India is a vast country and is gifted with a variety of soils and climates. Thus, almost all kinds of fruits can be grown successfully in this country. It is a matter of great surprise that inspite of provision of adequate resources, the per capita consumption of fruits here is perhaps one of the lowest in the world.
The existing orchards are not able to meet the present requirements of the country. Poor selection of planting material, haphazard plantation and poor management has made many orchards uneconomic. The term ‘Rejuvenation’ means renewal or making new or young again.
As applied to the orchard tree it would mean restoring the productive capacity of the fruit trees. The meaning of ‘Rejuvenation’ according to Chamber’s dictionary is ‘to recover youth character or to grow again’. Obviously, this would apply to those plants which have attained a stage where they are no more profitable from the grower’s point of view.
Causes which makes the orchard uneconomic
A survey of uneconomic orchards would reveal following defects:
i. Growth of wild shrubs and grasses
Wild shrubs and grasses continue to grow without any check under the tree and in between the rows. At a stage they develop into bushes here and there in the entire plantation.
It has been realized that vegetation removes quite a larger quantity of moisture from the soil and also ties up nitrogen so that it is not available to the trees at the time, though it may be returned later when the weeds die and decompose in the orchard soil.
Weeds harbour insects, pests and diseases too. When they become large enough they interfere in the orchard operations and some of them climb up the tree and by shading the leaves or due to their parasitic nature cause great damage to the main fruit crop.
ii. Overcrowding and unsystematic planting
In some of the orchards no regular or systematic planting is followed. The trees are also found to be planted so close that they form a dense overhead canopy which does not allow sufficient light to reach at different parts of the fruit trees uniformly.
The lower branches remain under perpetual shade. As a result of it the bigger branches remain devoid of small twigs or branchlets and ultimately this abnormality reduces the fruiting surface. In such cases, trees for want of space grow tall and bear fruits almost on periphery only.
These fruits in hotter localities are affected adversely by sun burn. This way the growers unfortunately suffer a double loss because on one hand the quality of the fruit and on the other the total produce both are considerably reduced. Free circulation of air is also checked and this results in development of pests and diseases.
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iii. Inferior varieties
The poor selection of planting material at the time of planting will cause a great loss throughout the life of the orchard. In most of the orchards trees have been raised from seeds and of inferior varieties. Seedlings of poor varieties are potentially poor and their performance is subjected to a wide range of variation so that even if they grow and function normally, they do not produce a crop that can fetch good price in the market.
iv. Damage due to adverse weather conditions, rodents and other enemies
Trees with damaged trunks, broken limbs and big hollow in the trunks are not uncommon in such orchards. Some trees may be found standing with only half their base. Many trees live for hundred years or more and grow to huge dimensions. Old trees with the advanced age have a tendency to develop hollows in their trunks and main branches starting from a crotch or from the point of bifurcation. The branches which cross one another rub together when fast wind blow and injure their bark. Rain water is deposited in the hollows produced and cause the bark and wood inside to rot. As the process continues year after year, larger cavities are formed. A historic Borsha mango tree of huge dimensions reputed to be over three hundred years old at Kalamsar in the East Khandesh district. In course of time the main trunk developed a hollow in which three to five persons could enter at a time.
v. Infestation of pests, diseases and parasites
The orchards which have been established in neglected localities are seriously attacked by number of pests, diseases and plant parasites. These enemies are so rampant that even in orchards otherwise in good condition, the production is very poor. These organisms devitalize the plants and destroy flowers and fruits in all stages of development.
Practices for rejuvenation
The first step while going to rejuvenate an uneconomic orchard should consist of a thorough examination of the causes which led to the tree in poor state. Efforts should then be made to rectify the defects. An attempt has been made in the following paragraphs indicating various suitable suggestions helping for rejuvenating an uneconomic orchard. Practices to be followed in advance before the trees reach at need of rejuvenation to protect the orchard from this malady have also been explained side by side.
i. Soil management practices
It is very important that the soil should intelligently managed so that it may be maintained in a condition suitable for meeting the needs of the trees without undue expenses. There should be proper vigilance regarding the physical condition of the soil and also about moisture and nutrient contents. These depend largely on the practices of cultivation, irrigation, drainage, manuring etc. Conservation practices should also be followed to maintain the fertility and topography of the soil.
It involves the elimination of wild shrubs and grasses from the land left vacant in between the trees. This practice has been found to prevent the surface soil from becoming it hard. Hard soil greatly adds to the difficulty of irrigation and interferes with the growth of roots of main trees. Manures, fertilizers, green manure and other organic matter should be mixed with the soil by means of regular cultivation. It would facilitate in aerating the soils and would kill a number of insect pests and other harmful organisms present in the soil.
