Avocados are distinct fruits with high fat content and calories. Subtly flavorful yet buttery, they are amongst the most popular fruits having nutrition profile similar to that of some edible nuts and seeds.
Some of the common names for this staple fruit arealligator pear, aguacate, butter pear etc.
Botanically, the fruit belongs to the family oflauraceae, the family that also includes some unusual members like bay laurel, cinnamon, etc.
Nutritional Value of Avocados
Avocados are, just like all fruits, rich in vitamins and minerals. The nutrition in avocados is unique however, just as unique as the flavor and texture of the alligator pear itself. They have a concentrated amount of cancer-preventing antioxidants, including potent cartenoids. They supply over a third of the daily recommended amount of vitamin K, a nutrient necessary to prevent blood clotting, and to assist with the absorption of calcium. The avocado is a good source of vitamin B6, which helps to lower homocysteine levels in the body, decreasing the risk for a heart attack or stroke.
They also have a significant amount of vitamin C, needed for immune health and tissue repair, as well as folate. Folate is a crucial vitamin for the synthesis and repair of DNA, making it a most vital nutrient working at the cellular level. One serving of avocado supplies ten percent of the daily recommended amount of vitamin E, needed for healthy skin, and blood sugar regulation; and, about seventeen percent of vitamin A for healthy eyes.
In the Philippines, however, it has not attained the popularity enjoyed by other fruits despite its early introduction in 1890. One reason for this is that it lacks that sweetness of such popular fruits as mango, banana and pineapple. To improve its taste to suit their palate, Filipinos eat avocado with sugar and milk. If Filipinos acquire the taste for the fruit, avocado can become a good market fruit and therefore source of income of small farmers in the countryside. Later, export market for fruit can be developed. Aside from the nutritional benefits that can be derived from the fruits, its various parts have several medicinal uses.
Avocado fruit is a rich source of Vitamin A and contains little amount of Vitamin B complex and E.
The ripe fruit can be eaten on hand and can be used in preparing salads, flavor for ice-creams, filling for sandwiches and quick desserts.
Various parts of the crop have medicinal benefits. The leaves when boiled is a remedy for diarrhea. Pulp is used to hasten the formation of pus in wounds and even stimulate menstrual flow. Seeds can be smashed and be used as fillers for toothache.
Avocado is botanically divided into three races: Mexican, West Indian and Guatemalan.
List of Avocado Varieties, Approved by the Philippine National Seed Industry Council.
|1. NSIC 95-Av-02 (Parker)||Prolific yielder, (500-700 fruits/season) bear fruit both during the late season & off season; fruit of excellent eating quality, possessing flesh texture (smooth & firm) w/ scanty fiber with flavor buttery & nutty; high edible portion of 87.0%. a fruit weighs 561.4 g|
|2. NSIC 97-Av-03 (RCF Morado)||Yield, 300-400 fruits/season. Significant small seed (about 9% of the total fruit weight skin easily peels off; testa does not adhere to the flesh with high edible portion (80.8%). A fruit weighs 391.5 g|
Soil and Climatic Requirements
Soil – it can be grown over a wide range of soil types provided with adequate drainage. For best production, deep, fertile, well-drained soils, particularly sandy or alluvial loam soils and have a pH of neutral or slightly acid are suited for avocado.
Climate – a climate with alternating wet and dry season and with minimum annual rainfall requirement of 750 – 1,000 mm is recommended.
It does not thrive well in places exposed to strong, excessively hot and dry winds.
West Indian Varieties – are very tender and are adapted to low and medium elevations up to 1,000 m above sea level.
Mexican Varieties – are the hardiest with respect to cold weather and can grow at elevations of 1,500 – 3,000 m above sea level.
Guatemalan Varieties – are intermediate and can grow at elevations of 1,000 – 2,000 m above sea level.
Generally, avocado can grow well from sea level to about 1,500 m in places with short or no dry season. Where dry season exceeds 4 to 5 months, irrigation is very important.
Seed Selection and Germination – seed used should be obtained from healthy and vigorous trees. Select large seeded fruits especially when intended for rootstocks to maintain seedlings quality. It is recommended to plant it at once. If in case it cannot be planted/propagated immediately, store it in the moist sand or sphagnum moss.
Seeds are sown with the pointed ends up and with about one-fourth of their length above soil level. Germination starts 2-3 weeks from planting or sowing.
Care of Seedlings – the seedlings planted in containers should be provided with temporary shade. Direct exposure to sunlight may injure the seeds and the emerging one.
Water the seedlings regularly and if the need arises, spray it with the recommended dosages of pesticides to control pests.
