In Punjab, maize is grown as a crucial kharif fodder on about 1.0 lakh hectares area. The fodder maize is beneficial for dairy cattle owing to its high nutritional quality (crude protein and in-vitro dry matter digestibility), substantially more biomass, and high fibre content. Moreover, maize can be conserved as silage and stover which can be used for livestock during the lean season. The crop is usually sown from the first week of March to the middle of September. However, the farmers growing this fodder maize face regular challenges due to the damage inflicted by the fall armyworm (FAW).
FAW is a notorious and polyphagous pest invasive to India and was first spotted in Karnataka's maize fields in 2018. Since then, it has quickly spread to every state in the nation, including Punjab, endangering all the maize growers. Besides maize, the attack of FAW has also been observed in other crops like millets and sorghum, where it causes varied degrees of damage. In Punjab, the first case of FAW was sighted in August 2019 in late sown fodder maize of a farmer’s field. Since then, it has spread throughout the state and has become a constant source of annoyance for all the farmers growing maize both as seed crops as well as fodder crops.
The larvae of FAW damage the crop especially when the crop is 10–40 days old. Their damage is marked by the papery windows on the leaf surface created by the scraping action of the young larvae. The older larvae burrow into the growing central whorls by creating round to rectangular holes. Further, clipping of leaves and extensive defoliation results from their voracious feeding.
The attack is usually witnessed with a lot of fecal matter which is being excreted by the larvae near their feeding window. If not closely watched over and promptly managed, the damage, which begins in patches, spreads quickly throughout the entire field. It is thus important to keep a regular vigil on the crop to spot its initial window of attack. For this, its proper identification is a must. The larva is distinguished by its white, inverted Y-shaped mark on the head and four spots arranged in a square pattern at the tail end. The colors of the larvae range from light brown to light grey to greenish brown. On the upper or lower surface of the leaves, the female deposits her eggs in clusters of 100–150 eggs, which are covered with hairy scales. The key to its management includes its early detection, close observation, and adoption of prompt control methods as discussed under:
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Farmers are encouraged to go for the mixed cultivation of sorghum, cowpea, and bajra with maize rather than growing maize as the sole fodder crop.
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Avoid the conventional broadcasting of seeds and adopt the line method of sowing using the recommended seed rate of 30 kg per acre.
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Complete the sowing window in a uniform pattern and avoid the staggered sowing in the adjoining fields.
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Scout the fields thoroughly to locate the egg masses and destroy them. Trace for the initial patchy window that marks its initial attack and get the control treatments early and precisely.
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For crops up to 20 days old, spray the crop with Coragen 18.5 SC (chlorantraniliprole) at 0.4 ml per litre using 120 liters of water per acre. Only older crops (those that are 40 days or older) require an increase in water usage per acre of up to 200 liters, along with an increase in insecticide dosage.
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Proper spray technique using the correct selection of nozzle (cone nozzle) and directing the nozzle in the direction of the whorl is key to its efficient control.
Farmers are strictly cautioned not to collect the maize fodder for 21 days following the spray of insecticides.