The water relation of the plant is of extreme importance both for vegetative growth and for fruit production. Irregular irrigations may cause fruit drop, fruit splitting and other disorders. Application of manure should be followed by watering so that the nutrients are readily absorbed. Soil around the tree base should be raised to form a platform so that water does not touch the bark of the trunk directly. In areas of scanty rainfall or limited water supply, special methods of moisture conservation such as mulching may be practiced.
Drainage is as important as water supply. The absorption of nutrients is affected to a great extent by the aeration of the soil which is affected by drainage. After prolonged stagnation of water roots below the soil surface die and they may not be replaced by new ones. In poorly drained orchards, effective steps like provision of drains etc. should be taken, so that there is not any interruption in the physiological processes of the plants.
Fruit trees live long, standing at the same place and bear crops year after year. In doing so, they constantly remove plant food from the soil unless an adequate return is made to the soil to replenish the plant part removed. Cultivation of green manure crops during early rains and turning of them in the orchard soil and create proper provision for their decomposition would greatly help in increasing the organic matter of the soil and this directly will influence the supply of various nutrients. If green manuring is not possible, a heavy dose of F.Y.M or compost may be spread throughout the orchard. Besides, individual trees should be manured with quick acting fertilizers. When the tree fails to respond to this treatment, a dressing of super phosphate and sulphate of potash or other similar mineral fertilizers may be done. Soil lacking in minor elements may also be corrected by adding certain chemicals possessing the same elements. Supply of trace elements is found to be more economic and effective through foliar sprays. This would enable to check over fruiting, fruit drop, fruit splitting, diseases and many other disorders.
ii. Thinning and filling of gaps
Overcrowded trees should be thinned to proper distance. Though it might create a loss of some trees, but would also greatly benefit those plants that are left behind. However, it is not useful to see many trees missing. In those cases gaps should be filled up by trees of superior varieties. While undertaking these operations attention should be paid to bring the trees in lines according to system of planting originally kept in view. Sometimes certain varieties of citrus which have been propagated vegetatively for many generations become somewhat lacking in vigour. For this process of rejuvenation, Swingle (1932) coined the term ‘neophyosis’.
iii. Control of pests, diseases and parasites
Unhealthy or diseased limbs should be cut off and pruned parts are suitably disposed. Bark boring caterpillars are prevalent in many orchards. Individual holes should be treated, cleaned and then a mixture of carbon bisulphide and chloroform (2:1) or any other insecticide should be injected in it. The plants should be covered with insecticide or fungicide before an attack is apprehended. Nematodes cause serious set back to several fruit trees, therefore, nematocides should be promptly applied. Among other steps included to check the effect of insects and pests are killing of weeds, loosening the soil around the tree or disinfecting it. Regular spraying of the orchard trees with insecticides and fungicides must form a routine practice.
The disbalanced root-shoot ratio can be corrected by judicious pruning. The branches which have died or broken or one which interferes with natural growth, and water sprouts should be removed. If the exposed wounds are big enough, they should be disinfected with arsenical paints. Old bearing trees that have reached their middle age have become some what low in vigour due to constant cropping or neglect, should be pruned heavily. Such trees respond better to a heavier pruning because of their reduced vigour. This treatment is to be supplemented with a heavy dose of manure later on. Rejuvenation in guava and peach plantation is achieved by heading the trees back almost to the base of the trunk. The low stems thus left produce vigorous growth and fair head is attained in two years. Grape vines are also similarly rejuvenated when they loss vigour. The deciduous plants respond better to severe pruning where as evergreen ones are said to grow slowly for some time afterwards. Root pruning also sometimes restore the vigour of unproductive plants.
v. Adventitious method of feeding
Old trees with weak growth can be envigorated by infusing the sap of younger seedlings into them. Several seedlings are grown close to the trunk of the tree. When they attain an age of two or three years, they are headed back to the height of 2′ to 3′ from the ground. The cut ends are shaped to a wedge from upto a length of about 2″ and are inserted into the bark of the tree. If needed both surfaces might be nailed and would be finally covered by grafting wax followed by firm tying with tape. If the tree is lacking in vigour due to unsatisfactory rootstock, the seedlings should be grafted into the scion not into the rootstock. In course of time, the seedlings get united to the tree and serve as its feeder. This could be practiced in mango, citrus, apple and in many other fruit plants. This method may also be followed when the collar region has been damaged.
vi. Repairing of wounds
Any wound on the tree if allowed to remain exposed may attract the organisms of diseases from the surrounding atmosphere. So they should be properly treated to encourage healing. If wound is small, simply painting with colour or any other disinfectant may suffice the purpose. In case of bigger wounds on the trunk, a special method of grafting called ‘bridge grafting’ is followed. Big hollows may be strengthened by scrapping off the inside diseased or rotten parts smearing the exposed portion with coal tar and filling them with bricks and kankar. These are finally plastered with cement.
vii. Top working and frame working
These are done to change the trees of inferior varieties into good ones. The scaffold branches of the trees are cut back 2′ to 3′ from the point of origin and when the new sprouts come out, they are budded or grafted with the scion of desired variety, keeping in view that the scion is compatible to the headed trunk. After top working, only scion branch is allowed to grow and the rest are removed promptly. Top working has been practiced successfully in many fruit plants such as aonla, bael, stone fruits etc. Mango plant has been top worked by side, bark, veneer and crown grafting and approach inarching as well as budding. So far as citrus plants are concerned, shield budding has proved most satisfactory though other methods of propagation have also been practiced thereby. For ber, ring budding was previously recommended, but now shield budding is gaining importance. Top working in loquat can be done by cleft grafting and in fig by cleft and side grafting both. Cleft and bark grafting and budding have been successfully practiced for rejuvenating apples. Peach trees are best worked by inlay bark grafting.