Propagation – avocado can be propagated either sexually (by seeds) or asexually (by marcotting, inarching, grafting, and budding). However, propagation through seeds is not recommended for the resulting plants do not come true-to-type. Sexual propagation is good only for seedling rootstocks.
Marcotting – marcotting is not recommended process, because it is laborious, slow and some varieties do not respond well to this method. Besides, it takes 4 to 5 months of marcots to produce roots.
Inarching – gives a very high percentage of success as good results can be obtained in both dry and wet seasons. There is no need of special skills & tools. Among its advantages are tree to be propagated must be near at hand, necessity of bringing the seedling to the branch to be inarched. A relatively slow process, it takes 8 to 62 weeks or more to separate the inarches from the tree. Inarching is recommended for small scale propagation only.
Tongue inarching is a modified form of inarching recommended for avocado. This method is the combination of the ordinary inarching & tongue grafting. In this method, the line of contact between the cambia of stock and scion is greatly increased, thereby shortening the period from inarching to the rate of severing the inarched branches by 4 weeks or more. Those overgrown seedlings not suitable for grafting and budding can be used. Tongue inarching is consider a supplementary method for use during the rainy season when grafting and budding cannot be done very successfully.
Cleft Grafting – this is recommended for larger scale propagation. Use rootstock about 6 to 12 months old with a stem as large as pencil. Select mature budstick with a well-developed terminal buds.
Shield Budding – it is also recommended for larger propagation. This method is fast and resulting plants are precarious, low spreading and uniform. Seedling stock for this purpose should be about 23 – 30 cm tall and its stem is pencil-size. Select mature budwood to facilitate easy bending.
Backyard Planting – dig a hole wide and large enough to accommodate the ball of the planting material.
Orchard Plantation – prepare the land thoroughly by plowing 2 to 3 times followed by two or more harrowings until good a tilth is attained. Stake the field with the recommended distance of planting.
Planting – transplant the planting materials when they are about 50 cm tall. The recommended distance of planting is 9 meters apart accommodating 125 seedlings per hectare. Align the trees in all directions and finally pack the base of the plant to let the root system recover early.
Planting can be done anytime of the year but the best time is during the onset of the rainy season. If planted during dry season provide the seedlings with irrigation and partial shade.
Irrigation – in areas with distinct wet and dry seasons, water supply is very essential during dry months, especially during the first 2 or 3 years of the trees. Young trees are very sensitive to heat and water should be given regularly. Irrigate every two weeks.
Fertilization – in the absence of specific soil analysis, the general recommendation of fertilization can be follows. Apply 100-200 g Ammonium Sulfate (or about 50-100 g Urea) per tree, one month after planting. Apply the same amount every six months thereafter. The amount of fertilizer should increase as the trees grow bigger. However, reduce the recommendation when supplemented with manure or compost. At the start of fruiting, about 500 gm of complete fertilizer (14-14-14) should be applied per tree twice a year. For full bearing trees (15 to 20 years old) apply at least 2 kg of complete fertilizer per tree per year. Half of the amount should be applied at the start of the rainy season and the season half at the end of the rainy season.
Pruning – avocado trees require only little training when properly established from the field. Only those decayed or dead branches that hamper its growth should be pruned. These varieties which have a vertical growth can be pruned judiciously to encourage horizontal growth.
However, pruning should be minimized when the trees start to bear fruits.
Intercropping and Covercropping – it is advantageous to use the vacant spaces in between the main crop by planting bananas, coffee, papaya, pineapple or short season crops (e.g. corn, mango) and vegetable (e.g. eggplant, tomato) crops. Intercropping contributes income benefits, helps improve the land through cultivation and suppresses the growth of weeds. Stop planting intercrops when no longer feasible. Leguminous cover crops can be planted at this period.
Diseases and Their Control
The following are the major diseases of avocado:
Root Rot – caused by fungus Phytophthora cinnamomi. This is commonly infecting trees in narrowly drained water logged areas as it attacks & rapidly kills the roots. The symptoms are yellowing of leaves, sparse foliage, wilting of leaves, die back of shoots and eventually the whole tree dies. The best method of control is the prevention of conditions conducive to the growth of the fungus.
Anthracnose or Blackspot – this disease is caused by the fungus Colletotrichum gloesporioides Penz. and attacks the twigs, leaves, flowers and fruits. This disease can be noticed when the fruits start to ripen. Symptoms can be seen as brown or tan-colored spots on green colored fruits and lighter spots on purple-colored fruits. Timely spraying with 4-4-100 Bordeaux mixture or Copper Sulfate (3 lb/100 gallon of water) should be done in monthly intervals or 3 months before the fruit matures. Frequent spraying is advisable when rainfall is heavy.
