Pest:Rice Thrips

Stenchaetothrips biformis Thripidae

This is a dark brown minute insect.Thrips are found in large numbers when the expected rains are not received.They are active creatures found in all stages inside the rolled up leaves.Eggs are laid in tender leaves and pale yellow active young ones that hatch out feed like adults by lacerating the parts and suck the exuding sap. In course of time they assume the adult winged condition.The total life cycle from egg to adult varies between 14-21 days.Nursery plants and young plants in the fields are affected.

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Symptoms

  • As a result of the thrips lacerating and sucking of plant sap rolling up and fading away of the leaf tips result.In the case of very young seedling the leaves wither.

Procedure for Observation

Randomly select 4 one meter plots per 0.4 Ha. From each plot select 5plants/ hills. Look for the infestation. Rate infestation as mild if there are less than 3 needle like leaves and as severe if there are more than 3 out growths with lower leaves also showing chlorosis and scorching.

ETL

  • One plant per sq.m showing chlorosis and scorching in nursery.
  • 3 needle like leaves per hill in main fieldl.

    • Control Measures

  • During certain unfavourable seasons thrips cause visible damage to nurseries and transplanted seedlings. A smart shower of rain is sufficient to remove thrips. In its absence the field may be flooded with water wherever possible
  • Make several sweeps with sticky traps to trap thrips . A wooden plank treated with thin film of greese will serve as sticky traps.
  • Spray Verticillium lecanii @ 20g/l or 5ml/l in case of liquid formulation. Insecticidal control can be obtained by applying Carbaryl 50 WP @ 250g +DDVP (Vapona 76 EC,Nuvan 76EC) 250 ml/Ha; Dimethoate (Roger 30 EC @ 600 ml/Ha;Quinalphos (Ekalux 25 EC 1000 ml/Ha).