Insect Pests and Management

Damage symptom of Banana Leaf and Fruit Beetle

Banana Leaf and Fruit beetle:

This is one of the major pests of banana in our country found almost all the varieties of banana.

Seasonal abundance: 

After winter February- April it starts infesting the plant. The peak period of infestation is July to august, mainly in the rainy season. Before winter the infestation rate of this pest is low. In severe winter the adults are not seen. Generally old gardens are more infested than new ones.

Nature of damage:

·         The adult feed the young unfurled leaves of the banana plant.

·         They mainly enter into the middle portion of leaf and there they feed the very young yellow leaf by scrapping.

·         After feeding, black spots are found on the matured leaf.

·         In severe infestation the leaf may lose its vigor and the growth of the banana plant retarded.

·         After fruit set, the beetles leave the leaf and started feeding on the smooth surface of young.

·        The young fruit becomes larger day by day and spot scrapping on the surface of fruit becomes prominent and turned blackish-brown.

·         Finally the matured fruit is spotted and lost its market value.

Control measures:

       I.            Cultural control:

·         Crop rotation must be followed to avoid this pest. Banana cultivation should be allowed up to three years in the same land.

·         More than two years ratoon crop should not be encouraged in the same land.

·         Clean cultivation, particularly the removal of grass, weeds from plantations where the population of this pest is high often reduce population levels enough to avoid the use of insecticides.

Bagging

    II.            Mechanical control:

·         Polythene bagging: after the initiation of mocha and before fruit set 42” long and 30” wide polythene which two terminal portions are open should be taken and tide with one open portion with rope and another portion should be tied near the base of the stalk of mocha. For aeration 20-30 perforation is required in the polythene.

Chemical control:

·         Diazinon 60 EC (2 ml/L) or Seven 85 WP (1.5g/L water) should be sprayed 5 days before flower initiation, first fruit setting and after all fruit setting.

Banana weevil

Banana weevil:

It is the major pest of banana. These species of weevil distributed throughout the country. The borers spread from plantation to plantation through planting material.

Favorable condition:

·         It flourishes well in moist places.

·         The weevil densities are higher in mulched areas.

Infested rhizome

Nature of damage:

· The larval damage starts at the outer sheath of the pseudo-stem.

·       The larva continues feeding into the inner sheaths, then bore into the plant’s base, roots and rhizomes.

·       The feeding tunnels are filled with dark color debris.

·       Young suckers have curled or rolled unopened leaves.

·    Heavily infested ones have dull yellowish green and withered leaves.

·      Older plants have yellow and floppy leaves with small fruits.

Control measures:

I.                   Management and cultural practices:

·         Only pests-free suckers should be planted.

·         The suckers should be immersed in hot water at 52-55⁰C for 15-27 minutes before planting.

·         To prevent their continuous breeding activities the plant residues should be removed after harvest away from the field.

·         Infested corms should be removed.

·         The cultivated area should be kept free from weeds.

II.                Trapping: Piece of old rhizomes or pseudo stems 1-2 feet long are cut down, split and placed on the plantation floor between plants. Adult beetles migrate into these stems and can be collected by hand and poisoned.

III.             Chemical controls:

·         Before planting, suckers and be trimmed, dipped in recommended solution. The insecticides should be directly sprayed or dusted on the surface of the pseudo stem and the soil around.

·         Fensulphaion has been found to control this @30 g/plant.