Management of leaf folder in rice

Yield loss is from 30-80 per cent
Insect pests damage rice crop at different stages of crop growth.
Among other pests leaf feeding insect pests are of major importance because of their ability to defoliate or to remove the chlorophyll content of the leaves leading to considerable reduction in yield.
Rice leaf folder, Cnaphalocrosis medinalis was considered as pests of minor importance have increased in abundance in late 1980’s and have become major pests in many parts of India including Tamil Nadu.
The yield loss is from 30-80 per cent due to leaf folder epidemic situation.

Symptoms of damage
Longitudinal folding of leaves and scrapping of green tissues. Eventually leaves become white and dry.
During severe infestation the whole field exhibits scorched appearance. Identification of insect pest
Egg is flat, oval in shape and yellowish white in colour. Larva is pale green, transparent and actively moving caterpillar. Adult is orange brown moth with many dark wavy lines in the centre and dark band on the margins of wings.

Management strategie
— Release Trichogramma chilonis thrice at 1,00,000/ha (if moth activity is noticed) and spray Bacillus thuringiensis at 1.0 kg/ha when the leaf folder crosses tolerance level.
— Avoid use of excess nitrogen
— Set up light traps to attract moth
Spray any one of the following: Fenitrothion 50 EC 1000 ml/ha (or) Phosalone 35 EC 1500 ml/ha (or) Quinalphos 25 EC 1000 ml/ha (or) Dichlorvos 76 WSC 250 ml/ha (or) Chlorpyriphos 20 EC 1250 ml/ha Carbaryl 50 WP 1.0 kg/ha (or) Fenthion 100 EC 500 ml/ha Profenophos 50 EC 1000 ml/ha (or) Neem seed kernel extract 5 per cent 25 kg/ha.

L. Allwin V. Radhakrishnan & C. Harisudan Tamil Nadu Agricultural University, Coimbatore