Avocado Pear Production
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.
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.
Climatic and Soil Requirement
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.
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
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.
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
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:
- 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.
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.
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.
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.
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.
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
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.
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
Peset and Diseases Management
Pest and disease
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, 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 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 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 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 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.
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 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 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
The following varieties make up the majority of exports:
Mature fruit do not ripen and soften on the tree. You must learn to judge when hard, green fruit is mature and ready for harvest. If an immature avocado is picked, it will not ripen to an acceptable eating quality and will often shrivel and develop fruit rot. Mature avocados can be recognised by the dull appearance of the skin, or shrivelling and yellowing of the fruit stalk.
When mature fruit is cut open and the seed is removed, the seed coat is dark brown and dry, and does not adhere to the flesh. Large fruit on the northern and eastern side of the tree, and fruit at the top and outside of the canopy, usually mature first.
Hass fruit must contain at least 23% dry matter and Shepard fruit must contain 21% dry matter for marketing in most Australian states. However, fruit will be more palatable and have better flavour if allowed to reach dry matter levels 3% to 5% higher than the 21% level. The standard also requires that fruit must ripen without shrivelling and decay. Check the maturity of the crop before harvesting by doing a ripening test and a dry matter test.
Avocados are picked by hand using ladders, picking poles and, where slopes permit, hydraulic picking platforms or cherry pickers. It is important to make sure pickers have sufficient knowledge of what is required. Some key pieces of knowledge are:
- Avoid picking during wet weather as fruit are more susceptible to skin damage and fungal infection.
- Avoid picking during extremely hot weather (above 30°C) if fruit are to be cool stored for more than two weeks as fruit are more susceptible to breakdown.
Cut the fruit from the tree using avocado snips, secateurs or shears, leaving 3 to 4 mm of stalk intact (for all varieties other than Hass).
Pick in several lots if the fruit is not a uniform size. Remove large fruit first, allowing remaining small fruit to increase in size. Harvest at least 50% of fruit within one to two months of it reaching maturity. This is important where trees set heavy crops because trees may be pushed into an alternate-bearing pattern.
Keep harvested fruit under shade.
Although trees may start to bear fruit in the second year, commercial quantities are generally not harvested until the third year. Yields are extremely variable across farms and districts, and will depend on:
- level of management.
Biennial yielding, where alternating high yields one year followed by low yields the next, is another major factor grower have to manage.
It is important to realise that the average yield across all Australian orchards is a low 9 tonnes per hectare. This reflects the variable genetic performance of seedling rootstocks and difficulties in properly managing the devastating Phytophthora root rot disease. On the other hand, very good growers using elite and uniform rootstocks and a high level of root rot management may achieve average yields of over 20 tonnes per hectare. For a new grower, achievable yields are somewhere between these extremes. Table 1 below provides an indication of achievable yields for one of the common tree spacing.
|Table 1. Achievable yields per tree (kg) and per hectare (t) for a new orchard under good management (based on a spacing of 8 m by 4 m or 312 trees/ha)|
Note: once trees form a hedgerow, a biennial bearing pattern with an ‘on-year’ and ‘off-year’ is generally established. https://www.daf.qld.gov.au/plants/fruit-and-vegetables/fruit-and-nuts/avocados/harvesting-and-yields
Fruit picked too early shrivels and lacks quality. The time of harvest depends upon the variety.
|Anaheim||June – September||Green|
|Bacon||November – March||Green|
|Bonita||September – November||Green|
|Corona||June – August||Green|
|Daily||September – November||Green|
|Duke||September – November||Green|
|Dickinson||May – October||Dark purple|
|Edranol||April – July||Green|
|Fuerte||November – June||Green|
|Hass||April – October||Black|
|Hellen||June – September||Green|
|Jim||October – January||Green|
|Mac Arthur||July – October||Green|
|Mesa||May – July||Green|
|Nabal||June – September||Green|
|Pinkerton||December – April||Green|
|Reed||July – October||Green|
|Rincon||April – June||Green|
|Ryan||May – June||Green|
|Santana||September – February||Green|
|Zutano||October – March||Green|
Note: The seasons indicated in the table are the approximate months of maturity. Seasonal, climatic effects and the district in which the tree is growing result in variation. Varieties not listed and seedlings vary greatly not only in fruitfulness, quality, and type but time of maturity as well.
