little needs to be supplied before flowering and before the early spring flush. Nitrogen in the form of manure should be applied in small amounts in December, increasing in January and February with smaller amounts again in March.
Young trees (up to 4 years old) can be fertilised with a n equivalent to 15N:5P:10K fertilizer at rates of about 450g for each year. After four years of age the amount can be increased to 13N:2P:14K mix at about 1 kg per tree. This application should be spread out at 10% in December, 40% in January, 40% in February and 10 in March. A general balance of other elements is easily maintained. Organic applications can be translated to around 3L of chicken manure and 20g or muriate of potash per tree per year and is best applied in conjunction with coarse mulch to control the onset of Phytophthora. The fertiliser program should be adjusted based on visual assessment of the tree vigour. When the trees are slow growing or yellow the fertiliser should be increased.

 

Maintenance

Due to the poor root system of avocados wilting in hot weather is difficult to avoid. Ideally under tree sprinklers are recommended to cover 60% of the root area of each tree. (Reaching 8-10m in diameter at maturity) Young trees require water twice per week in the growing season to maintain growth. The aim is to produce vegetative growth in the summer and hold the tree back in the spring period. Water should in fact be restricted from Autumn onwards until flowering, to offset the vegetative growth in this period. Irrigation can be increased from November onwards throughout the summer period. The maximum water quantity per week for a 4-year old tree is 750L per week. (Autumn and Winter rates should be about 1/3 of this amount) Tensiometers set to a depth of 20 cm as a young tree and 60cm as a mature tree will assist in determining the water requirements. https://www.daleysfruit.com.au/AvocadoMaintenanceSchedule.htm

 

Pest and disease

Cankers

Cankers are usually only minor diseases of an avocado tree, but they’re highly visible. These sores on tree trunks and branches may sink slightly and ooze gum, giving the sore a rusty appearance. Cankers can often be cut out of limbs, but cankers in trunks often kill affected trees.

 

 

 

Fruit rots

Fruit rots, caused by fungal pathogens, typically occur where sanitation is poor and tree stressors are high. These fungi may overwinter in plant debris on the ground around the tree, or in fruits that are left on the tree after harvesting avocados. Proper pruning and prompt removal of fruits will help stop disease.

 

Root rots

Root rots generally appear in areas with poor drainage or in trees that are chronically over watered. If conditions can be improved, the tree may be able to be saved. Sometimes, digging around the tree and exposing the roots will allow the crown to dry enough to prevent tree death.

 

Sunblotch

Sunblotch is a serious, incurable disease of avocado trees. Fruits are often discolored or scarred, twigs may develop red or yellow discoloration or rectangular cracks may develop in bark. Infected trees are also often stunted, but some trees show no symptoms at all, aside from a reduction in yield. Once contracted, sunblotch cannot be cured, but by purchasing certified disease-free stock and practicing good tool sanitation, you can stop the spread of sunblotch.

Wilts and blights – Wilts and blights are characterized by dead areas in trees, especially when only a part of the tree is affected. Wilts unsurprisingly cause sudden wilting and death in branches; blights may kill small branches or only affect the leaves themselves. Pruning the symptomatic tissues from trees and providing good support can help your avocado recover.

 

Avocado Tree Insects

Borers

Borers tunnel into avocado trees, where they feed or lay eggs. Entrance holes are highly visible and may leak sap and borer-weakened branches may break easily. Stressed trees are preferred by borers; keeping your tree healthy can prevent infestation. Cut out infested branches and dispose of them immediately.

 

Caterpillars

Caterpillars attack foliage, flowers and fruits and can cause substantial damage in a short time. Sprays of Bacillus thuringiensis are highly effective, provided that you can reach caterpillars, like leafrollers, who feed inside protective nests made of leaves. Making a special point to spray inside these folded over or silk-bound leaves will destroy the caterpillars inside.

Lace bugs

Intermittent pests of avocado, lace bugs damage leaves when they are present. Feeding sites cause yellow spots that soon dry out and stressed leaves will drop, exposing fruit and wood to ultraviolet rays. When symptoms appear, sprays of horticultural oils or pyrethrin are recommended avocado tree treatment.

 

Mites

Mites cause similar damage as lace bugs, but leaves may also take on a bronze appearance and the pests will be difficult to see with the naked eye. Some mites spin fine webs as they feed, similar to those of spiders. Treat them with horticultural oil; insecticides can cause population explosions.

 

Thrips

Thrips rarely cause serious damage to trees, but will seriously scar fruits. Scabby or leathery brown scars appear as fruits enlarge, sometimes stunting fruits. Careful pruning and fertilizing will help prevent thrips, who are attracted to tender flushes of growth. They can be destroyed with horticultural oil or pyrethrin. https://www.gardeningknowhow.com/edible/fruits/avocado/avocado-pests-and-diseases.htm