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Training and pruning are important operations. Both the operations form an indispensable process having direct bearing on growth and vigour of plants and yield and quality of fruits. A properly trained and pruned plant sustain heavy crop load and produce bounteous harvest of quality.
Training refers to the judicious removal of plant part / parts to develop proper shape of a plant capable of bearing a heavy crop load whereas pruning is defined as the judicious removal of plant parts like root, leaf, flower, fruit etc.to obtain a good and qualitative yield. Thus, it can be conceived that the training is related to shape and size of plants where as pruning is related with harvesting better yield and more so harvesting fruits of quality. Both the operations of training and pruning work together in maintaining shape and size of tree and harvesting desirable yield. Training is a treatment given to the young plants to get a suitable or desirable shape with strong framework. It may or may not involve pruning. Pruning is the removal of unwanted, surplus annual growth; dead, dried and diseased wood of the plants is called Pruning.
TRAINING
Before actually discussing the subject of training, it is necessary to understand the various terms used to make the subject more intelligible. Trunk: The main stem of the plant. Head: The point on the trunk from which first branches arise. Scaffold branches: The main branches arising from the head are known as scaffold branches. Trees in which scaffold branches arise with in 60-70cm height from the ground level are called low head trees and those in which they come out from the trunk above 120cm are called high head trees. Crotch: The angle made by the scaffold limb to the trunk or the secondary branch to the scaffold limb is called crotch. Leader: The main stem growing from ground level up to the tip dominating all other branches is called leader. Water shoot: A vigorous growing unbranched shoot arising on any branch or leader is called water shoot. Water sucker: The growth appearing on rootstock portion is called water sucker. The reasons for training fruit trees, ornamental trees, shrubs etc. are:
- There are no. of plants, which grow wild and don‘t bear if they are left to themselves and will not have any symmetry in their growth.
- Most of the time, the unpruned trees put forth vegetative growth only. Hence, bearing will be delayed.
- When plants are grown in rows at close spacing, they grow tall and occupy interspaces, making intercultural operations difficult to practice.
- For want of sunlight, the lower branches wither and die. The shaded fruits (apple, citrus etc.) fail to develop colour.
- Untrained trees will generally be less productive because of excessive vegetative growth for most of the time.
It is necessary to pay attention to the training of a plant during the first few years when it is young. In this period, its permanent framework is built up as decided upon by the grower. The main objectives to be kept in view in training the fruit trees are:
F 0D 8 To facilitate orchard cultural operations. F 0D 8 To provide an attractive appearance. F 0D 8 To admit more light and air to the centre of the tree and to expose
maximum leaf surface to the sun F 0A 7 for increasing production F 0A 7 for complete colour development F 0D 8 To protect the tree trunk from sunburn injury. F 0D 8 To secure a balanced distribution of fruit bearing parts on the main limbs of
the plant. Most deciduous and evergreen woody trees are best trained to a single stem with a low head. In case of pomegranate, custard apple and fig it would be better to train two or three stem plant and remove the other stems that may grow later.
In the tropical climate, the high-headed trees are unsuitable as their exposed trunks are subject to sunscald in summer. Low headed trees are common all over the world. In such trees the heads or crown is kept so low on the trunk that there is only a distance of 60-- 90cm (2—3 ft.) between the ground and the lowest branch. Such low headed trees come in to bearing comparatively much earlier, are able to resist stormy winds more effectively and their spraying and harvesting also become easy.
The formation of the main frame work of the tree is the most important part of the
training.
- Usually, two to four main branches are encouraged. These should be allowed to arise from different directions and also at some distance from one another, so as to form a well-balanced head.
- The frame work is greatly strengthened, if the branches are spaced at about 15cm distance with medium crotches (40—500)
- If two or more branches of equal size are allowed to arise from one place, they form a bad crotch and often split from their common joint.
The most important systems of training followed in most of the fruit crops are:
Central Leader system:
F 0D 8 In this system of training, the main stem of the plant is allowed to grow
only up to a certain height by beheading it in the young stage ie.within an year of planting and inducing all the subsequent vegetative growth by lateral branches F 0D 8 This results in the low head in which the bulk of the crop is borne closer to
the ground than in case of central leader tree.
Merits and demerits:
- It allows more light to reach all parts of the tree which is helpful (a) for better colour development of the fruit (b) fruiting area is spread all over the area of the trees.
- Trees become low headed. So, pruning, spraying, harvesting etc., are facilitated.
- The branches form weak and narrow crotches, which may frequently break under severe stress and strain such as bearing of heavy crop and strong winds.
- Sun scalding of central leader is also possible.
- The branches form very close to each other all most from the same spot.
- In this system the plants take a ‗‘bowl or vase‘‘ shape, which provides a good base for setting of frost. So this system is not suitable for high altitude areas where frost observance is common. Since the main axis is removed, it leaves the centre open and hence open centre and the tree looks like a vase (bowl), hence it is other wise called as vase system. This system of training is practiced in plums and peaches. Modified Leader system:
crotches.
