Mango suffers from the following types of physiological disorders:
Disorder # 1. Mango Malformation:
This disorder was first noticed in the Indian sub-continent towards the end of the last century. It is of wide occurrence in Punjab, Delhi and Uttar Pradesh. Its incidence is also noticed to some extent in Bihar, Paschim Bangal and Odisha.
The intensity of this disorder varies from year to year and variety to variety, the highest being in the varieties of Chausa and Bombay Green that is upto 90%. The only variety known to be free from floral malformation is Bhadauran which, on the other hand, is very inferior in fruit size and fruit quality.
Mango malformation is of two types, viz. vegetative malformation and floral or inflorescence malformation.
The complexity of the disorder is attributed to a set of factors including pathological, viral, nutritional and physiological aspects. During the 60%, the association of fungus (Fusarium monoliniformae) with malformation was reported. Later, emphasis on the role of mite Aceria mangiferae) as a carrier was laid.
Diseased tissues be pruned (removal of malformed terminals along with the basal 15-20 cm apparently healthy portion).
The most effective control measure is the spray of 200 ppm of NAA (Naphthalene Acetic Acid) in the month of October followed by deblossoming at bud burst stage can bring down the malady to a great extent.
Disorder # 2. Irregular Bearing in Mango:
This is one of the most burning problems of mango cultivation as it renders mango cultivation less remunerative to growers.
Cultivars like Totapari Red small, Neelum, Bangalore and Rataul do not show acute tendency of biennial or irregular bearing, but these varieties are grown only in Southern India and do not have superior fruit quality like that of North Indian varieties.
Some varieties like Langra, Bombay and Dashehari have a stronger tendency, which is very difficult to control, while others like Himsagar and Safadar Pasand are less alternate bearing.
The problem of biennial bearing has been studied in great depth by a number of workers during the last four decades. Several aspects like climatological factors, age and size of shoots, C/N (carbohydrate/nitrogen) ratio and hormonal balance have been studied.
The safest way to overcome or avoid the losses of biennial bearing in mango is to cultivate regular bearing varieties like Amrapali, Mallika, Manjirn, etc.
This disorder can be checked by the most appropriate spray of potash and NAA in the form of 200 ppm.
Disorder # 3. Black Tip of Mango:
This malady is widely prevalent in Punjab, UP, Bihar and Paschim Bangal and Odisha. It causes considerable economic set back to the mango growers.
Among the commercial cultivars, Dashehari is the most susceptible to this disorder, while Lucknow Safeda is the least.
Fruits are affected at the marble stage with a characteristic yellowing of tissues at the distal end. Gradually the colour intensifies into brown and finally black. At this stage, further development is retarded and the black spot at the tip gradually extends towards the upper part of the fruit. Such fruits prematurely drop off and become unmarketable.
Possibly, gases like carbon dioxide, sulphur dioxide and acetylene, which constitute the brick kiln fume are responsible. Affected fruits are also deficient in boron.
The disorder can be avoided by allowing brick kiln only at a distance of 1.6 km or 1 mile in the east and West and 0.8 km in the North and South of the orchard, taking into consideration the usual wind direction during the fruiting season.
The chimney height should also be increased to at least 15-18 m to minimise the damaging effects of the smoke in the orchard.
Disorder # 4. Internal Necrosis of Mango:
This disorder is quite distinct from that of black tip in mango. This disease is caused by boron deficiency.
This disorder can be corrected by soil or foliar application of boron. For soil application, Borax at 500 g/tree should be incorporated at the time of October fertilisation.
Disorder # 5. Leaf Scorch in Mango:
This disorder is caused by an excess of chloride ions which render potash unavailable. This disorder is more common in saline soils or where brackish water is available for irrigation or where muriate of potash is used as a fertiliser to meet the potash requirement of the plants.
This disorder can be checked effectively by collecting and burning the fallen leaves and using potassium sulphate instead of muriate of potash.
Disorder # 6. Spongy Tissue:
This is also called internal break down or soft centre. Generally, occurring in the fruits of Alphonso variety of mango.
In Alphonso, it is observed to all extent of as high as 30%. Other varieties are quite free from this disorder. This disorder has adversely affected the cultivation of mango in Maharashtra where Alphonso is prominently grown.
Apparently normal and attractive fruits, on cutting, show spongy developments in the flesh. The break down portion (tissues) is characterised by its pale yellow colour, soft and spongy, with or without off-flavour.
This disorder is often described as soft centre, white corky tissue or internal breakdown in Alphonso Mango.
Disorder # 7. Fruit Drop in Mango:
Fruit drop in mango is a continuous process amounting to about 99%, at various stages of growth. Of the commercial varieties, Langra is more prone to the disorders, while Dashehari.
The least in mango, only about 0.1% of tile perfect flowers develop fruits to maturity. The extent of fruit drop in mango varies from variety to variety and region to region.
Fruit drop in mango can be classified into three distinct phases:
i. Pin head drop
ii. Post setting drop
iii. May drop
Fruits dropping in the month of May when they attain considerable size decide the crop at harvest. Fruit drop is a complex problem involving several factors.
The extent of fruit drop in mango can be significantly reduced by regular irrigations during fruit development period.
Growth regulators like NAA (Naphthalene Acetic Acid) and 2, 4-D (2, 4-Dichlororphenoxy acetic acid) in varying concentration depending upon the variety and time of application can be sprayed. The optimum concentration lies between 10 and 15 ppm during the month of April-May.