Different varieties of avocados mature throughout the year, but each variety matures at approximately the same time of each year. Climatic factors may cause variations of 1 to 3 weeks. This characteristic has the advantage of holding the crop on the tree and making the time of harvest less critical. The storage life of fruit on the tree will vary from 2 months for Bacon to 8 months for Hass. Several pickings should be made to cover the range in fruit maturity. Avoid harvesting during wet weather as fruit are more susceptible to skin damage and fungal diseases.
Fruit of all cultivars must reach a minimum of 21% dry matter and ripen naturally without shrivelling before it can be harvested legally and sold. Fruit set can occur over a period of 4 to 6 weeks. Mature fruit has the following characteristics.
- fruit stem becomes more yellow
- when the fruit is cut and the seed is removed, the seed coat is dry and does not stick to the flesh, it is a dark brown colour
- dark-skin varieties will show a change from green to purple
It also helps to know the usual time of maturity for the variety by taking a fruit sample and let it ripen indoors. If the fruit ripens within a reasonable time (7 to 10 days) without wilting, and shows all the desirable characteristics of the variety then start harvesting. Fruit is hand-harvested from trees when mature using an array of picking aids. Harvest the largest fruit at the first pick. On the larger orchards, trees are harvested with the aid of hydraulic ladders (cherry pickers) while on the smaller properties picking poles are used to reach fruit. For most cultivars, fruit needs to be clipped with a ‘button’ leaving a short 3mm corky stem attached to the fruit on the pedicle end. This reduces the risk of stem-end rot invading the fruit as it ripens. Don’t drop fruit as bruising will occur? Check fingernail length to avoid puncturing fruit. Fruit is picked into large bins usually mounted on trailers to facilitate their movement to the packing shed. It is important to keep the fruit out of direct sunlight after picking to prevent it from heating. Place harvested fruits in the shade.
Practically ‘Hass’ fruits are snapped from the tree ensuring that the flesh is not torn around the stem as a tear provides a site for infection. This is a much quicker practice provided fruits are treated within 24 hours with fungicide to prevent fungal infection.
Commercial standards require fruit to reach 8% oil content before harvesting. Mexican types ripen in 6 – 8 months from bloom while Guatemalan types usually take 12 – 18 months. Fruits may continue enlarging on the tree even after maturity. Purple cultivars should be permitted to color fully before harvest. Guatemalan types can be stored firm, at 4.5 – 10° C. for up to six weeks. Mexican types discolor quickly and require immediate consumption.
Here is the minimum percent dry matter standard that various avocado varieties must reach before they can be commercially harvested and sold to the public.
|Dry Matter %||Varieties|
|18.7||Clifton, Covacado, Duke,Henry, Select, Jalna, Leucadia, Santana, Teague, 287, other fall/winter varieties.|
|20.8||Anaheim, Benik, Bonita, Carlsbad, Dickinson, Edranol, Elsie, Ryan, Itzamna, MacArthur, Nabal, Queen, Thille, other spring/summer varieties.|
Fruit should be harvested from the tree by a quick twist of the pedicel which will detach the mature fruits. The pedicel should then be clipped to prevent damage to other fruits.
Do not knock fruits off the tree. This will cause bruising and bursting of the fruit. Therefore, fruits should be picked by using a pole or by hand.
The picking pole can be made of bamboo or some light wood provided with a cloth or crocus bag and a notch with an inner sharpened edge at the end. The bag is used to hold the fruit until the pick is brought to the ground and the fruit removed. Depending on the size of the bag, a maximum of three (3) limbs can be picked. Hand-pickers standing on a ladder can also be used to harvest tall trees.
On a large farm, a platform mechanized system, elevating hand-pickers into the trees provide an efficient mode of harvesting.
Nutritional composition (1 fruit, size 76.2 mm in diameter)
- Water -284 grams (74%)
- Food Energy -370 Cal.
