Pest:Leaf roller

Cnaphalocrocis medinalis Pyraustidae

The adult moth has yellowish wings with grayish border and with one or two grey transverse lines on the wings.Eggs are laid singly or in groups.Egg period is 4 days. The larva passes six instars and become full grown.Pupation takes place in the leaf folds for a period of one week.Total life cycle takes about 5 weeks for completion.

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  • Pest 1
  • Pest 3
  • Pest 4
  • Pest 5
  • Pest 6
  • Pest 7
  • Pest 8
  • Pest 9
  • Pest 10

Symptoms

  • Plants of all stages are attacked by the pest.
  • The caterpillars cause damage by folding or rolling or webbing two or three leaves together and feeding from within.
  • When these leaves are opened up the larvae can be seen.
  • Infestation is more in shaded locations. Application of excess nitrogen favours the pest infestation.
  • Attack by the pest is usually in patches.
  • The larva scrapes the green matters of the leaves
  • The infested plants appear white on account of the removal of green matter.
  • A single larva is capable of damaging several leaves. The attacked leaves dry up. Very often all the leaves including boot leaves are attacked. In such cases photosynthesis capacity by the plants are reduced considerably.
  • The attack results in the reduction of yield to the tune of 10-20%.
  • Several parasites are recorded on the larvae. In the field a granulosis virus infects the larvae and as a result they burst releasing a milky white fluid.

    • Procedure for Observation

    Select 20 hills at random from 0.4 ha. Count the total number of freshly damaged leaves and total number of leaves per hill and work out the average.

    ETL

  • Two freshly damaged leaves per hill from planting to booting.

    • Control Measures

  • Egg parasitoid Trichogramma chilonis is effective against leaf roller. Six releases of the parasitoids at weekly intervals are required for a cropping season. For long duration crops the number of releases can be increased. Trichocards of T.chilonis have to be installed in the field starting from 20 days after transplanting or when the moths of the pest are observed in large numbers in the field. 5 cc Trichocards is sufficient for installation in one Ha.
  • Early clipping of infested leaves and their destruction will check the multiplication of the insects. However, wherever Bacterial leaf blight is a problem this practice should be avoided.Jayanthy and Lakshmi varieties of paddy are resistant to leaf folder.
  • Open up the leaf folds caused by the insect with the help of a thorny twig so as to make the insecticide/biopesticide application effective.
  • Apply any one of the following biopesticides/insecticides where the symptoms of attack are seen.Cows urine hot chilly mixture diluted in water (One L of cows urine + 10 L water + 30 g of well crushed hot chilli-filter and spray along the wind) Spray BT formulations (Biolep, Biobit, Delphin, Halt, Dipel etc) @ 0.7 ml/L of water. Acephate (Asataf 75 SP, Starthene 75 SP @ 1000g/Ha) Flubendiamide(Takumi 20 WG @125g, Fame 480 SC @50 ml/Ha) Cartap hydrochloride (Cartox 50SP @1 Kg/Ha) Quinalphos (Ekalux 25 EC,Quinalphos 25 EC @1000 ml/Ha) Carbaryl (Hexavin 50 WP ,Sevin 50WP,Carbaryl 50 WP @ 1.5 -2 kg/Ha) Phosalone (Zolone 35 EC,@ 1000ml/Ha)