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Avocado cultivation in India -Bulletin Book · November 2014
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AVOCADO CULTIVATION IN INDIA
P.C. Tripathi , G.Karunakaran,T.Sakthivel, V Sankar and R. Senthilkumar
Central Horticultural Experiment Station Indian Institute of Horticultural Research Chettalli – 571 248, Kodagu, Karnataka E mail: [email protected]
AVOCADO CULTIVATION IN INDIA
Avocado(Persia americana) is a native of tropical America. It originated in Mexico and Central America, possibly from more than one wild species. The early Spanish explorers recorded its cultivation from Mexico to Peru but it was not in the West Indies at that time. It was introduced into Jamaica in 1650 and to Southern Spain in 1601. It was reported in Zanzibar in 1892. It was first recorded in Florida in 1833 and in California in 1856. In India it was bought during first decade of nineteenth century. Avocado is the most nutritive among fruits. The pulp is rich in proteins (up to 4%) and fat (up to 30%), but low in carbohydrates. The fat is similar to olive oil in composition and is widely used in the preparation of cosmetics. Avocados have the highest energy value (245 cal/100 g) of any fruit besides being a reservoir of several vitamins and minerals (Table 1). The avocado is rich in copper and iron, two mineral constituents of antioxidant enzymes, avocados again prove their nutritionalquality. Potassium is also high in avocados, as it is has one of the highest potassium rates in tropical and non-tropical fruits and vegetables. The avocado is associated with lower blood pressure because it is high in monounsaturated fat. All amino acids are found in the avocado . Another benefit is avocados have been shown to maintain good cholesterol while reducing bad cholesterol. Avocado is mainly used fresh, in sandwich filling or in salads. It can also be used in ice creams and milk shakes and the pulp may be preserved by freezing. Three antifungal compounds have been isolated from the peel extracts of immature fruits of the Green cultivar. The avocados are found, to contain high proteins, their caloric value ranges from 1500to 2250 calories per Kg (i.e. 2.3 pounds). Our food analysts are of the view that theprotein content of an avocado is three times that of an apple, nearly equal to that of thelocal plantain and less than olive fruit Table 1. Chemical Composition of Avocado Fruit (per 100g of edible portion) Nutrients
Quantity
Nutrients
Quantity
Protein
1.7 g
Calcium
10.00 mg
Fat
26.4 g
Chlorine
11.00 mg
Total carbohydrates
5.1 g
Copper
0.45 mg
Crude fibre
1.8 g
Iron
0.60 mg
Vitamin A as carotene 0.17 mg
Magnesium
35.00 mg
Ascorbic acid
Manganese
4.21 mg
16.00 mg
Niacin
1.10 mg
Phosphorus
38.00 mg
Riboflavin
0.13 mg
Sodium
368.00 mg
Thiamine
0.06 mg
Sulphur
28.50 mg
Source: Madhav Rao and Abdul Khader, 1977 HistoricalBackground Avocado was introduced by anAmerican missionary, residing in Bangalore between the years 1906 and 1914 was from Royal Botanical Gardens,Ceylon. No extensive propagation of these with an eye on theircommercial possibilities was attempted til 1940, though theclimatic conditions and soil requirements in the region wereideal for their large scale cultivation. In fact, onaccount of its close resemblance to butter and identical lack of any taste it is sonamed in these parts as 'Butter Fruit.a few seedlings of their choice varietieswere also occasionally brought from their home country by the American missionarieswho came for periodical stays in India during 1912 and 1940. This is the reason than morethan a dozen varieties of Avocado grown in many parts of this region and hillstations like Kallar near Nilgris, Palni, Kodaikanal, Yercaud, Coorg, etc.The small avocado orchard in the Maharaja's Palace at Bangalore and in