- Protein -5 grams
- Fat -37* grams
- Saturated fat – 7 grams
- Oleic acid -17 grams
- Linoleic acid -5 grams
- Carbohydrate -13 grams
- Calcium-22 mg
- Iron-1.3 mg
- Vitamin-630 IU
- Riboflavin-0.43 mg
- Niacin-3.5 mg
- Ascorbic acid-30 mg
The avocado fruit is therefore a fat storing structure.
Cover loads to:
- minimise heating of fruit
- prevent sunburn
- stop dust from entering the picking containers.
- Avoid excessive delays between picking and delivery to the packing shed.
Handling in the packing shed
On arrival at the packing shed, place field containers (crates or bins) undercover to prevent sunburn of the fruit and build-up of field heat. An assessment of fruit quality on arrival will alert the grading staff to any likely defects. Early picked fruit may require testing for maturity before being cleared for packing. The quality and maturity assessments can be recorded on a receiver assessment sheet along with the number of field containers received. Cooling before packing may be necessary if delays are excessive. Tip field containers carefully onto the packing line.
Avoid drop heights greater than 20 cm. The flesh of freshly picked fruit is particularly susceptible to impact and vibration damage, and may shatter internally if dropped from greater heights. ‘Pimples’ or nodules on the skin can be damaged from abrasion or impact caused by poor handling.
Post-harvest chemical treatment
For control of anthracnose and stem-end rot diseases, treat fruit within 24 hours of harvest with the chemical prochloraz. Apply it as a non-recirculated spray over fruit on rollers or brushes. Follow label directions. The volume of spray applied must be sufficient to thoroughly wet the fruit (at least 15 seconds under the spray). If exporting the fruit, check that the importing country approves of the prochloraz treatment.
It is important to note that post-harvest treatment is not a substitute for field spraying – both are necessary to achieve high quality fruit. The performance of the prochloraz treatment is affected by:
- the level of anthracnose infection of the fruit at harvest
- the type, length and temperature of storage and ripening to follow
- the susceptibility of the fruit to disease development (for example, Hass on Duke 6 rootstock and Hass fruit with low calcium concentrations are more susceptible to anthracnose development with the result that the post-harvest treatment may not work).
Depending on its final destination, fruit from some areas of eastern Australia may need to be treated under an Interstate Certification Assurance (ICA) arrangement before being shipped interstate. This is to prevent the spread of fruit fly. Fruit in Western Australia must be maintained in an approved secure manner to exclude Mediterranean fruit fly before entry into other Australian states.
Record the details of post-harvest treatments on a post-harvest chemical treatment record. The record provides evidence that the treatment has been applied correctly and complies with food safety regulations.
Drying and polishing
Dry the fruit before grading and packing by blowing air over it on rollers or brushes or by passing the fruit through a heated drying tunnel. Check the operation of the drying tunnel to reduce the risk of any heat damage.
Fruit may be polished with brushes to improve presentation or to remove visible spray residues. Do not brush fruit for longer than one minute. Excessive brushing can cause abrasion injury, especially on Hass, resulting in an unsightly spotted appearance. Ensure brushes are of a suitable type for avocados and replace worn brushes as required.
Avocados are hand-graded for quality as fruit passes over rollers. All Australian markets expect fruit in a tray or box to be of one variety, sound (no broken skins from cuts or insect stings), clean, well formed, mature (at least 21% dry matter for Shepard and 23% for Hass) but not over-mature, and of uniform size. Reject fruit not reaching this minimum standard.
Avocados are typically sorted into two quality grades. The quality standard for each grade depends on customer requirements. To establish quality standards for each grade, the maximum acceptable level (allowance) of various defects on individual fruit must be defined. The tolerances for out of grade fruit in packages must also be determined.
Fruit is graded for size using different types of measuring equipment by:
- diameter (expanding rollers or belts)
- weight (mechanical or computer)
- volume (optical).
The equipment is adjusted to achieve the range of sizes required for packing. The size classes are known as ‘counts’ are established on the basis of how many fruit of a particular size will fit into the standard package. The difference between the smallest and largest fruit in a pack should not exceed 5 mm in diameter. Size classes or ‘counts’ range from 12 to 28. Fruit smaller than count 28 is placed into bulk packages and net weight is used to indicate the amount of fruit in the package.
