Mango Physiological Disorders A

Lecture To ToT trainees ( FFS) By

Mr. Allah Dad Khan Provincial Coordinator IPM

KPK MINFAL Pakistan

MANGO Black tip

• Coal fumes of brick kilns containing sulphur dioxide, ethylene and carbon monoxide are

• observed to be responsible for black tip. The damage has been noticed in the mango orchards

• located up to 200metres of distance from brick kiln. It is characterised by depressed spots of

Spongy tissue in fruit

• A non edible sour patch developed in the mesocarp of mango fruit is broadly termed • spongy tissue. The malady has been reported only in Alphonso. The peculiarity of this malady is • that external symptoms of the fruit affected by spongy tissue are not apparent at the time of • picking or at the ripe stage. These can be detected only on cutting the ripe fruit. This malady • renders the fruit unfit for human consumption. It is a physiological disorder in which fruit pulp • remains unripe because of unhydrolyzed starch due to physiological and biochemical • disturbances caused by heat in mature fruit at pre-and post-harvest stages. Single and double pre-

harvest dip of fruits in calcium solution significantly increased the calcium content in the ripe • fruits, whereas there was no significant increase in calcium content by post harvest Ca dip • treatment. The pre harvest dip significantly reduced the occurrence of spongy tissue in the ripe • ‘Alphonso’ fruits. The use of wind-breaks for protecting the orchard from warm air during May, • and use of proper precautions at post-harvest stage checks the disorder.

Malformation

• Among all the known diseases and insect pests of mango, malformation is undoubtedly

• the most serious. Depending on the plant part affected, two categories of the malformation,

• vegetative and floral, have been recognized. In vegetative malformation, the vegetative buds in

• the leaf axils or at the apical meristem of the younger plants, on activation, develop abnormally

• as compact rosette-like shootlets, bearing tiny leaf rudiments. Many such shoots may arise to

• form a bunch, hence it is also sometimes known as bunchy top. The problem is not serious in the

• grown-up trees. The affected new shoots on the old trees, however, become thick, stunted, and

• develop a whorl of small leaves. Floral malformation, in contrast, is very virulent and

• Fruit drop • In mango, there is a heavy drop of

hermaphrodite flowers and young fruits amounting to

• 99% or more. In general, in mango 0.1% or less hermaphrodite flowers develop fruits to

• maturity. The maximum drop of fruits in ‘Langra’ and ‘Dashehari’ takes place in the first three

• weeks of April and differs significantly from the drops in the following weeks. Fruit drop is to

• some extent associated with the variety, as the variety ‘Langra’ is more prone to fruit drop than

• ‘Dashehari’. Deficient nutrition of many developing embryos

• may be the most important internal • factor leading to post-fertilization drop in

mango. This results due to competition among over-crowded fruitlets on panicle. Degeneration of the embryo in the initial stages of its development

• may yet be another cause of drop. This occurs invariably, if the flowers are self-pollinated. 2,4-D

• produced better results at concentrations below 20ppm, because at higher concentrations fruit

• and seed development is retarded. Single spray of NAA or 2,4-D each at 20ppm or Alar 100ppm

• at pea stage of fruit gives promising results.

NitrogenDeficiency

Symptoms :

•Yellow undersized leaves, severe retardation of growth, twigs become yellow in color. Fruits smaller and mature early. Leaves small with general yellowing

• Correction Measure :Application of recommended nitrogenous fertilizers (80 kg N/ha) or foliar application of Urea 2-4% at fortnightly intervals

Phosphorus

Deficiency Symptoms :

• Retarded growth premature dropping of older leaves partial die-back from the tip small green younger leaves are borne at the tips of the branches. Some branches show die back. Leaf tip necrosis and premature abscission of leaves.

• Correction Measure :• Soil application of single super

phosphate or foliar application of ortho phosphoric acid 0.5 %thrice.

•

Potassium

Deficiency Symptoms :

• Darkening of leaves, reduced growth and vigour. Appearance of white, yellow or orange chlorotic spots in older leaves and distributed irregularly over both under and upper leaf surfaces. Necrotic areas develop along the leaf margins. Poor growth of roots. Die back with tip burn with small leaves.

• Correction Measure :• Foliar spray of KCl 2% at fortnightly

intervals.• •

Calcium

Deficiency Symptoms :

• Abnormal growth of young leaves and growing points resembling boron deficiency severe deficiency leads to death of the bud.

• Correction Measure :• Application of gypsum at 50

kg/ha.•

Magnesium

Deficiency Symptoms :

• Reduction in growth premature defoliation yellowish brown chlorosis featured by a green wedge down the central part of the leaf bronzing starting from the edge of the leaf rounded margin between each pair of lateral veins.

• Correction Measure :• Soil application of MgSO4 5-10

kg/ha a foliar spray of MgSO4 2% at fortnightly intervals.

•

Sulphur

Deficiency Symptoms :

• Symptoms first appear on young leaves with fading of green colour. Growth is stunted. Leaf tip remains green and with severe deficiency the whole leaf turns yellow.

• Correction Measure :• Soil application of sulphur

fertilizer•

Boron

Deficiency Symptoms :

• Deficiency is common in high rain fall areas, high temperature, soil acidity and calcareous soils. Fruits become brown in colour. Flesh may become soft and watery which cracks down to the centre.

• Correction Measure :• Application of 5-10 kg Borax / ha a

foliar spray of 0.25% Borax at 10 days interval or solubor at 300 gm/ 100litres of water.

Copper

Deficiency Symptoms :

• Shoots produced on long drooping S-shaped branches of previous growth are weak lose foliage and die back.

• Correction Measure :• Foliar spray of Copper oxy

chloride 0.2% at fortnightly intervals.

•

Manganese

Deficiency Symptoms :

• Deficiency appears on the middle of the plant. Interveinal chlorosis of leaves. Reduced growth leaf symptoms appear very late leaves show a yellowish green background with a fine network of green veins on the upper surface and disappearing after a few weeks mature leaves thicker and blunted. Specks of light grey to grayish brown colour appear under mid deficiency.

• Correction Measure :• Foliar application of MnSO4 0.2% at

fortnightly intervals.•

Zinc

Deficiency Symptoms :

• Leaf blade thickens leaf shape is distorted leaf margin up or down the tip may curve back interveinal areas leaves are usually smaller thickened leaf blade brittle spaced leaves show a rosette appearance. Some twigs die back flower panicles of trees showing little leaf symptoms are usually small irregular in shape drooping spikes.

• Correction Measure :• Soil application of ZnSO4 10 kg/ha or

foliar spray of ZnSO4 0.5% or nitrozinc at 150 ml /100litres of water.

•