thebungalows of a few Britisherswere plated during that period. The influx of Americans in very large numbers soon after the outbreak of the Second World War, renewed interest in the propagation of avocados.In the meantime the Government of Mysore opened a research station for non-citrus fruits at Hessaraghatta, Bangalore and about 150 avocado seedlings of differentspecieswere introduced in the research station. Later on these treeswere removed but lots of seedlings were planted in Bangalore and parts of Karnataka and Kerala. Lot of promising varieties avocado were brought for planting in Karnataka, Kerala , Tamilnadu, Sikkim and other states time to time for planting. The avocado cultivation has gain aoverwhelming popularity during last one decade due to nutrition properties of the fruits. Area and production The Avocado is originated in Central- South American countries. A lion’s share of the Avocado production of world, produced in these countries. Avocado production of the world was 4.5 million tonnesin 2012. Mexico is the largest producer and exporter of Avocado in the world. This Mexico is the largest avocado producer followed by Chile, Indonesia, United States, Dominican Republic, Colombia, Brazil, Peru etc (Table 2) . The Avocado production in Asia is limited but some of the countries like China, Vietnam, Korea. Mexico supplies 45 percent of the international avocado marketThe avocado market is still growing. Around 4.5 million are harvested commercially worldwide, over 1 million tonnes (25%) of which are traded
internationally. By now, the value of the international avocado trade amounts to 2.1 billion dollars. The USA is the number one importer in the world, followed by the Netherlands, which plays an important role as transit country in the international trade. The top ranking export countries are producing countries Mexico, Chile, and Peru. Table 2: Major avocado producing country of world (2012) Country Mexico Chile Dominican Republic Indonesia U.S.A. Colombia Peru Kenya Brazil Rwanda
Production ( Tonnes) 1 316 104 160 000 290 011 294 200 245 000 219 352 215 000 186 292 159 903 145 000
Country China Guatemala Spain Congo Venezuela Israel South Africa Cameroon Haiti Australia
Production ( Tonnes) 110 000 95 000 76 800 70 000 83 000 73 351 91 603 72 000 53 000 48 951
The production in India is very limited and they are not commercial plantation of Avocado.The agro-climatic conditions prevailing in various parts of the country appear to be favourable for bringing more areas under avocado. Presently, plantations are not well organized and they are scattered. Also, quite a good number of improved varieties are now available with higher yield potential. Avocados are grown scattered in southern tropical states like Tamil Nadu, Kerala, Karnataka, and Maharashtra. Also popular in the northeastern Himalayan state of Sikkim on hill slopes at elevations if 800- 1,600 meters. Avocados are grown at higher elevations frequently, to prevent soil erosion.Avocado is grown successfully in neighboring Sri Lanka, where goodquality fruits are harvested during May to August and December to January at different regions. Similar agro-climatic conditions to Sri Lanka are available in the Andamans and Nicobar Islands and in the tropical southern India. With proper varietal selection it should be possible to exploit also the possibility of out-of-season production, thus enhancing the availability of fruits for a longer period during the year. Avocado fruits produced in the country can be marketed without much difficulty, particularly to meet the requirement of the growing tourist industry. The mainland India and the Andaman and Nicobar Islands are attracting foreign tourists in a large number of places, where avocado could find a good market access. Avocado has also a good export potential.
