Everything you need to learn about cultivating litchi organically. Learn about:- 1. Introduction to Litchi Fruit 2. Climate and Soil Required for Litchi Cultivation 3. Ripening Time 4. Propagation 5. Planting Techniques 6. Training, Pruning and Canopy Management 7. Organic Nutrient Management 8. Weed Management 9. Intercropping, Mulching and Rejuvenation of Litchi 10. Harvesting 11. Insect Pest and Disease Management.
Contents:
- Introduction to Litchi Fruit
- Climate and Soil Required for Litchi Cultivation
- Ripening Time of Litchi
- Propagation of Litchi
- Planting Techniques of Litchi
- Training, Pruning and Canopy Management of Litchi
- Organic Nutrient Management of Litchi
- Weed Management of Litchi
- Intercropping, Mulching and Rejuvenation of Litchi
- Harvesting of Litchi
- Insect Pest and Disease Management of Litchi
1. Introduction to Litchi Fruit:
Litchi (Litchi chinensis Sonn.) belongs to the family Sapindaceae and is a subtropical evergreen fruit crop, which has highly specific climatic requirements. Probably due to this reason, its cultivation is restricted to only few subtropical countries in the world, where it is grown commercially.
In India, the commercial cultivation of litchi is restricted in the northern part, particularly in the foothills of Himalayas, Gangetic plains and Tripura in north-east. Leading litchi producing states in India are Bihar (44.20%), West Bengal (15.51%), Jharkhand (10.03%), Assam (8.55%), Chhattisgarh (5.32%), Punjab (4.57%), Odisha (3.49%), Uttarakhand (3.30%) and Tripura (1.89%). The annual production of litchi is about 580 thousand tons from 83 thousand hectares area with 7.0 tons/ha productivity (NHB Database, 2012-13).
2. Climate and Soil Required for Litchi Cultivation:
Moist atmosphere with abundant rainfall, free from frost are ideal for litchi cultivation. Further fog free dry winter, wet spring and mild subtropical summer have been observed to be highly favourable for blossoming, aril development and fruit quality.
Temperatures of 10°C from December to February and 38°C from April-June are considered to be optimum. The temperature should not go beyond 40.5°C in summer and below freezing point in winter. The subtropical to mild temperate climate in the foothills and valleys of Himalayas is also quite suitable for litchi cultivation.
Soil is the source of essential plant nutrients and thus, its chemical and physical properties are of fundamental importance. Litchi grows in a variety of soils but fairly deep well drained loam soil rich in organic matter is best for its cultivation. Litchi trees grow best in a pH range of 6.0 to 6.5. The roots of litchi trees have a symbiotic association with mycorrhizal fungi, which help in the nutrient uptake.
Thus before planting it is worthwhile to inoculate the soil in the pit with the soil collected from the root zone of litchi orchards. Commercially available mycorrhiza bio-fertilizer can also be used for pit inoculation. It can be grown on a range of soils, including sandy loam alluvial with pH 5.5-7.5.
3. Ripening Time of Litchi:
India has unique and distinct advantage as ripening of litchi starts from 15thApril in Tripura and harvest season lasts in other states up to end of June (Fig. 4). Thus there is enough time to exploit enhanced litchi export potential.
4. Propagation of Litchi:
Litchi is commonly propagated by asexual propagation techniques. Among vegetative propagation techniques, air layering is most common, however cutting, budding and grafting (wedge grafting) are also practiced to some extent.
Air layering or gootee is widely accepted method of litchi propagation, which gives the most satisfactory results. Air layering can be done at any time of the year as long as there is sufficient moisture, but best results are obtained just after harvest in rainy season.
Air layering is done when leaves of the previous growth flush have proper maturity. Branches of 10-25 mm diameter and 46-60 cm length are usually selected. A ring of bark measuring 2.5 cm width is removed and thin cambium layer beneath the bark is scraped away. The ringed area is covered by a layer of moss of about 2.5 cm thick and 10 cm long.
The traditional methods use soil, organic matter, sawdust and wood chips wrapped in cloth to enclose the rings. Alternatively, 2 parts of river bed soil, 1 part vermicompost and little bit of coconut peat can be used. The plastic wrap ends are tied tightly around the branch with string and sealed with plastic tape to keep rain water out.
Under adequate conditions (temperatures 25-30°C), two to four months after air layering, several roots are formed and are visible changing colour from white to creamy brown through the plastic film. The air layered branch is then cut off immediately below the plastic.
The wrapping is then removed and the rooted air layer is planted in a suitable container. Use of root trainers and organic matter rich rooting media has been found to promote the secondary and tertiary roots in the litchi air layers, which improves the establishment.
Air layers in litchi produce thick and brittle roots, which result in heavy mortality of rooted plants in nursery and field as well. However, after separation from mother plants, air layers are planted in root trainers containing nutrient rich organic medium which help to produce more number of thinner lateral roots and resultantly enhanced survival of air layered plants in the field.