The standard package used for domestic and export marketing is a single layer tray holding a minimum of 5.8 kg of fruit. Inserts with moulded cups are used to aid packing. The inserts are available in a range of counts from 12 to 28 fruit per tray.
Each fruit is placed into a cup with stem-end up and locked against surrounding fruit. The smaller the fruit, the more vertically it is packed. Tight packs are essential to prevent fruit movement and rub damage during transport. Avoid over-packing to prevent pressure damage, particularly when fruit is ripening in the package.
Fruit smaller than count 28 and second grade fruit are often packed into bulk packs that typically hold 10 kg of fruit. The bulk packs are volume filled and may contain fruit of even or mixed sizes.
For first grade fruit, small stickers are usually placed on each fruit. The stickers are used to enhance eye appeal and provide brand, region or variety identification. All major retail chains require PLU (price look up) numbers to be placed on the fruit stickers.
A trade description must be printed or stamped on at least one end of the package. The information must be prominent and indelible, with letters at least 5 mm high. The trade description must include:
- the brand name
- the name and address of the packer
- the word ‘avocado’
- the variety
- the grade or class
- a statement of contents (count or net weight).
We recommend that product identification codes, such as grower number, block number, quality assurance codes, ICA codes and packing dates, are stamped on each package to enable trace back of product if there are problems during marketing. https://www.daf.qld.gov.au/plants/fruit-and-vegetables/fruit-and-nuts/avocados/post-harvest-handling
A pre-cooling operation is generally carried out after packaging. Pre-cooling is of prime importance for the shelf life of avocado; it diminishes or slows the metabolic rate, ethylene synthesis and its action on the fruit, loss of texture, fungal infections, fruit ripening, and conditions the fruit for preservation at low-temperatures. Ideally, there should not be more than six hours from harvest to pre-cooling, and when this is not possible, the harvested fruit should not be allowed to reach an internal temperature higher than 26°C in the field and during its transportation to the packinghouse.
The quantity of the field heat is usually large, and cannot be eliminated fast enough in a regular refrigeration room. The freeze-blast method is the best suited for avocado pre-cooling. It is carried out until the temperature in the fruit reaches 6-7°C for “Fuerte” and “Hass”. The time that is required to achieve these temperatures varies according to the initial temperature of the fruit, temperature and velocity of the air, and the final temperature of the fruit.
However, it is important to end the pre-cooling process when the temperature of the fruit is 2°C above the ideal storage temperature. It is also of prime importance to assure that the storage temperature will not be lower than that established for the fruit, otherwise chilling injury can occur. The pre-cooling process lasts from 8 to 12 hours, with a relative humidity of 90 to 95% (Yahia, 2001).
Temperature control during the post-harvest stage is the most important factor that helps maintain the quality and increase the shelf life of many fruits. Refrigeration is also useful to control illness and pests. Generally, the shelf life of avocado is inversely proportional to its respiration velocity. It is of prime importance to avoid temperature fluctuations during transportation, because this can cause chilling injury, ripening, irregular softening, and rot (Yahia, 2001).
Storage of avocado
When avocado reaches the packinghouse, fruits of different batches are separated. The origin of the fruit, supplier, date, etc., should be registered. Before processing of the fruit, the lot shall be sampled in order to detect quarantine pests and diseases, and determine the general appearance of the fruit and its quality (stains, discolorations, injuries, mechanical damage, etc). At the same time, the characteristics of the particular variety are verified (Sánchez-Pérez, 2001). The response of avocado to storage temperatures (Yahia, 2001) varies according to temperature ranges, as follows:
- 10 to 25°C: the fruit softens faster as storage temperature increases.
- 5 to 8°C: softening is controlled, and it will only occur if the fruit is transferred to higher temperatures.
- 0 to 4°C, softening at these temperatures is limited by time, due to the risk of chilling injury.