Soil and climate Avocados cannot tolerate northern India’s hot dry winds and frosts, typically grown in tropical or semitropical areas with rainfall in summer and humid, subtropical rainfall areas. Intolerant to saline conditions and optimum range of pH is from 5 to 7, are characteristics of this unique fruit. The climate zone of avocados is from true tropical to warmer parts of the temperate zone. Avocados can be grown on a wide range of soils, but they are extremely sensitive to poor drainage and cannot withstand water-logging. They are intolerant to saline conditions. Optimum range of pH is from 5 to 7. Depending on the race and varieties, avocados can thrive and perform well in climatic conditions ranging from true tropical to warmer parts of the temperate zone. In India, avocado is not a commercial fruit crop. It was introduced from Sri Lanka in the early part of the twentieth century. In a very limited scale and in a scattered way it is grown in Tamil Nadu, Kerala, Maharashtra, Karnataka in the south-central India and in the eastern Himalayan state of Sikkim. It can not tolerate the hot dry winds and frosts of northern India. Climatically, it is grown in tropical or semitropical areas experiencing some rainfall in summer, and in humid, subtropical summer rainfall areas. Varieties All three horticultural races adapted to tropical and sub-tropical conditions i.e. West Indian, Guatemalan and Mexican have been tried in India. The cultivars of West Indian race are grown in localized pockets in Maharashtra, Tamil Nadu and Karnataka. In tropical and near-tropical areas, only West Indian race is well-adapted but its hybrids with Guatemalan (e.g. Both selection) perform well and are considered valuable for extending the harvest season. In less tropical regions, hybrids of Guatemalan with Mexican race predominate since they combine the cold hardiness of the latter with the superior horticultural traits of both and also bridge the two seasons of maturity. In the eastern Himalayan state of Sikkim, avocado has been introduced successfully in hill ranges with an altitude of 800 to 1,600 metres. Both the Mexican and Gautemalan races are grown successfully in Sikkim. In avocado-growing areas of Sikkim, temperatures range from 12 to 30°C with an average annual rainfall of 2,000 millimetres. The Mexican race is cultivated on mid-altitude hills (pH 5-6). The fruit of Mexican race are Small (250 g) fruit type, ripening 6 to 8 months after flowering. Fruits have thin smooth skin with a large seed fitting loosely in the central cavity. Oil content is up to 30 per cent in the fruits. Trees of this race are cold hardy. The fruits of Guatemalan raceare fairly large, weighing up to 600 g
and borne on long stalks. The fruits ripen 9-12 months after flowering. Fruit skin is thick and often warty. Seeds, held tightly in the hollow of the fruit, are small. The oil content in fruits ranges between 8 and 15 per cent. The fruits of West Indian race are medium in size and the fruit skin smooth, leathery and glossy. Fruits are borne on long stalks and require up to 9 months for ripening from the date of flowering. Its seeds are large, fitting loosely in the cavity. The oil content of the fruit is low (3-10 per cent). This race is suitable for warm tropical climates.The varieties Fuerte, Bacon, Zutano, Hass, Booth 7, Booth 8, Sharwil and Ettinger are reported to be promising (Table 3). Table 3: avocado cultivars grown in major avocado growing areas USA
Furerte, Hass, Zutano, Bacon, Reed, Gwen, Pinkerton,Pollock, Simmonds, Nadir, Booth 8, Lula, Hardee, Ruchle, Hall, Hickson, Monroe.
Australia
Zutano, Sharwd, Bacon, Purete, Hass, Green Gold.
New Zealand
Fuerte, Zutano, Hayes, Hopkins, Hass, Polock, Booth, Simmonds, Reed.
Israel
Fuerte, Hass, Nabal, Ettinger, Horshim, Wurtz, Ardith, Adi, Iriet, Gil
Brazil
Fuerte, Hass, Carlsbad, Nabal, Ryan, Edranol, Corona, Solano, Quintal, Fortuna, Ouro Verde
South Africa
Fuerte, Hass, Edranol, Ryan, Hayes, Pollock
Mexico
Fuerte, Hass, Bacon, Reed, Criollor, Zutano
Spain
Hass, Bacon, Furete, Reed, Sutano, Gwen
India
Green Type, Purple, TKD-1, Nabal, Linda, Puyevla, Gott-Froid, ,Furete, Pullock, Waldin.
Indonesia
AlpukatHijauPanjang, AlpukatHijauBundur, AlpukatMerahPanjang, AlpukatMerahBundur
The description of some of the varieties is as follows: Hass Predominantly Guatemalan but with some Mexican genes; a chance seedling of unknown parentage, selected by Mr. Rudolph Hass at La Glabra Heights , California; Flower group A; Oval shaped, small to medium fruits with pebby green skin forming purplish black when ripened and creamy, pale green flesh available throughout the year; 66-70 % recovery.
