The National Research Centre for Banana (NRCB) has said that banana stem weevil damage has been found in all banana-growing areas of Tamil Nadu, including Tiruchi, Thanjavur, Karur, Perambalur, and Pudukottai districts and suggested eco-friendly steps to control the pest.
All commercial cultivars are susceptible to the pest, the NRCB has said. Jelly exudation on the banana stem indicates weevil and grub activity inside the stem. This is the early symptom of the weevil attack. Depending on the crop stage, the jelly exudation varies. In the early stage, breaking of stem at apical region because of hallow pseudo-stem caused by grubs feeding is common symptom.
Instead of waiting for the early and late stage symptoms, the stem weevil activity in a field can be monitored by laying banana longitudinal split traps and if the weevils are attracted to the traps, control measures have to be taken up immediately, said B. Padmanaban, Principal Scientist (Entomology), NRCB, in a communication.
The female weevil selects about five months old banana plant and lays eggs inside the leaf sheath through the slits cut on leaf sheath. Before developing into pupae (resting stage), the grub makes a square hole on the outermost leaf sheath and makes a pupal case in the adjacent leaf sheath.
The adult weevil emerges through the hole made by the larva. The circular holes on the leaf sheath indicate the damage caused by grubs.
The banana stem weevil can be controlled by adopting integrated pest management, including application of insecticides and monitoring banana weevil activity in the plantations by placing banana stem traps. Longitudinal split traps, treated with pathogenic fungus Beauveria bassianasolution developed by NRCB, can be placed to attract the weevils, Mr. Padmanaban said.
Once the banana plant in infested with weevil, stem injection (of specified insecticide) is the only way to control the pest. However, the injection should not be given after the emergence of bunches.
For more details, contact The Director, National Research Centre for Banana, Thayanur (Post), Tiruchi-620 102 or Dr. Padmanaban by dialling 9442359253.
