Chilli or red pepper is a well known commercial condiment crop grown all over India. Thrips infestation is a persistent problem for chillies. Severe infestation leads to 30-50 per cent yield loss.

The thrips also attack other crops like tea, acacia, prosopis, castor, cotton, mango, onion, groundnut, chekkurmanis, pomegranate, pulses, brinjal, grapevine, citrus species and numerous weeds.

Infestation

Tiny crawling nymphs and adults lacerate leaf tissues and consume the oozing sap. Leaves are curled, crumbled, twisted, deformed and ultimately shed down. Buds become brittle and also drop down.

Severely infested leaves and buds develop bronze colour in appearance. Flower production and pod set are adversely arrested. Thrips also transmit leaf curl disease.

Adult thrips prefer to infest tender leaves and growing parts of shoots. An average of 100 eggs are laid by an adult at rate of two to four per day and the eggs are actually inserted into the leaf tissues. They hatch in five days. Nymphal and pupal period together last for another couple of weeks. Total life cycle is completed in 15-22 days. As many as 25 overlapping generations are observed in a year. Thrips reproduce sexually and by parthenogenitic viviparity. Summer season favours rapid multiplication of the pest.

Control measures

Avoid growing chilli after sorghum as sorghum is vulnerable to the pest. Do not follow chilli and onion mixed crops as both are susceptible to the infestation.

Inter crop with sesbania grandiflora to provide shade which regulates thrips population

Sprinkling of water over the seedlings checks the population to a greater extent.

Treat chilli seeds with imidacloprid 70 WS at rate of 12g/kg of seed. Soil application of carbofuron 3 G at 33kg/ha or phorate 10 G at 10kg /ha is preferable.

Spray any one of the following insecticides once in three weeks: imidacloprid 17.8 SL 3.0 ml/10 lit, phosalone 35 EC 2 ml/lit, dimethoate 30 EC 1 ml/lit.

(Dr. J. Jayaraj, Professor and Dr. N. Muthukrishnan, Professor and Head, Department of Entomology, Agricultural College and Research Institute, Madurai 625 104, Phone 0452 – 2422956 Extn:214, email: agentomac@tnau.ac.in)