Fuerte Mexican x Guatemalan hybrid ; collected by Carl Schmidt in 1911 from Atlixco, Puebla, Mexico; survived extremely cold weather in California , January 1913 and consequently named ‘Fuerte’ meaning ‘strong’ or ‘hardy’. Flower group B; Pear shaped, medium to large size weighing 170 – 500g. smooth green fruits of high quality with creamy, pale green flesh, easily peeled and available late fall through spring; 75 – 77 % recovery. Gwen Gwen is a selection from the University of California avocado breeding programme. It is a selection of ‘Thille’, which is in turn a seedling of Hass. Plump, oval, green, medium to large fruits turning dull when ripe, pebbly and thick in appearance with creamy, pale green flesh available late winter through late summer. Bacon A Mexican x Guatemalan hybrid; Originated 1928 in Bueno Park , California; Flower group B; Fruit ovate; mid-winter green-skinned variety of good quality, medium-sized weighing 170510g; Skin thin, green and glossy with leathery texture; Early maturing with very pale yellowgreen flesh, recovery 61 % . precocious with consistent production and higher yields than Fuerte. Zutano Mexican x Guatemalan hybrid; Selected by W.L.ruitt at fallbrook, California in 1926. Flower group B; Pear shaped, large fruit with shiny think, yellow green skin and light textured pale green flesh with light taste and moderate shelf life available fall through early winter. Recovery 65 %. Susceptible to anthrocnose and is moderately susceptible to Phytophthora root rot. A successful pollinizer for Hass.Tolerant to saline conditions. Reed Guatemalan; Originated on property of James Reed, Carlsbad, California, about 1948, probably ‘Anaheim’ X ‘Nabal’ hybrid; Round shaped, medium to large sized fruits weighing 270 – 680g ; slightly pebby thick green skin and buttery flesh with good taste and good shelf life, available summer to early fall Pinkerton Guatemalan hybrid; Originated about 1959 as a ‘Rincon’ seedling on the property of J. and W. Pinkerton, Ventura, California and thought to be Rincon X Hass hybrid, a semi dwarf, Flower
group A, Fruit pyriform, medium size weighing 230-425g, seed size is relatively small, mid season maturity with attractive cream coloured flesh, recovery 82%. Resistant to Anthracnose. Xanh Big sized fruits ( 170-180mm in length and 400-600gm weight), good quality fruits with light yellow pulp colour Pollock Originated in Miami before 1896; commercially propagated in 1901; oblong to pear shaped; very large, up to 5 lbs (2.27 kg); skin smooth; flesh green near skin, contains 3 to 5% oil; seed large, frequently loose in cavity. Season: early July to Aug. or Oct. Shy-bearing and too large but of superior quality. TKD 1: Developed at Horticultural Research Station, Thadiyankudisai of TNAU, Tamilnadu. The fruits are medium sized and round. Trees upright and semispreading hence suited for high density planting. Yield 264kg / tree. Fruits are sweet TSS8o brix, fat 23.8%, protein 1.35%. CHES A-1 Selection of seedlings of unknown origin identified by CHES Chettalli. The Tree medium (15-16 feet) spreading, leaf 20-22 cm long ,8-10 cm wide. Flowers in March –April and June July. Fruits borne in clusters of 3 to 5, medium size green, round weigh 200-250 g. ripen in May –June and September – October. Total Soluble Solids - 10.5 O Brix. Pulp-
pale yellow, Recovery -
60 percent. Yield- 300-500 fruit per tree
Propagation In India, avocado is commonly propagated through seeds. The viability of seeds of avocado is quite short (2 to 3 weeks) but this can be improved by storing the seed in dry peat or sand at 50C. Removal of seed coat before sowing hastens germination. In India most of the trees grown are seedlings in origin. The seeds taken from mature fruits are sown directly in the nursery or in polyethylene bags. When 8-12
months old, the seedlings are ready for transplanting. The
seedling trees toke more time to start fruiting and the yield and fruit quality is is highly variable.Due to cross-pollination, there is great variability in the seedlings produced from seeds, it is impossible to obtain genetically uniform plant as indicated for the formation of commercial orchards. These seedlings plants take long time to produce first crop and fruit quality in
