Banana is the second most important fruit crop of Mizoram after mandarin. Although, the climate of Mizoram is favorable for banana cultivation, moderate temperature (26 degree C) and high rainfall (2600mm) increases the incidence of pests which affects productivity. The most common insects in banana are pseudostem weevil, rhizome weevil, banana beetle and aphid. Bunchy top and Sigatoka are major diseases under Mizoram conditions.
Banana bunchy top disease is the most serious disease of banana. Once established, it is extremely difficult to eradicate or manage. The causal organism is banana bunchy top virus. Cavendish group is highly susceptible while Poovan is immune.
Leaves are emerged in bunches which show chlorotic edges. Severely infected banana plants remain stunted and usually do not bear fruit, but if fruit is produced, the banana hands and fingers are distorted and twisted. The suckers that develop from infected “mother” plant are usually severely stunted and leaves appear in bunches.
The banana aphid spreads banana bunchy top virus, which is present in the grooves of petioles. Aphids carry virus and while sucking sap, plants are infected with virus.
The most important factor in controlling banana bunchy top virus is to control the aphid vector (Dimethoate @0.02%) and rouging (removing and destroying) infected banana plants.
Sigatoka leaf spot
Yellow and black sigatoka are common fungal disease of banana. Cavendish group is highly susceptible.
The yellow spot on leaves starts from margin and proceeds to midrib on the older leaf. In severe case, leaves become completely yellow and ultimately dry up. In case of black siogatoka, black necrotic spots appear on the margin of leaves and in advance stage leaves completely dry up. The severity of disease increases in the rainy season
- The disease can be managed with the regular removal and burning of affected leaves.
- Spraying with Dithane M-45@ 0.1%
Banana pseudostem weevil
Banana stem weevil (Odioporus longicolis) is the most damaging insect and cause more than 30 per cent loss of yield. Cultivars such as Giant Cavendish and Dwarf Cavendish are more susceptible than Poovan.
The presence of holes and jelly exudation from pseudostem indicates the presence of larvae inside the stem. The white coloured larvae are responsible for riddling of pseudostem and causing serious damage. In the advance stage of infestation, the severely affected plant breaks or topples down along with the bunch. The weevil also infests suckers produced from infested mother plant.
- Regular removal of old, dried and infected leaves and dried sheaths of the pseudostem
- After crop harvest, the pseudostem should be removed and should be burnt
- Manual Collection and killing of adults.
Banana rhizome weevil
Banana rhizome weevil (Cosmoplitus sordidus) is also a damaging insect and directly affects the yield. Cultivars such as Giant Cavendish and Dwarf Cavendish are more susceptible than Poovan.
The weevil lays eggs into lower portion of pseudostem. The eggs develop into white larvae that riddle the rhizome by making tunnels. The larvae and weevil damage the central portion of pseudostem and reduce plant vigor and cause dead heart.
Control of this weevil is mainly preventative
- Selection of healthy and uninfected suckers.
- Treatment of rhizome with neem extract @ 0.4% for 1 hour
- Clean cultivation
Aphid (Pentalonia nigronervosa) is a serious problem on bananas, not for feeding habits but it acts as a vector of banana bunchy top disease the most damaging virus disease of this crop. Black coloured aphid colonies are found in the crown of the plants. Young suckers are usually the most heavily infested and shows bunchy top symptoms.
- Rouging and burning of diseased plants
- Spraying Dimethoate 0.0 2% (1.0ml/l)
Banana skipper/ leaf roller
Infestation is common during dry spell. Larvae cut a strip of leaf and roll it into a distinctive leaf roll. The larva, covered in a whitish powder, turns into a pupa or cocoon inside the roll. Rolled leaves originating from the midrib of plants are good indicators of banana skipper damage. Leaves that have been damaged by leaf rollers should not be removed, as they are needed for photosynthesis.
- Natural parasites kill the larva.
- Leaf rolls can simply be squeezed by hand to crush the larvae
Black coloured adult beetles are present in the groove of emerging leaves. They have the feeding habit by scrapping the fruits and young leaves and greatly reduce the quality and market value of bunch. Occurrence of this pest is usually the maximum during the rainy season
- Removal of weeds from basin.
- Removal of unwanted suckers.
- Application of alphamethin @ 0.01%
Source: ICAR Research Complex for NEH Region, Umiam – 793 103, Meghalaya