Cercospora Fruit Spot or Blotch – it is caused by the fungus Cercospora purpuren Cooke, and produces a slightly brown to dark brown spots confined on the rind of the fruits. On the leaves, the spots are angular, brown to chocolate brown and from irregular patches. This disease can be controlled by spraying the fruits and leaves with 6-6-100 or 4-4-100 Bordeaux mixture or wettable Cuprous Oxide (155 lb/100 gal. water) or basic Copper Sulfate (3 lb/100 gal. water).
Stem End Rot – caused by Diplodia natalensis Pole Evans. is a common disease of fruits in transit which lead to huge losses. The rot starts at the stem end and develops as fruits soften. Avoid wounding of the fruits during harvesting and packing to minimize the disease.
Scab – this disease is caused by Sphacelonia perseae Jerkins, and attacks fruits, young leaves, and shoots. It is a circular to irregular spots, brown to purplish brown, later fading to light brown. Scab can be sprayed with 6-6-100 Bordeaux mixture or wettable Cuprous Oxide (1.5 lb/100 gal. water) before the flowers appear during flowering, and 2 to 4 weeks later.
Insect Pests and Their Control
Mealybug (Planococcus lilacinus CKII)
It infects avocado as one of its many host plants. It is found on the young shoots or on the peduncle of fruits, from which it sucks plant sap. Fruits may drop prematurely if heavily infested by mealybugs. On avacado, it seldom needs control measures.
Avocado barkborer, Aegeria sp.
Often, a bearing avocado tree may be found with a trunk-wound oozing with jelled plant sap in which may be found caterpillar excretal pellets this bleeding is caused by the larvae of a clear winged moth Aegeria sp. The caterpillar feeds underneath the bark and may penetrate into the wood. The attack trees become unthrifty and may break easily in strong wind
Control: Simply excuse the wound, extract the larvae and paint the wounded trunk with coal tar.
Tussock Moth, Dasychira mendosa Hubner
The caterpillars feed on the leaves and/or on the flowers. These are voracious leaf/flower feeders causing mild defoliation or extensure destruction of flowers. These are locally called “tilas”. It has many host plants including guava, beans, pechay, santol, mango. Because of its polyphagous natural enemy, a branchonid larvae parasite , Apanteles sp. If infestation is serious enough, spray with appropriate insecticide
Atlas Moth, Attacus atlas Linn
Its caterpillar feed on the young and maturity leaves causing serious defoliation.
Control: Parasitized by Tricholygiabom bisum Bech, a large gray course-harred tiachinid fly. The strategy is done this way. Upon sensing the presence of the adult fly parasite, the caterpillar swings the anterior portion of the its body continuously from side to side to discourage the fly from approaching nevertheless, the fly will mount at the back of the caterpillars and lay many eggs, individually glued on the back of the caterpillar. The parasite maggots that hatch from the egg penetrate into and completely consume the inside tissues of the caterpillar which die in the cocoon before it could actually pupate. The maggot get out of the dead caterpillar and pupate inside the cocoon.
Bugs (Helopeltis vakeri Pop)
It infests the tender shoots and young fruits. The area around where it has fed collapses and turn black. Severely damaged young shoots die back.
Can be controlled with appropriate insecticide spray, if necessary.
Fruit fly (Dacus dorsalis Hendel)
Usually attack the fruits that are left to ripen on the tree. Fruit oviposites their eggs on the fruits and larvae destroy the fruits making them unfit for human consumption. This can be controlled by spraying any insecticides.
Harvesting, Packing and Marketing
Seedling tree bear fruits in 4 to 5 years after planting. Asexually propagated ones come into bearing much earlier.
Fruits are harvested from April to September and from one season to the next depending on the size of the previous crop, condition and flowering season.
Full bearing avacado tree may yield from a few to as much as 1, 200 fruits per crop year. An average of 500-600 fruits a year may be considered a fair yield.
The fruits of avocado are very perishable and it needs great care during harvesting operation. Fruit maturity is indicated by the appearance of reddish streaks in the case of purple varieties and green to light green on green varieties. Another indication of maturity is when the fruit produces a hallow-sound when tapped with the fingers.
Harvesting should be done by using a picking pole with a wire hook a net basket attached to its end to avoid injury of fruits.
Fruits should be placed in basket or box lined with packing materials such as dried straw, banana leaves, etc. for short distant shipment. For long distant shipment, the fruits should be packed individually with soft paper and packed in a single layered boxes.