Plantwise Factsheets for Farmers
Banana Stem Weevil
Recognize the problem
The banana stem weevil
attacks the plant during flowering and bunch formation stages and causes severe
yield loss by preventing bunch development. The early symptom which indicates
weevil and grub activity is the presence of jelly exudation on the banana
stem. Due to feeding by grubs, the pseudostem becomes hollow and can even
break at the apical region after a gush of wind. The grubs cause more damage
by making long tunnels in the pseudostem. This results in yellowing and
withering of leaves, exudation of sap from leaf sheaths, decaying of
peduncles and immature ripening of fruits.
incidence is at its peak during summer and monsoon seasons. The attack
usually starts about four months after planting, which coincides with the
initiation of the peduncle in the growing plants.
Follow clean cultivation practices
and in severe infestations, uproot and burn the plants
trapping- Cut old pseudostems into
lengths of 20 to 60 cm and split each of these lengthways. Then, place on the
ground near the corn bases with the cut surface downwards. Swab
the cut surface of these traps with biocontrol agents like Beauveria
bassiana (20 g rice chaffy grains formulation/ 3 ml in 100 ml of liquid
formulation) or 15 ml of entomopathogenic nematode, Heterorhabditis indica at 1 billion infective
juveniles (IJs) per ml. The volatiles from these stem traps attract weevils
that will be killed while walking on the trap surface within or after 24 hrs
chlorpyriphos 20 EC 2.5 ml/litre + 1 ml wetting agent or azadirachtin (5 ml/litre)
2 or 3 times at 3 week intervals.
infestation is noticed after 7 months of planting, stem injection with
systemic insecticide such as imidacloprid (0.2 ml in 500 ml water) is the
only way to control the pest. Do not inject insecticide after flowering.
- Matocking should be avoided i.e. the plant should not be left after bunch harvest for
recycling of nutrients in weevil endemic area.
When using a pesticide, always wear protective clothing and follow the instructions on the product label, such as dosage, timing of application, and pre-harvest interval.
The recommendations in this factsheet are relevant to:
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