In frame working, only the smaller branches and shoots are replaced by scion of desired variety. The frame working is not successful in tropical and sub-tropical fruit plants, while temperate fruit plants are successfully frame worked by stub, awl and inverted ‘L’ method of grafting.
viii. Wind breaks and fencing
Wind breaks are necessary for reducing the force and adverse effects of winds. The most effective are the double rows of tall trees, alternatively placed. Trees like sheesham, carambola, jamun, samal, paper mulberry and Terminalis arjuna can be effectively used for this purpose. Orchard area should be fenced with barbed wire along with suitable protective and economical hedge.
When not to rejuvenate
Before an attempt is made to rejuvenate the trees, the future income from the orchard should be taken into consideration. Sometimes it might be that the condition of the orchard is so poor that it is better to remove the old plantation and replace it by new one. It should be emphasized finally that trees during their first bearing years are not in need of re-invigoration even if they might be uneconomic. Satisfactory growth should be maintained by other cultural practices such as proper soil management, provision of adequate fertilizers and a water supply.
REJUVENATION OF OLD MANGO ORCHARD
Glimpse of a Mango Orchard
In mango, 40-45 years old trees exhibit decline in fruit yield because of dense and overcrowded canopy. These trees do not get proper sunlight resulting in decreased production of shoots. New emerging shoots are weak and are unsuitable for flowering and fruiting. The population of insect-pests and the incidence of diseases increased in such orchards. These unproductive trees can be converted into productive ones by pruning them. Intermingled, diseased and dead branches are removed. Thereafter, undesirable branches of unproductive trees are marked. At the end of December, these marked branches are beheaded at 1.5 to 2.0 meter from distal end and the cut portions are pasted with copper oxychloride solution. During March-April, a number of new shoots emerged around the cut portions of the pruned branches. Only 8 to 10 healthy and outward growing shoots are retained at proper distance so that a good frame-work is developed in the following years. These rejuvenated trees are fertilized with 2.5 kg urea, 3.0 kg single superphosphate and 1.5 kg M.O.P. per plant. The half dose of fertilizers is applied in the month of February and the other half at the end of June. The plants are irrigated at an interval of 15 days especially in the months of April, May and June for healthy growth of new shoots. In the first week of July, 150 kg of compost per tree is also applied. Unwanted emerging new shoots are regularly removed to maintain the tree canopy. It also helps in getting proper nourishment to retained shoots. After two years of pruning new shoots come into bearing and the yield of fruit increases gradually. Thus, old and unproductive trees are converted in to productive ones.
REJUVENATION OF OLD/UNPRODUCTIVE GUAVA ORCHARDS
Glimpse of a Guava Orchard
A procedure to rejuvenate and restore the production potential of old unproductive and wilt affected orchards has been developed, which employs pruning of branches at different periodicity and at different severities. Crowding and encroachment of guava trees with subsequent inefficient light utilization is an obvious problem with older orchards, if trees are not well managed. The internal bearing capacity of guava trees also decreases with time, due to overshadowing of internal bearing wood.
Rejuvenated Guava Orchard
The rejuvenation technology involves cutting of exhausted trees (showing marked decline in annual production) to the extent of 1.0 to 1.5 metre height above the ground level during May with the objective of facilitating new shoots. The newly emerging shoots are allowed to grow up to a length of about 40 to 50cm which could be attained in 4-5 months of pruning.
These shoots are further pruned out to about 50% of its total length in October to facilitate emergence of multiple shoots below the pruning point. Profusely emerging shoots in the inner canopy are also pruned out to promote branching. The multiple shoots developed as a result of October pruning are capable of producing flower buds for the rainy season crop.
Those farmers keen to harvest the rainy season crop can allow the shoots to bear buds and fruits. However, as the winter crop has more marketing edge and value due to quality with the onset of rainy crop, shoot pruning (50 per cent) is done again in May. This procedure of sequential and periodic pruning is continued every year for proper shaping of tree canopy and to ensure enhanced production of quality fruits during winter season.
Dr. Rakesh Sharma and Dr. Parshant Bakshi
Assistant Professors (Fruit Science), SKUAST-Jammu
Sher-e-Kashmir University of Agricultural Sciences & Technology-Jammu