In the recent past, thrips menace has drastically increased on groundnut crops grown all over Tamil Nadu.
Thrips are small insects and they appear on groundnut crop both in vegetative and flowering stage.
Female lays 60-70 single eggs into young tissues of the plant. The nymphal and pupal periods last 5 days each.
The adults are pale cream in colour. They are soft bodied and have highly fringed wings.
Unique feeding
The thrips desap the plant with their unique feeding apparatus and also transmit the deadly bud necrosis virus that impedes plant growth.
Nymphs and adults tear the surface of the leaflets and suck the oozing sap resulting in white patches appearing on the lower surface of the leaves and distortion of young leaflets.
The injury results in development of dull yellowish-green patches of the upper leaf surface and brown coloured (necrotic) areas on the lower surface.
Severe infestations cause bronzed appearance of leaf with curling and stunting of plants. High temperature with low rainfall favours multiplication and transmits groundnut bud necrosis virus.
Management methods
Uproot and destroy severely infected plants. Remove the alternative host plants.
Mulching would check the damage during the early stage of the plant.
Setting up of blue sticky traps at rate of 12 per hectare in the field will check the thrips population.
Apply safe chemical insecticides at recommended doses only if the population crosses 10 thrips per plant.
Application of ecofriendly pesticides viz., neem oil or pungam oil at 2ml/ha will be very effective.
Spraying of fipronil 5 per cent SC at 1.500-2.000ml/ha or thiacloprid 21.7 per cent SC 125ml/ha or thiamethoxam 25 per cent WG at 40g/ha or dimethoate 30 EC at 2 ml per litre of water at 25, 45 and 60 days after sowing will protect the crop from thrips menace.
(V.Radhakrishnan, Asst. Prof, Agricultural Entomology, N. Sathiah, Prof and HeadOilseeds research station, Tindivanam, TNAU,Tindivanam 604 002, mobile: 9952517010, email: drvradhakrishnan@yahoo.com)