unreliable. Vegetative propagation of superior clones of avocado by budding or grafting is essential to avoid these problem. Experiments conducted with two method of grafting (veneer and cleft) and two methods of budding (T and patch) in all the months of the year at CHES (IIHR) Chettallirevealed that after 90 days of grafting , the mean percent success was highest in cleft grafting (32.5%) while lower mean success was observed 8.3% in veneer grafting(8.3%), T- budding (7.5%) ,Patching budding(5.8%). Among different months highest mean success was recorded in month of September (32.5%) followed by 22.5% in the month of March and August. Among the differentcombinations of months and propagation methods, highestsuccess (70 %) was recorded in cleft grafting performed during the month of September . This was closely followed by same method done in month of March month (60%). The success in cleft grafting is higher than other three methods in all 12 months. The growth of the scion was also higher in cleft grafting than other methods. It was concluded that cleft grafting in the month of September and March were most suitable for the multiplication of avocado(tripathi and kuranakaran,2013). At the Fruit Research Station, Kallar, Tamil Nadu, layering as well as inarching gave up to 75 per cent success, while in West Bengal chip-budding is reported to be successful. In India, presently, there is no commercial nursery engaged in vegetative propagation of avocado, nor is there any initiative either at governmental or private level to undertake nursery production of avocado planting material. Field preparation and Planting The avocado plantation in a relatively new area required care in selection of the varieties. The varieties of both A and B groups should be selected and their flowering must overlap. The proportion of A and B group varieties can be 1:1 or 2:1. Avocado is planted out to a distance of 6 to 12 meters depending on the vigour of variety and its growth habit. For varieties having a spreading type of growth, like Fuerte, a wider spacing should be given. In areas prone to excess water, they should be planted on mounds as avocados cannot withstand waterlogging. In Sikkim, a planting distance of 10 x 10 meters on hills slopes is preferred. While in south India, when it is planted with coffee the plating distance varies from 6meter to 12 meters. The pits of 1 cubic meter size are dug during April – May and filled with farmyard manure and top soil (1:1 ratio) before planting. Planting is done in June-July or sometimes in September. In Coorg, a region of Karnataka , avocado trees are planted also as one of the mixed crops in a primarily coffee based cropping system(Tripathi and Karunakaran, 2013).
Nutrient management Avocados need heavy manuring, and application of nitrogen has been found to be most essential. In general, young avocado trees should receive N, P2O5 and K2O in a proportion of 1:1:1 and older trees in the proportion of 2:1:2. At a pH of above 7, iron deficiency symptoms may appear, which may be corrected by applying iron chelate at the rate of 35 g/tree. Various micronutrients (Fe, Zn, B) have profound influences on tree growth, nutrient uptake and yield of avocado. Integrated nutrient management with inorganic fertilizer, supplemented by organic manuring, is advocated for avocado. In Coorg area and the humid tropical region of Karnataka, Kerala and Tamil nadu the fertilizers should be applied in two split doses in May -June and SeptemberOctober. While in Northern India fertilizer may be applied in two split doses in March-April and September-October or just before and after the onset of the monsoon. Foliar application of zinc sulphate (0.5 per cent) and other micro nutrients may be undertaken in April-May or September –October. These micro nutrient may be applied as soil application along with other fertilizers (Table 4). Table 4: fertilizer schedule recommended for avocado. Elements
Age of Plant ( Year) 1
2
3
4
5
6
7& Above
Nitrogen (g/plant)
100
200
300
400
500
600
800
Phosphorus ( g/plant)
30
60
90
120
150
180
210
Potassium ( g/plant)
60
120
180
240
300
360
400
Farmyard manure(kg/plant)
-
10
20
30
40
50
60
Training and pruning The plants need to be given light pruning in initial stages for developing an open centre canopy. After that pruning is rarely practiced. In upright varieties such as Pollock top is done to reduced the tree size while in spreading varieties like Fuerte, branches are thinned and shortened. The dropping and ground touching branches need to be pruned for ease in cultural practices. Heavy pruning has been found to promote excessive vegetative growth, consequently reducing the yield.