PRUNING
Pruning may be defined as the removal of any excess or undesirable branches,
severity, changes the nutritive conditions with in the tree and consequently, limits or encourages fruit bud formation. Reasons for pruning
F 0D 8 There always seems to be surplus branches on a tree. But only those, which
are useful to the plant in holding up the leaves to the sun to grow strong. Those which will have little chance of doing so, because of shade or other reasons become weak and eventually dry up. Evidently the plant is making a selection and eliminating the useless branches. But this process of selection and elimination is a slow one. Till they are eliminated the useless branches also draw some nutrients which is a waste for the tree ultimately. If such branches are recognized and eliminated earlier will help in conservation of food in the tree for better production. F 0D 8 The second reason for pruning will be the removal of diseased twigs to
check the spread of diseases F 0D 8 In some fruit trees, fruits are borne on current flush (Ber, Grape etc.) which
will be obtained in large number after pruning of certain no. of old branches.
Objectives of Pruning:
- To remove the surplus branches and direct the sap flow in to the remaining branches.
- To develop a strong frame work which can carry the load of a good crop and can with stand strong winds.
- To train the plants to a definite shape. Ex. Fence, Hedge, Topiary etc.
- To thin out branches so as to admit more light into the interior of the tree top so that the inner wood also becomes fruitful.
- To limit the size of the tree top to a convenient one so as to render spraying and picking more easy and economically.
- To regulate the spacing and distribution / direction of branches.
- To distribute the fruiting wood in all directions and to maintain a balance between vegetative and reproductive phases.
- To improve the growth of the spur (A short lateral branch one inch or less in length with nodes close together, so that the leaves converge to form a rosette ) shoots and production of more flower buds.
- To check the further spread of the diseases.
- To maintain the vigour of the plant by removing the water shoots and other unwanted growth.
is reduced, their length is also reduced. Therefore, the net effect of pruning a tree is dwarfing, which is in proportion to the severity of pruning. Both the spread of the top as well as the spread of the root system are reduced. This also results in dwarfing of the plant.
- Production of water shoots: Severe pruning often activates resting or adventitious buds and buds on old wood may some time be stimulated to grow. They often produce branches, which grow vertically and very vigorously with long internodes; angular stems large succulent leaves and thorns (as in citrus). They are called water shoots or water suckers or bull canes. These highly vegetative water shoots are seldom fruitful till they are several seasons old. They are wasteful and unwanted because they draw much food and grow at the expense of the fruiting wood and are better removed as soon as they appear. However, they may be profitably used in some instances to fill in the gaps occurring in trees by lopsided development or loss of branches due to other causes. Eg.Citrus,Guava,Ber,Sapota,cashew etc.
- Delay in bearing: When pruning is severe particularly in early years of the fruit plant, bearing is delayed. Some times severe pruning may also lead to poor yields, because a major portion of the foliage and fruiting wood are lost.
Methods of pruning
- Thinning out: When a shoot is removed entirely from the inception (from the point of origin) so that, no new shoot arises from that place, it is referred as thinning out. This thinning is practiced in the removal of shoots arising in unwanted places, water shoots etc.
- Trimming: Cutting the growth of the twigs to a pre-determined level as in the case of fence, hedge and edge.
- Heading back: When the branches grow tall and vigorously without producing flowers, these shoots are headed back. When a branch is cut almost to the base, leaving a few inches of stump, carrying few buds, it is referred as Heading Back. These buds left on the stump will give rise to shoots which are important to the tree either being spur bearers or bearing flower buds or filling up of gaps in the tree or forming vegetative wood from which flowers may arise in the following year. The shoot from the bud nearest to the cut takes the place of the pruned shoot.
- Pollarding: Mere cutting back of the shoots, indiscriminately to reduce the height of the tree is Pollarding.
- Pinching (tipping): Removal of the tip of the shoot to stop its indeterminate growth or to encourage the growth of the lateral buds is pinching or tipping. This is practiced in marigold and chillies at the time of transplanting.
- Disbudding (nipping or rubbing): Nipping or rubbing of young buds preventing a chance of their sprouting is disbudding. When the buds arise in wrong places they are rubbed off. Similarly sprouts (Buds) on root stocks are disbudded.
- Summer pruning of deciduous trees and also the pruning of evergreens in the active growing season delays the formation of flower buds by prolonging vegetative growth. Pruning and Manuring The sudden invigoration of a number of buds due to pruning makes a demand on the food resource of the tree, because the new shoots are not yet ready to manufacture their own food. The reserve food in the plant often may not be sufficient to meet this demand of new growth. Further, pruning means loss of much foliage and wood. So, to compensate the loss incurred due to pruning and to meet the demand of new shoots the pruned trees should be manured heavily, otherwise the new shoots ultimately wither and dry. This is particularly important when old (Senile) or neglected trees are pruned for rejuvenation. Care of pruned wounds
Pruning leaves wounds and cut ends which should be protected to avoid the access of disease pathogens and insect pests through these wounds and cut ends .So, immediately after pruning, these cut ends and wounds should be protected by applying disinfectants like Bordeaux paste or blitox paste.
Unfruitfulness in fruit trees – Causes and remedies