The trunk and rooted area should not be buried more than 2.5-5 cm below the level of the soil in the container. Cup size of 340 ml to 500 ml of root trainers has been found ideal. Containers with newly transplanted air layered plants should be placed in a shaded area or green house for about two weeks with a light weight plastic bag placed over the plant to retain humidity until the plant begins to put out new growth.
Later on, the plants can be gradually exposed to full sun for hardening. Two or three vegetative flushes must appear before the plants can be hardened off in the open air prior to final planting.
5. Planting Techniques of Litchi:
Land Preparation:
Selected field should be deeply ploughed and then harrowed to root out the perennial weeds, roots of perennial bushes and heavy clods. After harrowing, proper levelling of land is done and a gentle slope is provided in one direction to facilitate irrigation as well as drainage of excess water during rains.
Litchi is an evergreen spreading tree, which attains the height of about 10- 12 m at its full growth and development. Light penetration in its canopy is also desirable for proper fruiting; hence planting in square system at a distance of 10 m x 10 m (accommodating 100 plant/ha) has been practiced.
Planting of litchi in double hedgerow system at a distance of 4.5 m x 4.5 m x 9 m accommodating 329 plants/ha has been found to be the best under conventional management and gave higher yield of equally good quality fruits up to 16 years of plantation. Medium planting density of 6 m x 6 m accommodating 278 plants/ha has also been suggested.
But under organic management plant spacing of 10 m x 10 m or 9 m x 9 m or 9 m x 7 m or 8 m x 6 m is most ideal, as these allow adequate space for growing intercrops, creating plant diversity using insectary plants and enhance proper air circulation and sunlight penetration for effective insect pest and disease management.
Before planting, pits of 90x90x90 cm dimension are dug at marked place during summer season in the month of April-May. Once the planting geometry is decided and the land prepared, the pits are dug for transplanting the saplings. This should be done one or two months prior to planting.
The main purpose of digging and filling the pit is to provide congenial conditions for plant growth and development, especially during the establishment phase. The pits should be invariably kept open during summer to expose the dug soil to heat and sunlight. Pits should be filled before the rainy season for proper settling of the loose soil.
Initial establishment and vigour of the litchi plant is governed by the available substrate in the pit. The pits should be filled with good quality substrate. Substrates mainly include farm yard manure, cakes, vermicompost, Trichoderma rich manure and biofertilizers along with soil containing mycorrhiza from litchi root rhizosphere and/or VAM culture. As a common dose, 30-40 kg Trichoderma enriched FYM, 2 kg neem/karanj cake, 1-2 kg vermicompost, 250 g bone meal is sufficient for one pit in a normal soil.
Manures carefully mixed with top soil should be placed at the bottom of the pit followed by lower soil mixture. The upper level of pit is kept 15 cm above from the field level. After filling, if rain is not there, the pits should be irrigated to settle down the soil.
Take out plant with intact earth ball from the soil in the nursery or polythene bag. Planting needs to be done during monsoon period when there is soil moisture and favourable weather. Place the plant in the centre of the pit, by removing the soil to put it in place. Press the moist soil around the plant and irrigate.
6. Training, Pruning and Canopy Management of Litchi:
At planting time, the plant is cut back to 0.70 to 0.80 meter if it is a un- branched tall sapling. If it is a branched one, it is reduced to three or four wide- angled branches to give it a proper balanced shape. In general, litchi plant is developed in a way that three or four wide-angled side branches form the framework, with the uppermost branch becoming the modified leader. Generally litchi plant grows continuously which results in a large canopy and it becomes congested.
In such a situation, over grown trees must be opened up. Thinning and pruning of unwanted branches can help open up canopies. Apart from this, topping and hedging can also be adopted if there is unwanted top and lateral growth. Under organic management opening up of canopies is essential to facilitate mixed cropping and allow adequate sunlight and air to contain insect pest and disease problem.
Irrigation plays an important role in raising and stabilizing yield and maintaining quality of a crop like litchi, which is more precious than other fruit crops grown in tropical or subtropical climate. Young plants up to 3-4 years are irrigated frequently from October to June. The period from July to September receives sufficient rain to fulfill the water needs of the plants.
If the rain during this period is scanty, the trees are irrigated at 15 days interval during October- November, at one month interval during December-February and at 7 or 10 days interval during March-July. The period from flowering to early fruit development is particularly sensitive to water supply. If moisture is inadequate at this stage, poor fruit setting and abnormally high fruit dropping results in poor crop yield.
Drip irrigation is the slow localized application of water drop by drop, at a point or grid of points on or just below the soil surface. The trickling rate, generally in the range of 4-8 lit/hour per emitter, must not exceed the soil’s in-filterability if run off is to be avoided.