However, recommended storage conditions may vary according to the avocado variety (as shown in the table below)
Physiological disorders decrease when temperatures are kept at 7.5<°C at the beginning of storage, and then are lowered to 3.5°C, instead of maintaining 5.5°C the whole time.
|Hass||2-10||4-10||7||Storage time of 7-9 weeks|
|Lula, Booth 8, Fuchs||2||10||7.5||Increase shelf life twofold|
|Fuerte, Edranol, Hass||2||10||—||Reduces internal disorders|
|Non-specific||–||25||—||Reduces disorders and increases anthracnose|
|Fuerte||2||10||5.5||Less dark spots in the pulp|
|Fuerte||—||25||5.5||Less dark spots in the pulp|
|Fuerte||3||0||24 h at 17°C||After this treatment, fruit can be stored at 2°C for 3 weeks|
|Booth 8, Lula||2||10||4-7||Storage time of 8 weeks|
|Fuerte, Anaheim||6||10||7||Storage time of 38 days|
|Waldin, Fuchs||2||10||7||Storage of 4 weeks, prevents anthracnose and chilling injury|
|Hass||2||5||—||Storage time of 60 days|
Types of packaging
Fruit is then size and quality graded, packed into (trays and boxes as determined by the importing countries) and pre-cooled prior to transportation. The packaging material varies according to the market, being cardboard, plastic, or wood. The most common containers are single wall corrugated fibre board or wooden boxes.
The first ones usually have a capacity of 4 kg with one level of fruit, while the second ones contain 10 kg, and the fruit is placed in bulk. The wooden box has a lower demand than the fibre board box. Cardboard boxes have different perforation designs, and resistance to compression: from 269.1 to 1345.5 kg/m2, approximately (López-López, L. and Cajuste-Bontemps, J.F., 1999). Most fruit is shipped in refrigerated trucks by road to markets in major cities.
In Australia, for some interstate markets an Interstate Certification Agreement (ICA) is necessary; this requires an insecticide treatment. Many grading machines have a heated drying tunnel before the fruit is polished with brushes. Brushing removes visible spray residue and shines the fruit. Avocados are usually sorted into two quality grades and a processing line. Size counts range from 12 to 28 fruit per tray. Smaller fruit are bulk packed into 10kg cartons. Plastic inserts with moulded cups are placed in the tray. Single layer trays weigh around 6kg. Fruit are stamped with small stickers. These have brand names, variety identification and, for supermarkets, PLU (Price Look Up) numbers. A trade description must appear on one end of the package in letters 5mm high. It includes the name and address of the packer, the word ‘avocado’, variety, grade, count and or weight. It may also include a brand name, grower number,ICAand QA (Quality Assurance) particulars and date of packing. Packaging specifications for other countries are as the followings:
Storage and transportation
‘Hass’ fruit are stored at 4 to 5 °C and other varieties at 6 to 8 °C. Refrigerated transport is used from most growing areas. Controlled ripening of avocados using ethylene gas is usually done by the market agents.
Market research has shown that more avocados are sold if they are offered to the consumer in a ready-to-eat condition. This has led to a system of pre-ripening fruit prior to stocking retailer shelves. Fruit is gassed with ethylene at a central location and held at 21°C until it ripens, then taken to the retail point of sale.
Avocado is also used for the confection of baked products (such as cakes), to elaborate fine soup mixes, appetizers, and in the production of cosmetics (oils, skin lotions, soaps, shampoos, etc.) due to its oil content. Avocado oil is appreciated because it contains biodegradable and easy to absorb sterol. The oil is sent to the United States, where it is refined and then sent to Japan and Europeans edible oil and cosmetic ingredient. Besides being an important cosmetic ingredient, the pharmaceutical industry considers the unsaponifiable fraction of the oil as a valuable raw material. From this fraction, the factor H is extracted, which is used in the pet food and cooking oil industries (SAGAR, 1999).
Types of products:
Frozen avocado – Original Chunky Avocado Pulp in 1, 2,& 6 lb. plastic pouches.
Avocado sauce- 100% Hass Avocado with minced onions and spices
Southwestern guacamole – Feisty blend of chunky avocado, red bell pepper, onion, jalapeños and spice
Non-refined avocado oil – oil is extracted from selected Hass avocados by mechanical processes
Avocado can be processed into avocado salsa, guacamole blend, avocado pulp, spicy guacamole, and avocado drinks. Upon receiving the fruit, it is washed in a machine with rotating brushes and chlorinated water (200 ppm). Then its temperature is homogenized to 5°C to allow an even ripening. Avocados are stored for 3 days at 20°C at a relative humidity over 85%, adding 10 ppm of ethylene. Afterwards, the temperature is lowered again to 5°C and the fruit is kept at that point until processing (3 to 4 days). Since many clients prefer a chunky texture, the fruit must be ripe and firm.
