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Fruit Crops

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Deficiency Symptoms Apple and Pear

Zinc deficiency of apple, commonly called 'rosette', is characterised by a dense cluster of small narrow leaves that terminate a branch which is usually leafless (Plate 1). Branch terminal are often affected first. The leaves become red & yellow in colour. Rosetting first appears on the spring growth. The trees bear less or no fruits.

Banana

Zinc deficiency checks growth of plant and in later stage chlorosis (loss of green colour) starts from leaf margins. The leaves become either entirely white or white towards the base with the rest of the blade showing chlorotic transverse strips alternating with greener bands. In severe deficiency, the fruit development is slow and the fingers are twisted, shorter, thinner and lighter green in colour than those of normal plants.

Citrus Fruits (Lemon, Orange and Kinnow)

Zinc deficiency symptoms appear gradually, only on a few leaves having small specks of yellow between the veins. Later the young leaves have irregular areas between the veins which turn yellow as the leaves mature (Plate 2). The affected leaves become entirely yellow in the case of severe deficiency but usually the irregular areas along the veins remain green. There is thus a sharp colour contrast between the veins and interveinal areas (Plate 3). The leaves also become very small and narrow, with pointed tips and the twigs may start dying back. The fruits on severely deficient trees generally have a smooth, light coloured thin rind.

Grapes

Due to zinc deficiency the growth of the vine is checked causing yellowing, drying and dropping of leaves. These symptoms are more pronounced in summer, when secondary growth starts. Upper leaves exhibit these symptoms earlier than those are other parts (Plate 4).

Mango

The leaves become smaller. At times numerous pointed leaves smaller in size emerge out. Interveinal chlorosis (loss of green colour) is very common. In acute conditions the branches start drying from the top (Plate 5). Yellow necrotic (brownish) patches develop on older leaves with drying of leaves. In some cultivars the leaves turn outwards with shrivelling in acute cases. In the nurseries, the apical portion of the young plants is affected and the plants become stunted.

Peach

Zinc deficiency causes waving, curling and yellowing (chlorosis) of leaves and margin of leaves turn upward (Plate 6). In severe cases leaves become small and rigid and defoliage start from mid portion of shoots and progresses upward. The formation of fruit buds is reduced and fruits are misshaped (small flat or elongated).

Guava

Zinc deficiency results in significant reduction in the size of leaves (small leaf) with interveinal chlorosis (loss of green colour). In acute conditions the branches start drying from the top, resulting in poor growth, less flowering and less fruiting. The fruits develop spots and cracks.

Papaya

Early effect of deficiency results in poor growth of 5 to 6 week old plants. Leaf blade size is reduced. Interveinal areas of young and middle leaves loose green colour (chlorosis). In severe deficiency flower formation is poor.

Pineapple

The first symptoms of zinc deficiency appear in the form of Iransparent spots on the young leaves which turn yellow. In severe deficiency the yellow spots become l.1lrge and brown and ultimately cause complete destruction of leaf tissues.

Amelioration Method

Zinc deficiency can be corrected by soil application of zinc sulphate by drenching method. In this method a circular trench is opened around the tree at a suitable distance depending upon the type & age of the plant. While soil application is possible in selected fruit crops, foliar application can be used for all crops. For raising nursery plants, soaking of seeds in zinc sulphate solution is also done to prevent zinc deficiency.

Soil Application Rate

The rate of zinc sulphate application in drenching method is given in the following table:

Name of Crop Radial Distance of trench Quantity of Zinc Sulphate Per Plant
Apple & Pear 50cm 100 g
Citrus fruit 60cm 200 to 250 g
Guava 60cm 200 to 225 g
Mango 200 to 240 cm 250 to 300 g


Foliar Application Rate

The concentration of zinc sulphate solution used for foliar spray in fruit crops is given in the following table:

Name of Crop Concentration Stage
Apple 0.2% In dormant stage
Banana 0.5% Repeated sprays at regular intervals
Citrus Fruits 0.5% 3 to 4 times in a year mainly during April, Julie & September
Grapes 0.1% 2 to 3 sprays in a year
Guava 0.4% 2 to 3 time during March-April and June-July.
Mango 0.2% 3 sprays in a year during March-April, June and September
Papaya 0.2% Repeated sprays at regular intervals
Pear, Peach 0.5% 2 to 3 sprays in a year
Pineapple 0.4% 2 to 3 times at the end of rainy season.

Note: For preparing 0.1% concentration solution dissolve 100 g zinc sulphate in 100 litre of water neutralized with 50 g slaked lime & filter through fine muslin cloth. The volume of Zinc Sulphate solution required for spraying shall depend upon age and size of the tree & can be approximated as follows:



Age of Tree Volume of spray solution
3 to 5 years 2 to 5 litre
6 to 10 years 6 to 10 litre
11 to 15 years 11 to 25 litre


Yield Response & Benefits

Due to zinc deficiency, as mentioned above, fruiting is adversely affected. By various experiments, the quantum of fruit loss on account of zinc deficiency has been approximated as follows:

Mild Zinc Deficiency Fruit loss upto 25%
Medium Zinc Deficiency Fruit loss of 40% to 50%
Severe Zinc Deficiency Total loss i.e. no fruits are obtained

Thus, zinc sulphate application in various fruit crops can be recommended for achieving substantial benefits.