This system, like the micro-sprinkler method, is very suitable for both flat and steeply sloping land. Some farmers prefer both drip and micro-sprinkler below the canopy to increase the humidity in the orchard at the fruiting time to avoid fruit cracking.
7. Organic Nutrient Management of Litchi:
As litchi is evergreen and grows well round the year, luxuriant intercrop growth is possible only during the early years of planting. In subsequent years intercrops can be taken mainly during rainy season and that too with lesser growth and biomass. One cycle of green manure crop (sunhemp, mung bean, urad bean, cowpea or Sesbania) when incorporated into the soil adds about 50- 80 kg nitrogen per ha during early years of planting while in later years it may add only about 30-40 kg of nitrogen.
Keeping the soil covered with green cover from July till February-March and frequent drenching of biomass with Jivamrit can ensure sustained biological activity in the soil. In rainfed areas, like in Tripura, Assam and parts of West Bengal where irrigation facilities are not available and taking intercrops during winter is difficult, ensure that soil remains covered with biomass mulch for moisture conservation, sustained microbial activity in the soil and for effective weed control.
Keeping all these situations in mind litchi trees are proposed to be manured both through soil application of different organic nutrient sources and through foliar feeding. For soil application prepare concentrated manure mixture by mixing 70 kg vermicompost or BD compost with 14 kg concentrated chicken manure or poultry manure, 10 kg neem cake, 5 kg wood ash and 1 kg of bio-fertilizer mixture comprising of Azotobacter/Azoispirillum + PSB + KMB + Trichoderma viride.
Mix all the ingredients with some water, keep the manure mixture covered in a heap for 48 hrs for incubation and apply. Concentrated manure mixture is most effective within 7-8 days of preparation.
For meeting the nutrient requirements at later stages plants are fed through leaves. A foliar feeding solution comprises of Vermiwash (5%) or Panchagavya (3%) or farm made protein hydrolysate (4-5 ml/lit of water). Any one or combination of two or all can be used depending upon the requirement.
8. Weed Management of Litchi:
In litchi orchards, owing to shallow root system, it is necessary to keep the weeds under check at least twice a year which otherwise may prove harmful to the growth and productivity of litchi plants.
Management of weeds can be done by taking following steps:
1. Destruction of weeds manually by cutting with sickle or turning into the soil with spade and cultivation of the land frequently and collection of the roots, rhizomes, runners, bulbs, etc. by hand
2. Tilling the orchard soil regularly provides a weed free environment in the orchard
3. Cover cropping and intercropping are other practices followed in litchi orchards to suppress the growth of weeds
9. Intercropping, Mulching and Rejuvenation of Litchi:
Intercrops of leguminous crops like cow pea, mung bean, urad bean, peas etc. can be easily taken. Green manure crops such as sunhemp, and cover crops such as clover can be ideal for nitrogen fixation and weed control. Apart from this, intercrops of kharif pulses in summer and light vegetables like tomato, pea etc. can be taken in winter.
Even cucurbit vegetables in summer and grain crops like Bengal gram in winter or legume crops can be taken which can be ploughed back in soil. However nutritional management and control of insect pests and diseases of intercrops must also be taken care of.
Mulching is beneficial to all litchi orchards. It is very much useful in plants raised under rainfed conditions or in adverse conditions. To cover the soil surface in and around tree basins in litchi, various kinds of organic (saw wood dust, crop residue farm waste, dry leaves) and inorganic (polyethylene of different colours) can be used as per availability and scale of investment.
It has been observed in general that litchi orchards after attaining the age of 25-30 years turn dense with compact top canopy bearing fruits only on the high- tops. Such plants yield less and pose problems in proper management such as annual pruning, pest control and harvesting.
For rejuvenation, heavy pruning of litchi tree is done at the height of 2 meters to 2.5 meters from ground level depending upon the girth and type of main trunk. Three to five main branches with outward growth from the base are selected for pruning at required height, with a plan of developing umbrella like or semicircular framework of tree canopy. Pruning can be done either with manual saw or power operated saw.
Care should be taken to avoid bark splitting. It is always advised to go for rejuvenation pruning in a phased manner. After care is very important to avoid any external infection at the cut portion, it should be pasted with Bordeaux paste or copper oxy-chloride immediately after pruning. Thinning of shoots at the appropriate time and selection of few widely spaced shoots is very necessary to make umbrella like framework.
The best time to go for rejuvenation is August-September i.e. mainly after the rainy season. Rejuvenation is labour intensive operation and it is extremely necessary to complete the operations in time for achieving the desired results. Intercropping can also be taken for 1 -2 years to augment the income.
10. Harvesting of Litchi:
Maturity Indices:
Following criteria may be followed to ascertain the litchi maturity. Skin colour is usually a determinant of ripeness. The fruit is said to be ready for harvesting when the pericarp is uniform red, (just when the orange colour has disappeared completely or almost completely, except in the case of cultivars which produce yellow or green fruit) and the protuberances have become smoother.