Processing begins with a selection step, where the unsuitable fruit is discarded, the peduncle is removed, and the fruit is submerged in chlorinated water (200 ppm) for 10 min. Then it is cut, de-seeded, peeled and put into a mixer with other ingredients, such as onion, chili pepper, fruit concentrate, erythorbic acid (to promote color retention), and ascorbic acid. The resulting product is vacuum-packed and sealed into co-extruded five-layer bags, with a high barrier to oxygen. They usually pack in 6 pound bags, because most of their customers are restaurants, but they also have a 250 g package for retail marketing. The bags are frozen in a blast-freezer at -30<°C, and afterwards the bags are stored at -18°C). http://www.itfnet.org/v1/2016/05/avocado-post-harvest-processing/
- The fruits must be clean, i.e. free from adhering soil and insects
- Mature, i.e. not ripe or soft, but at the stage which will allow the fruits to ripen normally and arrive at the market with the desired degree of ripeness.
- They must be of similar varietal characteristics, i.e. all fruits in any one lot must be of the same variety, must be similar in shape, texture, and skin colour.
- Must be well trimmed, i.e. the stem (pedicel) is cut off fairly smooth with not more than 6.4 mm beyond the shoulder of the fruit.
Fruits should be well coloured, i.e. the colour characteristic of the variety.
Well formed, i.e. the fruit has the shape characteristic of the variety.
Free from damage, i.e. any defects that seriously affect the appearance, edibility, or shipping quality of the fruits; or the general appearance of
the avocadoes in the container, e.g. sunburn, scars, or bruises.
Fruits should be classified by size according to the following definitions:
Uniformed in appearance, I.e. not more than 10% of packages shall contain fruits which show sufficient variation in size to detract from the appearance of the individual packages. The variation from the average length should not be greater than 3 mm. https://rada.gov.jm/publications/publications/post-harvest-marketing/item/490-post-harvest-management-avocado
Delivery to the packing shed
Transport picking containers carefully to the packing shed because the skin of freshly picked fruit is susceptible to impact and vibration damage. Damage to the ‘pimples’ (or nodules) on the skin can result in an unsightly spotted appearance.
The maximum delivery time recommended varies with the length of the marketing period and the fruit temperature (Table 1).
|Table 1. Maximum time between picking and delivery to packing shed|
|Marketing period (picking to retail shelf)||Max. delivery time to packing shed (fruit temp. under 30oC)||Max. delivery time to packing shed (fruit temp. over 30oC)|
|Less than two weeks||36 hours||12 hours|
|Two to three weeks||12 hours||6 hours|
|More than three weeks||3 hours||Do not pick|
Exporters of Avocado from Nigeria
[ change ]
|Jehovah-rabor Agrotech. Co. Ltd. (Exporter)|
Fruits : avocado, Mangoes, Oranges.
|Jamies Vegetables Nig Limited (Exporter)|
Fresh Vegetables & Fruits : Onions, Potatoes, Tomatoes, Carrot, Pineapple, avocado, Pear, Cabbage, Beetroot, Cucumber, Pumpkin, Okra, Corn, Watermelon etc.
|Oguntodu Michael Corporate Services Limited (Exporter)|
Fruits : avocados.
|Starcraft Industries Limited (Exporter)|
Dry Fruits : Cashew Nuts.
|Enbriden Nigeria Ltd. (Exporter)|
Dry / Dried Fruits : Cashew Nuts, Dates.
|Fine Living BPL (Exporter & Importer)|
Building Materials : Cement.
|Cookey Venture Global Services (Exporter & Importer)|
Timber : Kosso Wood.
|Veggie-Groce Ltd. (Exporter & Importer)|
Dry & Dried Fruits : Cashew Nuts, Dates.
|Nalmro Limited (Exporter)|
Dry Fruits : Cashew Nuts.
|Valla Andre Equity Limited (Exporter & Importer)|
Fruits & Vegetables : avocados, Drumstick.