Managing paddy leaf folder
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Sufficient quantities of potash have to be applied to control the pest
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THE LEAF folder (Cnaphalocrocis medinalis,) is an important pest of high yielding rice varieties.
High humidity and optimum temperature are conducive for rapid multiplication of the pest.
The moths are small, brownish orange in colour having wavy lines on the margin of the wing. The activity of the adult moth can be observed in the field during daytime.
Adult females lay about 300 eggs singly or in pairs on the young leaves. The greenish white caterpillars attack the crop at early stages.
Feeding material
They feed on the green matter of the leaf by remaining inside the rolled leaf after fastening the edges of the leaf together by silken thread.
This type of feeding behaviour leads to scorching and dying of the crops.
In severe infestations the whole area exhibits a scorched appearance and yield, especially in late sown crops, is drastically reduced.
— Avoid close planting and excessive application of nitrogenous fertilizers.
— Clipping the infested leaves reduces the spread of infestation as the caterpillars are found in folded leaves.
— Clean culture by removing alternate hosts such as weeds and apply sufficient quantities of potash fertilizers.
Biological method
Release of Trichogramma chilonis at 1.5 lakh and encouragement of Copidosomopsis nacoleidae are effective controllers of the pest as they are egg parasitoids.
Encourage Trichomma cnaphalocrosis (larval parasite), and Tetrastichus ayyari (pupal parasites) which suppress the pest spread.
Chemical control
Spraying monocrotophos 36 WSC at 1.5ml/lit or chlorpyriphos 20 EC at 2.0ml/lit is effective in the control of the pest.
J. MAHENDRA KUMAR
& MAHABALESHWAR HEGDE
Agricultural Research Station, Siruguppa
Bellary, Karnataka
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