Mango: Physiological Disorders and Management

MANGO

Introduction

Scientific name: Mangifera indica

Family: Anacardiaceae

Origin: India, Bangladesh, Myanmar

Mode of pollination: Cross-pollination

Pollinator: Housefly

Fruit: Drupe

Climate and Soil

  • Tropical fruit can be grown up to 1100masl. Best grown up to 500m.
  • Ideal temperature: 24-27 degree centigrade.
  • Bright sunny days and moderate humidity required.
  • High humidity during fruiting period causes powdery mildew and anthracnose.
  • Can grow from Alluvial to Lateritic soil, except Black Cotton soil. pH: 5.5 -7.5

Varieties

Very early varieties: Bangalora, Banganpalli

Early varieties: Bombay green, Bombay yellow, Himsagar, Kesar, Swarnarekha

Mid-season varieties: Krishnabhog, Alphonso, Langra, Zardalu, Dashehari

Late varieties: Neelum, Amrapali, Kaitki, Fajri, Mulgoa, Samarbahisth chausa

Fibrous varieties: Sukul, Baramasia

Fibreless varieties: Langra, Dashehari, Zardalu, Ranipasand

Moderately fibrous varieties: Fazli, Sipia

Regular bearing varieties: Amrapali, Neelum, Bangalora, Mallika

Planting

  • During Rainy season (August-September; at evening).
  • Pit dimension: 1m3 pits
  • Spacing: 8× 10m (HDP in Amrapali 2.5m * 2.5 m)

Flowering and fruiting

Flowering:  February- March

  • Generally, 8-10 months old shoots produced in spring and early summer produce flowers.
  • Mango tree produces blossoms and bears fruits mostly from terminal buds of its shoots.
  • Duration of flowering is 25 days
  • Normally 99% hermaphrodite flowers drop.
  • 15% of perfect flowers set fruit among which only 0.1- 0.25 % reaches maturity.

Problems and Physiological Disorders in Mango

  1. Fruit Drop

Natural drop of hermaphrodite flowers and young shoots are high accounting about 99% or more in Mango. Only 13-23% of the perfect flowers set fruit and only 0.1-0.25% reaches maturity. There are three different phases of fruit drop:

  1. Pin-head drop:

Causes:

  • Lack of pollination.
  • Low stigmatic receptivity.
  • Defective perfect flowers having defective embryo sac development at anthesis.
  • Poor pollen transference due to insufficient pollination agents and due to rain or high humidity and cloudy weather.
  1. Post-setting drop:

Causes:

  • Competition among developing fruitlets for nutrition.
  • Hormonal imbalance (deficiency of Auxin, GA, and Cytokinin coupled with a high level of inhibitors).
  1. May drop:

Causes:

  • Drought or lack of available soil moisture.
  • Unfavorable climatic conditions during fruit development, e.g., wind and hailstorm.
  • High incidence of serious diseases like Powdery Mildew and Anthracnose and pests like Hoppers and Mealy-bug.

              Control of Fruit Drop:

  • Timely control of insect pests and diseases.
  • Cross pollination of varieties must be assured by avoiding isolated planting of the single varieties.
  • Regular irrigation during fruit development period.
  • Application of PGR like NAA, 2,4-D, 2,4,5-T, GA3 @ 20ppm in last week of April and plant nutrients like Urea and Borax.
  1. Black Tip:
    • It is due to gases and coal fumes of brick kilns. The effect has been noticed up to 212m away from kilns.
    • It is characterized by the appearance of depressed spot of yellowing tissue at the distal end of fruits, which gradually increase in size, becomes brown and finally black. Such fruits never reach maturity and drop earlier.

Control:

  • Spraying of 0.6% Borax; before, during and after flowering.
  • Brick kilns should be restricted preferably 1.5 km to east and west and 0.75 km to the north and south of the orchard.
  1. Scorching of Leaves:
  • Brick red color appears towards the tip, along the margin of old leaves and subsequent collapsing of these tissues.
  • It is caused due to chloride ion toxicity and it decreases the potassium level in leaves.

Control:

  • Potassium sulphate should be used instead of Potassium chloride.
  • Irrigation water having high chlorine content must be avoided.
  1. Spongy Tissue:
  • Non-edible, yellowish, spongy-like patch with or without air pockets develop in the mesocarp of the fruit. It is specific in Alfonso cultivar.
  • Fruits remain unripe because of unhydrolyzed starch due to physiological and bio-chemical disturbance caused by heat in mature fruit at pre and post-harvest stage.

Control:

  • Harvesting mango when they are 75% mature rather than fully matured, reduces this disorder.
  • Mulching to reduce moisture stress.
  • Uses of wind break.
  • Sod culture.
  1. Biennial Bearing:
  • Biennial bearing is synonymous to alternate bearing which indicates yield variation in alternate years, i.e. one year of optimum or heavy fruiting is followed by a year of little or no fruiting.
  • Sometimes, periodicity of cropping and irregular bearing are erroneously used to describe the phenomenon of alternate bearing. However, irregular bearing and periodicity of cropping does not follow a systematic pattern like biennial/alternate bearing but an optimum yield is obtained only once in a number of years.
  • The tendency of irregular bearing is due to the poor management of orchard whereas biennial bearing is governed by genetic makeup.

Causes:

  • Climatic factors:

Climatic factors do not cause basic biennial bearing but their adverse effect converts an on year into off year directly or by promoting the incidence of various diseases and pests. Similarly, frequent frost or low temperature during flowering period adversely affects the fruit set.

  • Growth pattern:

In most of the biennial bearing varieties, there will be no new growth after fruit harvest. Poor flowering in off year is the result of poor vegetative growth in the on year and the profuse flowering in the on year is the is the result of profuse vegetative growth in the off year.

  • Carbohydrate-Nitrogen ratio:

Higher C:N ratio in the shoots favors flower bud initiation in mango.

  • Hormonal control of flower initiation:

The presence of high level of growth substance like auxins, gibberellins induced more number of flowers whereas decrease in this substance reduces the percentage of the flower bud initiation. Exogenous application of GA reduces the flower bud initiation.

  • Cultural practices:

Irregularity of bearing in mango is a cultural problem which can be corrected by influencing nutritive condition and other management practices.

  • Crop load:

Generally, moderate blossoming is one of the chief conditions of annual fruit bearing in fruit tree. The biennial bearing habit can be minimized by undertaking some measures that reduces the number of fruit buds setting into fruits.

Measures to overcome:

  • De-blossoming and Thinning of fruits:

The excessive no. of flowers or fruit-lets should be thinned out before pea-size stage. The removal may be done by hand or by chemical spray (de-blossoming with 3-chloroisopropyl-N-phenyl carbonate @ 250-300 ppm).

  • Pruning:

It is performed for the removal of old shoots and diseased portion of branches to facilitate normal vegetative growth and stimulation of flowering buds.

  • Cultural practices:

Planting wind break, regular ploughing, optimum manuring at appropriate time, ringing and adequate irrigation helps to overcome biennial bearing.

  • Smudging:

Creation of gaseous atmosphere around orchard may also be helpful for flower initiation.

  • Uses of PGR:

Spray of NAA, 2,4,5-T and Ethrel (200 ppm) favor flower initiation.

  • Uses of regular bearing varieties:

Mallika, Amrapali, Neelam, Bangalora, Red small etc.