Management of Non Bearing Mango Trees (Part 2 of 4)
Management of Non Bearing Mango Trees
After plants are established in the orchard, those are managed in such a way to maximize the tree growth and to get a good tree framework with well spaced spreading branches and open center canopy to support heavy yields expected under good management . Plants are supposed to bear fruits 3 – 4 years after planting. Therefore, non bearing tree management system is followed until trees bear after third or fourth year. Then the management system should be carefully switched on to that for bearing trees.
It may be observed that flowers are produced and fruits set even during the first year of growth. All the flowers must be removed until 3rd or 4th year to allow the plants to get a good growth before trees are ready to bear full crops.
Various aspects of non bearing tree management practices are discussed below. These practices may have to be worked out differently depending on agro-ecological region, variety and soil type etc. However, the discussion will be centered on the general principles that should be considered in performing each and every practice.
Young trees must be frequently irrigated until the plants are well established in the field. Thereafter, up to about 3 – 4 years plants must be regularly irrigated as determined by soil moisture status. During vegetative growth period, every effort sh ould be made to provide plants with sufficient water. For use as an estimate in calculation of water requirements and as a general guideline for irrigation frequency, it may be safely say the water requirement of young plants as 75 mm over the root zone for every 3 weeks. However, the quantity and frequency may have to be modified depending on the soil type and climatic conditions. Sandy soils will have to be irrigated more frequently than the clayey soils. Irrigation frequency may be adjusted according to rainfall and ET during each season.
In relation to water quality for irrigation, mangoes are classified as having a medium tolerance to poor water quality. Problems come up if water having EC of over 2000 m cm-1 or water with chloride ion content of 800 mg/L or more are used.
The recommended fertilizer mixture for non bearing mango trees have a higher N content than that recommended for bearing trees. This is because plant need more N at young stage to promote tree growth. DOA recommends 16-20-12 mixture for Dry and Interm ediate Zones and 12-14-14 for Wet Zone. In wet zone mixture, as the phosphorus source less expensive rock phosphate is used instead of Concentrated Supper Phosphate (CSP).
Fertilizer requirements for plants increase annually. It is always better to split the annual quantity as far as possible and this is very important under sandy soil conditions. Also fertilizer dose for the rainy months in the Dry Zone should be appli ed after the peak high intensity rains are over to minimize leaching losses of nutrients.
Fertilizers can be placed as a band spread approximately 30 cm from the base of the plants and should be incorporated to the soil mechanically without severely disturbing the roots. Irrigation is necessary afterpecially N if urea is used in the fertil izer mixture. Soil incorporation is not necessary if under tree sprinklers are used for irrigation of trees. Then fertilizers can be effectively incorporated by irrigation.
Weeds should be completely removed from the root zone as it competes and tap water and nutrients applied to plants. Use of cultivation tools are not recommended as it disturbs the soil and damage active roots. Use of systemic herbicides and a heavy mu lch may satisfactorily control weeds with out disturbing the roots. If this is not possible it is better to mow down the weeds rather than doing clean weeding around the base of trees.
Weeds in between plants and between raws may be mowed down mechanically using a tractor mounted mower, a hand operated grass mover or by manual slashing. Weed lopping may be used as mulches around the trees.
When chemical weed killers are used, it is better to use systemic herbicides to control weeds around the trees. Also this may be useful to control other noxious weeds such as Illuk, Kalanduru and Mana grass elsewhere in the orchard since these weeds c reate lot of problems in orchard management. When weed killers are used polyget nozzles should be used to enhance the efficiency of chemicals. Care should be taken to avoid direct contact of chemicals with the green tissues of plants. Always use chemical s on actively growing weeds. If weeds are dried, mow the weeds before a rain and apply chemicals when weeds are in an active growth stage to maximize the efficiency of chemicals and for effective weed control.
Mulching the trees is an important and very rewarding practice. Mulches are effective in conserving soil moisture, root zone temperature control, weed control, and erosion control. As mulching materials most organic plant materials can be used but har d to decay materials with high C:N ratios are better to use. Materials like rice straw, rice husk, dried weed lopping, saw dust etc. may be used for mulching purposes. Some materials like fresh coir dust may be harmful as the leachates from these materia ls may interfere with tree growth.
When mulches are used, care should be taken to inspect trees regularly for any termite activity and take control measures. Termite activity may be increased with mulch application. In the dry zone, care should be taken to prevent trees from fire damag e during the dry season.
Plants should be pruned early to allow development of a strong open frame. Remove top to force 3 – 4 side branches about 60 – 90 cm above the ground. Thereafter, when the side branches are ready to prune, remove top of those branches to force further multiple shoots to get a spreading growth habit. To train branches as spreading limbs, staking may also be useful. By pruning this way, plants must be trained to have an open, well spaced and spread canopy.
This pruning and training process must be a continuous activity. All this can not be done in a single pruning or two. Therefore, growers must regularly visit the plants and prune them as an when necessary. Also pruning must be commenced when the plant s are well established after transplanting, but before any major growth has been started.
Plants should be regularly inspected for any build up of pests or diseases and appropriate control measures are taken. Usually mango has very less pests and disease problems at young stage. Termites, leaf eating caterpillars or leaf cutters, mango tip borers and mango webbers may be found damaging plants. Anthracnose may be a problem sometimes on developing flushes. Plant protection specialists may help in identifying pest and disease problems and in recommending appropriate control measures.