Irrigation
In India, avocado is grown in those areas where rainfall is high and fairly distributed throughout the year. Therefore it is grown under rain fed conditions and irrigation is generally not given. Irrigation at intervals of three to four weeks during the dry months is beneficial.Sprinkler irrigation has been reported to improve the fruit size and oil percentageand advances harvesting time. To avoid moisture stress during winter season, mulching with dry grass/dry leaves is desirable. Flooding is undesirable as it promotes root rot incidence. Intercultural and weed management Deep cultivation in avocado orchards should be avoided because of surface roots.Intercropping with legumes or shallow-rooted crops can be done in young orchards which can smoother weeds also. The monoculture plantation of avocado may be maintain with sod culture. The weed are major problems in high rainfall zones of south India . The use of gramexone or Ghyphosate is recommended to control weeds. In coffee based plantation system, scruffling done for coffee is sufficient to control weed. Care should taken that the roots of avocado not disturbed during scruffling. Flowering, pollination and fruiting Avocado starts bearing at 5-6 years after planting and has a marked tendency to biennialbearing which is prevalent in a number of other fruit trees. But there is specific problem infruitset as far as avocado concerned.In avocado, the inflorescence is a compound panicle. The individual flowers aremorphologically bisexual having fertile male and female organs. But they exhibit dichogamy viz., the male and female organs coming to maturity at different time thereby avoiding self pollination of an individual flower. In dichogamy, they are protogynous viz., the female partscoming to maturity before male organs. The type of dichogamy in avocado is a complicated oneunique to avocado-the diurnally synchronous dichogamy. The female parts of all flowers thatopen at a time in a particular tree will mature simultaneously and hence behave functionally asfemale flower. The male parts of same flowers will come to maturity when the flowers opennext time and hence all of them behave as male flowers during that period. By this the crosspollination between flowers of the same tree are also ruled out. The situation is further worsenedby the fact that all the trees of a particular group will be exhibiting the same sex phase at a particular time and the opposite sex phase during the next opening of the same flower. So if thetrees of single group are planting in mass, they will not set fruit and each group requires
interplanting of trees of mother group, the two groups being compatible with one another.Based on this unique flower behaviour, avocado cultivars can be divided into two groups A& B. In group A, first opening takes place in the morning, second opening during the afternoon of the following day. In group B, first they open in the afternoon then again nextmorning. Therefore, every morning A-pistils can be fertilized by B-pollen, while duringafternoon B-pistils are ready to receive A-pollen. Studies on flowering and fruiting behaviour of 40 accessions of avocado was carried out at CHES, Chettalli revealed that number of panicles/shoot ranged from 2.6 (PAI-4) to 13.8 in PA-VII-2. The panicle length ranged from 4.1 cm in PA-XII-1 to 16.1 cm in PAXVII-2. The number of flowers per shoot ranged from 16.71 to 218.96. The panicles were produced on terminal bud and most of them were determinate type. The flowering period ranged from 15 to 28 days. All the flowers were hermaphrodite. The double opening of flowering was noticed in all the accessions. In first opening only stigma was receptive. In second opening was next day when only anther dehiscence took place. Most of the flowers opened in the morning time between 8 to 10.00 AM but some of the flowers opened in the afternoon between 2.0 to 5.0 PM . The average initial fruit set was 3.62%, it was highest (8.74%) in PA-VIII-3 and lowest (0.50%) in PA-VI-1. Average final fruit set was 0.32%. Heavy fruit drop was observed after fruit set. The main reason for low fruit set is peculiar flower