In varieties, which produce red fruit, there should be an even deeper red colour at harvest time. The most reliable guide to maturity is titratable acidity (TA) or the ratio of total soluble solids (°Brix) to titratable acidity.
Recommendations vary, but a TSS:TA of 40 or greater is recommended for commercial fruit. In practice, however, most orchards of litchi are harvested on the basis of taste and general appearance.
Litchi fruits are harvested in bunches along with a portion of the branch and a few leaves as it prolongs the storage life of fruits. Fruit harvesting starts early in the morning and gets over by 10 AM.
However, in those cases where the pre- harvest contractors manage the orchard, they make the decision on harvest time at their convenience. Plucking is done carefully without damaging the branches of the tree. The labour employed for harvesting are often unskilled and are not trained properly for harvesting. It often results in damaging the tree.
Grading:
At the farm level, fruit is graded mainly on the basis of colour and size and for any damage/injury to the fruit. Damaged, sun burnt and cracked fruits are sorted out and the other fruits are packaged in bunches along with the twigs and leaves. Most common grades are of extra class, class I and class II.
Packing is often carried out in a pack house or shed, to protect fruit from the heat. Where shelter is not available, operations are best located in a cool, shady area, where, temperature should not be more than 12-15°C. A good box for packing fruits should be light in weight, shallow and rigid enough to protect the fruits, it should have few holes for ventilation and rope handles on either side for lifting the box.
After harvesting, fruit should be packed as quickly as possible, as their quality deteriorates markedly if they are exposed to sun even for a few hours. For domestic markets litchi is usually packed in small card board boxes or wooden crates. Square baskets less than 30 cm height give good protection against injury.
Proper packing of fruits is important in maintaining freshness and quality and preventing fruit decay during transit for marketing to distant places, these are lined with litchi leaves or other soft packing material as paper shavings, wood-wool, etc.
Pre-cooling of fruits should be done before cold storage because without pre-cooling, browning could be more rapid compared to the storage of pre- cooled fruits at 2-5°C.
Individual fruits are usually packed in 2-4 kg card board boxes. Usually such boxes are treated with sulphur by burning sulphur in a closed chamber at 2-3°C and 85-90% RH. However for organic products sulphur treatment will not be allowed and only proper cool chain will be maintained. After this boxes are pre-cooled and stored.
Storage:
As litchi is highly perishable in nature, storage is not done at farm level. Since it requires low temperature and humidity conditions to have longer shelf life, proper cool chain has to be maintained for storage. The relative humidity should be kept at 90-95% throughout storage and transport. Controlled atmosphere storage (3-5% O2 and 3-5% CO2) and 5-12°C reduces skin browning and slows down the losses.
11. Organic Insect Pest and Disease Management of Litchi:
Pest management in litchi organic farming is an integrated approach combining cultural, mechanical and biological strategies in first place and using botanical and organically acceptable chemicals only as last resort.
First and foremost strategy for organic pest management in litchi is creation and maintenance of diversity, which includes permanent diversity plantation on boundary and internal bunds, (such as Gliricidia, Leucaena leucocephala, perennial pigeon pea etc.) on borders and pesticidal value plants such as Adathoda, Ipomea, Calotropis, Vitex (nirgundi) etc. randomly in between border plantation and aromatic grasses such as lemon grass on internal bunds and seasonal diversity through intercrops (mainly leguminous crops), flowering plants and trap crops (such as marigold, basil etc.)
Second strategy involves manipulation of cultural practices to ensure a balance in natural processes, which in turn keep the pests below the economical threshold limit.
Important cultural practices include:
1. Use of resistant cultivars and disease free planting stock.
2. Growing legumes as cover/intercrop and its incorporation in soil
3. Keeping soil covered with living vegetation and or crop residue.
4. Use of neem cake and drenching of tree basin with Trichoderma viride, T. harzianum and Pseudomonas fluorescens.
5. Collect egg cards of beneficial insects for release such as Trichogramma, Chrysoperla, Telenomus etc. which are available from state Bio-control Labs.
6. Install pheromone traps
7. Install yellow pan water trap/sticky traps 15 cm above the canopy for monitoring and mass trapping of moths
8. Set up light traps 1 trap/acre 15 cm above the crop canopy for monitoring and mass trapping insects. Light traps with exit option for natural enemies of smaller size should be installed and operate around the dusk time (6 pm to 10 pm).
9. Grow flowering plants along the orchard border by arranging small plants towards the crop and taller plants towards border. Important insectary plants include mustard, sunflower, alfalfa, marigold, carrot, French bean, cowpea, maize, spearmint, peppermint, coriander Ocimum etc. After flowering these plants can be used as green manure/mulch.