Rejuvenation of Mango Orchard
One of the main handicaps that have led to slow pace of evolution of the mango industry in India is the preponderance of seedling trees which are mostly of inferior type seedling plantations of “desi” mango varieties, the fruit of which is essentially “sucked out” rather than “eaten”, are still found in the countryside, where no commercial cultivars are grown. Mango is a huge tree: a single tree growing in the open can occupy up to an acre of land. It can bear fruit for 60 years. The yield may vary from a few kilograms to a ton, depending on the age and bearing capacity of the tree. There are reports that nearly 30-35% seedling mango trees, which had been bearing good crop of high-quality mangoes for juice and pickle, are old and unproductive and waiting for uprooting and sale for wood across the region. Manuring of such orchards is rare. Thus due to bad sanitation the trees are generally affected by mango hopper, stem borer, shoot borer, die- back, gummosis, powdery mildew, black tip and mango malformation. Besides, the trees are erratic in their bearing habit and the fruits produced are mostly of inferior quality, fetching little price in the market. Because of their large stature, it is difficult to apply insecticidal and fungicidal sprays. Thus such plantings are more a liability than an asset. The commercial plantations of grafted mango trees that have grown old and are not bearing good crop are also being replaced with new plantations. Planting of new orchard may involve a cost of Rs. 80-90 thousand per ha. Uprooting of inferior seedling trees and other low or non-bearing mango trees below 20 years can conveniently be top- worked with scion woods of commercial varieties. The process provides fuel wood worth of Rs.40-50 thousand and orchard space may be use for inter crops. The process of top working or rejuvenation includes removal of old twigs and restoration of new shoots, propagation of desired variety on theses newly emerged shoots. The process may take 2-3 years to be effective.
The process can be started in the month of December -January. Select unproductive orchard, mark the branches behead them keeping 30cm stubs on 3-6 major limbs. A clean cut should be given to the limbs with a sharp saw to avoid bark splitting. Start beheading from base to the top. Paste cow dung slurry or copper oxichloride paste (dissolve 2 kg of copper sulphate in 15 litres of water; mix 3 kg of quick lime in 2-3 litres of water and then add the remaining 12-13 litres of water; mix the two concentrated solutions)on cut portion. If the old trees are infected with fungi, do not behead the limbs since the stubs may not sprout. Several sprouts will come up on these stubs. Plough the orchard and prepare it for inter crops. Make basins below the plants. Irrigate the plant and apply 1 kg urea per tree. Control stem borer if it has appeared. Remove weeks sprouts, control foliage feeding insect pests and grow summer season inter crop. Take proper care of inter crop and sprouts. Select the best one or two sprouts on each stub and graft them with the desired cultivar. Remove the rest of the sprouts gently by giving a clean cut close to the stub so that these may not re-sprout. If any of these shoots are left they will overpower the newly sprouted grafts. This way one will have 6-12 grafted shoots. These grafts sprout within 20 days of grafting. The shoot above the sprouted graft should be headed back by keeping only one whorl of old leaves in November. These leaves provide food to the newly sprouted graft. Newly sprouted grafts should be covered with rice trash or plastic bags to save the grafts from frost or severe winters in December. The covers may be removed in February-March. While removing the covers, the polythene sheet used for tying the graft union should also be gently removed. The old sprout above the graft union should also be re-cut, keeping only the newly sprouted grafts. Care should be taken that grafts should not get damaged since these cannot tolerate even small pressure. For at least two years take care that no sprout should come up on the tree limbs other than the grafted shoots. Top-worked trees come into bearing within five years, depending upon the grafted cultivar. The old superior mango trees (dusehri-langra, etc) can also be rejuvenated similarly. If the tree is older, it is better not to head back all the main branches simultaneously, to avoid a sudden shock to the tree, which could result in the splitting of the bark of the main stem. The tree can be converted into a commercial variety in stages. In the rejuvenated trees, select 6-12 outgrowing sprouts on the 3-6 stubs during June. Remove the rest of the sprouts. These selected shoots grow very fast. During August, the apex of the shoots may be pinched to check the fast growth. This will also help in the development of side branches. The main trunk of this tree should be wrapped with hessian cloth or gunny bag during winter to avoid bark splitting. The land rendered open to sun after top-working can be utilised for growing crops till the trees come into bearing. With rejuvenation, the benefit of an established root system of the trees can be utilized profitably. These trees can bear a good crop for a number of years once more.
Economic impact: The decision to radically prune a tree should be studied carefully from a financial point of view. Will the expected increase in harvest value more than offset the lost harvest value? Naturally, there will be a significant drop in mango production with the radical pruning to reduce the height of the tree as cutting back large limbs to reduce tree size is always risky with mangoes as one may lose two or more years’ production, depending on the amount cut back. Some of the value of this lost production will be recaptured through the sale of the wood cut from the tree However, if the timing is right, flowers can develop on even large branches which have been cut back. This production will be lost while the tree re-grows enough branches to produce the quantity of mangos lost due to the radical pruning. Pruned tree produce several times more mangos than the un-pruned tree because it will have more branches capable of producing mango. Additionally, some lost harvest value may be recaptured through pruning practices applied to the re-grown tree to manipulate harvest times to capture higher priced markets.