opening process. Avocado has perfect flowers produces bisexual flowers but exhibit dichogamy. Thus self-pollination is almost impossible. The pollination is mainly performed by insects. The studies conducted at CHES, Chettalli reveled that insect species including 7 hymenopterans, 7 dipterans, 3 coleopterans were recorded on avocado flowers. Among all the visitor groups, hymenoptera order constituted the major pollinators (52.66%), followed by dipteran order (39.57%) and coleopteran was the least (7.62%) of the total pollinators in avocado orchard. In the group of Hymenopterait was found thatApis cerena as major pollinator with 17.56% followed by Apis florea with 11.3%. Similarly 8.82% of Tetragonula sp. and ants each followed by 6.16 % of wasp were observed. A. cerena starts foraging from 6.00 AM and continues till 12.00 Noon. However, it was observed that the peak foraging period for A. florea, Tetragonula sp. was from 9.00-12.00hrs. Of total bee population,A. cerena had the maximum number of visits (7.87 visits/30min/bunch) followed by A. florea (5.06vists/30min/bunch), and Tetragonula sp. and ant species (3.96 visits/30min/bunch) each.
Fruit harvesting and yield Avocado plants raised from seeds start bearing five to six years after planting while grated plants stars yielding in 3-4 years. Mature fruits of purple varieties change their colour from purple to maroon, whereas fruits of green varieties become greenish-yellow. Fruits are ready for harvest when the colour of seed coat within the fruit changes from yellowish white to dark brown. Mature fruits ripen six to ten days after harvesting. The fruits remain hard as long as they stay on the trees, softening only after harvest. The yield ranges from about 100 to 500 fruits per tree. In Sikkim, fruits are harvested during July to October is the usual harvesting time. In Coorg area fruits are available from June to October . In Tamil Nadu, July-August is the peak harvest time. Post-harvest handling, storage and marketing Avocados do not ripen on the tree, and fruits soften only after they are picked. Fruits need to be picked carefully. They should be harvested at the correct stage of maturity. In India, fruits of 250 to 300 grams in size are preferred. Most popular varieties are Hass, Fuerte and Green. Hard, mature fruits are harvested and allowed to ripen during transport and distribution. unripe avocados can be stored for up to four weeks at 5.5 to 8°C. Presently, there is no organized marketing system for avocado as the production is small and production areas are scattered. Pests and diseases The Anthracnose root rot, leaf spot, Stem rot, The scab are the major diseases affecting avocado. Anthracnose Anthracnose is becoming major problem but effecting the fruit yield and quality. It is caused by Colletotrichumgloeosprotioides. The symptoms are developed in the fruits either or after harvest initially the symptom is large light, brown circular, lesions which turns into dark brown or black colour of the sometime. Infection results in shedding of young fruits. Remaining fruits become deformed. The copper based fungicide copper oxide, copper trioxide may be used to control this disease in the initial stage. The orchards sanitation like burning of fallen leaves and fruitshelp to reduce inoculum. Post harvest treatment of urns to control the disease is also recommended inmany countries. Controlled atmospheric storage of fruits in 2% O2 at 7.2oC for 3-4 weeks helps to prevent the development of the fungus in storage. Phytophthora Root Rot
The most serious disease of avocado is the root rot caused by Phytophthora cinnamoni,leading to death of plant. The disease effects the roots and they became black and eventually die which effects the overall growth and yield of the plants. The disease situation is aggravated by ill drained and waterlogged conditions. Metalaxyl (Ridomil) mixed with soil before planting or applied as a soil drench controls root rot at least for four months after treatment. Soil drenching of Ridomil (1gai/10 lit) controls root rot.This disease may be minimized by using tolerant varieties , avoiding water logged areas for planting, soil solarization, use of metalaxyl, potassium phosphonate may be used. Avocado scabSphacelomaperseae Oval or irregular brown or purple spots on fruit with rough texture are formed. High humidity encourages scab growth and spread. Use of tolerant varieties and spray of copper containing fungicides helps to control the scab problem. Insect Pests Mites, mealy bugs, scales are the important insect pests of avocado. Mites Three species of mites prey on avocado trees. The avocado brown mite lays eggs on the tree's leaves, and in large numbers damages and destroys the plant's foliage. The perseamite also harms avocado tree foliage, leading to fewer fruits, though the six-spotted mite typically only causes leaf discoloration. Predatory mites will keep the population of all three mites under control, as will avoiding the use of chemical pesticides that kill their natural enemies. Mealy bugs (Planococcuscitri) Mealy bugs are not major problem in avocado but use of insecticides kills the natural enemies of mealy bugs causing major problem. Mealy bugs are sexually dimorphic. Yellow eggs are produced in a loose colony of waxy filaments. About 50-100 or more than 100 eggs covered in an ovisac are deposited by female. Mealy bug breeds continuously on different hosts like citrus, Murraya koenigi, coffee in Coorg region. Mealy bug observed on fruits during SeptemberOctober months. It was found both on the immature and ripened fruits. The mealy bugs produced large quantity of honey dew, which attracts other insects and these insect lay egg on the fruits and deteriorate the quality of fruits. Mealy bugs are tend to be serious pests in the presence of ants because the ants protect them from predators and parasites.These may be control by release of lady bird beetle, Cryptolaemus montrouzieri at 10 beetles/tree after fruit set.
Spraying 150ml dimethoate + 250ml kerosene in 100 of water (or) 10g of carbaryl +10 ml kerosene in 10 l of water gives effective control of mealy bugs. Thrips (Scirtothrips perseae) Obvious feeding by Thrips scars on fruit. These scars begin as scabs or leathery patches and spread across fruit. The adult insect is orange-yellow in color with distinct brown bands and reaches 0.7 mm in length.Insect thrives in cooler temperatures and may undergo 6 or more generations per year.Addition of coarse organic mulch about 6 inches thick below trees may help to reduce survival of Thrips pupating in soil. Selective insecticide should be selected to control these insects so that minimum damageis done to populations of natural enemies. Fruit fly (Bactrocera dorsalis, B. caryeaea) Very less percentage of fruit fly infestation was noticed on rambutan. Fruit fly infests the ripened fruits. Its infestation is more in southern states. The female fruit fly lays eggs on the mature fruits with the help of its pointed ovipositor. After hatching the maggots feed on pulp of these fruits and the infested fruits starts rotting and fall down. As a result brown patch appears around the place of oviposition. The maggots come out of the affected fruit and pupate in the soil.Preharvest IPM combined with sanitation (Collection and destruction of fallen/infested fruits) + Placing Methyl eugenol trap @ 4-6/acre + In severe infestation spraying of bait spray (Decamethrin (Decis) 2ml+ 100g of jaggery in 1 litre of water) is recommended. Avocado has high nutritional value and usefulness of it,s high quality fats in promoting health of heart and circular system is attracting lot of people to use it in their daily diet.. The growing use of Avocado oils and fats in cosmetics is also a reason of increasing popularity of this fruit. In India, consumption of Avocado is limited to high elite group of large Metropolitan cities but with increasing awareness about the health concerns, the demand of avocado is increasing. In India, alarge area is suitable for cultivation of Avocado. There is good scope of Avocado cultivation in India but there is need to develop better varieties for Indian conditions and development of production technologies for Avocado.
REFERENCES 1.
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